DIY Schroeder Tonearm???

[wolf_moses]

The Frank Schroeder tonearm patent was finally granted in the US in Oct 2006.

See below for link to the USPTO website.

You can view the pages of the patent one by one by clicking on the "Images" tab at the bottom of the page, though you have to download a plug-in called alternatiff for this option.



http://patft.uspto.gov/netacgi/nph-P...&RS=PN/7086071

[mclandy]

Hello!

Thanks to all discussing in detail and very substantiated about DIY Schroeder Tonearm. It was also your input, which helped to realize - after a year of unregular research, testing and build - my first DIY-Tonearm also making use of the Schroeder bearing.

If you want to have a look at the complete history and the final product, you might visit my homepage at
http://www.frank-landmesser.de/bau_tonarm.html
which is unfortunately only in German but on the other hand well pictured.

Greetings,
Frank

[MRupp]

Linked from your WEB site I found this so-called DIY site, which at a first glance appears to be selling a Schroeder clone?

http://www.musicallife.de/index.php?...emid=6&lang=en

I wonder whether this has been authorised by Frank Schroeder and - if not - whether this would not be an infringement of his patent rights

[krishu]

Hi,

this is a different kind of magnet bearing, so one could only argue about the visual similarities and the headshell design

Christian

[berlinta]

Hello MRupp,
The company Musical Life is not authorized to produce any "clones" of my arm, in fact, Mr. Fuchs(now affiliated with Musical Life) who is the "designer" of the magnetized ball bearing arm first sold very poor copies of a Reference arm via a german sales platform until I had to put an end to it.
Their current top arm utilizes a principle that was designed and briefly persued by the late Thomas Scheu and Dr. Feikert, then abandoned due to several serious flaws.
Since I didn't patent/register all of the design features - I didn't think of the headshell (and the overall appearance, worth a "Geschmacksmuster"), duh.. - it has been copied by Clearaudio and now Musical Life.
Although I admire Frank's efforts and understand that he is proud of his achievements, the link to Musical Life and the publication of construction drawings are not to my liking and I do consider having them withdrawn, in fact I will be kindly asking him to do just that.
And lastly, an arm built as per the drawing on Frank's page will exhibit unexceptably large changes in tracking force when one changes VTA.
But, most importantly, he likes it better than his previous(commercial) arm :-)

Greetings from Berlin,

Frank Schröder

p.s.: Starting tomorrow, I'll be attending the Munich HighEnd Show, so should there be any questions around this topic, please wait until I'm back(22nd)

[krishu]

Hello,

thanks for making that clear. Do you mean Walter Fuchs?

If VTF depends on VTA then warped records vary VTF (heavily!). This is the same behaviour as my first attempt to build a Schroeder clone showed. I had the opportunity to talk to Frank some time ago about this problem. He explained a bit and now I know that it is not easy if not impossible to make a Schroeder clone. We read a lot about Schroeder clones; I would rather call them tonearms inspired by the Schroeder design.

Cheers
Christian

Edit: I looked at the pictures on mclandys website and noticed that essential parts of the bearing are missing, not to speak about the geometry.

[berlinta]

Hallo Krishu,
Nein, der Name lautet Robert Fuchs.
Walter Fuchs hat genug eigene Ideen... ;-)

Grüße,

Frank

[krishu]

Aaaaaah, verstehe

The I guess I saw the copies some time ago but they were ugly

Gruß
Christian

[lesie ho]

GOOD!!!GOOD!!!

[krishu]

By the way:

Nordic Concept MK II, with NC Magnapivot tonearm

The Nordic Concept Magnapivot tonearm is made using the principle “Less is More”. Simplicity is important to make a product long lasting and easy to use. Materials are Delrin, chromed brass and carbon fibre. Internal wiring is silver.
The principle of bearing is a combination of a Kevlar wire, which by the way can hold 30kg, - and magnets. Below the midweight powerful static magnets are stabilizing and balancing the bearing.
On top of the tonearm two adjustment rings can be seen. The top one is used to adjust the gap between the magnets/VTA. The lower one is used to change the anti skating force.
The cunterweight is easily moved along the tonearm tube to ensure proper tracking force.
On the back of the player RCA and grounding cords are attached to the connector plinth.

Cheers
Christian