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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
damianm71fb1
1 posts
 
Let me ask youguys a question. I've printed out the thread and I'm still reading thru it so I hope it's not been answered before.

I'm using a very crude version of this tweak on my backup 'table, a Sony with no antiskating (the arm is a POS). It seems to have cleared things up a bit.

My take on the tweak was a thin metal spatula (what I had at hand) for which I found what I thought was the mid-point, affixed with a couple tiny drops of glue to the top of the tonearm casing. I looked at it with a flashlight from all angles and it appears to be straight.

I later made 5-coin stacks, held together with drops of glue, and added one to each side of the rod, just for the heck of it. I can't say I'm noticing much further improvement.

Anyway, about antiskating. I noticed the rod isn't quite centered on the tonearm pillar (wonder just what I was doing when I marked the mid-point on it), but rather one of the sides is hanging out more than the other.

This end is on the 'outside'. Is this the 'right' side for the offset weight to counteract the skating force, or should I mount it the other wayround?

Thanks!
twl OP
3,251 posts
 
Hi Damian, while the unequal weights may possibly effect a change in anti-skating, it is not recommended to do that. It has other effects too, which might include affecting the azimuth, causing unequal bearing loading, among other things. If you need to adjust your anti-skate, I'd recommend approaching it from a direction that influences only anti-skate.
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rauliruegas
13,112 posts
 
Dear friend: I have around 18 tonearms. You have a point that maybe it's valid, but when a tonearm manufacturer has a good design and a good execution ( it does not matter wich kind of tonearm bearing design ) you don't have to worried about it. If with this " mod " you have a different sound maybe is because your tonearm is not first rate.
By the way, you say that a heavy tonearm is a bad traking arm ( vertical ), well this is not in that way. All depends on the cartridge/tonearm match and in the tonearm bearing.
Cheers.
raul.
twl OP
3,251 posts
 
Rauliruegas, yes I agree that if the tonearm is properly designed, that there will be no need for my tonearm mod. Unfortunately, it seems that many are not properly designed. So, improving the lateral mass is appropriate in many cases, but not all. Also, it depends greatly upon whether the cartridge is low, medium, or high compliance, as to whether additional lateral mass is even needed. In any case, this mod is strictly for OL Silver and Rega tonearms, and it has been demonstrated that they perform better, with many cartridges, by having additional lateral mass placed in the proper location.

I have never presented this modification as a "panacea" for all arms and all cartridges, but strictly for Rega and OL Silver arms with lower and medium compliance cartridges. Other arms may also benefit, but that would have to be determined on a case-by-case basis.

Thanks for your comments.
zaikesman
3,017 posts
 
Tom brings us back to the point about cartridge compliance and the efficacy of doing a mod like his. I have been thinking about this recently since I installed a van den Hul DDT-II Special in place of my previous Benz-Micro Glider M2.

The vdH's have higher compliances than is usual for most MC carts (and their upper-line models even more so than mine), yet the DDT does not seem to suffer from being run with the same viscous fluid damper settings I used with the Glider. But I'm not sure this would be the case if I had Tom's mod instead of the KAB damper, due to the point I made somewhere above about the added mass imparting not only increased resistance to lateral deflection of the tonearm (as does the viscous fluid), but also continuing intertia once put in motion (which damping fluid does not have).

This sheds some light on a problem that baffled me near the top, namely why Tom felt the mod increased susceptibility to skipping on scratches: it's the intertia - I just didn't put the two together before. There's probably a 'threshold' effect at work: light scratches may actually be less prone to cause skipping with the added weights installed, but these kind of scratches might not normally cause skipping anyway - while scratches beyond a certain magnitude (that acutally cause the stylus to break contact with the groove) may cause a lateral arm deflection that is less easily brought back under control once begun due to the added mass inertia.

Anyway, we see that increased lateral mass mandates matching to a relatively low-compliance cart, such as Tom's Shelter. This is of course no different a concept than the standard one about matching compliance to overall effective arm/cart mass, with the exception that Tom's use of increased *lateral* mass *only* means that there will be little or no effect on system resonance excitability due to infrasonic warps, footfalls and the like, or LF mechanical feedback (which tend to be primarily vertical in nature), nor due to the low bass content of lateral-cut (mono) or diagonal-cut (stereo) recorded music (since the added mass only lowers the resonance point, presumably already below the 20 Hz maximum). So bass performance is enhanced, tracking is maintained, and skipping susceptibility is worsened (but not if your records don't have scratches).

Still, you could say about viscous fluid damping that the bass performance should be likewise increased, tracking may even be slightly improved (fluid does provide a bit of extra vertical damping, though not as much as laterally, due intentionally to the shape of the paddle), and susceptibility to skipping is ameliorated (or at least reduced in magnitude when it occurs). At least one could think so. In my own listening tests with the fluid damper, I mostly heard a cleaning-up of the soundstage, a purer, more extended treble response, and bass that sounded more natural in timbre but not necessarily more extended or dynamic (those tests done with the Glider). I can state that the damper doesn't worsen skipping, but haven't done the tests to state that it really improves this aspect either. In any case, fluid damping does seem to permit the use of carts in any compliance range (indeed, the KAB product, dedicated as it is to the Technics SL-1200 table/arm, will likely be most often used with high-compliance MM carts featuring relatively high-mass tips and cantilevers, such as the models made for club DJ's and hiphop turntablists).

But since KAB evinces no interest in coming out with a fluid damper for Rega-sourced arms (despite my opinion on the market potential there), Tom's mod would seem to be it for owners of such arms - provided (as he states) that they are running a cartridge of suitable compliance. Looked at that way, what he essentially did was come up with a clever method to improve the match of his tonearm to his choice of cartridge, without paying a penalty in reduced trackability.
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