Simple mixer circuit?

Put a resistor in series with each channel and tie them to the PA amp input. Put another resistor from there to the common ground of both channels and the PA input ground. Use any convenient value in the 1-10K range for all 3 resistors. If you want to also reduce the level, make the input-to-ground value smaller.

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

On Fri, 16 Jan 2004 05:58:03 -0800, Bob Masta wrote (in article ):

Can the third resistor be a trim pot? This way it could be a level control.

Thanks,

Yes.

I read in sci.electronics.design that DaveC wrote (in ) about 'Simple mixer circuit?', on Fri, 16 Jan 2004:

Yes, it can. For consumer audio interfaces, the output source impedance can be as much as 2 kohms, so it would be best to avoid series resistors below 5 kohms or so, to prevent distortion.

Since you are just summing the two stereo channels, you don't need to consider what happens if one source is disconnected. But in the general case, if you disconnect one source, the level from the other source goes up. The lower you make the resistor to ground (the end-to-end resistance if it's a pot), the less increase you get, but the lower the normal output level.

Or if you dont need the level control, 2 resistors is fine, no need for the 3rd.

Regards, NT

In article , snipped-for-privacy@privacy.net mentioned...

You can use a simple "Y" cable from Rat Snack. Or I would put a couple 10k resistors on the back of a triple RCA jack. One resistor from each channel to the center pin of the middle jack, which goes to your PA.

It works perfectly with out it, it isnt needed. Its upto the in and output devices if theyre cap coupled or not, but either way it'll still work fine.

Regards, NT