Simple Output Attenuation Help

[chriscool]

I built a tube screamer kit some time ago and since using it with my new guitar the stomp box output is very sensitive. It's pretty much always to loud. I need to very simply add a voltage divider to the effect return inside the box. Something like -6dB. I could use some help with figuring out the values. I gotta play on a radio show tomorrow and only have enough time to run to Radioshack and grab a couple of resistors. Any help would be great. Thanks.

[midwayfair]

Chances are you already have the resistors in place necessary to accomplish this.



That 10K emitter resistor and Rb (and I guess the output pull-down resistor) form a voltage divider. I've always found it a little weird that they bothered with an output buffer and then slapped 100K on the output anyway. I mean, doesn't that just make the output impedance the same as the volume pot before the buffer? Anyway, you can increase Rb, decrease the 10K (try 1K), or you can also increase the 1K in front of the volume pot.

[chriscool]

Thank ypu for your reply. It is a replica kit from General Guitar Gadjets so I am not sure if it's completely the same. I don't have the time to take it all a part and replace a resistor. I just want to splice in a voltage divider from the effects send wire that goes to the 3pdt switch. -6dB 2 resistors?

[GibsonGM]

Ain't quite the way to do it, but it could work for you in a pinch. I haven't run the calcs for direct dB conversion, but -3db is half power, which I'm shooting for here.  -6 dB is half of the half we just cut, ha ha...never mind.  This should give you more control with the volume pot.

Try running the signal through a 1k resistor...right after it, place a 1k to ground.   That will cut your signal a little less than half.

If that's not enough, you can go 1K > 680 ohm to ground, and so on.   The 680 will cut a little more than half. 

Consequences may be a change in tone....loss of highs. You can 'jumper' the 1k with a bypass cap (anywhere from 100pF to .1u, have to experiment) to bring back the highs...there are a dozen ways to do this, but this may in fact work for ya.

let us know if this works!