2. analog
  3. 1032024188

Strange Tonearm Tweak. Long

As you all know, I am a little different. I like to read and study stuff like tonearm technology. I noticed that some of the better unipivot designs have employed "outrigger" style outboard weighting systems on their arms, that work like a tightrope-walker's balance pole. This not only balances azimuth, but also gives the arm better stability to lateral deflections from the cartridge suspension, so the arm is not moved when the stylus is pushed laterally by the groove information. I began to think on this, and I wondered why no gimbal-bearing arm makers are doing this. Surely since the vertical plane rides on a vertical axis bearing, there is still some chance for the arm to be laterally deflected by the stylus, when the stylus should be doing all of the moving, not the arm. I think that this is why they use heavy arms, but a heavy arm in the vertical movement plane is not good for tracking. A heavy arm in the horizontal movement plane is good for resisting sideways deflection that would impair pickup function.

So I decided to try increasing the mass of my tonearm in the lateral plane, while keeping it light in the vertical plane, by the use of "outrigger" weights, just like a unipivot does.

I bought lead fishing weights that looked like long rifle bullets(just the lead part) They were about an inch long and about 3/8" diameter, and weighed 12 grams each. I drilled into the bases about 1/4" and press-fitted them onto the nuts that hold the arm into the bearing yoke, so they stuck out straight sideways, like sideways spikes. This put the weight out pretty far to the sides as outriggers, and kept the weight centered exactly around the bearing pivot axis so it did not increase the vertical mass significantly, but it did very slightly. It did not influence the tracking force at all.

So now the arm had outrigger stabilizers on it in the horizontal plane of motion.

I put on a record and sat down to listen. Let me tell you, fellas, this was a mind blower. I have never heard this much information come out of a cartridge before. I heard sounds on records that I had listened to for 30 years, and never knew those sounds were on the record! And I have had some pretty good analog gear in my time. And what I didn't own, I heard at the audio store I worked at. This is the most astounding mod I have ever heard on a tonearm. And it cost me $1.49 for the fishing weights, and I got 3 extras.

The only slightly negative thing about it, is that it increases the anti-skating force, so you have to cut that back a little, and if you have some marginal scratches that might skip, they are more likely to skip with this mod, due to the resistance to sideways movement provided by the outriggers. I had this happen once last night, but I didn't consider it a problem.

But the increase in dynamics, and detail and overall sound quality is astronomical. It blew me away.

I have a DL103, which is a very stiff cartridge, and it may be that this is not needed for a higher compliance cart. But, I think that it would be good for anything that is medium or lower in compliance.

The key to it, is that it only increases the resistance to sideways movement, without interfering with the effective mass of the arm, or the vertical swing movement that needs to stay light to track warps. I played some warped records with this mod, and they played just as well as without the mod, except they sounded better.

I have a pretty good analog setup now, but I can say without reservation, that this mod made my rig sound better than any analog rig that I have ever heard in my life. I have never heard a Rockport.

Stabilizing the arm against unwanted lateral deflection increases the information retrieval and dynamics by a very large percentage. If your arm is not set up like a Rega style arm, then you can glue a 1 ounce long rod across the top of the bearing housing(sideways) like a tightrope-walker's balance pole. Use lead if you can, it won't ring. You don't have to do any permanent changes to your arm that might wreck its resale value to try this out. If it has anywhere near the effect on your system as it had on mine, you won't be taking it off.

It may come close to the movement of your cueing lever, so make sure you have clearance to use it. Mine was close, and I have to come in from the side now to use the lever, at the end of a record. That is fine with me! This was a major, major improvement in the sound of my rig. It is staying permanently. As in "forever".

If you are a little tweak-oriented, and not afraid to do stuff like this. You should try it. It will knock you over.
twl
twl OP
3,251 posts
 
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.
basement
245 posts
 
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.
twl OP
3,251 posts
 
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.
basement
245 posts
 
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.
zaikesman
3,017 posts
 
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.
More to discover