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Did you want MY voltage measurements?

71.178.165.184

In Reply to: RE: That is helpful posted by Penguin on April 05, 2015 at 10:21:35

Mine might not be relevant, because my amplifiers use the MA2 power supply, essentially, which mainly means that my input and driver stages run on ~+/-400VDC. Plus I have heavily modified my driver stage. But I don't think you meant that anyway. You've gotta measure your own amps to find out what's up, I am sure you know.

BTW, if you still own the Sound Lab, the marriage to Atma-sphere can be rescued. It's too detailed to describe here, but send me a private email and we can discuss. There are actually two solutions, one available from SL and the better one (IMO) available from another source (maybe). The latter allows you to eliminate the high pass filter in the SL crossover, i.e., to go no crossover. The crossover is the culprit that lowers the input Z across the midrange and sucks up amplifier power and generally makes life difficult for tube amplifiers.

Follow Ups:

I just need some pointers as to what is meaningful to measure - Penguin 07:37:16 04/06/15 (4)
a circuit diagram is the most definitive source for that. I really do not have the time nor the energy to trace it through, If push comes to shove the solution is to take it to a reputable repair shop...like Bill Thalman, let him futz with it. if i had a circuit then i could figure it out :). Or just give up and take it to Bill. If Ralph was driving distance this would not be a dilemma.

dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut
- schematic - Ralph 09:29:00 04/06/15 (3)
  You will find a schematic that is quite similar to your amp at the link below. The driver voltages will be nearly the same:
  
  Cathodes of V1 about 0.3V
  Plates of V2: about 175V
  Cathodes of V4: about -65V
  Plate of V4: about 275V
  
  B+ and B- are about 300V
  
  To get an idea of your power tubes take a look at this link
  
  If your power tubes are good it may be that some of the resistors in the output section have failed. In your amp the larger resistors on the power tube sockets are 1 ohm 5 watts. Some earlier versions have 3 watt resistors.
  - schematic on DIYaudio.com (Open in New Window)
  - Thank you - Penguin 20:08:01 04/06/15 (2)
    You are great :)...
    
    Thank you again.
    
    dee
    ;-D
    
    True terror is to wake up one morning and discover that your high school class is running the country.
    
    quote by Kurt Vonnegut
    - Follow up? - Lew 08:58:59 04/15/15 (1)
      Have you had time to evaluate the amplifier using the schematic? Have you identified the issue?
      Thanks.
      - on the stack of things.... - Penguin 09:05:00 04/15/15 (0)
        
        In Reply to: RE: Follow up? posted by Lew on April 15, 2015 at 08:58:59
        
        gardens took priority :(....Honeydo list expansion....
        
        dee
        ;-D
        True terror is to wake up one morning and discover that your high school class is running the country.
        
        quote by Kurt Vonnegut

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