OTL Asylum

OTL, Output Transformerless Amplifier User Group.

Return to OTL Asylum

Message Sort: Post Order or Asylum Reverse Threaded

I'm in for a big hurting....

24.141.114.174
Posted on February 6, 2023 at 18:31:05
AJ
Audiophile

Posts: 532
Joined: February 24, 2001









Picked up recently

Beveridge 2SW-1 speakers with the built in OTL amps in the base

The amps will need a lot of attention. The speakers and subwoofers are physically in excellent condition. The panels look good and measure well. Fingers crossed. One amp is painted black from the factory, the other natural aluminum. Circuitry is the same on the amp, driver, crossover and sub amp. I surmise something went poof at one point and a replacement amp was secured.

Also with the documentation is a 10 page instruction guide on replacing " blue resin rim transducers" for aluminum trim transducers dated October 15 ,1978.

Perhaps there was a fault or leakage with the bonding resin and the factory sent out new replacements-- I've never seen a pic of anything but aluminum trim transducers . This doc is fascinating Beveridge history.

This pair will add to my model III's which I converted to direct drive. I looked for 30 years for a pair of local Beveridges. Now I have 2 sets. LOL.

I am deciding on how or if I will approach the restoration myself- lots going on here and I have numerous unfinished projects sitting on the bench in a head of these .

I've spent the last week re-familiarizing myself with the circuit and sorting " in stock " parts vs. Ordering new.

This will take some time


 

Hide full thread outline!
    ...
RE: I'm in for a big hurting...., posted on February 7, 2023 at 04:14:52
rogerh113
Audiophile

Posts: 508
Location: San Francisco South Bay
Joined: October 20, 2014
 Nothing like finding something you have been a long time searching for. Likely it will be great fun and satisfying. I am guessing it will be moving up the priority list to the top....

 

Dust can be a major factor when dealing with high voltages, posted on February 9, 2023 at 12:21:45
Ralph
Manufacturer

Posts: 4778
Location: Minnesota
Joined: April 24, 2002
 So a good cleaning is probably in order.

Beyond that, change out all the electrolytic capacitors. Sitting does them no good and neither does age.

Looks like quite the project- good luck!!

 

RE: Dust can be a major factor when dealing with high voltages, posted on February 9, 2023 at 17:10:37
AJ
Audiophile

Posts: 532
Joined: February 24, 2001
 Thanks Ralph,

I have thoroughly cleaned them 2x and the dirt just keeps on coming!

3rd time will be the charm. Certainly, tracking from dirt and dust can cause fireworks easily in an amp like this. Just getting familiar with them as I collect parts.

I think in today's environment it would be tough to build something like this and not be concerned for safety to the end consumer and agencies. The interlock- such that it is - is pretty crude.

Even though I worked on Thryatrons and such - I have healthy respect for these things.


 

RE: I'm in for a big hurting...., posted on February 11, 2023 at 14:20:19
6bq5
Audiophile

Posts: 4392
Location: SF Bay
Joined: August 16, 2001
 Congratulations on the acquisition-
DM me and I can share with you some of the known issues regarding this speaker system and what service outlook looks like-
Did you get an RM 3 with this system?

Happy Listening

 

RE: I'm in for a big hurting...., posted on February 12, 2023 at 04:52:01
AJ
Audiophile

Posts: 532
Joined: February 24, 2001
 Thanks very much,

I will send you a note.

 

RE: I'm in for a big hurting...., posted on February 25, 2023 at 08:15:03
Baranyi
Audiophile

Posts: 359
Location: Midwest
Joined: January 11, 2005
Contributor
  Since: August 31, 2012
 The black amplifiers were very early and more typically used with the original model 2. The silver amplifiers were later and seen with the 2SW series. I actually have a silver amplifier that Harold Beveridge converted to use with a model 2 amplifier. Other than the solid state amplifiers that some had for the bass modules, the primary difference was the crossover in the amplifiers.

 

RE: I'm in for a big hurting...., posted on February 27, 2023 at 04:26:24
AJ
Audiophile

Posts: 532
Joined: February 24, 2001
 Thanks for this information.

The boards and component values for the amp, crossover and sub amp are identical.

The only difference is that the silver one has the fan servo board and the black anodized one does not but has the eq switch on the back. I think Modjeski called it "air more air."

 

RE: I'm in for a big hurting...., posted on March 1, 2023 at 16:34:50
Baranyi
Audiophile

Posts: 359
Location: Midwest
Joined: January 11, 2005
Contributor
  Since: August 31, 2012
 AJ,
The weak part of this design is the power transformers. I have had a number of amps that I bought with bad power transformer.

 

RE: I'm in for a big hurting...., posted on March 1, 2023 at 19:11:37
AJ
Audiophile

Posts: 532
Joined: February 24, 2001
 Baranyi

That would make them a practical door stop. Do you have the specs or did you have to use multiple off the shelf transformers to get things going?

Life got in the way here for a while. I will begin testing the transformers soon.

 

Page processed in 0.029 seconds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]