DIY Schroeder Tonearm???

[dr.knibbeling]

Hello ,
I would like to start to build a nice tonarm and this thread has made me really enthousiastic.

Does anyone know the thickness (diameter) of the Palisander or ebony tonarm ?

In this way it is possible for me to 'calculate' the rest of the dimensions of the tonarm.

Thanks

[krishu]

Hi,

you can use any tonaerm pipe material and/or diameter; I'd say the most important thing considering size are the magnets/poleplates, everything else depends on these tiny parts.

Cheers
Christian.

[dr.knibbeling]

Hi Christian,

I understand.

What is your main reason to use 15 x 5 mm magnets instead of 10 x 5 .
The problem of 'hanging over' or difference in VTF increases with the increase of the diameter of the magnet. One small point would be ideal .
The bigger the diameter of the magnet , the critical will be the ajustment of parallelling the two magnets.

Dr. K

[krishu]

Hi,

we chose 15mm because of the power of the magnetic field. But I think 10mm is enough; the arguments you stated are worth thinking about.

Cheers
Christian.

[sigmapower]

This is my realization.

http://it.photos.groups.yahoo.com/gr...c=gr%26.view=t

[krishu]

Originally posted by sigmapower
This is my realization.

http://it.photos.groups.yahoo.com/gr...c=gr%26.view=t

Hello,

can you please put photos here; your link is a yahoo group; I don't want to become a member there.

Cheers
Christian.

[krishu]

Originally posted by krishu
Hi,

we chose 15mm because of the power of the magnetic field. But I think 10mm is enough; the arguments you stated are worth thinking about.

Cheers
Christian.

This was no good idea; The arm diod not work properly this way; we'll try a two-string arrangement later on, using magnets of minor diameter - maybe magnet balls.

Cheers
Christian.

[dr.knibbeling]

Hi Christian,

For me, the work is slowing it bit down.
I will start the arm late this year.
But I will follow this thread.

Magnetic balls are maybe not a bad idea. But I hope you have enough magnetic force to pull the arm.

dr. K.

[MJSM]

Hello All,

I have not visited the site for a while now and have not previously contributed to this thread, but wanted to do so now having built my own Schroeder look-alike.

See picture here

Before I go any further, I would like to say an enormous thank you to Frank Schroeder for the inspiration and for all of the help and encouragement I see him giving to this forum, not many designers/manufacturers would do that.

I have to admit that I basically reverse engineered my 'copy' by studying the reference design and 'guestimating' the dimensions based on 'known' elements such as headshells and cartridges, and then by trial and error. If you visit my website at Mynetplace you can see that there are two revisions of the arm bearing.

The whole thing started with a Goldring Lenco rebuild which, once completed, was begging for a decent arm to lift the performance up to what I reckoned it could aspire to. There are not too many options for the Lenco since the low platter height rules out many possibilities due to lack of VTA adjustment. Linn arms (almost any arm can be fitted) are good but tend to go for silly prices on Ebay, so having been outbid too many times to mention, I decided to 'bite the bullet' and try the Schroeder design for myself.

As can be seen from the photos, my arm differs substantially from the original 'Reference' in that the bearing assembly is mounted through the deck via the inner Pillar (as opposed to the outer one in the original). This is due to the fact that I wanted to retain the Lenco plinth (metalwork part) intact without hacking it to pieces. The original arm 'hole' is therefore utilised for the Schroeder arm by machining a pillar with two steps, one to prevent the bearing pillar from falling through the deck, and the other to support the bottom plate.

The outer pillar (brass) also has a step at the bottom to retain it above the lower bearing plate, together with three Allen 'grub' screws to retain it in position. The upper and lower plates, and the inner pillar are made from a material called Fortal which is basically a heat-treated Alluminium Alloy, it's a wonderful material for this type of thing as it is easy to machine and polishes up beautifully once completed.

I must admit that the Armwand itself was donated to me by a very generous forum member over on the Lencoland site, it is beautifully made out of four pieces of wood, ebony for the top and bottom, and Cocobollo (not sure about the spelling here) for the sides. The four piece construction neatly removes any need to drill a hole through the middle once the wood-turning is finished.

I am unsure of the strength of the magnets I have used as I bought them off Ebay, there are no holes in them as I dont use the magnet for securing the thread, instead, I run the 'spare' length back to the back-end of the arm and secure it with a rawlplug and screw !!!. This might sound crazy but it works well and allows the thread to be replaced very quickly and easily, a major design consideration in my book. The magnet in the arm is a press fit, 'secured' with locktite so that it can be removed if necessary for a thread change, the magnet in the bearing pillar is glued in with araldite. Magnet size is approximately 3/8" (approx 9.52mm) for both the top and bottom, thickness is about 6mm.

The counterweight was nearly too much for my little lathe (Emco Unimat 4) to handle due to the diameter (nearly 2" as I recall), such was the weight requirement. In the end I 'finished-off' the arm with a static counterweight (small one) and a larger moveable counterweight which seems to work fine.

I must admit to being disappointed at first but this was quickly resolved by adding a decent cartridge to the mix. The Benz L2 MC cartidge (I also splashed out and bought the matching Benz Lukashek PP1 phono stage) makes for a grin factor that I hope all analogue addicts can experience one day.

All in all, I am very pleased with my arm/deck combination, it was by no means cheap as I had to by a lathe and some other machine tools for the project (of course I still have them for use on something else ....) but it was a very gratifying experience to hear the end result after some 5 months of work and re-work.

Hope you like it .........

Mike
"Life is uncertain, eat dessert first"

[Paul Dimaline]

Very nice work Mike, have a virtual pat on the back!