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
Well Doug, it's great to be able to move up in the world. I'm real happy that the Silver and HiFi mod were able to get you through the early times with good results.
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
Stefano, thanks for your question, and I'm glad you enjoyed the thread.

In my opinion, a cartridge with a compliance of 25 is not going to move the RB250 laterally. The standard effective mass of the RB250 should be sufficient to laterally stabilize that cartridge.

I don't think that adding any additional horizontal mass would be productive in this case, and there is a possibility of causing a mismatch in mass/resonance if you do add horizontal mass to the tonearm with a high compliance cartridge, such as you have.
In a purely aesthetic vein, I was in the store other day to find weights for my OL Silver. In the store I visited, there was literally an array of lead and brass weights in a variety of colors. Black, which matched my arm perfectly, gold, silver, tortiose shell, neon colors. Some looked VERY cool. Guess the fish can tell a difference too!

I JUST set up the arm the other day with a Denon 103R. Tried it sans weights first and things were pretty damn good. Then, last night, I took two 1/2 oz. weights and drilled out the centers a bit and matched their weights on a digital scale until each was 11.75gr. Installed and spun again. OK, this invention is probably the biggest bang for the buck (well, actually cents) in the history of audio. The additional detail was not to be believed unless heard and the tightening of the bass was kinda scary. So much so that I wondered if it could actually be attributed to such a seemingly meager mod. But, I am not willing to take them back off to find out.

Bravo, Tom! Good work!