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Old 14th June 2012, 01:30 AM   #1
Einric is offline Einric  United States
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Default RCA Victrola 8V91

I have come across this RCA 8V91 in the local Good Will.
Does anybody have a radio museum membership that would post the schematic for me.
I think this is most likely a mono amplifier inside since there is only one speaker however there is 4 wires going to a round socket on the speaker frame before the OPT on the speaker frame.

They are only asking $59 for the whole unit and I was wondering if it would be worth re-purposing the internals.

Any Thoughts?
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Old 14th June 2012, 02:27 AM   #2
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Looks like an AM radio to me. Notice the tuning cap. on the left side of the photo.
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Old 14th June 2012, 03:01 AM   #3
Einric is offline Einric  United States
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Yes it has AM & FM along with a 78rpm player
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Old 14th June 2012, 01:39 PM   #4
Einric is offline Einric  United States
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I'm wondering if this is a 2 channel amp?
It has two 6V6GT's but the single speaker says 5W on it so that rules out PP operation.

Would these internals be suitable for a guitar amp in the event that it is mono operation?
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Old 14th June 2012, 03:47 PM   #5
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Here's the schematic.
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Old 14th June 2012, 04:51 PM   #6
Einric is offline Einric  United States
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Thanks Eddie, this is perfect.
It does look like a single channel operation.

I will study this schematic.
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Old 14th June 2012, 05:01 PM   #7
Einric is offline Einric  United States
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It appears that the two 6V6GT's are in parallel operation, am I correct?
However one is going to the top of the OPT and the other is to the bottom.
Sooooo.....is this some type of PP design?

Any technical impressions of this circuit if I were to re-purpose the amplifier into a guitar amp?
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Old 14th June 2012, 05:21 PM   #8
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They are operating in normal PP configuration. Ground any wire of the secondary of the output transformer to the moving coil. In case of OT short, a resistor/fuse will blown, but you reduce electrical shock risk. For a guitar. I believe you will need some preamp. AM detector usually place more than 1V across volume control.
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Old 14th June 2012, 05:31 PM   #9
Einric is offline Einric  United States
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I was thinking about building something like a Mono Aikido and tie it in at the T3 location bypassing the other stuff.
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Old 14th June 2012, 05:54 PM   #10
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Perhaps you can use the pentode section of the FI (6BA6/6AU6) as the audio preamplifier, rewiring it.
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