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
Hi Tom,
thanks a lot for your most clarifying post. It worked even for a dummy like myself :-). It seems I'll start looking for an available lead shaft. Thanks a lot.
Stefano
Alex, that sounds like a workable idea. Maybe you should try a mock-up of it and see how it sounds.

That's all I did. I had an idea, and tried it out to see if it worked to produce better sound for me. I'm sure that there are plenty of other improvements to be discovered, that none of us has thought of yet.

The stuff that I made is just another "stepping-stone" towards improved sound and improved design ideas in tonearms. There will be others who are spurred on to make further improvements on top of what I have done, or entirely different directions. I'm just glad to have been able to contribute something back to the hobby.

Regarding your particular design idea above, I think it is interesting to use a counterweight "lift" in front of the bearing, instead of a "see-saw" behind the bearing. This may have some interesting resonance effects, and possibly with careful implementation, could result in some resonance-reducing effects in the armtube. This would require experimentation.

I think it would be worthy of trying out to see just what you can get out of it. After all, tonearms aren't the most complex items in the world, and most of us could actually build a whole tonearm that sounds quite good, if we set our minds to it.

I enjoy seeing some other insights into the tonearm design issue, and love to see the seeds of innovations being brought to life.

Go for it.
Umm...mebbe, but I dunno. I think this one resides in the thought experiment file (along with most of my others :-) For one thing, it violates the KISS principle. For another, a string attached to the tonearm and pulled taut will have a very defined resonance, like a guitar string. But mostly, I just can't fathom why doing this would be beneficial. As opposed to your HiFi concept, which stemmed from an actual theory of its positive effect. I'd just be mucking around in the dark with no clear idea of why. This only occurred to me in response to your post about hanging counterweights, but taken to the max. If I have an opinion on this at all, it's that a conventional counterweight would probably be just as good or better in the real world. But if someone can explain to me why 'decoupling' the counterweight is ever attempted in the first place, maybe I'll change my mind and decide I could be on to something...
It would have to do with resonance modes and reflections in the tonearm system, regarding the interconnected masses, and their positions, and the method of their contact with each other.
I didn't do any measurements with my hanging counterweight. I just "theorized" that it might be good to get all the mass down at the level of the record(and remove the mass from being bolted to the armtube), and tried it. It was a little better than the Heavyweight.

Sometimes you just have to go with your "gut feeling" and try things.
Hi all,
following Jeff Spall masterwork at www.william-reed.net/rega, I'm trying to apply some ideas to my RB 250 arm, and just wanted to share with your experience/thoughts:

I already equipped my Rega 250 with an Expressimo endstub and counterweight and experienced a totally different sound from it. A good idea seems to have cw weight at a level which is as near as possibile at platter level.

Now, while rewiring the arm with a cheap ultrathin wire I got (BTW it seems quite difficult to remove the enamel out of it), I thought of taking some more mass off the arm.

The principle behind this would be to concentrate mass arm near the pivot, so reducing vertical inertia of the arm.

So, last weekend, I cut out the lifter (most uncomfortable, but I decided to accept the drawback).

Now, while Jeff pattern is spiral, Michell Technoarm has an array of 2 x 11 holes, all located in the inferior arm hemi-part.

Thinking of mass distribuction, where the reduction of mass would give more benefits???

Thanks for sharing,

Ciao,

Stefano

P.S.: Would be sensible taking the paint off with a sanding approach (a la Dremel) be a way to achieve a sort of hardening of Alu (similar to bead blasting)?