Interesting DIY Tonearm

[pixpop]

A friend sent me these scans of a DIY tonearm project from Japan.

Pictures here

Looks like he's hoping to eliminate tracking error. Lot of parts, though.

Anyone here understand Japanese?

[guglielmope]

Very interesting design!
Anyone here understand Japanese?
Ciao
Guglielmo
Italy

[oshifis]

This design solved one problem and introduced several others.

[Nanook]

basically it looks like a better quality version of the Garrard tonearm. Said to have tracking error in the same range as a 5' (yup that's feet) tonearm.

The issues are mainly the requirement to pivot the headshell, and to do it while retaining zero play.

The Garrard arm's main weakness was the unequal (when compared) length to the actual tonearm "main" arm. I know I have one.

I think the concept has a lot of merit. Unfortunately I am not sure it can be realized without too many comprimises. I may try to modify my arm to improve the pivot bearing.

stew

[bambo]

Hi there,

now this is really great. The pseudo-tangential arms like those from alan william say (implemented on Garrard zero) or its original (?) the Burne-Jones arm. They just deserve to be copied. That means DIY or commercial! How come none of the k€ tonearm companies even try. It must be way easier to sell 'simple' designs for big complex sums And of course such a complex design CAN be executed really nice, also with regards to the pivots. Have a closer look at the impressive tangential (but passive and therefore silent) design from Micha Huber:
http://www.tonarm.ch/home_e.html
COOL, but costly. So DIY. I just wish I had studied some japanese. Untill then, I'll have to wait for someone real nice who will translate the article.

enjoy your favourite albums!
Mark

[jeff spall]

Originally posted by oshifis
This design solved one problem and introduced several others.

Yes. absolutely.
Just because an arm has no tracing error doesn't mean it's a linear tracking arm.

The huge difference is that a true linear tracker has the stylus forces always acting straght down the arm tube, fed into the bearing at right angles. Result, no bias forces and no changes with dynamic loading.

These arms will still both exhibit all of the bias (antiskate) problems of an ordinary arm because they still have (varying) offsets. Given that they introduce a lot of extra parts, joints, friction and mass into the equation I suspect the performance would be much worse in that respect than a normal pivoted arm.

[bambo]

Hi there,

sorry for me being a believer, but I don't see why "the design solved one problem, but introduced several others". I think it's the other way around, actually
And for the era concerned, the zero arm was, concidering the asking price, plenty good: Very short, stiff arm; Made of Berrylium (OOOOHH): strong and extremely light so that any rotational inertia objections are simply not valid. Further the design sports a very, very low tracking error. The patent describing the design (e.g. DE2121398A1) mentions an a tracking error of -64 arcseconds at the inner grooveradius. This is really low! And IF one gets all the pivots to work nicely (i.e. truely silent ) it can work true wonders.

Said to have tracking error in the same range as a 5' (yup that's feet) tonearm.

Well, Nanook, you are too humble. An error of -64 arcseconds at the inner useable radius (DIN norm just 57.5 mm at that time) would require a "conventional" (Baerwald protracted) tonearm having an effective length of 15.1 meters (SI). The romans (possibly some chinooks as well) would speak of 49.5 foot. Anyway, Nanook, your source lost one order of magnitude somewhere along the the line Now, if anyone out there can make such a long arm, rigidly and with less than 25 g effective mass, please give me a buzz. I am pretty sure a source of unobtainium would have been discovered in case anyone indeed could....

kind regards,
Mark

[Conrad Hoffman]

The more I study the battle of forces applied to a cantilever, the lower my opinion of offset pivoted arms. IMHO, tracking error is only part of the problem, and maybe not as large an issue as commonly believed. As Jeff says, the introduction of offset is what causes skating force. The Zero 100 arm is a pivoted arm with offset, so it's just not in the same category as a linear tracking arm. It's clever and neat, but it also introduces a lot of complication for what it accomplishes.

[jeff spall]

Hi Conrad, I believe you are thinking the same way that I am. How is that linear arm project going?

My big concern with these arms is that all of the energy needed to move the extra joints, pulleys, string(!) and the six extra bearings ( ) in that Burne-Jones design is being supplied by side force on the poor little cantilever.

Personally, I wouldn't want to trade a bit of tracing error for a huge increase in mass and friction.

[Conrad Hoffman]

When the weather gets warm I'm going to start cutting metal and experimenting, but I'm a bit frustrated. Like everyone who's come before, I can't solve all the problems in any one design. Arms are a nasty trade-off! I also find, in spite of any protestations to the contrary, I'm swayed by aesthetics. If a design looks "bad", I have trouble considering it, even if the math says it's the greatest thing since sliced bread. BTW, the things on your web site are brilliant! I'm surprised you don't already have a linear arm up there.