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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
zaikesman
3,017 posts
 
Just to keep things perking along here, while we wait for Twl's beta testers to ring in, I remembered a thought recently which first occurred to me quite some time ago, concerning the Dyna 'arm design discussed above.

I actually had this design idea come to me in a dream (talking now about separated pivot points for the horizontal and vertical components, with the vertical bearing being closer to the cartridge), believe it or not, but realized after I woke up that it was merely a variation on the Dynavector. However, this dream was not about the possibility of increasing the horizontal mass per se.

My dream was inspired by the idea of making such a design in order to greatly increase the tonearm length, for more correct tracing of the groove, and therefore lower distortion, by comensurately reducing the angle errors inherent in any pivoted 'arm, while still maintaining a low vertical mass. This remains a valid concept, but one which Dyna declines to exploit in their normal-length 'arm. One could conceivably employ this type of design to make an 'arm, say, 30" long (with the naturally increased horizontal mass that would come from such a long 'arm), and still achieve a low vertical moving mass by placing that bearing point at a more conventional distance from the cartridge. Such a design would address Twl's theory about higher horizontal mass, while offering tracing accuracy much closer to a linear-tracking 'arm. (It would also allow - indeed, require - the decoupling of the 'armbase from the plinth, something which carries with it both potential advantages and disadvantages, or at least inconveniences.)
twl OP
3,251 posts
 
That is an interesting concept Zaikesman. I would attack that in a high rigidity approach. Possibly like a wishbone suspension arm made of carbon fiber and wide spacing at the pivot area, and coming to a "V" at the forward area, where the bearing set for the vertically moving arm would be. The counterweight could then be located between the "V" arms, since there would be much less offset angle. In fact, if you could adjust the bearings close enough, you could use 2 unequal length vertically moving arms, and achieve a "automobile suspension" method of keeping the headshell level, even while tracking a warp. Eliminating VTA changes as it rides the warp. This increases complexity, but sounds like a cool idea.

Now if we could only come up with an idea that would allow us to play scratched records without clicking or skipping, we would really make a million.

Still no word from the Beta testers.
basement
245 posts
 
That is an interesting point. You have strange dreams. Do you ever have dreams where you take an rb-250, cut the armtube and put the lead between the two pieces to make it longer?
Actually, seriously, that is a good point. It makes me want to measure this all that much more. It doesn't seem like it would be too hard to measure the differences betwwen the amount of mass as far as their effect, but I am having limited succes learning how. I got a line on a occilascope, but it will have to wait a couple months. I also heard that you could get a computer program and an a/d converter, but I haven't checked that out.
It would be pretty easy to make an armboard, or make more/other appropriate parts I would think, For me I think the hard part would be figuring out how long to make it and figuring the placement of the mass. Actually, figuring out what exactly the mass is doing in a way that could be calculated.
nrchy's avatar
nrchy
2,124 posts
 
I have to agree with Tom's original statement about him being a little strange. I thought this idea was also a little strange, but since I've corresponded with TWL in the past and I have an arm with which this tweak would work, I contacted him and asked about it. I had to drive to his remote mountain hideout and kidnap some of his cats before he would agree to let me try his invention.
First I sat down and listened to an old favorite. Then I attatched the lead wieghts to my Rega RB 900 arm and sat down for a second run through the same LP. It was a MFSL lp which they claim is able to survive repeated listening. I'm still puzzled about how to explain what I heard the second time around. The strangest aspect of change was the fact that I had to turn down the volume on my pre-amp?!? By the time I was through the first two tracks the differences were more obvious. The soundstage was much different. It wasn't deeper in the sense that it went farther back but it came out farther toward the listening chair. I don't think the soundstage was wider than before but it seems to disipate more gradually. There appears to be more height too. I'm talking about inches not feet, but it's noticeable. And the air! There is much more air around voices and instruments. The LP I listened to had some good Grand Piano and bells. The first time through I noticed them but they were nothing special. The second time there was soo much more presense and authority to them. The bells actually startled me. I expected them, but I did not expect how *real* they were going to sound.
I know this sounds crazy. I'm having a hard time believing it, and I heard it!
TWL is on to something here. I don't know much about the technical aspects of this mod and I know nothing about how it would measure but I told you how it sounds. Go figure!

I have no idea how much the parts and labor would cost to produce this tweak for mass consumption, but for me to buy an arm that sounded that much better than my already good RB 900 would set me back well over $1000. If I could sell my arm for $500 I'd still have to come up with another $700 to $1000 for the better arm. If I could buy this tweak from TWL for $100 I'd be making out like a bandit!
zaikesman
3,017 posts
 
Actually, Nrchy, what Twl said was that he was 'a little different' (than what, I don't know); *You* said he was a little strange (but who am I to aurgue?). ;^)

I find it very interesting [Sorry to interupt, but y'know, whenever I see that phrase, 'very interesting', around here (and I use it a lot), I can't help but say it to myself in that faux-German voice Artie Johnson said it in on Laugh-In as he peered through the bushes with his binoculars. Do you think I have a problem? Or maybe I'm just...'a little strange'?] Uhmm, where was I - Oh yes, I find it very interesting that Nrchy and I have seemingly arrived at fairly divergent sonic assessments regarding the tweaks we enacted (I just went back up top to reread Twl's original post, but all he specifically remarks on is increased 'dynamics and detail'). This could lead one to believe that the two tweaks (horizontal mass-increase damping, and fluid damping) are really not that closely related in the ways which they operate. Thinking about it, I'm actually surprised no one has offered (to the best of my knowledge) a retrofittable fluid-damping kit for Rega 'arms, considering how ubiquitous the design is. Another market?

Twl, your idea about the VTA-correcting double-hinged 'arm, while not persuasive to me as such (wasn't it you who said something to me, someplace earlier up this thread, about not getting too complicated - besides, I'm still not convinced that a momentary VTA error of a few degrees during a warp is really a big deal), reminds me of another variation on this theme. I believe I remember a design, probably from the 70's, and probably not all that up-market (although I can't think of who actually may have made this for the life of me), wherein the headshell was hinged on a bearing permitting it to rotate in the horizontal plane, and a separately-pivoted (from the tonearm) 'control arm' was employed, not quite parallel to the tonearm but running alongside it on the outside and swivel-attached at the headshell, for constant correction of the headshell's offset angle as the tonearm moved across the record, through a slight 'parallelogram-ing' action. Anybody know what I'm talking about here ('cause I'm not at all certain that I do!)? I do agree, Twl, that something along the lines of a wishbone, truss, or I-beam design would have to be enlisted to make an extra-long tonearm as rigid and non-resonant as it would need to be.
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