DIY Schroeder Tonearm???

[bgruhn]

Originally posted by binspaul
Hello Bill,

Thanks for your guidance. Without your suggestions, I would have gone void. Farnell (www.farnell.com) is having a good stock of nylon rods. What is the best diameter for the bearing rod - 15mm/20 mm ? By the way, what is your suggestion on bearing guides ?

Still waiting for my neodymium magnets to arrive....

Best regards,
Bins.

Hello Bins,
Sorry to have taken so long to reply. I have been very busy with home improvement projects. I hope I am guessing correctly on the parts names you are using for the bearing assembly You say "bearing rod", I understand that to be "spindle". You say "bearing guides", I understand "sleeve" or "bushing" or "journal" as in Journal bearing.

If we are talking about the same parts, then I can answer your question with the dimensions I used on my TT. Nothing sacred here, I used these dimensions because they looked reasonable and were sizes of stock I had on hand.

1- Nylon rod diameter = 5/8"
2- Bearing rod diameter = 1/4"
> material = silver steel
3 - Bearing housing = Aluminium, diameter = 2" Not critical.

Next week I will draw a sketch and post it if you need to see something. I wonder if we should start a new topic?? This is way off the subject of Schroder tone arms.

BIll

[binspaul]

Hello Bill,

I think it is better to create a new thread. Can we use the following as the main bearing ? Please suggest.

http://export.farnell.com/jsp/search...equestid=33984

Why do we need to use the aluminium section in the tonearm (for the rear end where the magnets are attached) ? What advantage do we gain in doing so ? Is there any disadvantage if we use the wood for the entire tube ?

Regards,
Bins.

[bgruhn]

Originally posted by binspaul
Hello Bill,

I think it is better to create a new thread. Can we use the following as the main bearing ? Please suggest.

http://export.farnell.com/jsp/search...equestid=33984

Why do we need to use the aluminium section in the tonearm (for the rear end where the magnets are attached) ? What advantage do we gain in doing so ? Is there any disadvantage if we use the wood for the entire tube ?

Regards,
Bins.

Bins,

The chief reason I see for using the aluminium section in the tonearm is to make fabrication easier to do and more precise. (You
could design an all wooden model but it would look quite different from the typical Schroeder designs.) The aluminium section where the counterweight goes makes counterweight adjustment easier and there is much less chance of damage from locking screws. The thing to remember is that there is no ONE way of building the tone arm and that any given choice may require some modification somewhere else to compensate for some parameter that gets upset with the change.

Frank Schroeder mentions that his designs take advantage of EDDY CURRENTS for additional damping. I have not fully analyzed what is taking place here, but without the aluminium sections I think there would be no conductor material to allow Eddy Currents to be generated or to support the flow of such currents. This could be the single most important reason to use aluminium.

Best regards,

Bill

[berlinta]

Hi Bill,

"Frank Schroeder mentions that his designs take advantage of EDDY CURRENTS for additional damping. I have not fully analyzed what is taking place here, but without the aluminium sections I think there would be no conductor material to allow Eddy Currents to be generated or to support the flow of such currents. This could be the single most important reason to use aluminium. "

Right on the money...

I have built several arms with armwands made entirely out of ( a single piece of ) wood. Without special treatment, the end stub will "sink" or bend downwards over several years. Although the counterweight typically weighs only between 170 and 250gr, many woods cant take this constant bending pressure. The again, one can put a metal or Cf rod or screw through that section.

Counterweight impedance matching is another issue....

Have fun,

Frank

[Badge]

I have just started with this thread and construction of the arm. I first looked at the Well Tempered arm and bought materials for that build. I then switched to this one and decided to keep the arm the same. That is a carbon fiber tube. Once the wires are in place it will be filled with sand and sealed. I will probably fill the short length were the counter weight is located with a more dense ballast? Not as nice as a wood arm, but perhaps as good?

[binspaul]

Hi,

1. Do we need to fill the tonearm tube with sand or other damping materials ? How is it done in the original Schroeder version ? Will that increase to the overall arm weight ?

2. How did you implement the tonearm lift ?

Regards,
Bins.

[Jeffrey Davison]

Hey everyone....

For those that are building up their own DIY Schroeder tonearm... what length are you making yours?

I'm going back and forth between 9 and 12 inches. Both geometries are doable as I have yet to build a plinth for my deck. A 12 would be better sonically, but the longer tube has me thinking about potential long term arm warpage and a larger footprint for the plinth to take up. The wood I'm using is nice and stable, but being an instrument builder I know the potential is there, especially when seasonal humidity does it's thing, and it does get very humid in the summer and very dry in the winter in Atlanta Ga.

I'm starting to accumulate the raw materials right now.. I have a nice pieces of air dried Ebony 2" x 3" x 28" that I'll cut up and turn to make up a few arm tubes. I have some Vectran chord, even less strech and stronger than Kevlar, I have some N52 magnets and a Jelco arm lift.

This week I'll be sketching up some preliminary drawings. I'm armed with about 100 photos of all the DIY and genuine Schroeder ams. I have a compy of the patent and copies of the arms instruction manuals, plus links to a lot of forum threads about the arm.

I do have a background in musical instrument building and mechanical engineering and industrial design. This looks to be a fun project.

I'll eventually mount this arm on a Garrard 401.

Jeff Davison

[binspaul]

Hello Jeff,

Nice to see you also in the same direction. You can have a look at the suggestion made by Stew at: http://www.diyaudio.com/forums/showt...28#post1832428


Do post your ideas and observations as it will be really helpful for us also.

Best regards,
Bins.

[bgruhn]

Originally posted by binspaul
Hi,

1. Do we need to fill the tonearm tube with sand or other damping materials ? How is it done in the original Schroeder version ? Will that increase to the overall arm weight ?

2. How did you implement the tonearm lift ?

Regards,
Bins.

Bins,

1- I don't know if it is necessary to fill the arm tube with sand or anything else. All the arms I have built so far have been filled with very fine and dry sand right from the start. Will that increase the weight? Come on now, answer your own question.

2- I am still, at just a tad under 80 years, active in the repair and restoration of fine antique clocks. So I have extremely good fine muscle control and eyesight. So, I just pick it up and put it down where and when necessary.

Regards,

Bill

[binspaul]

Hi Bill,

That's nice, but risky. Sand will be having some amount of magnetic particles, right ? Are you using any process to filter that out ? What about chalk powder or wood dust ?

Can we use the dimension values given in the attached image for this implementation (at least some) ?



Regards,
Bins.