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

Showing 10 responses by zeneize68

Hi TWL, thanks a lot for this great thread and information sharing. I just learned of your tweak. Owing a 250, with expressimo cw, and a cart with a much higher compliance 25 µm/mN (so 5 times DL103's one), I was thinking if, in your opinion, a linear model might be common sense in order to find weight lateral size.

In this case I immediately thougt of 12/5, i.e. about 2.4grams/each "stabilizer". Is it too simplicistic (apart from try and listen :-) )?
Thanks a lot, Stefano
Ciao Tom,
thanks a lot for your kind answer!

Meanwhile, yesterday I tried with a small amount of tack and used 2 small bits of an unknown metal (each about 2,3 gr.).

I must say that, at least, I didn't hear any drawbacks with my Goldring 1042. Indeed, I seem I have listened to smoother and more extended highs. Bass are - quite - good (as before).

BTW, I'm going to some more DIY on RB250 (rewiring, remove lift, remove some paint at cartridge end), thanks for your suggestion!

Ciao,

Stefano
Ciao Tom,
thanks a lot, I already got an Expressimo stub and cw which satisfied me a lot! The idea behind your strange tweak intrigued me and I tried to estimate the math relationship between cartridge lateral compliance and additional rotational inertia given by your extra weights, in order to get a general solution...

I'll try to study it in a physical mood...

Ciao, Stefano
About the hanging counterweight,
is it possible to point me to a photo of such implementation? Isn't it loosely hanging and, therefore, blurring the rotating inertia of the arm? Please let me understand :-)

Ciao, Stefano
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
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)?
Thank you Tom,
I think (at least hope ;-) ) I'm aware of it. The overall resonance frequency of my actual setup would benefit from such a reduction. Should I need more mass, e.g. by changing cartridge, I thought I could add it nearer the pivot (or, e.g. by adding a damping foam inside the arm).

Any recipe for DIY bead-blasting?
Finally it plays!
My TT, born as a string driven unit, build on a
rectangular shaped plywood with cadberg and scheu
pieces, now is a nice drop-shaped, multi sandwich,
lead filled unit.

It's suspended on air (inner tube). The
motor unit drives the platter "crossing" a flywheel.

The arm, now rewired, sounds much more precise and free of resonances.

All in all, I'm very satisfied. LP sound quite good.
I've only a residual hum (apparently not related to
arm grounding, but I still have to investigate).

Another 250 is sitting, waiting for a hanging cw test...

Ciao,

Stefano
Hi all,
Eric many thanks for sharing the VTA/VTF/Antiskating procedure!

The hanging cw trick is still waiting...

Woud you mind explaining the Thorsten advice about cart/arm decouple? Is it similar to Len Gregory "The isolator" principle?

Stefano
Hi all,
I succesfully tested the tweak efficiency with a higher compliance cart (Goldring 1042, 24N/mm lateral compliance) and something around 5gr. weights.

I guess the idea to add inertial mass "is here to stay", even if with different masses and/or geometries for different cart compliances.

Stefano