2 Preamps on 1 PCB ?

[CaptainMorgan]

Hi, I am building a SS-Guitar amp and i want to build a very simple preamp for an AUX-Input to play with backing tracks. Can I put 2 preamps on 1 board and use the same power supply for both ? Or will the 2 preamps influence each other ? I thought I just take 2 inputs, and mix the signals together in 1 output, which goes in the poweramp.

 

[TANDBERGEREN]

Should not be any problems doing so.
Just check your cirquitry for common mode rejection.
High rejection is better.

 

[nigelwright7557]

So long as you have good decoupling and smoothing the power supplies shouldnt get any modulation of the audio on them.

Sometimes dual pre amps have RC decoupling on each supply to stop any modulation on the supply.

 

[JMFahey]

Since you are mixing them anyway, interaction is the least of your problems.
Plus the CD signal will have very little gain and will be mixed at high level practically at the Power Amp input, so ....
Go ahead, it's an easy task.

Have a look at the way others do it (Laney/Fender/Marshall/Peavey/etc.)