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Atma-sphere MA-1 Bias and DC offset adjustment (older model)

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Posted on October 1, 2016 at 10:21:24
kngo44@gmail.com
Audiophile

Posts: 4
Location: California
Joined: October 1, 2016
I have an older version of the MA-1 Amplifier with 5 6sn7 driver tubes and 12 6As7 output tubes (serial # 065). I can not find any information on Bias and DC offset adjustments. Please help. Ken

 

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RE: Atma-sphere MA-1 Bias and DC offset adjustment (older model), posted on October 1, 2016 at 10:26:35
kngo44@gmail.com
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Posts: 4
Location: California
Joined: October 1, 2016






Here are some pictures.

 

RE: Atma-sphere MA-1 Bias and DC offset adjustment (older model), posted on October 1, 2016 at 17:17:38
mcdonald43
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Posts: 160
Joined: November 21, 2009
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  Since:
January 14, 2010
Ralph should be here shortlty with the information you need...
They're way different than my MA-1's.

 

This amplifier is updated to what looks like some form of MkIII., posted on October 3, 2016 at 08:28:18
Ralph
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Posts: 3153
Location: Minnesota
Joined: April 24, 2002
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  Since:
April 1, 2002
-As a result the Bias is automatic. You only adjust the DC Offset.

Depress the Test button on the rear panel, adjust the DC Offset control for a zero ('0') reading on the meter. Do not do this when signal is applied as the meter can be easily damaged.

Check it again after 1 hour of operation.

That's it- pretty easy.

 

RE: This amplifier is updated to what looks like some form of MkIII., posted on October 3, 2016 at 08:57:30
kngo44@gmail.com
Audiophile

Posts: 4
Location: California
Joined: October 1, 2016
Hi Ralph,
From what you can see, could you tell me the history of this amplifier? Has it been updated? Thanks. Ken

 

That's what I'm saying., posted on October 3, 2016 at 10:33:05
Ralph
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Location: Minnesota
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Its a MkIII; beyond that I can't speculate without seeing what's inside.

 

RE: That's what I'm saying., posted on October 10, 2016 at 21:12:52
kngo44@gmail.com
Audiophile

Posts: 4
Location: California
Joined: October 1, 2016



Hi Ralph
Thank you for the instructions on setting dc offset. The amps are working well. I have another picture inside the amp for you to look at. Hopefully you can give me more info on the amps. ken

 

Yes- its Mk3.1 nt, posted on October 11, 2016 at 10:03:32
Ralph
Manufacturer

Posts: 3153
Location: Minnesota
Joined: April 24, 2002
Contributor
  Since:
April 1, 2002
-

 

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