Based on the documentation on the musikding website there is no R8 or C2. The link below has a pic from the website. I'm very new to electronics, I thought I was supposed to just leave those out. Was I supposed to jumper them or something?
I was wondering are those 0.1uF caps polarised? Both legs were the same length and there weren't any markings suggesting negative or positive.
The only other thing I can think of is the fact that the kit was missing one of the 560pF cap (C9), so I put a 470pF and a 100pF cap in parallel instead. I figured 570pF is close enough.
Ainm wrote:I was wondering are those 0.1uF caps polarised? Both legs were the same length and there weren't any markings suggesting negative or positive.
No. The circuit diagram shows polarised but the board has holes for either and the ones they supplied are non-polarised.
Progressive test. Make yourself an audio probe and find out where you're losing the signal.
Disconnect the output from the output jack. Solder a 0.1 uF cap and another piece of wire on to it to use as a probe while your amp is acting as an audio tracer.
Find an audio source for the input, obviously. If you have a synth this is no problem but you can use anything with a continous signal.
Compare the input and output for each transistor stage. All of them have some gain so generally the signal on the collector (marked c) should be louder than the signal on the base (middle pin).
1. Pot 1 pin 1 (red wire) should be louder than IN
2. As Q2 is a clipping stage the output is not necessarily going to be a lot louder but compare the base (middle pin) of Q2 with the collector (marked c). You should be able to turn down the input/sustain to a point where there's no distortion and the output should be noticeably louder.
3. Same applies for Q3 as for Q2
4. Compare the base of Q4 to the collector of Q3 to make sure you're not losing a lot through a problem in the tone circuit.
5. Compare the collector of Q4 to the base of Q4.
Where are you losing the signal?
Low tech version:
Use the "touching the end of the cable" technique of providing a signal source. Get a paper clip, straighten it a bit. Touch it to the various points in the circuit to see where you get an unexpected result.
