Bad quality sound

[ingrowing_whale]

Hello,

I've just finished building a LPB2 booster off the website www.generalguitargadgets.com and it boosts the volume ok but It also adds a buzz to the sound even when the boost is set to a lower volume than the normal signal. If I change the polarity of my DC power supply there isnt the sound anymore, but the volume isnt boosted anymore and you can only turn the volume down. I used Xicon 0.1uF capacitors. Could it be because of this? all the other parts are exactly the same as on the schematic.

whats the problem??

[calpolyengineer]

AFAIK the LPB2 and other boosters don't boost the volume, they just boost a specified frequency range (usually highs). As for that buzz problem, the only thing in there I see that could cause that would be the NPN. It might not be biased right, it could be a bad bipolar, it could be something else.

First, I suggest you follow aron's "what to do when it doesn't work" and post the voltages up here. There are many people in this forum who would be more than happy to help you out if you can give them enough info about the problem.

After you get all the voltages tested, I would swap in a new NPN to see what happens and/or put a 4.7k resistor in series with a 10k trim pot to replace R3. If the buzz goes away by adjusting this trimpot, then you had a biasing problem. You can then read off the resistance of the trimpot, add 4.7k, and that is your new R3 value.

Then again, it could always be something else in which case I will have to defer to a more experienced debugger.

-Joe