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AC Booster (Quasar) Problem

Started by MullisMan, September 09, 2011, 02:28:40 PM

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MullisMan

I've taken the AC Booster schematic and breadboarded it, but I removed the input and output buffers.  I've verified the wiring and checked all my voltage levels, but I'm getting a very low output signal.  At full volume there's still a volume boost, but it's not like the actual AC Booster, which I own.  I've tried three different IC's, the 4558, TL072, and the OPA2134, and all have the same volume issue.  The tone stack works like it should, and I know that tone stacks can cause loss, but if the original works just fine why shouldn't this one?  I've included the schematic to show what i'm working with.  Any suggestions?

I can include voltage readings on the IC as well.

On pins 3 and 5 i'm getting 6.8 volts
Pin 8 I'm getting 9.46 volts
Pin 4 is 0
On the output pins and pins 2 and 6 I have 6.8 volts as well.



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mgwhit

You might need some kind of reference to ground on pin 2 of your IC.  Try putting a 10K shunt to ground in front of your C4.

MullisMan

Wouldn't that be for a non-inverting op amp configuration?  Since I have the virtual ground connected to Pin 3 I figured that wouldn't be needed.  That's also the way the actual AC Booster is connected.

mgwhit

Yeah, I think you're right.  I nearly broke my brain over what I thought was going to be a simple op amp breadboarding experiment a couple of weeks ago.  I finally just set it aside and spent the next few days boxing up some boards I had already finished just to chill out.  Good luck!