DIY Schroeder Tonearm???

[Jax]

I have always wonderd, why bend the arm? Is there any reasonable explanation as to why some arms are bent?

Of the TT's I have owned, only one had an S-shaped arm, the AR. I also had an ERA with a straight arm. I could not hear any difference in tracking between these two. But that was long ago, around 1985 when I went digital and stayed digital until last Friday. I could no longer look at my old collection of vinyl unplayed for almost 20 years.

So I bought a Pro-ject 1 Xpression. It came with a straight carbon-fibre arm and an Audio Technica AT-95 installed. I thought I would find a good cartridge later.

I'm deeply impressed with this TT, even with the AT-95. It can play my most warped record. None of my others could. It has to be the lightweight carbon-fibre arm. My reasoning would be that an S-shaped arm would have a higher moment of inertia while a straight has the lowest possible.

Geometrically, none of the arm shapes track better than the other but the straight will have a lower inertia.

Maybe I should do something with the old AR like a new arm? I no longer have the ERA unfortunately.

[krishu]

Hello,

we made draweings before machining, of course. I some time i will publish the most important ones on my site www.krishu.de

so far, there are only pictures.

But I think it really is not necessary to have drawings. What is so difficult to think about? There is not just one proper solution. Everyone of you might have seen a tonearm so he/She can imagine, which diameter, length of pipe etc. can be used. Size and shape of magnets has been discussed here before. Weight and Size of counterweights can be figured out ... and apart from all that: we ourselves just thought and tried, but did NOT simply copy. So there may be mistakes or less good details in our solution. Would you like to copy them as well?

Cheers

Christian.

[Magura]

Nope, i have no intentions to copy your tonearm, but sure intend to copy the good parts of any tonearm. Thats the way to get forward. If we all went back to the invention of the wheel every time we did something, we sure would end up with something close to stagnation.

The point of what i wrote was to make this a group effort. Since the goal is more or less the same for all of us.

Cheers

Magura

[krishu]

Hello Magura*,

I think I see the point.

But we have rarely something to show which can not clearly be seen anywhere. What is interesting is the source of magnets, strings etc. This has been discussed exactly here.

Apart from that I don't refuse to show my drawings. As I hope I said before, I will publish them on my website within next weeks/months. First, I have to edit them.

The most knowledge considering special schroeder tonearm topics I got from the Patent, which obviously and unfortunaltely is only available in German. There is enough description about materials etc.

Apart from that Schroeder specific things you can look anywhere for senceful tonearm pipe, hedshell, counterweight etc. shapes and materials a.s.o.

We used a carbon pipe of 1/2" diameter, stuffed with balsa wood. The rest is mainly bronce, the magnets are 15×5mm N50 neodymium, the "polplatten" are steel and the same dimensions.

Cheers
Christian.









*does that mean the breaks company Gustav Magenwirth Bad Urach?

[Magura]

Originally posted by krishu
Hello Magura*,





*does that mean the breaks company Gustav Magenwirth Bad Urach?

Yes it does...as in the brake people


Do you have a link to the patent?

Im doing ok in german, so i guess it would be fine goodnight reading.

Why did you use such a big carbon tube? Wouldnt 8 or 10 mm be plenty?



Cheers


Magura

[krishu]

Hello magura,

you can find the link in this thread as well as on my website.

Patent

I did use 12mm pipe because i used it for my unipivot before and because some others use it (e.g. Clearaudio, we call it Klirraudio here ). It is not really heavier that 10 mm pipe but much stiffer. But one has to dampen it, we will do that using balsa wood.

Frank schroeder suggests different wood types as e.g. ebony, which is available from Thomas Scheu www.scheu-analogue.com for example.

Cheers
Christian.

[AuroraB]

Wouldn't self expanding PU foam be enough damping ???

Inserting a welding rod before it cures would give enough space to pull the wires through.....

[fdegrove]

Hi,

Inserting a welding rod before it cures would give enough space to pull the wires through.....

But would also cure the wires whithin...

Cheers,

[AuroraB]

There is no problem in removing the rod after curing...
coat it with vaseline or similar, and give it a few twists after curing.....
A thin plastic tube, straw or similar, with a rod inside for strength during placing, is another possibility.....

Actually, -I am very interested in this thread,--
sometime ago I finished the bearing for a Teres,- with good result, and is now planning for a plinth. I have several pieces of heavy 50 mm MDF, but I wanted to something better. Just struck a deal with a guy running a water jet cutting plant for corian, and also PVC, which will probably end as a laminate of PVC and alu for the platter.

[krishu]

Yes, there are many ways to dampen the carbon pipe. We chose the balsa wood one because of its simplicity.

Cheers
Christian.