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So, I just put together a muff today on a Madbean Gruntbox board. Everything went well, bypass works as it should and the led lights up when the effect is engaged... BUT, the circuit isn't affecting the sound as it should- it sounds the same as if it were bypassed with just a tad bit more noise. Can any of you give me any pointers for getting this thing working?

Audio probe! If you haven't tried already?

Pictures are helpful too.

Just finished probing it and was not able to get any change in sound. I also plugged it in backward and had the same result, so somewhere the input is connecting directly to the output, but I cannot find where. I've quadruple checked all soldering joints and can't find anything amiss. I also hardwired the input and output directly to the board with the same results.
No camera on hand, so no pictures until tomorrow or the next day.

Skarrgus wrote:Just finished probing it and was not able to get any change in sound. I also plugged it in backward and had the same result, so somewhere the input is connecting directly to the output, but I cannot find where. I've quadruple checked all soldering joints and can't find anything amiss. I also hardwired the input and output directly to the board with the same results.
No camera on hand, so no pictures until tomorrow or the next day.

Double check the 3pdt switch because it would be pretty hard to get the input and output connected on the pcb. You could desolder the input and output wires to the pcb then you can check if the in and out are connected through the pcb with a DMM.
Opps should've read that properly.. then in that case it is the board somehow, that's really hard to check because it could be connected anywhere by wrong values or a solder bridge etc.

mysteriousj wrote:

Skarrgus wrote:Just finished probing it and was not able to get any change in sound. I also plugged it in backward and had the same result, so somewhere the input is connecting directly to the output, but I cannot find where. I've quadruple checked all soldering joints and can't find anything amiss. I also hardwired the input and output directly to the board with the same results.
No camera on hand, so no pictures until tomorrow or the next day.

Double check the 3pdt switch because it would be pretty hard to get the input and output connected on the pcb. You could desolder the input and output wires to the pcb then you can check if the in and out are connected through the pcb with a DMM.
Opps should've read that properly.. then in that case it is the board somehow, that's really hard to check because it could be connected anywhere by wrong values or a solder bridge etc.

Followed all parts values, and checked them, and they are all right. No solder bridges. Also desoldered and resoldered all iffy looking joints. Same issue. I'll try to get some photos up tonight.

Your transistors in the right way round? (always worth double checking the pin out with the datasheet)

plug the transistors into your transistor testing machine to find the correct BCE if you dont have a data sheet. also, do a continuity check with the probes on the input and output pads of the board with nothing connected to power or cables. and dont do it on a metal table either. if you have continuity 0 ohms then its probably a solder jumper. obviously the transistor is connected to the output cause thats where the noise would come from in a broken pedal. but pepsi is probably right, transistor pinout is most likely the obvious mistake that a lot of people make.

Pinouts checked and are all fine. 1096ohms on the multimeter when checking continuity.
Checked the voltages of the transistors and all were about the same:
B: ~0.6-7
C: ~4.5
E: 0.05

Your voltages are perfect... and you say you've ruled out the switch?

The switch is fine, I disconnected it to hardwire the jacks to the board with the same issue. I also rigged up the switch as a simple effects loop which worked perfectly.

Edit: Just tried another audio probing, this time with the input fixed and probing around with a wire connected to the amp. Regardless of which component I poked, it would pass signal.

this is a mystery haha . Okay so you have about 1kohms between input and output right? Does it vary if you change the volume pot? If it doesn't change when you adjust the volume pot then it means your short happens after the volume pot. Could the jacks be a problem?

Volume pot has no effect on the signal other than adjusting the amount of hiss.

fuck! i've just finished building my first muff too. and believe it or not I have the exact same problem. My volume pot works but it's a clean tone with some random noise/oscillations I'm doing mine on vero. I'll have a better look at it tomorrow when I have some time.. this is too funny.


EDIT: YESSS! Got it going. I was using a crappy printout and couldn't see some cuts . Once I made them it's great. post some photos of yours and i'll have a look if you're still having troulble

did you connect all the wires to the gain/sustain pot? maybe you didn't ground it?