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 Post subject: I need help identifying this phonograph tube amplifier
PostPosted: Oct Sun 18, 2020 2:32 am 
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Joined: Aug Tue 11, 2020 2:46 am
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This amplifier is in a Mitchell branded phonograph. There are literally no markings or numbers of any type on the machine or the amp, except for the faded number 26 stamped on it. There is 1 - 12AX7A tube and 2 50C5 tube 3


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 Post subject: Re: I need help identifying this phonograph tube amplifier
PostPosted: Oct Sun 18, 2020 2:50 am 
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Location: Tucson, Arizona U.S.A.
It's probably pretty generic. The schematic for any similar amplifier should be close enough. Check the back of RCA tube manuals for a sample circuit.

If what you want is the brand of the amplifier, if it came from a Mitchell phonograph, then the brand is Mitchell unless you can find evidence that it has been changed. This doesn't tell you who actually made it since it could have been custom labeled for the store that sold it.

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 Post subject: Re: I need help identifying this phonograph tube amplifier
PostPosted: Oct Sun 18, 2020 3:46 pm 
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Location: Detroit, MI USA
Some Mitchell products actually appear to have been built for them by Sonora, but that's not going to be much help either. Mitchell was a relatively small manufacturer in Chicago back in the day in comparison to the well known ones, and their products didn't appear to have been widely distributed like some of the bigger brands were.

As already noted, these units are very generic. Worst case, you sit down and draw the schematic by hand, which doesn't take long on something so simple.

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 Post subject: Re: I need help identifying this phonograph tube amplifier
PostPosted: Oct Sun 18, 2020 4:59 pm 
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Location: Mountains of Mourne. Ireland.
Random RCA three-tube amplifier service manual attached below.
12AX7A is "split-in-two" on the schematic for clarity. lol


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