#1
Hey all, I've got a silly mod I wanna do to my fender frontman 15g, just because I have to keep my soldering up somehow. So I decided that I wanted to take the od channel on this thing and make a second clean, or at least less dirty channel. So I opened it up and said "aha, leds!" And removed them, because I've had amps in the past that used leds for clipping, figured I didn't have much to risk by removing them. Of course, I still have distortion on that channel, it was pretty much completely ineffective. What I saw next were three ic chips. Now I'm figuring this is where my clipping is coming from. My question is, is there anything else I should try to remove clipping, or am I stuck with it? Thanks ahead of time
I'm just a kickin' and a gougin' in the mud and the blood and the beer.
#3
Dang, taking them out did like, nothing. I'm guessing that the only other place to look is the ics?
I'm just a kickin' and a gougin' in the mud and the blood and the beer.
#4
I think you'll want to try raising the value of R15 and R22. I suggest waiting for a sure answer as I'm not a super expert like many of the other members here. But thats what I'd try if it were my own.
#5
leave R15, remove R23, and lower the value of, or jumper, R22 to bring the op amp closer to unity gain

EDIT: if you also replace the 4560 opamp for another TL072 it will clean things up a bit more
Epiphone Les Paul Plus Top
Jet City JCA5212RC (SLO Modded)
Ibanez WD7 Wah
Mad Professor Sweet Honey Overdrive
TC Electronic Flashback Triple Delay
TC Electronic Trinity Reverb
#6
Thanks guys, ill try it out next time I pick up some more parts, I don't have much in the way of electronics giblets since I gave a bunch of parts to my friends dad for a pedal build or 5 lol. Ill report back with results
I'm just a kickin' and a gougin' in the mud and the blood and the beer.
#7
So I'm back. Jumpered 22 removed 23, liked what I heard. Next step, sucking treble out, and adding bass if possible. I'm sorry to be asking to be spoonfed, but I still am in the developing stages of understanding amp design, why this works that doesn't and so on. Again I appreciate all the help guys, feel free to explain to me why something works, or not, I just know UG has a lot of good info., so fire away!
I'm just a kickin' and a gougin' in the mud and the blood and the beer.
#8
well, why the mod you already have done works was this: the resistance in the negative feedback loop (between the output and - input of an opamp) controls the gain, at zero resistance it operates at unity gain (ish, only the really expensive ones are that accurate) and as the resistance increases the gain does, which drives the rest of the opamps in the circuit harder causing the distortion you hear even without the clipping diodes. as for the less treble more bass, do you want that just on that channel or overall?
Epiphone Les Paul Plus Top
Jet City JCA5212RC (SLO Modded)
Ibanez WD7 Wah
Mad Professor Sweet Honey Overdrive
TC Electronic Flashback Triple Delay
TC Electronic Trinity Reverb