Go Back   Home > Forums > >

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

DIY  Schroeder Tonearm???
DIY  Schroeder Tonearm???
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools
Old 26th April 2010, 07:14 AM   #501
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Renron: I think others have covered the brass/aluminium issue better than I can, but the essential for electrolytic corrosion is the electrolyte - in my case sweat. I can only assume that if you put the two parts together without getting sweat on them, there's less of a problem.

You can estimate the effective mass of a pick-up arm using f = 1/2*pi*sqrt(m*c). Where f is the subsonic resonant frequency (found using the test record), m is the effective mass, c is the compliance of the cartridge. Usually, you don't know the compliance of the cartridge, so you have to do two tests, one with an extra mass perhaps (15g) stuck to the headshell (and balanced out), and solve the two equations simultaneously to extract the effective mass of the arm. Frankly, I've never done it. As you've pointed out, a low compliance cartridge needs a high mass arm and vice versa.

As it happens, I have a Denon DL103 and am thinking that what it needs is a brass body (to get the effective mass up). But that would cause problems going onto the aluminium headshell.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 26th April 2010, 08:53 PM   #502
Renron is offline Renron  United States
diyAudio Member
 
Renron's Avatar
 
Join Date: Jan 2007
Location: Sacramento
EC8010,
I did a bit of research yesterday on galvanic corrosion between dissimilar metals. What I found was very interesting.

Ya' know, you just never know where a project will lead you, and the seemingly unrelated facts you'll learn.

Here is a text and chart of reactionary values of dissimilar metals.
Added moisture aids the galvanic process, ie; sweat, humidity or worse yet acid environments.

Only sure way is to prevent continuity. I'm going to use one of these as a gasket between the tower pieces and the gallows arm.

Ron
Attached Images
File Type: png Galvanic text.png (65.6 KB, 1330 views)
File Type: png Galvanic table.png (70.8 KB, 1298 views)
File Type: jpg gasket 001.JPG (66.0 KB, 1288 views)
__________________
"If it doesn't work properly, hope it catches on fire"- Nelson Pass @ BA3
"I fired up the prototype. Literally." The Prophet Pass.
  Reply With Quote
Old 27th April 2010, 12:18 AM   #503
Renron is offline Renron  United States
diyAudio Member
 
Renron's Avatar
 
Join Date: Jan 2007
Location: Sacramento
Going off on a tangent here, but, Zinc Phosphate, which I use as a conversion coating on aluminum prior to powder coating has a fantastic side benifit. It's dielectric as well as a corrosion prohibitor! I'll try it out and see if it works on polished surfaces of aluminum and brass. Easier to detect any etching if it's polished first. Once again, just thinking out loud.

Ron
__________________
"If it doesn't work properly, hope it catches on fire"- Nelson Pass @ BA3
"I fired up the prototype. Literally." The Prophet Pass.
  Reply With Quote
Old 28th April 2010, 07:52 AM   #504
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Yes, I have a table like that in a book I bought when I was a kid. Your insulating sheet should work fine. I suspect that your zinc phosphate idea will depend heavily on how good your finish is (surface projections will punch through).
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 7th May 2010, 04:42 PM   #505
Jeffrey Davison is offline Jeffrey Davison  United States
diyAudio Member
 
Join Date: Sep 2006
figured it was time for a bump.....

bump
  Reply With Quote
Old 11th May 2010, 03:12 AM   #506
binspaul is offline binspaul  India
diyAudio Member
 
binspaul's Avatar
 
Join Date: Feb 2009
Location: Cochin, Kerala, India
DIY  Schroeder Tonearm???
Hi JD,

Happy to see you are still following this thread. I was busy with my phono stage and mono blocks project. Some of the parts of my tonearm is still pending delivery and so I am patiently waiting....

Best regards,
Bins.
  Reply With Quote
Old 11th May 2010, 10:15 AM   #507
westend is offline westend  United States
diyAudio Member
 
Join Date: Jul 2005
Location: shorewood
For any brass to dissimilar metal joints, PTFE thread compound is cheap and effective. Neversieze is an old favorite, too.
  Reply With Quote
Old 11th May 2010, 05:14 PM   #508
Renron is offline Renron  United States
diyAudio Member
 
Renron's Avatar
 
Join Date: Jan 2007
Location: Sacramento
Jeff,
How did you calculate the length of the gallows arm(s)?
Does it matter?
The only thing I can think of where it could be a problem is if it's too short, the counterweight would bump the arm.

Almost finished with my mechanical drawing to give to the machine shop. I still can't believe how detailed and complicated this is.............it looks so simple at first glance.
Ron
__________________
"If it doesn't work properly, hope it catches on fire"- Nelson Pass @ BA3
"I fired up the prototype. Literally." The Prophet Pass.
  Reply With Quote
Old 12th May 2010, 03:48 AM   #509
Jeffrey Davison is offline Jeffrey Davison  United States
diyAudio Member
 
Join Date: Sep 2006
The arm was a co-development with the plinth I was building for my Garrard 401. I laid out various configurations of arm length and geometries and ended up desciding on a 10 1/2" effective length arm. I decided the dimensions of the plinth and where I wanted to place the arm to get the length and width of the plinth to what I was after as far as size

From there I simply drew up the arm components to accomadate travel across the record and clearances of the components during arm travel at the same time keeping in mind the original layout and intent of the Schroeder Reference arm.
Not really that complex if you break it down to the individual components. Of course there was a lot of trial and error developing the final drawings.

You have to look at the arm in 3 dimensions, (or at least conceptualize it) and keep in mind what everything is doing in relationship to each other.

For example...the plinth and turnatable you are going to use to be able to see how much adjustabiltiy you need to design in. I gave myself a range to be able to dial it in once built. a byproduct of this is to let me put the arm on different tables if I so choose.
If you look at the attached drawing, you can see the arm at rest position and at full swing. I then designed the bas and arm to accomodate this movement. The arm geomerty came first, then the rest of the support componets came after.

JD
Attached Images
File Type: jpg plinth.jpg (104.4 KB, 1141 views)
File Type: jpg side view.jpg (88.7 KB, 1133 views)

Last edited by Jeffrey Davison; 12th May 2010 at 03:53 AM.
  Reply With Quote
Old 12th May 2010, 01:15 PM   #510
Renron is offline Renron  United States
diyAudio Member
 
Renron's Avatar
 
Join Date: Jan 2007
Location: Sacramento
JD,

Thank You, very detailed without being prescribed. As usual.
Your CAD drawings are superb, and a work of art in themselves. The gallows length is, as I would have guessed, variable. Depending upon it's relationship to the platter. I cannot foresee any issues with being too long, perhaps vibration? Probably not.
It occurred to me, that unlike most TT arms, this one needs to be located on the axis of the string / magnet point rather than the center of the tower platform. Something to keep in mind when drilling a hole in the plinthe ........................ this rabbit hole keeps getting deeper and deeper........LOL.
Wifee and I are going to see Alice in 3D today, hence the rabbit reference.

Ron
__________________
"If it doesn't work properly, hope it catches on fire"- Nelson Pass @ BA3
"I fired up the prototype. Literally." The Prophet Pass.
  Reply With Quote

Reply


DIY  Schroeder Tonearm???Hide this!Advertise here!
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Linear tracking tonearm vs. Pivoting tonearm Don Nebel Analogue Source 5 31st May 2015 03:55 AM
My DIY Turntables and Schroeder based tonearm konstantin Analogue Source 24 26th March 2010 05:35 AM
DIY Schroeder "Clone" Capt Zach Analogue Source 18 3rd March 2006 06:57 PM


New To Site? Need Help?

All times are GMT. The time now is 08:26 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki