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Mystery OTL maybe??? (pic attached)

108.26.50.22

Posted on February 17, 2016 at 08:12:34
Rich Brkich
Dealer

Posts: 789
Location: Near Syracuse, New York
Joined: April 3, 2000
Contributor
  Since:
July 1, 1999



Customer sent me this pic of old used OTL amp he picked up. He says it looks like it is built in a computer type rack mount chassis....

Ralph (& fellow OTL fans), is this a Atma-Sphere unit???? Except for using a circuit board, it looks like a Atma-Sphere OT given the layout, use a 6AS7's...but I have not seen one before that looks like this.





Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison

 

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Its amazing where these things turn up., posted on February 17, 2016 at 09:18:00
Ralph
Manufacturer

Posts: 3214
Location: Minnesota
Joined: April 24, 2002
Contributor
  Since:
April 1, 2002
This is an amplifier that was built by a friend of mine, based on the early MA-1 circuit, but using 8 power tubes per channel. I'm pretty sure it runs series filaments.

If I remember right this amp was built as a one-off about 1985 or so.

 

RE: Its amazing where these things turn up., posted on February 17, 2016 at 10:54:04
AJ
Audiophile

Posts: 478
Joined: February 24, 2001
Contributor
  Since:
February 4, 2007
Quite a bit of skill there on the part of the builder for a "one-off"

Looks like nice work and a lot of resources and time put into the effort.



 

He hand-taped the circuit board but had it made at a local shop., posted on February 17, 2016 at 11:21:02
Ralph
Manufacturer

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Location: Minnesota
Joined: April 24, 2002
Contributor
  Since:
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He got some of the parts from us. The chassis was re-purposed.

 

RE: He hand-taped the circuit board but had it made at a local shop., posted on February 18, 2016 at 12:02:04
Lew
Audiophile

Posts: 8777
Location: Bethesda, Maryland
Joined: December 11, 2000
Looks like REL TFTF coupling caps in there, although from this view I am not sure. Were those available back then? Toroids are advanced as well.

 

I'm pretty sure it was not built with the Teflons; they were added about 15 years ago., posted on February 18, 2016 at 12:38:34
Ralph
Manufacturer

Posts: 3214
Location: Minnesota
Joined: April 24, 2002
Contributor
  Since:
April 1, 2002
But we've had the toroids going 'way back.

 

Yes, they are REL caps, posted on February 18, 2016 at 19:55:45
ruffian
Audiophile

Posts: 2
Location: nj
Joined: March 27, 2009



The chassis is undoubtedly from a 6U rack mount computer. It does have REL-CAPs in it. And it does say ATMA-SPHERE inside.

 

RE: Mystery OTL maybe??? (pic attached), posted on August 20, 2016 at 21:55:50
used-hifi
Audiophile

Posts: 481
Location: portage IN
Joined: March 18, 2003
Ralph, wonder if these were built by Fred Deviur that was close friends to Mr Robert Fulton
Fred had a recording studio in his house...but worked an engineering job at Honeywell



Lawrence

 

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