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Hi
I just got me a Crate FlexWave 65/112 combo amp. Despite being dirt cheap it sounds surprisingly good and “distortion”wise almost compares to my tube amps. However, being in pursuit of that perfect sound, I still wish to modify the distortion channels.
Here’s a link to the schematics: CRATE FLEXWAVE GUITAR AMP.PDF Service Manual free download, schematics, eeprom, repair info for electronics
Here’s what I’m unhappy with:
A - The overdrive channel has insufficient gain. It also sounds like the diode clipping after stage IC2-B occurs mostly in the lower frequencies. While the lower chords sound OK, as I play higher up the neck I can actually hear clean undistorted signal coming through.
B - The high gain channel has more than enough gain, but has the same problem with undistorted signal coming through. It’s less emphasized, actually barely audible, but it’s there and it bothers me. Both channels share that IC2-B stage.
C - The high gain channel has some sort of a low frequency boost around 600-800 Hz which is impossible to get rid of and ruins the sound. My guess is that this has something to do with the “Shape” filter circuit located after the tone stack and IC3-A. The “Shape” control is not active for the overdrive channel which sounds ok without it.
So far I’ve decided to short the Source and Drain of Q1 to provide some more gain for the overdrive channel and also to make the Shape control switcheable by installing a switch between the wiper of P3 and the Drain of Q7. Please comment on these mods.
I will also appreciate any suggestions for changes to that IC2-B stage. It looks like a very unusual circuit to me and I have no idea what exactly those diodes and Q6 and Q7 are doing. Same with the D3 and D4 zeners at IC2-A. Please HELP I just need to get rid of that clean signal
.
Thanks
I just got me a Crate FlexWave 65/112 combo amp. Despite being dirt cheap it sounds surprisingly good and “distortion”wise almost compares to my tube amps. However, being in pursuit of that perfect sound, I still wish to modify the distortion channels.
Here’s a link to the schematics: CRATE FLEXWAVE GUITAR AMP.PDF Service Manual free download, schematics, eeprom, repair info for electronics
Here’s what I’m unhappy with:
A - The overdrive channel has insufficient gain. It also sounds like the diode clipping after stage IC2-B occurs mostly in the lower frequencies. While the lower chords sound OK, as I play higher up the neck I can actually hear clean undistorted signal coming through.
B - The high gain channel has more than enough gain, but has the same problem with undistorted signal coming through. It’s less emphasized, actually barely audible, but it’s there and it bothers me. Both channels share that IC2-B stage.
C - The high gain channel has some sort of a low frequency boost around 600-800 Hz which is impossible to get rid of and ruins the sound. My guess is that this has something to do with the “Shape” filter circuit located after the tone stack and IC3-A. The “Shape” control is not active for the overdrive channel which sounds ok without it.
So far I’ve decided to short the Source and Drain of Q1 to provide some more gain for the overdrive channel and also to make the Shape control switcheable by installing a switch between the wiper of P3 and the Drain of Q7. Please comment on these mods.
I will also appreciate any suggestions for changes to that IC2-B stage. It looks like a very unusual circuit to me and I have no idea what exactly those diodes and Q6 and Q7 are doing. Same with the D3 and D4 zeners at IC2-A. Please HELP I just need to get rid of that clean signal
.Thanks