Strange Tonearm Tweak. Long

Alright PsychicA, here you go...

(I'm going to post a version of this report as a separate review as well, since that's essentially what it is, but I do not want to remove it completely from Twl's long-running thread, so here it is in its entirety to continue the conversation - I hope Audiogon doesn't object!)

I got my KAB fluid damper kit for the Technics SL-1200 installed yesterday, and I managed to audition one cut twice in close proximity both with and without the damper, by playing it just before I put the silicone in the trough, and again just afterwards. I also replayed a few other things with the damper activated which I had just played the day before without. So these are my very initial impressions, and since I'm writing this after only one day, I'll have to post any further findings another time if need be.

First of all, let me say that this damper is a very nicely turned-out product, and it doesn't detract in any way from the appearance or operation of my SL-1200, but at half the price I originally paid for my whole TT/'arm new back in the 80's, there's not a lot of perceived value at $150 when you crack open the small foam-lined plastic box and find a little curved machined metal tray (embedded with a set screw for attachment to the 'arm's base, etched with the KAB logo, and painted silver to match the 1200), a tiny plastic paddle with an integral collar and thumbscrew to tighten onto the 'arm (sourced from SME), a syringe of goopy fluid for filling the trough with (sans replaceable cap for storage, an ommission KAB should rectify), some fairly prefunctory instructions, and a hex key, although I don't doubt that KAB's return is fair on this quite specialized accessory. I was unprepared for just how viscous the 'viscous fluid' really was, never having used this type of damper before - that gunk be seriously thick.

In addition, I noted that the paddle which attaches to the tonearm presented less of a resistive 'face' to the fluid contained by the trough in the directions of motion (horizontal and vertical) than I was expecting might be the case (the KAB website has some good new pictures up of the damper in set-up and operation). Its broad side is a bit curved though, in the opposite direction of the curve about the pivot point made by the trough, and it is oriented at a slight angle to both the 'arm's arcing path of horizontal movement through the trough, and to the vertical component of a record warp, since it's not installed pointing straight down from the 'arm, but is offset about 10 degrees toward the direction of the platter.

Let me also just list briefly the audio chain I am listening to this gizmo through:

Benz-Micro Glider M2 .8mv MC cartridge > Technics SL-1200 TT and 'arm (modified with: Symposium shelf underneath sitting on Focalpods soft footers, Michell delrin record clamp, MusicDirect polymer tonearm wrap, and Sorbothane replacement mat) > Camelot Technologies Lancelot battery-powered op-amp phonostage with 54dB gain (modified with 392-ohm Vishay VHS loading resistors and resting on Audioquest Sorbothane pucks) > Cardas Cross 1m RCA IC > InnerSound FET preamp (with Synergistic Research Master A/C Coupler PC) > Harmonic Technology Magic One 1.5m RCA IC > VTL MB-185 Signature circa-200w all-tube monoblocks (with Shunyata PowerSnakes Sidewinder PCs) > Cardas Cross 8ft speaker cable > Thiel CS2.2 3-way floorstanding full-range speakers > and all electronics fed from Audio Power Industries PowerWedge Ultra 116 PLC (balanced AC to front-end components) and supported on a Salamander Synergy Twin 40 rack. Everything is set up a comfortable distance away from walls in a medium-sized living room, with the listening distance being about 10ft.

I listened to three disks from the 60s, acoustic jazz from the Jazz Crusaders LP Uh-Huh, rock from The Who LP Sell Out, and pop from Gary Lewis & The Playboys LP New Directions, and two from the 70s, acoustic jazz from the McCoy Tyner LP Extensions, and rock from the Richard Lloyd LP Alchemy. The Jazz Crusaders 9 1/2 minute cut entitled "Blue Monday" was the track critically auditioned back-to-back first without and then with the damper. Differences noted with the damper in use were pretty consistent across all the cuts I auditioned.

OK, now to the listening. As a preface, let me say that I wasn't expecting huge changes, and I didn't hear huge changes. After all, everything else is staying the same besides the addition of the damper and paddle, so why shouldn't it sound more similar than dissimilar to the sound I have come to expect? I haven't listened for long yet, but I think I do already have a pretty good handle on what this product is going to do for the sound.

I certainly did look foward to some degree of positive improvements for my investment. However, as is often the case in actual practice, the improvements I got turned out to be not the ones I necessarily had in mind when I ordered my unit. I suppose after years of making step-by-step upgrades to my system, I should be better prepared at this point as to just what to anticipate for the next tweak or change. Yet I still manage somehow to be surprised as often as not, a situation which is funny to me, because there are definite similarities underlying a lot of the fundamental improvements I have experienced in the past - such as the principle Less Is Sometimes More.

I decided to acquire this tweak based partly on a set of expectations I had intuited from my deductions about how such a thing must work in operation. I reasoned, if the damper prevents the 'arm from dissapting as unwanted motion energy which should instead be going into forcing the stylus to faithfully transcribe the groove, then I should hear 'more'. More impressive dynamic peaks, more bass slam and weight, more soundstage space, more transient impact, maybe even a little more overall volume. There were a couple of things I was hoping for less of - less surface noise, less HF grain, although I wasn't consciously aware of any objectionable presence of the latter. KAB's inscription on the damper's box promises "deeper bass" and "clearer midrange", as well as "improved tracking", and Kevin A. Barrett (KAB) also mentioned that customers sometimes find more of a sense of 'time slowing down' when listening with the damper fitted, though I don't personally tend to subscribe to such notions myself.

Well, if I had been expecting 'more', in many ways 'less' is what I got, and the things I did get more of were generally not what I had suspected beforehand. In retrospect, everything I heard does make sense given what the damper ought to be doing, but it definitely took my experiencing it to arrive at that conclusion. The very first things I noticed when listening with the damper activated were the cymbals on The Jazz Crusaders cut. They were exhibiting greater HF extension now, and were noticeably smoother. I wasn't expecting that, but I liked it.

I tried to listen for deeper bass, or more explosive transients, but couldn't find them. The soundstage didn't really seem any more expansive than before. The horns did sound a little less foward now, though. When the piano solo came on, I realized that an obsidian-like sort of dark glassiness that had somewhat shrouded the instrument before, had been replaced with a more open, pillowy-natural gentleness as the keys were being purposefully tickled from the outside left rear of the soundstage. When the stand-up bass solo followed, the centered image floated in space just as effectively as before, but had lost a certain talky, PA-like quality to the sound of fingers on strings which had previously rendered it as more of an electronic reproduction of a bass, and instead sounded more naked and true.

I slowly started to realize that although the soundstage wasn't any 'bigger'-seeming, it was effectively deeper, because I could now 'focus my ears', so to speak, more precisely all the way to the backmost reaches and still maintain the sense of clarity and definition. It began to dawn on me that, instead of enhancing the leading edges of transients, what was actually happening was a cleaning-up of their after-effects. Everything within the soundstage was less perturbed by everything else.

Rather than seem incrementally louder, the overall volume, if anything, was actually slightly subdued with the damper doing its thing. But added background texture was reduced even futher, resulting in an apparent universal improvement in S/N ratio. I'm not talking about surface noise as such here, which I didn't notice too much one way or another on these relatively clean disks, but a reduction in what must surely be the artifacts of spurious vibrations and their reflections. The whole presentation sounded tidier, tighter, and clearer, the ever-so-slightly reduced apparent amplitude probably a function of the effective subtraction of reradiated stored energy in the form of ringing. Less is more.

Dynamic events taking place in different areas of the soundstage had less of an effect on one another, permitting the instruments to go about their business without smearing or the imposition of added harshness as compared to before. The result, prehaps paradoxically, was to make gains for my analog reproduction resembling some of the more favorable attributes of CD, for aspects such as separation and contrast, while at the same time actually adding liquidity through the removal of intermodulation. Decays, not the onsets, of transients were the big winners with the damper in place, exhibiting a newfound cleanliness and precision that allowed me follow the flow the music with less guesswork. Image focus became more crystalline-pure and unwaveringly stable, less prone to fluctuate with attacks and crescendos. Although I'm not big on the concept of 'pace', I would actually say that, if anything, the music now seemed to move along at a slightly brisker clip, unencumbered by the dragging disturbance of throwing a larger wake in its trail.

In the big picture, I'd characterize the changes wought by the addition of the fluid damper as being on the order of about 10% or so (quite good), but in the particular areas upon which it has its greatest effects, I'd say they were more like 50%, which I think is excellent. No, I didn't get 'more' bass or dynamics, but I got less of what the presence of such information in the grooves can do to the more fragile parts of the sonic tapestry. In my estimation, what I'm hearing now with the damper is more faithful to the music mastered into the vinyl than what I was extracting previously, mostly through the reduction (if not the outright elimination) of some of the more pernicious effects engendered by the process of attempting to trace microscopic squiggles with a flexibly mounted needle attached to the end of a freely swinging arm.

I have not yet tried to ascertain the improvements wrought, if any, on the trackability of warped records, or the possible effects of the damper on reducing susceptability high-level acoustic feedback, for instance, but I will post updates when/if further developments make themselves known to me. For now I am exploring and enjoying the smoother and cleaner ride through the grooves the KAB damper is affording my cartridge and tonearm.

Well Basement, that sounds like the yoke, which would be the piece that holds the suspension donut.

About reproducing the warp, if the cartridge is held properly in place, and is doing what it is supposed to do, it will reproduce anything that excites the stylus. If that happens to be a warp, then that's what you'll get. If the cartridge is allowed to do anything else, then you will lose additional information than what you are trying to preclude from entering the system.

About the RIAA curve, the things Zaikesman said are accurate, although the bass info is still the largest bumps in the groove from what I have heard on the subject.

There is some disagreement on my "all notes start at DC" theory, but I think that is a subject for another thread.

Zaikesman, Good luck with the stuff you're doing with KAB. I hope you can get some good stuff going with them for your TT.

Oh, I almost forgot, the yoke, what part is that? TWL, the peice I was refering to was not the suspention component, that metal piece with the big hole in it, the one you have to look through to see the coils, often made of brass?

Zaikesman, I think we are all a little lost here in this, but that is what I think makes this worthwhile-A better, more sophisticated comprehention of what habbens in this area, which I think is aat the fundamentals of what makes a tonearm work well. Regarding the unmodulated groove, and the output happening in that region, is yes, caused or modulated by the warp, not something pressed into the record.
I think where TWL is on this, that I tend to agree with, is that the cartridge will, and should, be capable of reproducing this, evan as it is artificailly produced by the warp. My guess, which I'm not sure is correct, is that because it is produced does not nessesarily mean that is the resonent frequency produced by the arm/cartridge combo, but am I wrong?
Regarding the transient that you just spoke of, I don't understand this, but it may be what I am trying to understand. Could you please explain with more?

Basement, I believe you refering to the yoke.

I am getting a little lost as to where exactly this conversation is now heading, but I will make a couple of observations and hope that they will be relevant (at least to what has been written above, if not to anything important in actual practice).

1) Information in the circa 10Hz range is not intended to be transcribed in the grooves, having been mastered out beforehand. Content in this range is usually limited to warps which are vertical in nature, although a cutting lathe can inscribe rumble of its own, unrelated to the musical signal and horizontally cut.

2) The RIAA curve dictates that bass information is transcribed in the grooves at a much reduced amplitude when the record is cut, then boosted back to flat by the phono preamplifier. So these frequencies do not represent a high physical amplitude at the surface of the record.

3) As Basement implies, DC = an unmodulated groove, i.e., no signal at all. An amp will generally not pass DC, and a loudspeaker does not produce an output from a DC input. Which is to say that there is little pertinence in the notion of 'flat to DC', IMO.

4) Twl's statement about the attack of a tone rising to its fundamental before falling back to DC doesn't jibe with my own understanding. To the best of my knowledge, the attack of an ideal transient event, were it reproduced perfectly in theory, would rise in a straight vertical line over no elapsed time to a frequency = infinity, before falling back smoothly to the fundamental. In practice, transients rise very fast, over a very small span of time, to a very high frequency, before falling quickly but with some ringing back toward the fundamental.

OK, moving right along...

Kevin at KAB is sending me my damper assembly (you still here, Psychicanimal?), so I should have that in hand in a few days. He says that the paddle (which, BTW, is sourced from SME) is curved, and therefore has a damping component in both planes, although he says the vertical predominates - we'll see if that is my impression as well once I actually get it installed. Also, he says there are other paddle profiles available from SME. We had a long and interesting conversation, during which I suggested a product idea he is taking under consideration (completely unrelated to yours, Twl), and I will keep you informed if this goes further (it would likely be only of marginal interest, if at all, to folks on this forum in any case).

Awaiting Nrchy's beta-test results whenever he's a go...

Yes, Basement I am beginning to get your drift. The stylus/cantilever must move in order for a signal to be generated. Simply having the cantilever out of line, doesn't necessarily generate a signal. But if it is out of line, then when a signal is traced, the coils will be out of center and a channel balance problem will be heard. Also the maximum deflection ability of the cart will be impaired in the direction of the side that it is off-center towards. This is a bad condition, and should be avoided. It will also cause increased record wear on one side of the groove.

The warped record I played had mostly vertical movement, and so I'm sure it was the vertical play that caused the woofer movement. I didn't try to see if the cartridge riding the warps coincided exactly with the woofer movement, although I am sure that is what was causing it. The record sounded terriffic, even though the warps were pretty bad.

The "thing that the cantilever sticks through" is called the suspension ring or donut. It is a rubber ring that is set to flex at a particular rate for the cartridge design. Butyl rubber is considered on of the best, but many types of rubber are used.

Don't forget to email me your shipping address, or I can't send you these weights.

I'm glad you tried the warped record. I'm having trouble trying to explain what I mean as far as the amplitude of the movement and the amount. I'm trying to think of the proper terminolgy, bot I'm at a loss, as I have been, but I'll try to get closer. I have a feeling you might already be aware, you just can't understand the way I am attempting to explain it, so here it goes. I'll use extremes.
Say you had your anti-skate so off that it caused your cantilever to be way off to one side, (ignore all the obvious mistrackings for the sake of explaining). It would not cause movement of your bass drivers because the cantilever would be fixed. The cantilever has to be in motion, no matter how fast or slow, to cause a signal. (evan one you can see, such as movement of the woofer, but can't hear)
But if the cantilever were to move slow enough, no matter how far from center, there could be still no signal.
So while the movement of the woofer, in real use moves for something like the duration of the movement of the cantilever, it is actually the speed (technically the frequency) that is causing the woofer to move.
To get back to real life for a moment, In playing that frisby, you were able to actually observe the movement of the woofer and still get exceptional sound, yes? That indicates a good macth between cartridge complience and arm, as the warp/wow frequency was obviously present and did not affect the sound quality by causing an unwanted resonence that would interfere with the frequencies you were listening to.
You are right about this, I'm sure of- we will not ever be able to eliminate the warp/wow frequency. It will always be present and the cartridge will always be able to pick it up.
Were you able to observe movement in the catilever/suspention while this was happening? Also, are you sure that the woofers were moving to the sideways motion and not the vertical? In fact, if you follow what I am attempting to communicate, I wonder if you could observe movement of the woofer while not observing movement of the cantilever, and visa-versa.
Let me know if I am coming across, or the proper terminology whatever it is. I can't actually ever recall such a discussion ever taking place. I have more and more questions, but I don't want to confuse things to much just yet.
I found in an issue of stereophile, april 1996, (vol 19 no 4) in the review of the clavis d.c., MF gives a very thorough account of the inner workings or cartridges, this one particularly. He names many of the parts, except what that thing is called that is in front that the cantilever shoots through. It may not relate to our topic, but it may be interesting to you, evan if it may be redundant, so you could tell me more properly what the heck I'm talking about.

Was the CD a simultaneously-recorded version of the same session? ;^)

Yes, there is a difference in cantilver speed, depending on the frequency of the "bumps" in the groove that it is trying to trace. Larger amplitude bumps, in the lower frequencies, require faster velocity than the smaller "bumps" in the high frequencies, because there is more lateral deflection and return, for a given amount of rotation of the record. Also, the speed differs at the outside of the record, and the inside. The record is larger diameter at the outside, and therefore has different speed at those grooves, than the inside.
Also, I feel that the warp excitation of the mass/resonance is far less critical in the horizontal plane, because the warp movement is primarily in the vertical plane, and that is not being changed by this mod.

As an experiment last night, I played an extremely good recording by John Klemmer, recorded direct-to-disk on virgin vinyl. This beautiful record suffers from some of the most complex warping of any record in my collection. It has a dish warp, and several varying radius warps all around the perimeter(a real shame). However, I played this record on my TT(with the weight mod on the arm) and I found that the arm tracked the warps very well, and also the slight out-of-round that was there. The only noticeable thing was the woofer cones were bouncing, like would normally happen on a large warp anyway. Believe it or not, even with the intermod that this woofer bounce makes, the sound of this recording is unbelievably good, and the cartridge tracked even the most difficult dynamics like a train on a track. So as far as I can see, this does not hinder the vertical performance of the arm at all. And it shouldn't, because the design is only applied on the horizontal performance parameters. This arm with my mod, was able to track the most difficult warped record I have, and provide awesome audiophile sound quality and tracking while doing it. Just for fun, I turned on the CD player, and played one of my CD's, while I was making a cup of coffee, and it sounded like the system was broke! The sound of this TT, makes a very good CD player sound like something is wrong with it. A good record on this TT absolutely destroys a CD player, even with my best CD. Like I said, the Sony 9000ES CD player sounds like it has something wrong with it, in comparison to this TT setup. If anyone ever came over here, and listened to that comparison, they would laugh out loud.

Oh yes, I gotta try the weights. I would highly appreciate a set of yours, as then I can be sure I am trying exactly what you are using.
My statements regarding cantilever flex are exactly as you say. It is not actually the cantilever that is flexing, but the suspension. That can get confusing. I dont know or remember what that peice is called that the cantilever is attached to, that peice of wire, but anyway, I am observing the movement at the center more or less as you desribe.
The warp/wow that I am refering to is not nessessarily something that I would expect to tame, but the way I understand it, all combonations of arm mass and complience have or produce a resonent frequency, a frequency that is the natural frequency that will cause them to vibrate in sympathy. That is why usually the goal is to set that between the lowest frequency produced by the record, (or for clarification, the music or noise pressed into the record) and above the frequency of the warp/wow.
If the resonent frequency is in a place that is likely to get "exited" then that may have a tendancy to mask or alter the information we want.
I'm not sure if this is conventional, but I am trying to define that there is a difference in the speed of the cantilever movement and the amount of movement altogether.
I'll try to dig up some references so I can be more accurate in my descriptions and definitions, and also you can see what you think if I can find them and get some to you. I also seem to remember the SME use to have a damping trough available, so I'll have to see if any are available. The KAB site I checked out, and the damping trough seemed as though it would require quite a bit of modification for use on a rega, and zaikesman, if you are reading this, it will be very interesting to hear what this does for you.
I also think it would be interesting for us to try and measure these things. If anyone has any info on what is required, I would be extremely interested.

Basement, first, if you would like a set of these weights for your RB300, email me. They should make an improvment on the Clavis. That is not a "whippy" cartridge, and the cantilver/suspension should be quite stiff. These weights are easy to apply, and stay put, in just the right place. I really would like your feedback on this.

Next, I think I am beginning to understand what you are saying. One thing that needs clarification is your term "cantilever flexing". Is the cantilever actually flexing, or is it just moving in its rubber suspension? This is an important difference. The cantilever itself is a stiff tube, and should not flex. Flexing loses information, and imparts an unwanted resonance in the system. If the movement you refer to is small, and near the center, then it is actually suspension movement you are seeing. Flex, if it does occur, would only happen at the end of suspension travel.

If I understand you correctly, and correct me if I'm wrong, you are concerned with the very low frequencies that may be caused by warp/wow in the range below 10Hz. You feel that if the cartridge is actually tracking these frequencies, that it may be detrimental to the system, and the cantilever especially. This is because you feel that the large movements that occur at this range may bend or break the cantilever, and these frequencies should be prevented from entering the system anyway. Right? And your concern leads you to believe that the arm should move laterally at these frequencies to relieve the sidewards stress on the cantilever, and to preclude these frequencies from entering the signal chain. Right? Tell me if I understand this the way you mean it.

Now, going on the assumption that I understand correctly, you are actually referring to the matchup of the lateral effective mass/cartridge compliance. If it is minor warp or off center problems, yes the arm should move laterally on the bearing to account for these eccentricities. These problems are slow dynamics compared to the rapid lateral accellerations of the stylus during tracking of low frequency playback dynamics. An object has much more resistance to movement when a rapid accelleration is applied, than when a slow push is applied(Force=Mass x Acceleration). The slow movement of the record groove during warps and off center travel is easily handled by the arm bearing, and the arm moves laterally quite easily in this circumstance. If you are saying that the warp/off center record is causing a quick massive 1/4" or more movement that causes the weight of the arm to stay in place, and makes the cantilever move dramatically sideways because the record movement is too fast for the arm to keep up with it, then that record is a Frisbee, not a record.

My theory on this issue is this. The transducer should respond all the way down to DC. All frequencies begin at DC at the beginning of the attack, and quickly rise to the fundamental tone, and then decay back down to DC again. This is the structure of all notes. If we avoid the reproduction of the lowest octave, then we change the structure of the note, as we hear it. Even if the rest of the system cannot reproduce this, it has its effect on the sound. It is an attack, sustain, decay, timing issue. The resonant frequencies in the cartridge/tonearm cannot be avoided, but can be tuned out of the most offensive areas.

So, IMO to purposely allow the tonearm to move laterally at these frequencies, for the purpose of avoiding their reproduction, as a preventative of cantilever stress, is a counterproductive measure. It is my view that all frequencies from DC and up, should be included in the information chain of the source transducer, regardless if the other elements in the signal chain can reproduce them or not. If not, the natural structure of the tones, and the PRaT will suffer.

So, to sum up on this subject, I feel that the cantilever should be subjected to all these forces, but should remain in its properly centered relationship with the groove at all times, if possible. This may not be entirely possible, but it is a goal that we should try to attain with the improvements we are considering.

If the record is defective or warp damaged to the point of causing extraneous peaks in the frequency response at very low frequencies,or causing undue stress to the cantilever, that is a problem with the record, not the playback system. The playback system should track all the information on the record, if we are to even hope to get the best reproduction.

Regarding my unconventional thinking, it may be somewhat unconventional, but it is not original, or new. Others, such as Dynavector have addressed this directly, with an entire design(the 505-507 series) with this idea as the goal. And Graham, as well as other unipivot makers are using some form of this also. The Transcriptors Vestigal arm, addressed inertia and had 35 times more lateral inertia than vertical inertia. And the Vestigal was made in the 70's.

Hopefully, I have understood your idea, and have addressed some of the points you raised. If not, please re-explain, and I will try again.

TWL, I think we are having some misinterpritations here, but when we are speculating, as I am, that will often be the case.
I agree with you on all your reasons and speculations behind your mod. I also find them highly intelligent and insightful. I also understand that you are looking for superior tracking. I get the idea that you think that I was implying you weren't. I think that our separation in understanding is in the flexing of the cantilever and the speed that I am refering to. Or, if you will, the offset from perfectly center that is encountered in the circumstances of cantilever flexing.
The speed I am refering to is the warp/wow frequency and the lowest bass frequency. The amount of movement I am refering to are very, very slight. At the level of evan a fraction of a cantilever width. I am not trying to imply that because I can see it, that it exist, or that it doesn't exist if I can't, I use my eyes as an aid. The cartridge I am using is a clavis d.c., and as you know, the arms are an older model immedia and a rb-300. I do observe movement in both, but I don't consider it unusual movement or out of spec. Just to be clear on what I use my eyes for, if I see movement, I use that for a clue, or try to find clues by looking for movement, and then I attempt to identify what I am seeing by checking the set-up and listening.
When the complience and mass of an arm are considered matched, the resonent frequency is suppossed to be between the warp/wow frequency and the lowest bass frequency, I beleive that is 5-10 khz's. THAT is the movement I am refering to. This happens as the cantilever is moving to track the record, which is determined by the mass and complience of the set-up. How much it moves and how fast it moves are two different things, I leave it open for debate as to how much, as I don't know. I know that in most proper set-ups, there is movement, and that it is desired by traditional thinking to minimize it. (I'm still refering to the amount of movement, not the frequency).
While I suggest that your canilever is moving, I am not saying that it is mistracking-the contrary. I have to suggest that it is moving more than it was because by adding weight to a given application and changing nothing else there should be more movement in the cantilever, and that is based on having the arm remain more static than it was. I don't mean to imply that it is more static than it should be, or that there is more deflection than there should be, but I do contend that at the extreme of such an experiment that there will. I am forced to consider, however, that if you increased the amount of movement but changed the other parameters, such as the frequency, or other things that I am not aware, that superior results are/were gained from your experiment at the expence of greater movement at the cantilever. Please don't take that as me saying that you are ignoring movement there, Or that you are not looking to minimize it, or that you shouldn't, but if you don't consider what movement is taking place, or what could take place, then I don't think we can be able to asses the differences that are taking place.
The way I see this, is that adding mass of that amount in the horizontal plane is unconventional thinking, evan as the theory and evidence for it may be sound. I also believe that your assessment of the improvements in sound are true, as I would say from what I have learned from you I would have to guess you are quite competent in that area. All of the evidence that I keep learning as I explore this is leading to this not only being the case, but is causing me to have to stretch in my understanding of tonearms. So I might stretch your theories.

You know, it's been so long since I took a look at the KAB site, I guess I forgot which plane the damping operates in. Considering that the grooves are actually cut at a 45 degree angle, I would suppose that a little of both horizontal and vertical damping would be a good idea (which ties in well with my idealized theoretical above). I'll make a point of asking Kevin at KAB about this aspect.

As far as the threshold hypothesis goes, I can't agree with your analogy about lifting a weight. Weight is not the issue here, mass is. If the weight you couldn't lift was floating in space, and you attempted to push it away from you, you would move both move in opposite directions, according to your respective masses. In theory, when you or I jump up in the air, our push-off sends Earth moving infitesimally in the other direction; there is no real threshold - a practical one, yes, but no absolute one. Or to put another spin (sorry again) on it, if the arm was really so massive that the cantilever's suspension couldn't overcome its mass to move it when transcribing a groove modulation, then it also couldn't move it across the record as it played - the suspension would just keep deflecting until something gave way. If a force applied at the stylus can move the arm at all, then it can move the arm period.

KAB is a pretty cool site. That fluid damper rig looks like it will work fine, and it looks real "factory" like. Very clean and professional. It seems to me that they are primarily promoting a vertical damping, but it appears from the photo that the paddle can be rotated to provide a lateral damping effect. I expect that this will make an improvement in sound quality on your 1200. Let us know. I am sending a set of these weights to Nrchy tomorrow, so we can get some feedback on how they work on his Sota/RB900 system. He's got a Benz Glider with a 15cu compliance, so we'll see how this works with a medium compliance cartridge on a Rega arm.

Time to go watch "The Sopranos", so I'm being brief. Basement & Twl, my TT/arm was mentioned above (OK, way above), but it is a garden variety Technics SL-1200 with its stock arm. Also as mentioned before, the damper will be from KAB, and it is specifically designed for the Technics (the KAB website has some interesting stuff - check it out). FWIW, the arm is about 11-12g, I believe, which is supposed to mate fine with my B-M Glider M2. If you are familiar with this design, Twl (and who isn't?), you will know that there is no way a weight could be attached to the left side of the horizontal axle, because the sideways-U shaped bracket that fixes the upper vertical bearing is in the way. I'll have to get back to you on the other stuff after the show. :-)

Basement, I wish my eyes were as good as yours. Now that I'm over 45, I can't see up close anymore.

About the off-center records, I don't really see this as a problem, because the mass increase is easily moved during the long arc of an off-center record. The shortest arc that it could have to navigate would be 180 degrees, because the hole is only off-center in one direction from the center. That means that the record will start to move one way for 180 degrees, and start moving back for 180 degrees. On the outside of the LP, if there was 1/8" off-center, the stylus would have to adjust only 1/8" over 19 inches of groove travel(the circumference of a record is about 38 inches). This could hardly be called a rapid movement. The low bearing friction could easily handle this. And 1/8" off-center is a hell of a lot. I personally would not even play a record that bad. None of my records are even close to that far off. I do have some warps though.

Adressing your statement about the "speed of the cantilever", the cantilever is designed to operate at the speeds and distances it will encounter in the RIAA curve that is encoded into the groove. These parameters are known and designed-for by the cartridge makers. I see no way that a well-designed cartridge will be caused to mis-track by the proper orientation of the arm over the groove. If you are saying that the damping or horizontal mass increase will cause the arm not to properly track the off-center record, I have already covered that topic. It can track the off-center record. If the record is so far off-center that a damped arm cannot track it, then that record is junk. I cannot consider items like that in my design. A high-performance Ferrari suspension is not made for going "off road". We have to assume at least a decent level of record quality. I will accept the loss of some defective records, in the pursuit of improving the sound of 99.9% of my collection. The slightly off-center records are not affected by this design.

On the next issue, I agree with all 3 of your points regarding increased mass on tonearms. The problem with cantilever breakage on ET arms is generally attributed to the TT not being level. With the low friction air bearing and the lack of anti-skate on linear arms, leveling is crucial on these arms. The other cause of breakage was the "Groove guard" ridge, that caused a rapid accelleration of the stylus into the lead-in groove, as it slid down the side of the "Groove guard" ridge. This is why many recommended the starting of play after the first groove into the first song, with these arms. Fluid damping reduced these hazards. These are cases of "runaway, out of control mass" as we talked about in the previous posts. On pivot arms, this is less problematic since there is usually higher bearing friction in these, as well as an anti-skating mechanism. However the "Groove guard" can be a pain in the ass, at times.

Continuing to address your points. The use of fluid damping in addition to horizontal mass increase is not out of the question. It may be a good combination for reasons previously stated. I have not tried it yet. I have already addressed that I don't think that there is any possibility of damaging the cantilever with any of these systems. We want the cantilever to move as much as needed to retrieve the info off the record, and no more. If the cantilever is stiff enough to not bend under these stresses(no cantilever should bend), then these methods of keeping the cartridge centered should only help matters. It is the mass of the arm moving away from groove-center that may damage the cantilever. None of these systems allow the cartridge to move off groove center, even on off-center records, as previously stated. The entire purpose of these mods is to keep the cartridge groove-centered in all circumstances. I really don't follow your point of saying that these mods will cause/allow the opposite of their intended purpose. They do not impede the long slow movement of the arm during tracing of the groove spiral, or even off-center records. They only stablize the cart/arm during quick movements of the stylus, particularly during dynamic bass activity. If you are seeing your cantilever moving sideways because of an off-center record, then your cartridge is too high compliance for your arm. Or your records are really bad. What kind of cartridge are you using? This may be the reason why you had dead sound when you increased the mass. If you have a med-high compliance cart, your arm may already have enough mass to provide stabilization. If you can see your cantilever moving off groove-center, then something is drastically wrong.

Regarding your last sentence, I am not promoting the idea of preventing the arm from moving with the groove spiral. I want it to move with the groove spiral. I just want the arm/cart to remain centered over the groove while it is moving with the groove spiral. This is the aim and purpose of my mod. Remaining centered with the groove, and still being able to move enough to trace the spiral, is not a mutually exclusive combination. It can do both, and do it quite well. And it does not carry with it any greater danger of breaking the cantilever.

I wanted to offer you some of my weights to put on your RB300, but now I'm not sure if your cartridge can handle them with the records you are playing. Tell us what cartridge you have. If I think you can benefit from these, you are welcome to them. I am a little concerned right now that you might be over-weighted as it is now.

Thanks, Zaikesman. I agree that with the low bearing friction, there may be some movement allowed with the mass system. I cannot say that absolutely no lateral movement is present over the groove. But I can definitely say that it is much reduced, because of the results of greater dynamics, crisper detail, and bass I got with it. I may not even have the best ratio, because I did not try a bunch of different weights. But by luck, I got a pretty good result on my first try.

I have thought of making the weight on a threaded shaft, so it could be adjusted for distance from the pivot. This would complicate the prototype, but production would be just as easy. You may have caused a price increase :^). It would certainly be more applicable to a wider range of cartridges with a system like that. But the spread would have to be equal on both sides, or you'll be changing the anti-skate force.

What type of arm are you using, Zaikesman? If you have a way to fix these weights onto your arm, I could send you a set for evaluation on your TT. I know that they easily go onto a Rega arm. I would like to get some feedback on this. I am already sending a set to Nrchy, who has a Rega RB900. And if Basement wants some to try out on his RB300, he can have some too. They don't cost much, I just get them at the fishing store. If you think you could somehow get them onto whatever type of arm you've got, just email me your address, and I'll send a set to you.

By the way, I think that there is a sort of "mass threshold". As an example, if I am lifting weights, and I keep increasing the weight, at some point I won't be able to lift it. The static moment of inertia will be too high for me to overcome. That is the "threshold" that I am looking for with this system. If the mass is higher than the cartridge can overcome with its suspension, then the theoretical infinite mass can be approximated. As long as the arm can still move freely to track the groove spiral. Since the spiral tracking occurs over a long arc, the low friction of the bearing should allow this to occur, but on the quick dynamic spikes of the groove info, this mass should be sufficient to virtually eliminate arm deflection, if the mass is calculated correctly. Do you agree with this hypothesis?

The effect of the cantilever deflection in the reverse is a real thing. I've read about it and observed it. When you get your fluid damping devise (where are you getting it, by the way, so we may obtain our own), you may be able to observe it as well. I am blessed with near sightedness, and if I may pause to brag, I can count the seven strands or litz wire in cardas. To make it easier to observe, I get my mag-light and look head on at the cantilever, observing its revative movement with the cartridge. Then also I sometimes find a spot in the background and observe both the movement of the cartridge and the cantilever as it traverses the record. It is much easier to see with a record that is more off-center than usual, but it is rare that I find a record that I can't observe as being off-center. I have, and do, observe less movement of the cantilever when I damp the arm.
I'm going to jump around- first, yes the last sentence is speculation, I'll explain why later,
I am seeing two separete reasons/uses for damping fluid.
The one reason, is the centering of the cantilever in the coils. The other is the taming of unwanted frequencies.
On the first point on fluid, I am suggesting that the cartridge is a more accurate transducer with its cantilever centered in the coils.
On the second, There is both the issue of the speed at which the cantilever moves (which translates to unwanted bass information, the movement of the cantilever transmitting a bass frequency, which is the 'bell curve' stated above) and the control of the other frequencies higher in the audioband, the resonences.
Now I bounce again. You are correct in your statement of the tonearm being of mass according to the complience, as one reason tonearms are heavier than they used to be, and mass having other purposes. The current thinking in design is to keep the moment of inertia as low as possible in all planes, and at the same time, add as much mass as possible while keeping the moment of inertia low. Tonearm makers are also adding mass at their bases (no doubt allowable by better tables). This can be likened to the effects of a heavy platter being a better sink for resonences, as opposed to just better speed control. Or a heavy suspensionless table as opposed to one that seeks only to isolate.
The other trend, although not new, is the use of new lightweight materiels. The reason for this is not simply to make the arm lighter, but to make the arm stiffer by using more of these stiffer materiels. The stiffer the arm is, the more energy is channeled to these massive energy aborbing bases, and the more solid the headshell is at the cartridge as a result of all this.
Now I bounce back to the meat of our discussion. If we explore the use of damping for the second reasons I stated above, and we explore what is happening at the cantilever as far as movement (I like the bell curve analogy) we may be able to get better results by substituting mass for the reasons we use fluid in that area. The evidence I use to support this is that 1) arms have been getting a lot heavier, and that they seem to be attempting to put it where the moment of inertia would be lowest, 2) The graham arm has its weights slung out at an angle for stability and proper tracking of the cartridge offset angle, and may be enjoying the effects of greater horizontal mass as a side effect, 3) the reputation of linear trackers to have good soundstaging qualities, as they have a disproportionate horizontal mass to their vertical mass, perhaps an overlooked side effect in their quest for accurate transcription.
All of these arms use fluid, however, and in the case on the linear trackers, before it was made available on the E.T., the heavier armtube had a reputation for snapping cantilevers, for the first reason I stated above for the use of fluid. The wheaton also uses fluid, (a real heavywieght), slung out in what seems effective for tracking more than transferring resonences, and of coarse the immedia and graham both depend on it for proper operation.
Further evidence I suggest, and this is perhaps the most compelling, is that the rb-type arms are the lightest in this class, and that they have all benifitted from adding more weight from aftermarket counterweights, And in the deliberate attempt to add weight only in the horizontal plane, seems to have shown results disproportionate to simply adding more weight, and was added in what was stated in the beginning of the thread as perhaps an oversight to why the graham works so well. (the rega does not need counterwights for lateral stability the way the graham does).
I would correlate that fluid on a rega is a rarity and that it is also a lightweight.
So my thoughts now are, do we need to emply fluid on the rega to explore this to a higher limit, and also, if we choose to use more mass, if we would be better off not using fluid for certain applications. There may be trade offs as to how much we allow the cantilever to move in relation to the cartridge, wheather or not the cartridge/arm would work better being in a static position over the record, and reap the benifits of stability, at the expence of letting the cantilever out of center,(or evan if we could get dangerously close to causing damage).
What is particularly fascinating to me is that I have never heard of adding weight for the purpose of modifying the behavior at the cartridge end, but certain evidence shown here seems to support it. That is why, although I believe that to allow the arm to freely with the groove, as opposed to remaining static, is better, I am willing to question it.

Very well broken down, Twl. I agree about the fundamental aims you suggest. Your analysis of the probable dynamic response limitation of a fluid damper reinforces the reasoning behind Mr. Townsend's implementation I was expounding on above.

But I must point out a flaw, or at least a simplification, in your characterization of mass-damping as a "static" system. Assuming negligable bearing friction (and this might not always necessarily be the case, but for now I will assume that a premium bearing's friction will fall below the level where it would play a larger role in dynamics), the horizontal mass of the tonearm does not entirely resist the arm's deflection by the cantilever, as you state, but conforms to the basic principle 'for every action, there is an equal and opposite reaction'. In other words, the motion of the stylus will produce deflection in the cartridge/tonearm which is inversely proportional increasing mass of the cart/arm (and also to increasing cart compliance), but this delfection will not = zero, just as in the fluid-damped example. (Had it = zero, you then would have been implying that there existed some 'mass threshold' for deflection, which your unmodified arm hadn't yet crossed, but that had been crossed once you added the extra mass. Of course, and again assuming bearing friction isn't mucking the system up at this point, this isn't the case; there is no 'mass threshold' - it is a continuum, and you have simply moved down the scale in the direction of less deflection.)

What the levels of allowed deflection would actually be in each example of these respective damping systems is unknown to me, and I would guess is likely to remain so. Obviously, in each case there are many variables to be played with that would affect the answer. To achieve an optimum balance of dynamical attributes for any given cart/arm combination, the fluid system allows for relatively easy adjustment via modification of the fluid level, so the mass-damped system should probably feature a method whereby the user can either change the amount of applied mass, or more likely adjust its distance from the pivot point, like a common counterweight adjuster, either by sliding or helical means. (Twl, did I just suggest a major price increase? :-)

Ok, we have a couple of suppositions here, and I will try to address them as I see them.

First, it seems we all agree that the headshell/arm should position the cartridge directly centered over the groove, and should maintain that position as it plays the entire record.

Next, we all seem to agree that it is possible for the cartridge compliance to move the arm out of the ideal position, especially if the arm has insufficient lateral mass, or no fluid damping.

Now, our contentions are that with either increased lateral mass, or fluid damping, this problem can be mitigated/eliminated. But, both solutions introduce their own potential problems which need to be dealt with.

It initially seems as though the fluid damping creates less inhererent possiblity of problems, because it does not have a mass that could be set into motion, and thus go out of control. However, the problems introduced with the fluid damping system, as I see them, are these: The paddle must be set into some level of accellerated motion before it can begin to work, therefore it will allow some arm motion to occur before the unwanted movement becomes damped. If the arm does move before damping occurs, then it has to move back, and could be slowed by the damping during its return to the center. This creates a bell-shaped amplitude curve regarding its movement away from center and back to center. Granted, this will be a small amplitude, but it will be there none-the-less, due to the requirement for the arm to laterally accellerate to a certain speed before damping occurs. So therefore I conclude that fluid damping has static/low amplitude limitations, and works best in higher amplitude/ high acceleration conditions. And, in all cases, allows some unwanted movement to occur before coming into play, as it is a dynamic system.

Increased lateral mass has what appears to be more difficult inherent problems associated with its use in this application. This increased lateral mass can be accellerated out of control, if the mass is insufficient to perform its intended task. Momentum would take over and create mayhem. Return to center under these conditions would be out of the question, as the arm would be flying across the record surface. However, there is something here that works in favor of increased lateral mass. It is a static system that raises the "moment of inertia" to a point where the cartridge compliance cannot overcome the static moment of inertia. In this case, the cartridge is stabilized over the groove center, with no movement needed, or allowed, to work. So the stabilization, if sufficient, can be complete, with no lateral accelleration(movement)of the arm needed to bring the stabilizer into play.

So, what we have here, as I see it, are a dynamic control system, and a static control system. The dynamic system requires some movement of the arm to work, but then comes into play very aggressively to limit movement. The static system doesn't require any movement to work, and in fact cannot allow it, or it will spin out of control from momentum. Or at best, create a nasty "swinging door" effect, which we definitely don't want.

Now, my assessment of these systems, is that we really don't want to allow any deviation of the arm from the center of the groove, so that the stylus will do all the moving, not the arm. So, from an absolute performance point-of-view, the static system of increased lateral mass allows no deviation, assuming sufficient mass. But, if the mass is insufficient, or if some unforseen large accelleration enters the system that can overcome the static moment of inertia, it can have a major disruptive effect. The dynamic system, while allowing a small degree of deviation from the ideal, will control any large accelerations very well, and will never get out of control(except at the very low accelerations, which it does not control at all, due to the "damping threshold").

So, where do we want to go with this? Do we allow some movement, and then quickly stop it, or do we allow no motion, and possibly get out of control if a large force enters the system? Or is there another idea, or combination of ideas that would better resolve the problem without causing additional ones?

There are some other issues that enter into this discussion also, and they are, how are the other aspects of arm function affected by these mods? There is no question that the added mass system can cause a change in vibrational modes that may or may not be benign. The fluid damping does not have this characteristic. It has no potential problems in this area, and even may tend to damp some larger vibrational modes. It is less "cartridge dependant" for its correct operation. On the other hand, if the cartridge is selected with all the correct capabilities(low compliance), then the increased mass of the static system, may enhance the vibrational and resonant modes to not need any damping, or need less damping. And if lead is used, especially in the proper locations, damping may occur by the lead material itself. I believe that this is happening on my tonearm, with this mod. Another benefit that I believe I am getting from this is the reduction of bearing chatter, due to the increase of the static "chatter threshold" by placing the lead weights directly on the bearing axle. This greatly increases the mass of the axle, and is much less likely to chatter in the bearing, because it is too heavy for the vibrations to excite/move it in the bearing races. This does not come into play with a unipivot, obviously, since the unipivot has tons of PSI on the pivot tip already. But interestingly, the added mass(PSI) on the tip, is what causes the unipivot to be chatterless.

I could ramble on about this, but please give your comments on what I've said so far.

I will respond to some of your points if I can, Basement. First off, I myself have no direct experience with using fluid damping (yet - I expect to before very long), so all of my information comes from what I have gathered on the subject from various sources, and a lot of my assumptions in the above posts also stem from nothing more formal than just my own common good sense and scientific/mechanical aptitude/intuition (which, believe me, is merely a little better than average, and not the result of extensive education or training). In short, I am no expert.

Your supposition about out-of-phase movement of the cantilever relative to the cartridge body/tonearm, and its causing of positive amplitude errors, is interesting. But do you know for a fact that it is true? I would liken this view of the situation to pumping a swingset for increased altitude, or the cracking of a whip. The other view would be that of trying to push a tackling dummy on a muddy field and having your feet travel the other direction instead - it would result in less motion of the dummy. We could call the first example the "whip-crack" model of relative motion as it affects signal amplitude, and the second example the "traction" model.

The traction model seems fairly straightforward - any unintended deflection of the arm causes a signal undershoot. The whip-crack model would be a good deal more complex. When attempting to push the tackling dummy in the mud, your result will be similar no matter when you engage in pushing. But when cracking a whip or pumping a swing, timing is everything. Get the frequency wrong, and you'll get negative acceleration, not positive. So presumably, the whip-crack model would often show a similar result to the traction model, and only sometimes result in signal overshoot, depending on the conditions of groove frequency, velocity, and amplitude. I do not know which, if either (or even both, under differing dynamic circumstances), of these possibilities is valid.

As far as the Townsend damper design goes (something this thread has enlightened me to), I would surmise the reason he moved the damper out the arm's radius close to the cartridge is because that is where the arm's motion will be greatest in amplitude and velocity, relative to the same damper installed closer to the pivot point as is common. This is very ingenious, as it both increases the effectiveness of the fluid's damping properties, and simultaneously eliminates the cartridge's leverage advantage vs. the normal arrangement, while also ridding the cartridge/damper interface of several inches of potentially resonant and flexible intervening armtube length. It does sound ungainly as hell though (and scary to boot - who wants all that viscous fluid above the record surface?)

I'm not sure I understand the reasoning for the conclusion you draw in your last sentence, since you don't seem to have provided an explanation of why you feel this to be the case (mass being superior to fluid). I would comment regarding your observation about the increase in average arm mass, that this has to be taken in the context of average cartridge compliance - these two parameters evolve hand-in-hand as they must, but it is the compliance issue that leads the dance. My own feeling, as it has developed over the course of this thread, and for reasons I explained in my previous posts, is that a theoretically ideal system would probably be infinitely low in mass in both planes, and hence inertia-less in all directions, and entirely resistively damped, whether by fluid or some equivalent. Of course such is not possible, but it does tend to point away from increased-mass solutions - not that they won't be effective in some ways as well, and maybe even just as good for practical purposes, though I am somewhat skeptical of this right now.

Keep in mind I am still trying to grasp a lot of this myself. I'm still wondering about the benifits/consequences of the differences/simularities. Zaikeman makes some really good points in that last post. Keep in mind here that the most commonly used fluid for damping, silicone, is newtonian, that is, it resist faster movements disproportionally to slower movements. Ideally, slow movements get no resistance, fast movements get great resistance.
Ideally, we tune this to follow that slow moving warp or eccentricy with no resistance, but resist movement faster than that.
Now picture a high complience cartridge on a heavy arm. The arm stays put, the cantilever follows the record.
Now picture a low complience cart on a really lightweight arm. The arm can follow it anywhere, but it is not a good enough 'base', if you will, to allow the cart to do its job. potentailly, the cartridge just throws it around, and it can't transmit the information.
Now, if the arm has some resistance, and the cantilever flexes, but the cantilever also is stiff enough to pull the arm, the arm goes in motion after the initial deflection to follow the cantilever. As the arm chases the cantilever, and the cantilever then is pushed the opposite way, the arm and the cantilever are both moving in opposite directions, and we get movment in the cantilever that is greater than the initial deflection. In this way, we get cantilever deflection that is greater than if the arm was not allowed to move at all.
In the above post, the statement that fluid resist movement constantly as opposed to mass resisting movement initially is a good explaination of how we use fluid to tame these unwanted cantilever deflections. But that is just one reason for fluid.
Fluid is also used to tame the arm of movement that does not allow the arm to transmit information, movement or vibrations that would allow information to be lost at the cantilever, (that is why townsend put the trough at the headshell, but I believe that it might have been a failure).
In my experiment with the immedia and the pennies, it is highly faulted, for those reasons you mentioned and others. the weights were literally just flopping front to back, and this would most problably cause some bad stuff. The purpose was to try to demonstrate to myself the possibility of substituting mass for damping fluid, as well as add mass to the horizontal plane. If in fact I did hear what I thought I was hearing, that is a wider feild and better separation between instrument, despite the degragations, that is something. I might not be able to go too far with the immedia though as it is already a heavy arm. The added mass may be too much. Also, what I was hearing might be side effects of the degragation.
Zaikesman, please ring in with some of the arms you used with fluid damping, I can see some good info here that may help us, as you seem to have a pretty good handle on this damping of fluid.
I'm going to follow up on some of that stuff and see if I can see what's happening. For now, I contend the following possibilities; Mass is highly desireable, and better than fluid for the taming of unwanted frequencies, (notice that arms have gotten a lot heavier), and that mass might be better placed than the current understanding of it's use, or that it may have more use than one. (or my understanding needs to catch up).

Basement please clarify your points, we need to know more accurately what you mean, so we can discuss intelligently with you.

About your question about the fluid damping with the Rega arms. I don't know if anyone is doing that. The Townshend Rock TT's use an unusual fluid trough that swings across the record, and damps the arm at the headshell end, all the way across the record. When you put on a LP, you have to then swing this long curved trough across the LP, and when you put the tonearm onto the record, the paddle in the headshell dips into the silicone in the long trough. Totally unique. No-one else does it this way, that I've heard of.

While you are on the web, go to the Dynavector site, and look at their description of the 505 and 507 tonearms. They have a very good technical presentation on lateral mass increases. Also, go to some unipivot sites, and read what they say about the silicone damping. Maybe we can combine these two, and get something rolling.

I think you had your weights on shafts that were too flexible. The paper clips are too thin to stabilize the weight that is hanging almost 2" out there. They allow the weight to vibrate, and cancel out some information. I did not experience anything like that in my modifications.

Zaikesman, I used poor terminology in my last post regarding the term "run-out". In machine shop lingo, the "run-out" is the amount of eccentricity in a rotating piece, like a rod on a lathe. If there is "run-out on a LP record, that means it is rotating eccentrically(ie, off-center hole). I'll avoid that term since it confuses things with the run-out or lead out groove on the LP.

Ok, now my point was that with both fluid and mass methods, the rotational variations caused by the off center hole, happens relatively slowly over a long arc of the record. Both the fluid and mass methods can trace this movement easily, with no disastrous results. There should be no erratic movement of the stylus in the groove as a result of this. The arm still has relatively free movement in tracing slow arcs with both fluid and mass damping.

Now to move on, I think this discussion is very productive, and with a little care to make sure we are all on the same page, I'll comment on your input, and Basement's.

What you say about the mass staying in motion once it starts is very true. The amount of mass needs to be looked at real hard to make sure we don't get a swinging gate effect. That is important. On the other hand, once the fluid gives way to some movement, the paddle is also resisted from returning to center by the fluid. So this needs to be taken into account also. We have not come upon the perfect solution yet. But, we are making some headway.

I am still of the opinion that using both methods is somewhat redundant. But there may be some middle ground. Perhaps a mass increase, along with a tuned fluid damping could provide high inertial resistance, with the mass being controlled from overshoot by the fluid damping? IMO the mass provides a static increase in the resistance to movement, while the fluid requires at least some small dynamic movement and velocity, to come into play. So with both, there may be better control. Maybe we need to look into this possibility.

Regarding the sophisticated servo-operated control systems you mention, it has been my experience that mechanisms generally muck-up the works. I like to go by the simple route, if possible.

Now, Basement has done some experiments with his Immedia, and had some negative sonic results in some areas. From his description, my feelings are that the weight hung on the paperclips created a vibrating mass on the ends of the thin paperclips, and caused sonic impairments. My belief is that the shafts needed to be very rigid to preclude this problem. My weights are 3/8" solid lead shafts, and they are firmly pressed onto the bearing nuts and glued, so the mechanical connection is secure. There is no thin shaft with a heavy weight on the end. This may have led to Basement's problems. I don't know.

Basement - Have to say that I too, either do not understand most of your post, or may even disagree with some of it, but my uncertainty about what you have said puts me on hold from commenting specifically. But I am picking up (sorry!) that you are wondering about possibly combining Twl's hoizontal mass increase with fluid damping.

Twl maintains the two perform basically the same function, so this would be unecessary. But this makes me rethink that proposition a little more, and whereas yesterday I was inclined to think the same thing, I now have another thought occurring:

As it regards initial resistance to horizontal arm deflection at the onset of a transient, I would say yes, mass-damping and fluid-damping are probably accomplishing about the same thing. But - as is actually contained within the implication of my last post - there might be a difference extending beyond that initial event, as it concerns inertia. Fluid-damping is essentially free from interial effects. In other words, both mass-damping and fluid-damping will resist being set in motion, but once they are, the mass will tend to want to remain in motion, whereas the fluid will always tend to resist further motion. This suggests that the ideal horizontal mass for accurate transcription of the groove modulation by the stylus/cantilever would be infinitely large, but that the ideal mass for accurate tracing of the groove path (which affects coil-centering) by the cartridge/tonearm would be infinitely small.

I know - no duh! The same is actually true in the vertical plane as well (although here gravity comes into play [and is exploited] as well), and this just brings us back to restating one of the central dilemmas of designing a record playing machine in the first place.

But it does have me fantasizing about things like: A truly ultra-low mass cartridge-carrying system which depends on fluid damping in *both* planes and uses a spring arrangement or equivalent for VTF; Or, how about attempting to capitalize on cutting-edge technology to create an ultra-fast, tonearm-less sensor/processor/actuator system which 'reads' the position of the groove path and record surface height via a laser sensor just in front of the cartridge, and then uses a microprocessor controlling an utra-quick precision actautor mechanism of some sort to positively locate the cartridge body in the optimum position and attitude to enable the stylus to extact the maximum information from the groove modulation through continuous real-time adjustment, possibly incorporating processor monitoring of the cart's signal itself to constantly calculate correct coil-postioning via the electrical L-R separation and phase info? Whew, boy!

(BTW, Twl, I also didn't understand some of your comments responding to my last post, about the run-off groove and degrees and such, or their relevance to my post. Maybe my post itself wasn't clear. Then again, I am eminently unqualified to know what the hell it is I'm really talking about in relation to all this stuff, so rather than worry about incomprehensability due to runaway pedantic excess, I should probably worry about acute embarrassment due to runaway ignorance flaunting! :-)

P.S. Edit: Basement, I wrote this prior to your latest post.

It took me a long time to understand as well. Now I'm grappelling with mass and it's relationship with damping. If you are like me, you think about this stuff all the time, and things come to you, (obviously, look at whats come back at us).
This part I think you might be missing- you mention that all (most) your records are not off center. While there are quite a few that are obviously off center, what we are talking about here within the cantilever/coils is microscopic. All records are off center, evan if just a fraction of a groove width, they aren't manufactured to the kind of tolerences we are striving for. If you dismiss this, then you shoot for the arm staying put at the cartridge. Really, what we want (in theory) is the arm to stay put directly over the cantilever. The key to this, with fluid damping, as stated by Z above, is the viscosity. Control the resistance selectively at selective speeds (traditionally, the speed being the frequency of the warp/wow). To see it, you definitely need to get in and look at the cantilever at the cartridge to see how much it is moving in relation to the cartridge. to measure it, you definetly need test records and the like. ( I don't have these resources, maybe you do).
There is more to controlling frequencies then just keeping the coils centered, though. There are, I believe and suspect, differences and simularities between fluid damping and mass. We are not done with this yet.
Last night, I put my immedia back on to test some of this. I drained some fluid out until the arm could tilt easily to one side but come back without overshoot. Then I weighed some pennies, came up with 5 pennies on each side to be about 12 grams with electrical tape, and slung them out with a paper clip. They are about 1.75" out on each side, just below the record height, slung out at the same angle as the cartridge, and just taped on the top with a piece of electrical tape, over the center of the bearing, and they swivel front to back because of the tape. archaic, but they increase the horizontal mass considerably with minimum effect on any other parameter.
What I thought I heard was a wider soundfeild with more separation between intruments. But the induvidual instruments seemed more truncated, less air and detail around them. The high end seemed more recessed with a loss in detail. I didn't adjust damping at all between the two. I did notice more movement of the cantilever, at least I thought I did. Sounded similar to adding to much damping, and of coarse this experiment is extreme, I didn't play with it any further.
One resource I don't have lately is too much time. I am currantly getting more enjoyment in the tweak factor by hearing your results.
The immedia has damping, and it is easy to control and adjust/change, but it is also much heavier than the rega, I plan on starting another thread if you don't to see if anyone has tried fluid damping with the rega, and if any is readily available.
This is a new tonearm you are designing, isn't it? You are changing the parameters of the design. Seems to me you are somewhere roughly as far from the rb-series as the ol 750 is.

Basement, I don't understand most of the first half of your post. The second half I find alot of agreement with.

IMO, the fluid damping is aiming at the same goal as the horizontal mass increase. If a tonearm is equipped with one, it doesn't need the other. It is 2 ways of attacking the same problem of unwanted lateral movement of the arm, being pushed by the cartridge compliance.

If this goal is accomplished by either of these methods, the cartridge coils will remain centered over the groove, where they should be. This centering effect will allow the stylus/cantilever/coil assembly to retain its "center reference" and achieve maximum dynamics and information retrieval, which is lost when the arm is moved from side-to-side by the stylus tracing action.

The arm damping of ringing frequencies is an entirely different matter altogether, but an important one. No one feature of an arm is going to solve all problems. There must be a combinations of correct aspects to the design to get the best results. And these may vary with the type of cartridge to be used.

I may have to design an entirely new tonearm to fully exploit all of these things, but I lack the resources to do that. So in the meantime, I am simply tweaking, and enjoying it.

We have two ideals here, maybe three. As far as tracking goes, the arm should have low enough a moment of inertia to follow the cantilever wherever it wants to go. The stiffer the suspension, the more the arm will follow. If the arm is sufficiantly heavy, or the suspention has enough give, then the arm will stay put as the cantilever follows the groove. This is not ideal. But the arm should be of sufficiant resistance to provide the cartridge a good base for transmitting this information. The frequency of the movement of the cantilever should be faster than the movement of the groove but slower than the frequencies in the groove. This is naturally where the relationship between mass and complience comes in, the stiffer the cartridge, the more mass is desireable, but the mass should not be too high as to allow/cause the cantilever to deflect.
Throw fluid damping in and then we have a relationship between complience/mass/and resistance of the fluid, and changing one changes the other. Fluid is desired where the arm is to light to be ideal. Fluid is nessesary where the arm is heavy enough to cause the arm to 'wag' at a frequency enough to cause to much more stress at the cantilever caused by the wagging itself, if it is more than the suspension can handle. I understand linear trackers had a tendancy for this. (linear trackers have a reputation for bigger soundstages, and I am starting to see this as my eyes are being opened).
The one ideal I am speaking of is the centering of the coils. The ability of the arm to track the groove without overshoot caused by the mass of the arm. Fluid damping has traditionally been effective in this ideal. The other ideal is the mass of the arm being ideal for the control and or transmission of frequencies in the audioband, maybe more. I think that there is definitely something to this adding of mass in the horizontal plane that perhaps the makers of the best tonearms are missing right now. All of the evidence and information I have learned on this thread seems to support this.
This leads me to the question of fluid damping. One of the main reasons fluid damping has been employed is for the benifits of sound quality, caused by the controlling of frequencies by the behavior of the arm. I suspect that perhaps, some of these benifits may be caused because these arms may be deficiant in mass in certain areas, and I am questioning that if the arm/cartidge interface is ideal, and the ill effects are within the ability of the suspention, if fluid damping is evan desired. On the other hand I wonder if it would then become nessesary or more desired as a result of the added mass of the arm, as the complience/mass interface is now being severely shifted.
Rega arms have traditionally not needed or used fluid damping because the design of the origional arm was such that the arm provided good damping of unwanted frequencies while at the same time providing low mass, something that the rb-300 did/does exceeding well considering. But now as we tweek the arm closer to the ideal, and closer to better compatibility with these stiffer cartridges, we are getting away from the origional design. This leads me in the direction of thinking that now we may want damping on a rega.
But then again, these cartridges may be stiff enough that we may be getting past damping altogether. Fluid damping, while having some simalarities to mass is also different. What is happening at that critical place at the cartridge suspention and the effects of mass, damping, and complience, is what I am thinking of and wondering about.

Zaikesman, agreed. No cause for more weight than necessary for the given application. And I believe that higher compliance carts will need less than my DL103 does. None of my records are visibly off center, so I can't really check out the behavior of that possiblity. The ones I have played work well. Since even off center records would have at least 90 degrees of travel during the runout area, I don't think that the weight would make any difference. The ability of the arm to follow the spiral seems to be completely unaffected by this mod. There is less need for anti-skating though.

About the fluid, are they using something different than what is used in the cueing mechanisms? I know that stuff gets thin over time, and leaks out.

I would add to Basement's and Twl's comments about viscous fluid damping, that the fluid becomes progressively more resistive to motion the higher the acceleration factor gets, meaning that the fluid-bathed paddle connected to the tomearm is most greatly damped at the highest frequencies, which means at the onset of transients, which is a Good Thing. The fluid is not very resistive (viscous) at low frequencies (slower accelerations), so it allows the arm to trace the spiral very well, but it probably won't stabilize the arm as much for the bass range as Twl's mass-loading. The flipside to this could be that with a record where the groove wanders a little out of round (a lot of records), the fluid damper would let the arm follow, while the mass-damper may cause the arm to press harder against first one groove sidewall, then the other, as it attempts to trace the ultra-low frequency undulation side-to-side. There would probably not be too much of an audio consequence from this, but if true, the effect would likely cause somewhat greater wear to pressings pronouncedly exhibiting this flaw, indicating that the added weight should be kept as low as is possible to still reap the sonic benefits.

Where do I send the money for this mod, and what cool name do you associate with it?

Basement, I have some cats, with plenty of hair. People some times ask me if I own anything without cat hair on it. I would have to say no. Maybe my entire house is well-damped. Just kidding, but I do have some cats.

Regarding your thoughts on damping, the arm should always remain centered over the groove. The arm should never move by stylus deflection. If it does, you lose bass information, possibly other information, and dynamics. The stiffer a cartridge's suspension(compliance)is, the more likely it is to deflect the arm during play. If the arm has sufficient mass in the horizontal plane, the cart cannot deflect it, as the horizontal moment of inertia(of the arm) is higher than the cartridge can overcome. This is the ideal relationship for maximum information retrieval from the groove. However, the arm must be free to traverse the record from start to finish, unimpeded by friction. The high moment of inertia in the horizontal plane, does not increase friction, but merely resists momentary, microscopic "wagging" that would otherwise impede correct pickup function. The fluid damping strives to duplicate this function by applying "shock absorber" type damping, against this "wagging" tendency. Neither of these methods should have a deleterious effect on the integrity of the cantilever, since the cantilever is supposed to be designed to move the distances involved with the velocities involved. Merely stabilizing the tonearm should have no destructive result on the cantilever. To the contrary, it should provide better functioning of the cantilever/stylus to do their intended tasks of groove tracing. Arm wagging has always been a bugaboo for analog rigs. The single minded desire for light weight arms, disregarding the need for lateral stabilization has allowed this modification of mine to become possible. The funny thing is that unipivot designers achieved some of this by striving to keep the azimuth level, but also got some of the benefit of lateral stabilization in the bargain. I think that this is responsible for alot of the improved sound of the high end unipivots recently, espectially the Graham. Gimbal arm designers totally ignored this because their arms were already stable, and didn't think of the lateral stabilization need, with the exception of Dynavector. Unfortunately for them, they did some other things at the same time that caused other problems to surface, and their arm never really caught on. And many people thought it was just a heavy arm, in a world of light arms that were all the rage.

It is interesting that this lateral stabilization is at the heart of turntable design, with aerospace tolerance bearings and heavy platters, and belt drive, being used to ensure that the groove does not wiggle sideways under the stylus. But the same thought escapes tonearm designers who allow their arms to be easily moved around in the groove by the very information that they try to retrieve. So all of this effort by the TT makers to keep that groove stable, is largely lost by the arm moving around. The perfect relationship of arm to platter is perfectly rigid and non moving with respect to the lateral plane. It should only follow the spiral. The bearings are highly-spec'd and tubes are built with great care to reduce vibration, and all kinds of technology is used to make them do everything else. But, still they let the headshell end of the wand get shoved all over the place by the cartridge. Isn't that wierd? Now to be fair, alot of cartridges are high-compliance and don't have much "push" to them, and alot of arms have enough lateral mass to stay fairly well in place. So for many applications they are ok. For the low-compliance crowd, things are not ok. If you have a Koetsu, or a Lyra, or a Shelter, or a DL103, or alot of other really good high end carts, then your arm is very likely not up to the task of getting the best from them. And the more you try to go to a lighter arm, the worse things get. And all these makers are trying to use featherweight materials like titanium and carbon fiber to make things even lighter! And here comes ol' TWL, that wierd-o from outer space, saying that we need to increase mass in the magnitude of ounces, not grams! But only in the horizontal plane, and in the right place. No wonder his TT sounds good. His arm stays in place.

$49.95 in normal retail = about $79.95 in audiophile retail. What do those dropped counterweight mods sell for? You'll be doing two weights instead of one, so yours should be a bit more.

Zaikesman, the damping I was refering to is fluid damping and besides sound its effect on the cartridge is this; when the arm is put into motion, lets say to the left, the weight of the arm resist the motion, and then goes into motion to the left, pulled by the cantilever. when the cantilever then goes back to the right, the arm is still going left, and so the inertia arm of the puts additional stress on the cantilever.
How much stress is put on the cantilever is affected by how heavy the arm is. (actually not the weight, but the inertia, which is affected by weight).The higher the complience, the more the cantilever flexes to a given amount of weight, and if the cantilever can flex enough, and the arm is heavy enough, the arm can be put in motion.
The real idea is to keep the cantilever centered, not having to much resistance to movement so the arm follows the cantilever, but enough resistance to keep it from overshooting.To achieve this, a fluid of a certain viscosity is used, the viscosity permits slow movement with little resistance while faster movement is resisted. So you can see that the tuning of the viscosity, and amount, could achieve this.
Here's where it gets complicated-damping with fluid can have similar effects to adding weight, as the fluid restricts movement. Fluid can have positive effects on sound. How much is attributed to keeping the coils centered or the restriction of movement, or the adding of the solidity and resistance to vibrations is one question in my head. the other is that as weight is added, and fluid is not, this makes the arm more prone to going in motion.
Fluid can have negative effects as well. Besides the cantilever to be less centered by not having it tuned properly, or causing more stress than intended, to much damping kills the sound quality. In my experience, Adding damping cleans up the sound and widens the stages, and tightens aand focuses the bass. After a certian point, then the sound starts to get dulled in the high end, then becomes veiled and then more diffused past the point it was before it was added. There have been some instances where adding any at all caused this.
So there is the object of my curiousity, one or two of them, among others.
The damping you are refering to, Zaikesman, is damping the armtube for ringing, and it is always a good idea. I have always had good results, no matter how good or bad the arm, no matter how good the match of arm and cartidge. One of my favorites-a drinking straw, of slightly smaller diameter than the inside of the armtube, and stuff the space between the straw and the inside of the armtube. This provides a pretty good surface/dialectric for the wire as well. (seems better then having it smushed against the armtube). I want to try cat hair, but my doner cat moved on. My theory is that cats seem to absorbe sound,and they are always sneeking up on stuff. In the wild, they have to be sound absorbant, so there may be something evolutionary to that.
Twl, fifty bucks, that would be a bargain. Seems like a hard way to make money, as I don't see much profit there. I think a lot of people would be into it though.

I am always up for a good way to lose money. If I produced these, would anybody buy them? What would you be willing to pay for an easy mod that improved your analog rig? Considering for the RB250, I would have to get new bearing dust covers, and the weights, and affix/screw them together, paint, package, and market. And hopefully make a few dollars. :^) Sounds like around $49.95 retail to me. What do you think?

Well Twl, then you know what the next step is - design and market the commercial version of it! Let me see how it's coming along during the prototype stages if you're going to be looking for investors...

(Come to think of it, if you weren't thinking about designing a whole new arm around this idea, maybe you could just make a retrofit mod kit for Rega arms...shouldn't be too killer, market's there and waiting...)

I think that the Dyanavector 507 reduced vertical mass is good for tracking warped records, but it requires that the cartridge be matched to the lower mass for proper resonance function. I also don't really like the short radius arm for the same reasons you guys are talking about, VTA/SRA changes of large magnitude on warps. I believe that this outrigger mod supercedes the Dynavector approach.

Yes V., I realize that. Still think you'd hear the warp before the change, though, and besides, any heightened tracking ability would tend to make up for this shortcoming in my estimation, but I guess the best solution is not to have warped records! (Which would rule out many of mine...)

Basement, are you refering to a tomearm wrap? I have one of these from Music Direct installed on the integral arm of my Technics SL-1200, just on general principle. It's a ribbon made of very thin, very stretchy black rubbery stuff that sticks to itself, which you wind around the arm in an overlapping spiral fashion. Couldn't vouch for what exactly it does, though. It's been on too long, and too many other things in my system have changed since it was installed (including TT items such as cartridge, mat, and support). Trying to remove it and reinstall it later would probably compromise it physically, it seems to me, so there it remains. I can tell you that the arm does seem well-damped by it (in the sense of not ringing), and that it adds negligable mass. It also stays put quite nicely, and looks quite ugly.

Basement, cantilever damage is more likely with higher compliance cartridges than lower ones. Since they flex so much easier, they are more likely to get flexed beyond their limits and break off. The low compliance ones are much stiffer and have a stiff suspension, so that is less likely. Of course you can break off any cantilever if you try hard enough. Lyra carts are relatively low compliance.

Regarding damping, silicone fluid damping for this application is troublesome, because of 2 reasons. The level of the stuff in the trough is critical, and nobody can really say how full to make it for best results. You have to "tune" it to your cartridge compliance, and that is a little "iffy". but it can be done. Second, the viscosity of the damping silicone changes viscosity over time, so the damping will change also. If you are not paying attention, or, don't change the silicone, you may lose the damping. The inertial weight system is a one-time deal that stays the same, once you install it. It could also need tuning to the cart, but once you are higher than the needed level, being somewhat heavier is no big deal. So my way of thinking is to tune it to a real stiff cart, like a DL103, and then it will be more than sufficient for any more compliant cart(which is all of them - the DL103 is the stiffest cart made).

I just had a scary thought-might want to put some of that tweaky brain-power to it, or at least calm my fears if you already know;
What of the possibility of premature cantilever wear or damage? I understand that underdamped arms or the wrong arms can cause this. (I'm starting to become a little weary of trying this with my clavis d.c., and actually, I'm starting to wonder about it evan with the arm now in it's present state, as it seems really underdamped in feel). Also, do you think that you might achieve evan higher results by adding some damping to your arm, in addition to what you have done?

Yeah, Viridian, I had wondered before about the angle issue with the Dynavector design, though I hadn't considered a potential resonance problem. I came to the conclusion that the VTA change is probably of no real consequence on a good condition, clamped record, but even if there is enough of a warp to make a difference, the moment of slight misalignment would be over in an eye blink, not a steady-state condition. However, one main virture of their design, whatever it's flaws (and I've never used or heard one), we haven't mentioned yet: It has the potential to greatly *reduce* effective mass in the vertical plane, not only increase it in the horizontal plane. Same VTF accomplished with less mass = less interia, which should result in better tracking, no?

Yeah TWL, next thing your going to tell us is you built your own speakers.

Then your going to tell us you assembled a kit turntable, a battery system to power it, then aided the design of a Berning amp, and who knows what else.

Oh that's right, you did do all that.

Thanks very much, Marty. I enjoy all of my time here with you and the rest. Cheers.

Viridian, I agree. They were onto something, but the execution, while being a complex beautifully made machine, lacks certain important things and includes problems, that were not needed. I am sure that my mod is not perfect, but it is a simpler solution than the Dynavector, and does not introduce as many problems as the 507 does. As of this time, I am not noticing any audible problems with the horizontal mass/resonance change. In fact, the sound overall is just great.

I went to the Dynavector web page, and read the info on the 507, and it was very interesting. They had a very good description of why a tonearm should have high lateral mass and low vertical mass. It is notable that the way record grooves are recorded, the bass information is almost totally lateral in deflection, and are the largest movements for the stylus to trace. This makes the stylus more likely to move the arm laterally away from the center of the groove, thereby losing bass information and dynamics. The Dynavector web site describes the need for greatly increased mass in the lateral plane. This seems to be the major reason for their design of the 507. They called it "bi-axis" design. It appears that my mod gives similar results without having to change the tonearm. If the tonearm is already light enough in the vertical plane for good warp tracking, then all that is needed is to increase the lateral moment of inertia, through this weighted outrigger modification.

Twl, what you figured out is what I was actually attempting to suggest - hence my description, "...calculated effective mass equivalent..." referenced to the tracking force itself, which is of course measured out at the stylus tip. I wasn't intending to include the arm's mass in the total increase, since it's already there, just to suppose that an increase in the horizontal plane inertial resistance equivalent at the stylus tip to that represented by the applied VTF in the vertical plane would be eminently safe. But again, as probably evidenced by the Dynavector design or a linear tracker, an increase far beyond this, such as you seem to have done, certainly appears to be OK.