[sdiy] The TL072

[Ingo Debus]

Am 20.02.2009 um 17:54 schrieb Altitude:

> The reason I am focusing in on the mix amp is when I tap the  
> individual
> outs, the SNR is quite good but the mixed outs have a substantial  
> amount of
> noise.  Should I be looking elsewhere for the source?  There really  
> is not
> too much in the signal path

It depends on how many inputs the summing amplifier has. Even if the  
gain for each input is low, the noise gain can be pretty high if  
there are many inputs.

I once replaced the opamp in the summing amp in my DIY 12 input mixer  
(5534 vs TL072) and got noticably less noise. The summing amp has a  
gain of only 1 for each input, but with 12 inputs the noise gain is 13.

Ingo