Paralooper Problems

[a soBer Newt]

Hello all I recently built up a moosapotomus paralooper It work just fine for about a min then slow fades away to static; I let it sit overnight and it worked again for a short period of time before fading away.  I am diving it with a signal generator at -60dB which about the same level as me tapping on the tip of the 1/4".  I used caps that I scavenged off a different project,could this slow "death" be caused by a bad cap most likely from overheating when desoldering?  Voltages seem to be just fine I will post them later to help with the debugging process.

Thank you all for your time.

[PRR]

> a bad cap

Yes; or missing resistor.

Voltage-checks working and not-working would be a path to understanding.

[a soBer Newt]

Thanks PRR, It was in input cap I replaced that and bang worked; I went ahead and replaced all the caps as to not worry about them going bad on me. 

I know this circuit is designed for bass players but the only filtering section that I can find is in the last gain stage, this is by observation of sweeping frequency up to 20k, I would like to adapt this circuit so that it would be able to go up to 20k I don't think that it C9 and R10 that are the filter but I could be wrong. 

Please point me in the right direction, I am trying to lean this stuff.

schematic http://moosapotamus.net/THINGS/paraloop/paralooperSCH.gif

[ubersam]

R6 & C5 form a low-pass filter with a cut-off around 1.5KHz. Lift C5 to let more treble through the clean side of the blend. C9 & R10 form a high-pass with a very low cut-off freq.

[a soBer Newt]

R6 & C5 form a low-pass filter with a cut-off around 1.5KHz. Lift C5 to let more treble through the clean side of the blend. C9 & R10 form a high-pass with a very low cut-off freq.

Thank you.
so should I just remove C5 or should I mod the circuit with a lower value cap and resistor to change the cutoff point?
I did some calculations 1nf and a 1k resistor would start the cut off frequency up around 15k and at that its very gradual. 

R13 severs as to drop the voltage to the output correct?

Thanks for everything!

[ubersam]

You're welcome

so should I just remove C5 or should I mod the circuit with a lower value cap and resistor to change the cutoff point?

That's up to you. Another idea is to connect C5 through a SPST so you can have the option of leaving it on or lifting it.

I did some calculations 1nf and a 1k resistor would start the cut off frequency up around 15k and at that its very gradual.

Actually, that would be 159KHz. A 1K R and 10nF C will give you a cut-off of 15.9KHz (which will be @ -3db, 20KHz will be roughly another -3 or -4 db below that)

R13 severs as to drop the voltage to the output correct?

Quoted from R.G's article here: http://geofex.com/circuits/what_are_all_those_parts_for.htm

"This same resistor isolates the opamp output from highly capacitive loads that could make the opamp unstable, and prevents overcurrents from damaging the opamp, if needed."

[a soBer Newt]

ubersam thank you so much I will read through RG's article several times and have questions for sure.