DIY Schroeder Tonearm???

[mgreene]

With all the recent talk about unipivots and such, has no one ever considered knocking off a magnet stabilized string pivot like the Schroeder? I have been considering a DIY arm just to add a mono cartridge to my TT. This implementation "looks" fairly simple Assuming you have a source of wood and carbon fibre, the only things slightly out of the ordinary are the neodium magnets, which are fairly ubiquitous on the web.

See pics and a review of the Schroeder's stuff at his website: http://www.schroeder-tonarme.de/

Mike

[Brett]

Originally posted by mgreene
With all the recent talk about unipivots and such, has no one ever considered knocking off a magnet stabilized string pivot like the Schroeder? I have been considering a DIY arm just to add a mono cartridge to my TT. This implementation "looks" fairly simple Assuming you have a source of wood and carbon fibre, the only things slightly out of the ordinary are the neodium magnets, which are fairly ubiquitous on the web.

I've thought about this too. It does look straightforward, and I have a spare tonearm mount on one of my TT's....
I'd try a carbonfibre arrowshaft as the tube.

I have a couple of other projects to finish first, but I'm very interested in doing a 12" version.

[CV]

Hi fellas,

It might *look* straightforward, but if you read the hifi+ interview with him (it may be available on his website), you'll see it's not quite simple; takes hours + hours to drill the tiny hole through the Nd magnet for instance. I wonder if drilling un- or demagnetised Nd and then charging the magnet would be easier.

Anyway, makes very interesting reading.

cheers

[mgreene]

Brett, CV,

I went to the archery store this weekend. A nice, good sized, carbon fiber shaft costs a wopping $5.

As to drilling the magnet, etc., - the interview is not on line where I can find it. CV - can you give us the technical gist of the interview?

Had a few more thoughts over the weekend. Might be possible to simplify construction and get a better result using misc parts such as various aftermarket upgrade parts (arm weights and VTA devices) for Rega and other arms.

Regards

Mike

[fdegrove]

Hi,

You guys think it's simple?

No way.

Keeping magnets in place around a pivot is not simple at all.

Moreover, all the energy from the catridge has to be drained by the shaft, you see it ain't all that simple since there is no other way to drain of spurious energy.

Not that I want to discourage anyone of course,

[CV]

Hi

...the interview in hifi+...

The Nd magnet is an extremely hard material; trying to drill a tiny hole in it and get rid of the swarf material (which is strongly attracted back to the block) is a nightmare. Took him about 8 hours to go a few mm IIRC...

Will try and dig out the magazine and see exactly what he had to say.

Why not try drilling a tiny hole in a cheap ferrite magnet and see how you get on with that?

cheers
cv

[fdegrove]

Hi,

CV,

No need to dig it up.
There's a scan of the article on Frank Schroeder's tonearm on his website.
See the link in the first post.

Thought I'd save you the trouble,

[mgreene]

Thanks CV. Something comes to mind - Schroeder is building with long term quality control in mind - I may be able to epoxy - if it eventually comes loose w/o destroying the cartridge it won't be a big deal.

Frank - Schroeder's interview is not included in the material on his website.

Mike

[mgreene]

So Frank,

What's the secret? It hadn't occured to me that the magnets could be unstable in this configuration - only a few thousandths apart.

Mike

[fdegrove]

Hi Mike,

What's the secret?

The problem as I see it is that the N/S relationship of two magnets is easlily disturbed when one is moved and the other held stable.
Surely you recall the force it takes to keep them in repelling position when held by hand?

This is a problem another German designer (it may even have been the same designer, I can't recall) faced with a similar offering about 15 years ago.

I really haven't got a clue how this one works, admittedly I only took a quick look at the pix on his site.
It seems to work well enough but untill I fully understand the design I'd better zip it.

Cheers,