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.
In my first paragraph, I meant to say that the "horizontal movement plane is on a vertical axis bearing".
Just another thought, Twl, that it could be a combination of your enhanced tracking stability and the lead dampening of any vibrations going to the gimbal/axis.

On the market, there is some very thin self-adhesive 1" roll of lead that could be applied to test this idea, maybe on the other axis. McMaster-Carr carries some a 5 mil roll but minimum is 36 yards at $1 a yard. Like some spare sent to you? Oh, don't let your kids/dog/cat, etc. start licking your tonearm weights!

Good show TWL. The idea is to get the most mass below the pivot point of the arm. In a unipivot this certainly increases stability. Interestingly, the Express machining counterweight for pivoted arms functions in much the same way. The teardrop shaped counterweight puts more of it's mass closer to the plinth than most OEM weights. One can see similar designs in turntable syspensions; the Linn and VPI HW-19 balance the bearing assembly and arm board on top of the springs whereas the Oracle and SOTA hang the works below the springs. One should however always be carefull in increasing the loading on any type of bearing. Bearings are usually only designed to accomodate the mass of the arm tube and counterweight itself. This is why the use of heavy turntable weights that fit over the spindle to stabilize the record were shunned by many manufacturers after they realized that their bearings were wearing more quickly than planned. Increased loading can cause excessive bearing wear and even Brinelling (flat spotting) of the bearings. Always consult with the manufacturer before adding mass to an arm.
TWL: From your description is seems (to me) that you are adding weight directly to the tone arm bearings (both vertical and horizontal) not to the tone arm itself. Do I have this right?
Viridian - I already use the Expressimo Heavyweight, and found that to be a very good improvement also. I did not consult Origin Live about this, and am quite sure that they do not consider it necessary. This would be the typical response from manufacturers. I feel confident that this mass, in the way it is applied, will not compromise the bearing integrity. If anything, I believe that it may enhance the bearing life, due to chatter reduction, because of the increased mass of the bearing axle and lead damping.

Todd - I think that the lead dampening effect on the bearing axle is a benefit of this mod. As I said to Viridian, this added weight and dampening will decrease chatter by raising the chatter-motion threshold above what the cart can put out. Thanks for the offer of lead ribbon, but I already have some. I have not tried it on the arm though.

Dekay - That is correct. The lead weights are like extensions of the tonearm bearing axle and are outside the bearing housing, so it is not affecting the effective tonearm mass/resonance. They also have minimal effect on the vertical movement because they are small diameter, and concentric with the center of the axle. Therefore the moment of vertical inertia is hardly affected at all, but the horizontal moment of inertia is greatly increased. The only change to the loading of the vertical pivot bearing is on the thrust face. The total increase in weight is only 24 grams, but the wide positioning of the weight is the key to increasing the moment of inertia required to move the arm. This is what really stabilizes the arm to the movement of the cartridge. And man, does it work!
TWL: Very interesting, though I cannot see an "easy" way to try this with my old SME (short of Super Glue:-)
Very interesting approach Twl, but the analogy between stabilizing outriggers on a unipivot design arm and what you've done for your gimbal bearing design arm is somewhat incomplete. Azimuth control should not be a problem with quality bearings in a gimbaled design, but you don't seem to be affecting the center of gravity with your implementation anyway (unlike those "dropped" counterweight Rega retrofits). It seems to me, what you've really accomplished is most similar to what a viscous damping trough arrangement can do, albeit perhaps with lesser attenuation of high frequencies. The goal is to increase the tonearm's resistance to lateral deflections that occur at much higher velocities/frequencies than just the spiral groove's dragging the arm across the record, thus increasing the amount of information able to be transcribed accurately by the stylus. It does seem as though you've hit upon a simple, inexpensive mod to accomplish just that, although I'm curious as to why your mod would actually increase susceptability to skipping - like a viscous damper, it seems as though it should in fact decrease this tendency, since a skip is basically a rapid lateral deflection of the arm. For my decidedly non-audiophile-approved Technics Sl-1200, I intend to soon order a dedicated retrofit viscous damper assembly from KAB, and I hope I'll hear some of the benefits with my Glider that are blowing you away.
Quote: "For my decidedly non-audiophile-approved Technics Sl-1200, I intend to soon order a dedicated retrofit viscous damper assembly from KAB, and I hope I'll hear some of the benefits with my Glider that are blowing you away."

You mean "non-Voodoo approved". A true, knowledgable audiophile like Bill Parish, Dejan Veselinovic, Thorsten, Sedond or *yours truly* will admit it's a good TT. Not to mention the one (electrical engineer) member here who modded the Quartz Lock circuit board in his'...

And yes, adding the fluid damper WILL blow you away. Everything will seem it's happening in another time continuum. Get ready. I can play the innermost grooves of a Barbara Streitsand album w/ no breakup whatsoever using a modest Ortofon X5 MC. With a Benz Glider expect even higher performance and speed.

From TWL's experiment now I understand why Kevin Barrett does not want the fluid trough filled more than halfway. He's aiming, then, at achieving lateral damping over vertical. That also helps explain the shape of the paddle. Good, I just received a srynge full of silicone for refilling (I relocated), so I'll add a little at a time and listen carefully. Very well. Just when I thought I knew it all...

Life is good.
Geez, PsychicA, didn't take long for my post to pull you out of the woodwork...You mean after all this time you didn't 'get' the principle of this gizmo you've been all over me to go ahead and order?! Well, just so's I don't earn one of your 'encouraging' emails tonight, please know that the only reason the damper's still pending in my set-up is because of my recent move - combined with some more urgent upgrade necessities mandated by same, which I now believe I have adequately filled. I promise to get on the phone to Kevin soon... :-)
Yes guys, this mod is similar to a damping trough mod, with similar goals. I didn't really lower the center of gravity any with this, because I would have encountered clearance problems with the cueing lever and other stuff. I also wanted to achieve some added weight and lead dampening to the bearing axle(outboard). If I could have lowered the center of gravity, and still achieved the other goals, I would have done it. And azimuth control was not part of the goals, because with my arm this is not a concern.

The arm doesn't really "skip" easier with this arm mod, what happens is that, when it encounters a scratch that is just enough to make it skip, it doesn't jump to the next groove, but "sticks" in the same groove, because of the lateral resistance to quick movement. Perhaps I should have used more accurate terminology.

I think that the silicone trough mod you guys are getting should give similar results, to what I am getting here. It is a totally awesome improvement. Dynamics and information retrieval is staggering. Amazing what you can get out of a cartridge when you allow it to work like it is supposed to!
Quote: "You mean after all this time you didn't 'get' the principle of this gizmo you've been all over me to go ahead and order?!"

Yes and no---Yes, because I have an old Disctracker by Discwasher damper and have been using it on every cartridge I've had except a Shure V15 III and my most recent Ortofon X5.

The Disctracker is a piston like vertical damping device that is attached on the headshell. It really helps bass response and trackability, especially on a Sumiko Blue Point. It made me realize my LPs were better than my CDs. When I purchased my 1200 I bought a Grado Prestige Blue and the Disctracker also significantly improved performance. I did not want to use it on a more delicate Ortofon, though.

So truth is I've been used to *vertical* damping for years and years and thought that a lot of the improvements switching to the fluid damper came from removing the weight and the L-to-R inertia added by the Disctracker. Now I understand that lateral damping is the key player in keeping the stylus in contact w/ the groove as it accelerates from side to side.

I received an e-mail that says this:

"oh ya, re glider - yer ortofon will likely extract more info from the disc - better stylus profile."

I got confused with the Benz ACE. That Ortofon tip goes deep in the groove and extracts a *lot* of information. It's finicky to set up and intolerant of dirty records, but definitely a time proven classic.

can you post a picture of this tweak?

Twl - I'll try to post here about what I find when I try the damper mod. It also occurs to me that achieving a high level of disparity between the horizontal and vertical tonearm masses is exactly what Dynavector has done for a long while now with their unusual double-pivoted tonearm design.

Animal - The ACE is below the Glider in the B-M lineup. My Glider is the current version "2" series, and has the same 6 X 40um Fritz Geyger mirror-polished stylus as is used on the $1,300 level Wood Body series, for whatever that's worth.
Zaikes, the Dynavector 507 was addressing this idea, and that is a good observation. My problem with the way they did it was that it introduced a whole other set of bearings, counterweights, and resonances that probably did more harm than good. What I really like about my mod, is the simplicity, and form-follows-function design. No additional complexity at all. And all of the great inherent aspects of the arm are retained, with the addition of the increased lateral stability. I'd be interested in hearing how the fluid damper mod works out for you. You may even be able to try different fluid viscosities to see which works best.

Jvr - Unfortunately I don't have a digital camera, so I can't post pics. But, it just looks like a spike sticking out from each side of the bearing housing. Perfectly concentric with the horizontal tonearm bearing axle. The arm now looks like a cross at the pivot point. That's it.
That "Fritz Geyger mirror-polished stylus" is the one my Ortofon uses--don't know about size, though. Excellent response. So, having a better cartridge than what I'm using should bring even more music once the damper is installed. I would add a little at a time and listen carefully. As for different viscosities, I'd definitely consult w/ Kevin. Im sure he's done his homework.

I can't do anything to my system yet because Dan Wright still has my Swans speakers. The crossovers should be back from Jena Labs sometime next week and Dan will do the installation and final burn-in. I don't want to change anything in my setup. Just moving to another apartment is enough of a change...

After reading this, I was compelled to put my table on the work bench and study my rb-300. I noticed that the nuts on the end of the vertical bearings do not move with the arm. This supports your extrordinary theory. There would be no movement in the vertical plane of this extra weight.
Then there is the damping factor of the bearings, and/or the area at them. This to me also makes perfect sense.
As if I'm not intregued enough contemplating the origin live mod, now this.
I haven't tried any of these, yet.
These questions burn in my quest for analog reproduction; How much of this tweek is attributed to the damping or manipulation of resonences at the bearing point, and how much is attributed to resistance of movement of the horizontal plane?
As far as the resistance to movement in the plane, it would seem to me that resistance to movement in both planes would be as desirable, up to the point that the cantileler would remain centered. Of coarse, while movement to the contrary would be undesirable, the resistance to movement which allows the transducer to transfer/produce the signal is critical, it would seem to me that resistance in the vertical plane would be desirable as well. It seems to me also that records seem to want to jog the cantilevel horizontally more so, or as much, as vertically, as record clamps hold the record relatively flat, and nothing can be done about records being off-center. It would seem to me in theory that benifits would be had vertically as well, if not more so.
As for adding weight for resonence control, I can't help but notice that all of the most recent improvements to the top tonearms have been in making them heavier. The emergence of the rpm, the subsequent improvement of the graham (1.5 to 2), then the added improvement by making the bearing mount more massive, (2.2).
Compared to these arms, it seems that the rega is behind in weight, and it seems that where the weight is added is important, both for resonence and resistance.
Please keep these tweeks and knowledge coming. They are HIGHLY enjoyable. It would seem the cutting edge is right here on a-gon.
Basement, all tonearms already incorporate a greater vertical than horizontal resistance into their design (that is to say, beyond the biaxially uniform effective mass of the tonearm/cartridge combo itself) - the Vertical Tracking Force (VTF). Exactly how that tracking force should be calibrated is dictated by the cartridge's suspension compliance (and I would surmise cantilever length/effective tip mass), and is specified for all cart's. Correct VTF achieves the proper balancing act of allowing the stylus to accurately transcribe the vertical accelation of the grooves, while permitting the arm to respond to warps in the playing surface of the record. If you think about it, during set up of a typical tonearm, first the arm with installed cartridge is precisely balanced out by adjusting the counterweight to find the zero VTF calibration point, and then the tracking force is applied by moving the counterweight toward the pivot. Since gravity only affects the arm in the vertical plane, while the VTF is increasing, the amount of inertial mass resistance in the horizontal plane is actually slightly decreasing at the same time, as the counterweight is moved in toward the bearing center. Twl's idea adds back that leveraged mass and more, but keeps it out of the vertical plane of motion.

It would be interesting to know whether there is actually an optimum amount of resistance that should be applied in the horizontal plane, where performance would begin to suffer beyond that point, or whether more is always better up to the practical limits of the bearings, the anti-skating, the cantilever suspension, and the vinyl itself. One easy guess for a safe bet would be to add a calculated effective mass equivalent to 2X the tracking force (1X to bring the horizontal inertial resistance back up to what it was at the VTF zero point, 1X more to bring it up to equal the applied VTF point), since you already know the cart suspension can handle that. But looking at the massivity of the aforementioned Dynavector arm (the vast majority of which appears to pivot only in the horizontal plane), it seems as if it might be safe to add horizontal effective mass orders of magnitude greater than the VTF. (I suppose this is a determination that must be accounted for in linear tracking arm designs? I'm not personally familiar with any of these, but it seems to me that by the end of an LP's worth of play, a lot more mass will have been moved through a much greater distance than with a conventional tonearm.)
Zaikesman, I think you are on the right track for calculating the proper mass, but I would throw something else into the mix. The added weight in the case of my modification is at the pivot point. The stylus deflection is occuring about 9 1/2" away, out on the end of the tonearm. This distance causes the force vector to be increased dramatically by the leverage involved. Therefore the weight increase at the pivot must be far greater than equal to the lateral deflection at the stylus. This is the reason that I used long weights, that stick out an inch from each side. I am using the leverage factor to increase moment of inertia on my outriggers, just as the leverage factor increases the moment of inertia of the stylus, with respect to the pivot point. Since the tonearm is about 9 times longer than my outriggers, the outriggers must weigh more to compensate for this distance. In order to have a 1 to 1 ratio of outrigger weight to stylus force, you would have to have outriggers with a weight, in my case, of 2.75 grams(1.375 each)plus the effective mass of the tonearm. If the effective mass of these were the same as the tonearm (11 grams)+ the weight(1.375 grams x 2) then the total mass of each outrigger would be 6.875 grams, or a total weight of 13.75 grams. The lead weights are 12.25 grams each. About 90%. I didn't include the cartridge weight or equal the distance, but I did get the weight 1" outboard of the bearing yoke, so that helped alot, and used the materials at hand. And since there are 2 outriggers, my effective horizontal mass increase is at least 24.5 grams(plus the 1" width increase on each side). This is almost double(180%) the combined tonearm mass and stylus force. So when you add the existing tonearm mass(which also provides lateral stability), there is nearly an effective tripling(280%) of the horizontal stabilization. In addition, since the outriggers are equal weight and equidistant from the pivot, they are inherently counterbalanced. And they add no vertical mass. It may be possible to fine tune this even better, since I did no fine tuning at all. I just put them on, and voila! It worked so well that I didn't need/want to fuss around with it.
Basement, what Zaikesman said about the Vertical Tracking Force is true. However, increase in vertical resistance(mass/inertia) is also bad. The light weight of the arm in the vertical plane ensures good tracking on warped albums. If vertical mass is increased significantly, the arm will leave contact with the groove when it encounters a warp, due to the upward inertia imparted by the warp. Once the high mass is set into motion, it will continue to fly upward by momentum, and leave contact. This is bad. A small increase at the pivot area is not significant in this regard, though. In the case of my Origin Live Silver Tonearm, the bearings are relocated into the yoke, and the weights on my arm do rotate with the axle. This does make a very small increase in the vertical moving mass of my arm. Being that the weights are small diameter, the actual increase in vertical moment of inertia is small. If I had used large diameter discs instead of small shafts, the increase in vertical inertia would have been significant. This is not a good idea in the case of the OL arms. Use the bullet shaped shafts to minimize this. Also using discs would have ruined the advantage of moving the weight as far outboard as possible. The idea is to get the weight as wide as possible, since this increases the moment of inertia(resistance) by a multiplication factor. This allow the use of less weight, and gives a higher factor of resistance. If you make it too wide though, it gets in the way of everything and could get snagged off during use. This one inch long weight seemed like a good size.

You really need to start doing something with your arm. You have a diamond in-the-rough there and it would greatly reward you if you modded it. If you start with the OL end stub and the Heavyweight, you would really be getting somewhere. Be careful to not damage the bearings when you are removing and installing the end stubs. Don't apply any torque to the bearings! Isolate the bearings by holding the arm tube between the pivot and the end stub.
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.
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.
The problems with the design of the Dynavector tonearm are twofold. First, the short end of the arm that is attatched to the vertical bearing causes a much greater change in VTA/SRA when tracking less than flat records. The other problem is the seperate resonance points in the vertical and horizontal planes. The vertical resonance, in particular, is somewhat higher than in a conventional arm due to the reduced mass of the vertically moving part of the arm. With certain cartridges this can cause resonance problems within the audible range.
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.
Twl, your inquisitive and experimental interest in the hobby is so reminiscent of the 1960s and 70s. The gear was not so well made back then; more art than science, or, some might say, the perfect balance of art and science. All audiophiles had to constantly experiment with intriguing ideas like your own. The sport was much more participatory back then. We even built kits on occasion. The hands-on aspect of the hobby has been largely lost. Computer, home theatre, work, kids, all vying for time. The manufacturers producing the product-of-the-month. Squeezing the soul out of the gear. No wonder we are having a hard time attracting more enthusiasts. I am glad that we still have people like you in the game. It makes it all worthwhile.
Thanks very much, Marty. I enjoy all of my time here with you and the rest. Cheers.
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.
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?
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?
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).
Zaikesman, your observation is on the money, however realize that the vta/sra with the Dyna arm will be changing continuously with the rise and fall in a warped record. Even in the case of a pinch warped record where the change in vta would be over in a moment that moment would occour 33.33 times per minute, hardly negligable.
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.
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.
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...)
Cool stuff Z and T; an even quicker way to lose money than the stock market.
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?
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.
$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.
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.
Where do I send the money for this mod, and what cool name do you associate with it?
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.
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.
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.
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.
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 - 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.
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 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.
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).
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.
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.