Plimsoul stage 2 is weak?

Started by alphadog808, December 10, 2013, 04:18:00 AM

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alphadog808

Hi guys,
  So I finished building a plimsoul clone from tagboard effects(so it's a vero) and it seems that the stage 2 knob(dual gang) doesn't do much.  From my understanding, it adds hard clipping to already soft clipping on the board(sustain). 

The hard clipping is done via 2 leds and when I turn the stage 2 knob up, the leds light up and get brighter due to plucking harder and/or turning the knob higher.  However, I don't really hear a big difference in gain.  I was testing under low volume, but it seemed that it maybe only added some brightness, if anything.  I notice that if I have the sustain set very low, the stage 2 barely does anything.

With all that being said, I have looked over the layout on the board and it looks ok, I've checked and sawed the board for solder bridges, no change.  I still have to go over the components again to make sure the right ones are being used.  Anyone have any thoughts where I might want to start checking to see why I'm not getting that extra boost from stage 2?  I've attached the vero and schematic below; I think the vero is based off this schem..

BTW, the stage 2 is a dual gang; I'm pretty sure it doesn't matter, but does it matter which pot set I use for stage A and stage B? 

Thanks in advance!




duck_arse

that dual pot is drawn so that one half increases as the other decreases, with lugs 2+3 short in the first, and lugs 1+2 short in the second. have you checked the wiring to the pot?
You hold the small basket while I strain the gnat.

alphadog808

Quote from: duck_arse on December 10, 2013, 09:40:35 AM
that dual pot is drawn so that one half increases as the other decreases, with lugs 2+3 short in the first, and lugs 1+2 short in the second. have you checked the wiring to the pot?
Hey Duck, thanks for the input.  I just double checked the dual pot wiring and it's fine...as long as it doesn't matter which gang is A and which is B(top or bottom gang).

dwmorrin

Do you have a scope to check the output of the second op amp?
The "Stage 2A" pot gives maximum gain when terminals 2&3 are connected.
If I didn't have a scope, I would disconnect terminal #3 of Stage 2B, to take the diode clipping out of the equation, and check that Stage 2A indeed increases the gain.
The benefit of the scope would be to see if, perhaps, you've already reached the maximum gain of that op amp stage... once it's fully clipped, it's not going to go beyond that, no matter the position of Stage 2A.
Maybe try turning the sustain down first, to verify the operation of Stage 2A.

alphadog808

Hmm.  No scope, but I can try your other test.  I was able to mess with it at louder volume today and the stage 2 does do something, maybe just not a pronounced as I would have guessed.  I need to retest tho, I thought about your last comment before you posted and I think if I keep the sustain low, the stage 2 doesn't do much; almost like there isn't enough signal for stage 2 to boost...thanks for the insight!