What is function of two Qs in this pre?

[k brown]

What are Q102 and Q104 in this mic pre? - constant current sources for Q107/109?

 

[mhelin]

Yes

 

[k brown]

Thanks - never seen this in a compact mixer pre before (Yamaha MG10/2).

 

[JohnRoberts]

Yes the input devices have current sources feeding the emitters, but the negative feedback is only brought back to the collectors so the input devices are not held constant current by the NF loop. This topology can sound OK but will have measurably higher distortion than the popular Cohen topology.

JR

 

[Chandra]

Resistors 116 and 117 (10k, 10K) keep the CC emitters at -7.5 volts, which prevents the Q101 and Q103 emitter voltages reaching below -7.5 volts.
Regards.