Fender M80 modification

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revgunn
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Joined: 28 Apr 2012, 07:20

Post by revgunn »

I've got a 1990 model Fender M80 Chorus 212 and an 89 Fender M80 112. Currently I have no extra income for buying gear so I need to fix what I have to use for a gigging amp.

The clean channel is great on both although the pots a a little scratchy on the 112. The OD channel is the problem.
I found some mods to use on another forum, and I wound up doing those to the 212. So far so good, it sounds a lot better.
( I made C11 .0047uf and I changed R26 and R27 to 10k I also changed the clipping diodes to switches, with SW1 being a red LED and a Yellow Led, and SW2 being 2 1n4001's and 2 1n34a's) The 1n34a's sound really good but I'm having a bit of a gated sounding decay at lower gain. And I need lower gain. I'm doing Classic and Southern Rock and some Country.

The 1n4001's are sounding really good at low gain with a bit of a mid boost to the clipping. I really like it.

I'd like to add a better tone stack, or get a bit more control over what's there. Its pretty basic, with only a Contour and Presence control.
The contour is a mid cut I think and the presence is treble, but its too high of a frequency now that I've changed that cap.

I want a Marshall type tone stack and those kind of EQ settings. I just don't know where to add them in to the existing circuit. I'm also not certain which cap to change the presence control in to something more usable. If someone could help me I'd really appreciate it.

Next, I need to install a switch to the headphone jack so it can be used for direct to the PA without turning off the speakers.

I've attached the schematic for the chorus amp. I'm trying to learn to read these and what is what but its slow going.
m80_chorus_sch.pdf
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