SOLVED Duck Box - TL072s making it squeal like a pig

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PangeaDestructor

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instead of quacking like a duck?

Hi All, I built the Duck Box and it came together really easy. I had TL072s on hand, so I dropped them in rather than waiting on 4558s, which I've generally found to just be the noisier version in my builds. It works, but the attack is so sensitive that even barely plucking a string causes it to sound like a dog's squeaky toy. Before I go pulling out those 072s, is the IC substitution the likely culprit here or should I be ok with that and look elsewhere?
 
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TL072 opamps are JFET input with a 13V/µs slew-rate. 4558 opamps are BJT input with a lower slew-rate of only 1.7V/µs. So I'd wager the higher slew-rate and much higher input impedance of the TL072s are the culprit. Get some 4558 dual opamps in there and I bet it'll clean right up.
 
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Cybercow said:
TL072 opamps are JFET input with a 13V/µs slew-rate. 4558 opamps are BJT input with a lower slew-rate of only 1.7V/µs. So I'd wager the higher slew-rate and much higher input impedance of the TL072s are the culprit. Get some 4558 dual opamps in there and I bet it'll clean right up.
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it's bothering me the the led suddenly isn't working. There's nothing about replacing those ICs that could have affected that, right? Problem has to be that I messed something else up while doing it?

I get 8-9v at the protection diode and on the anode led leg. I've never had to troubleshoot a non-working led, so any help on finding the source would be much appreciated.
 
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