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741 op amp - offset null - why never used?

Started by lars, December 02, 2014, 01:49:43 AM

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lars

I've noticed that pretty much every guitar distortion pedal circuit I've seen that uses a 741 op-amp doesn't connect pins 1 and 5 for the offset null adjustment. Why is this? I recently breadboarded an ESR graphic fuzz and decided to hook up these pins (10k pot with wiper to ground). Oh, man, did this make the circuit do some crazy, interesting stuff! I could adjust it to get a gated fuzz very similar to an EHX micro synth, or I can get some weird raspy nintendo sounds. I would highly recommend adding this as an external control if you're building that circuit.
It would be interesting to see just how other vintage circuits would react by hooking these pins up (dod 250, dist+, Big Muff V4, etc.)

culturejam

I suspect it's not done much in pedals because it's not a well-documented thing to diddle with.  ;D

This is a pretty good explanation of what the offset null adjustment is for:
http://electronics.stackexchange.com/questions/55870/what-is-offset-null-in-ic-741

It's really not there to adjust audio parameters, so I suspect most circuit designers avoid it altogether since it is: 1) usually not necessary and 2) leaving off a pot or resistor reduces complexity and cost.
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