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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
tphalieros
39 posts
 
Hi Tom
I was reading all the responses to your tweak and got a stiff neck! I don't have the technical mastery of theoretical parameters of the tonearm's design. I have a very good intuitive understanding of the fundamental physics that are involved in a correct design, one that employs natural principles to it's function. This is the reason that I regard the frictionless "Schroeder" type of arm to be the most natural sounding which also implies that it must be the most musical sounding. The German reviewer said so when he compared it with the SME and other top quality arms. It didn't have the best base,(which is understandable given it's design) even though all the information was there, but in the concert hall, one does not hear "base" standing out, but a seamless wall of sound.
I have designed one such tonearm but I am stuck in the technical aspects of how much strength the magnets that stabilize the arm should have, so that it's inertia relative to it's mass, is not excessive. This of course can be achieved by increasing the magnet's gap so that their strength is decreased making the lateral motion easier.
What I am asking is, if there is a formula that can be understood by a layman, to calculate how strong the resistance of the arm should be in proportion to it's mass. In other words, what is their ideal ratio?
Thanks in advance!
Ted
twl OP
3,251 posts
 
Ted, the needed lateral mass is relative to the compliance of the cartridge suspension. The lower the compliance(stiffer), the more lateral mass is needed for proper stabilization of the arm.
eldartford
4,262 posts
 
Low inertia is needed in the vertical plane so as to track warped records. But many records don't have the spindle hole placed exactly right, so there is some side-to-side arm motion, similar to warp but in the other plane. Your arm modification would make that problem worse.
twl OP
3,251 posts
 
Eldartford, any spindle centering problems cause quite slow moving variations in the tracking of the groove by the tonearm. This mod handles that with no trouble whatever. Any relatively slow movement of the arm in a side-to-side direction, can easily be managed, and are managed by a tonearm with this mod. A record with even 1/8" off-center hole punch will only vary by 1/4" over a full rotation, and it is spread out over the whole rotation. This is nothing that would cause a modded arm to have any trouble. The arm moves with the groove as it tracks toward the center of the record quite accurately, manages off-center records as well as that arm ever did without the mod, and makes sound better. I'd consider that a successful result. If the arm has a wildly off-center hole punch, I'd consider that a defective record, and I don't design my arms to handle defective records, to the detriment of their ability to play normal records better. You could also say that if a record has a warp like a potato chip, then an arm wouldn't handle it, but is that the fault of the record or the arm? Even so, my modded arm tracks off-center records like a champ.
basement
245 posts
 
I should be working instead of spending time here, but I can't help myself. Besides, I have had a lot of benifit and fun from the interest this thread has spurned, so I feel I should put in another 2 cents.
Thank you Mr. Rockonroni for mentioning your appreciation. Your description of how it effects how you can easier identify mistracting and setup is insightful. It is helpful that you mention such because besides the obvious advantage of being able to set up better, it is an indication that what is lost are likely distortions, and what is gained is likely more accurate. I should mention that my experience in that area mirrors yours; mistracting errors seem to be easier to identify for what they are, they seem to 'stick out' more obviously.
I think it worth mentioning that although I have not wieghed it, the mass the HIFI adds is closer to the immedia than without, (I say I haven't wieghed it but it is obvious enough it is not nessesary to know that), so the only issue would be the correlation between mass and sonic benifit, not any danger of excess wear or damage (or not functiong or tracking properly).
Furthermore, the sample I got (the only one I have used) came reamed out to fit one the ends, but not with any glue, and I fastened it by pressing it on, and did not use anything to help hold them. They fit pretty darn good at first, but one would occasionally fall off. As this continued they fit less secure. I then put more effort into 'cramming' them on and I noticed the sound improved. Perhaps there is a correlation with the fact that they are lead and right at the bearing, having some sort of damping effect, similar to other mods that have been succesful on rega's.
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