SOLVED Another Electrovibe troubleshooting thread

[neiltheseal]

Hi everyone. I know this has been done to death but I couldn't find this issue in the other threads.

So I have build a clone of the electrovibe and everything seems to work well, except that the sound is extremely distorted. I suspect that this is an issue with biasing the transistors.

I did an audio probe and the distortion seems to be at around Q8. Does anybody have any tips for biasing the transistors here?

All of the pots work, the bulb flashes and the gain/bias trimpots affect the signal. I have chorus and vibrato mode working and the sound throbs, it's just that the signal is very distorted.

I also checked all of the resistors and they are the correct value (except for one that I had to replace but the issue persists).

Build docs are here. Any help would be appreciated.

Transistor Voltages are below if helpful:

Q15
C - 1.7
B - 1.3
E - 0.95

Q5
C - 4.1
B - 1.7-2.1
E - 1.5

Q6
C - 10.5-11
B - 4.1
E - 3.5

Q8
C -10-11
B - 4.2
E - 3.5

Q9
C - 14.5
B - 4.5-4.6
E - 4.2

Q10
C - 9.79
B - 7.4-7.6
E - 4.5-4.8

Q11
C - 14.2-14.7
B - 5.5-6
E - 5-5.5

 

[neiltheseal]

When comparing the Electrovibe to the Mad Bean Harbinger, I find it interesting that the electrovibe powers the transistors with 15v and the bulb with 18v, but the Harbinger does the opposite (transistors at 18v and bulb at 15v). Is there a reason for this?

I was hoping I could compare voltages to the madbean version but mine are way off due to the transistors taking power from 18v instead of 15v.

 

[neiltheseal]

This is solved. Voltage regulator was backwards. I'll leave this up incase others can learn from my willy mistake