Rabco SL-8E Linear Tonearm - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

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

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 Search this Thread
Old 16th July 2013, 06:54 PM   #1
diyAudio Member
 
Join Date: Dec 2006
Default Rabco SL-8E Linear Tonearm

In the old days the 60s and 70s, the Rabco was considered one of the best tonearms ever made. My Rabco is gone. I had my turntable and the Rabco shipped to me when I moved and both were damaged. That's life. Do you still have your Rabco? Please post your pictures and any mods you have done to it.
  Reply With Quote
Old 17th July 2013, 02:00 AM   #2
diyAudio Member
 
Join Date: Dec 2006
We need bear and his friend Al pictures of the Rabco, a radical upgraded mod with precision bearings, a light arm, and phototransistor.
  Reply With Quote
Old 18th July 2013, 01:01 AM   #3
diyrayk is offline diyrayk  United States
diyAudio Member
 
diyrayk's Avatar
 
Join Date: Aug 2012
Location: Dearborn, MI
Quote:
Originally Posted by audiostar View Post
In the old days the 60s and 70s, the Rabco was considered one of the best tonearms ever made. My Rabco is gone. I had my turntable and the Rabco shipped to me when I moved and both were damaged. That's life. Do you still have your Rabco? Please post your pictures and any mods you have done to it.
SL8E modified with low mass viscous damped unipivot arm and photoelectric variable speed servo drive.
Attached Images
File Type: jpg 1 IMG_3830.JPG (173.1 KB, 375 views)
File Type: jpg 2 IMG_3881.JPG (164.5 KB, 365 views)
File Type: jpg 3 IMG_3896.JPG (145.5 KB, 365 views)
File Type: jpg 4 IMG_3842.JPG (212.1 KB, 360 views)
File Type: jpg 5 IMG_3865.JPG (163.2 KB, 356 views)
  Reply With Quote
Old 18th July 2013, 04:04 AM   #4
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Hmmm... somebody call?

_-_-

I'd say that the Rabco has been bested by a range of other tonearms, even highly modified like Al's is, although his works very nicely and sounds excellently as well.
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 19th July 2013, 02:03 AM   #5
diyAudio Member
 
Join Date: Dec 2006
The old Rabco of the 60s is of course obsolete. But bear and your friend Al could make a new servo control built from scratch Rabco like tonearm. It would be a good exercise. An
updated and new 2013 version.
  Reply With Quote
Old 19th July 2013, 04:31 AM   #6
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
@audiostar, you don't have PM enabled... I think I know who you are but thought I'd ask to be sure.

Probably the weak link in an updated Rabco is the track + traverse mechanism. But oddly enough, as truly simplistic as it is, it does work ok. There are much more high precision methods to do the job. Goldmund did essentially this. For a lot of money.

Al's version uses the old "cats wisker" contacts to move the motor and traverse the carriage. This works out ok, probably the error is less than you get with a just slightly offset center LP. So, the tracking error is low, and lower than your better pivoted (non compensating) arm. Imperfect in theory, regardless.

My version used a lamp and a phototransistor circuit for proportional control of the motor. So, properly set the max error was less than the all or nothing contact method, and of course would tend to be rather fixed error for a record whose spiral was "faster" than normal (cut hot)
since the pivot offset of the arm to keep up would slightly more than a standard LP where the arm would have been set up to turn on the phototransistor just enough to continuously move the arm.

Maybe an ideal version would be a linear motor of some sort, or maybe a bi-directional motor with a nil-loss push-pull belt to drive it, so the arm could be set to track back-and-forth with an offset LP.

But there are so many slick arms and slick techniques today (not to mention just air bearings) for arms and tracking error correction that I doubt there is much of a market for an updated arm of this type. The price would be super-high to produce it as a precision product, I would expect.

Anyone want to sign up for the pre-sale roster??
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 22nd July 2013, 05:20 AM   #7
diyAudio Member
 
Join Date: Dec 2006
bear,
Thanks for your comments. I really liked the Rabco and I am disappointed that it is not feasible to build a new Rabco like tonearm. But there is an alternative to the Rabco. Please check out the thread here at diyAudio DIY linear tonearm started by vynuhl.addict. This is for a linear tonearm that is mechanical without a servo and no air bearing. Your expertise and knowledge would be welcome on the thread. Would like to see your version of a tonearm in regards to this thread.
  Reply With Quote
Old 26th July 2013, 02:41 AM   #8
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Well, it is quite feasible... but you have to do all the work.

A small machine shop would be quite sufficient.
Small lathe and mill.
Even those combo Chinese late/mini-mills would be sufficient, that and a source for the proper bits of metal... you could even transplant the gimbals and bearings from a standard tonearm assembly...

But as a product, that's a horse of a different color. That gets expensive quickly.
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 21st December 2013, 01:55 PM   #9
gvasale is offline gvasale  United States
diyAudio Member
 
Join Date: Dec 2013
Location: webster, ma.
I'd like to have some more details about repairing/updatig the sl8e. I've had one for years & it's not doing to well. Both servo motors are good, but it failed to track. It is somewhat disassembled, and the electronic assembly was certainly primitive. I have plenty of the 2n 3705 transistors.



Thanks
  Reply With Quote
Old 21st December 2013, 05:43 PM   #10
diyAudio Member
 
Join Date: Nov 2010
Location: Prescott, Arizona
Default Repair?

Quote:
Originally Posted by audiostar View Post
My Rabco is gone. I had my turntable and the Rabco shipped to me when I moved and both were damaged.
Hello audiostar,

Can't you rebuild the damaged Rabco?
Make a project of the effort and improve as you go.

Sincerely,

Ralf
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
SL-1200 Tonearm rewire 6L6 Analogue Source 8 11th May 2014 09:25 PM
Harman-Kardon Rabco linear-tracking turntable cyclecamper Analogue Source 1 18th April 2013 03:12 AM
Anyone wants to build or sell me a d.i.y tonearm for a technics sl-1200 murphythecat8 Swap Meet 2 19th July 2011 05:46 PM
Linear tracking tonearm vs. Pivoting tonearm Don Nebel Analogue Source 1 4th November 2007 10:49 PM
Rabco SL 8E transport noise audio-kraut Analogue Source 0 30th October 2004 03:11 AM


New To Site? Need Help?

All times are GMT. The time now is 10:06 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2