buffer is cutting out - HELP!

[ninjadave7]

i built the amz opamp buffer and put a jrc4558 in it.  i'm running it at 18v off a y-split from a pp2 power supply.  when i hit the les paul hard the buffer cuts out and then fades back in.  nothing else is in the chain, what could be going on?  is 18v too much?

[ninjadave7]

amendment - it is not working, but only at 18v, not at 9v, at 9v it sounds like the power isn't even on... i'm mystified.

[John Lyons]

Voltages?

[petemoore]

I built the amz opamp buffer and put a jrc4558 in it.
  Dual opamp: pin 4=gnd., pin 8=V+.
I'm running it at 18v off a y-split from a pp2 power supply. 
  Sounds simple enough, have you measured V+ and a V_ from where the two floating voltages are connected [call that the midpoint or Vbias].
  when i hit the les paul hard the buffer cuts out and then fades back in. 
  Sounds like a problem tone, misbias to be more specific, the hard notes 'push' it into some semblance of 'bias' [that's stretching words but to express it].
   nothing else is in the chain, what could be going on?
  I would call it a problem or not working circuit.
  is 18v too much?
  I've never had a problem with it, but then I checked out the 'for whats' before applying voltage to components..every component I've purchased came with instructions, suggested reads. The DMM can generally tell you what the voltage at X position [X might be where a cap would be connected in a circuit], if not some contemplation or calculations can find the voltage that will appear there.
  the opamp data sheet say 40vdc max IIRC [check that for us would you?]
  For simplicity/safety sake simply make the capacitors ratings 10% or more greater than the reliable supply voltage applied to it. 16v would pop if it sees 18v.
  Never overvoltage the rating on a capacitor, add 10% to that for 'incase of'.
  The R's should be 1/4w, the diodes...have data sheets to, generally pretty sturdy...I don't recall studying every diode data sheet to be certain though, and don't know which diode if any I'm not referring to.
  That Debuggin' page is by far your best bet, what I typed above is based on missing content, whatever I said..it could easily be something else. 

[Paul Marossy]

amendment - it is not working, but only at 18v, not at 9v, at 9v it sounds like the power isn't even on... i'm mystified.

I'm confused. Do you mean it's working at 18V but not at 9V?

[ninjadave7]

yes, that is so baffling to me.  the y-split definitely delivers +/-18vdc on the meter, in response to the earlier post, and the buffer is fine at that voltage, but when i plug into a regular dc cable off the pp2, one that is known good and powers other pedals, the buffer sputters like it's not getting power.  both the caps are rated at least 25V so i know they aren't overpowered, and the resistors are 1/4w.  an rc4558 can handle 18v no prob.  i'm mystified.

[Paul Marossy]

Are you talking about the opamp buffer on this page? http://www.muzique.com/lab/buffers.htm

[ninjadave7]

yes, the one right below the initial opamp buffer, with voltage divider biasing.

[ninjadave7]

but i didn't have a tl071, so i used an rc4558 and just jumpered/cut so the pinout worked. 

[Paul Marossy]

but i didn't have a tl071, so i used an rc4558 and just jumpered/cut so the pinout worked. 

Did you double check your connections? Maybe you have something switched around on the inputs of the opamp.

[ninjadave7]

i tore it all apart and reassembled on a different board and it works now.  thanks for all your help!

[Paul Marossy]

i tore it all apart and reassembled on a different board and it works now.  thanks for all your help!

Cool. Yeah, sometimes that is what it takes to get something to work, you just have to start over. I've done it several times.