i have a very old Line6 Flextone amp, that doesnt really work to well, so i decided to try and modify it; this is the problem that has arisen.
1 ; i have no clue about circuitry, but im quite tech smart and able to catch on
2; id like to have my preamp bypass the effects , and amp models, basically have a basic preamp with a gain stage, 3 band eq, and bypass the rest, leaving the master volume, gain, bass mid treble, and channel volume,
no clue how id really do this , but if someone were able to offer a bit of advice it'd be greatly appreciated
Frankly, I am not the one here to even give advice on this matter at all. In fact, looking at this schematic kinda scares the crap out of me as far as any modifying anything at all. I will attach this file here that I found on the MEF website as it could prove to be helpful for others that might be able to help you. Good luck :)
The problem with such amps is that there's not much analog stuff inside (which you would be able to Mod).
They basically digitize guitar signal up front, feed it into a monster proprietary DSP with "secret" (for us) programming which does *everything* and just at the end they decode that back into analog and feed the power amp.
Lots of black magic in the middle where we have no access. :(
{Thanks Doc.}
Well basically, you can't.
What you have is a computer that receives the analogue guitar signal and turns it into a digital stream ("Audio ADC/DAC"). The computer (second sheet) reads the positions of the various controls as digital values ("Pots Floorboard ADC"), then applies those digital values to software algorithms in a Digital Signal Processor ("Audio DSP") ranging from simple (volume scaling) somewhat complex (tonestack/EQ) and mind bending (emulation). Having done all that in the digital domain it then converts the resulting digital value stream back into an analogue voltage again ("Audio ADC/DAC") which is then analogue amplified for the output.
If you are a very serious code hacker you could dump the contents of the TMS27C517 ROM and AK93C45AF EEPROM that contain the software (assuming that it isn't protected somehow, which I'll bet it is), dis-assemble it (a very major task), work out how it does its stuff (another major task), write new code for the SC80C31 CPU and TMS57070 DSP, re-assemble and test (a doddle after the above), and get it back into the computer somehow (the least of your problems).
I've done a fair bit of this sort of reverse engineering over the past forty-odd years and I wouldn't touch this with the proverbial barge pole. I'm not trying to be unkind but tell you truthfully where you stand - if you haven't worked out the above yourself you have absolutely no hope at all of modifying it. It's not so much an amp as a Single Board Computer, and as such it's a world away from banging a new card in a PC, or cutting some traces and adding some wire links, we are talking many hundreds of hours of skilled work.
You could leapfrog over the computer with a entire new analogue preamp, but seriously, if you want a different amp, sell this one and buy what you want.
Sorry I can't be more encouraging or help with this one.