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lafayette pa 622 -> Guitar amp conversion
lafayette pa 622 -> Guitar amp conversion
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Old 1st August 2013, 01:18 AM   #1
dsulliv5 is offline dsulliv5
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Join Date: Jul 2013
Default lafayette pa 622 -> Guitar amp conversion

Hi good folks of diyAudio - I have been lurking about for a while enjoying the goings on about the joys of working on simple amplifier circuits. I scored a 1969 Lafayette PA amp in working condition the other day and want to make it into a decent guitar amp. It already has a 1/4" input jack and handles a guitar signal pretty well. It just needs some improvements to become a respectable guitar amp.
See schematic lafayette-pa622a-schematic.jpg

The first thing I want to do is remove the two aux-ins and the common volume control for the two aux inputs. It appears to generate a lot of noise. This vol control is in addition to the 'mic' vol control so it is redundant for my purposes. In the photo the 'mic' volume is on the right and the shared volume (CCW from 12:00 turns aux 1 up, CW from 12:00 turns aux 2 up) is on the left. Can I disconnect the cap and resistor from the top of the shared volume pot and connect it to the lead that comes out of the bottom of the shared pot, thereby bypassing the aux input vol?

there is also a single tone control which I would bypass if I had any idea what that would do to the circuit as well. It has a .02 cap on it and I believe it is a 1 Meg pot. So perhaps I should improve it before removing it completely. Any ideas about how to improve the tone?
The amp already has lots of gain - probably from the 6AV6, but I don't even know what that is doing although it looks like it is being used as the PI.

Anyway - any guidance would be appreciated.
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Old 1st August 2013, 03:05 PM   #2
DF96 is online now DF96  England
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Instruments and Amps forum?
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