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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
 
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.
nrchy's avatar
nrchy
2,124 posts
 
Where do I send the money for this mod, and what cool name do you associate with it?
zaikesman
3,017 posts
 
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.
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.
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