TomWaterman
Well-known member
Hi!
I want to implement an output volume control trim to my API style pres and although was told back at TT that a switched output pad would work, I have been looking at the Seventh Circle A12 schematics as this unit will implement an output control differently.
Schematic is here:
http://www.seventhcirclestudios.com/SCA/A12/docs/IO.pdf
I have a few questions concerning this layout....
The two resistors R15 and R16 (series 10k resistors) in the feedback loop? replace the single 20k as seen in the other schems like Fabios etc. Why is the second series resistor (R16) a trim pot? What benefit does this add to the circuit - trimming gain stabilization??
The output trim I'm guessing is the 10k trim pot (R19)?? Unfortunately I'm not understanding that part of the circuit very well.....can anyone help with an explanation of that, the use of the parallel diode and why that part of the circuit is connect to B+ and B- though 22k resistors, which I am presuming is the +- power rails??
Thanks for any help with this - sorry for the newbie questions...
Cheers Tom
I want to implement an output volume control trim to my API style pres and although was told back at TT that a switched output pad would work, I have been looking at the Seventh Circle A12 schematics as this unit will implement an output control differently.
Schematic is here:
http://www.seventhcirclestudios.com/SCA/A12/docs/IO.pdf
I have a few questions concerning this layout....
The two resistors R15 and R16 (series 10k resistors) in the feedback loop? replace the single 20k as seen in the other schems like Fabios etc. Why is the second series resistor (R16) a trim pot? What benefit does this add to the circuit - trimming gain stabilization??
The output trim I'm guessing is the 10k trim pot (R19)?? Unfortunately I'm not understanding that part of the circuit very well.....can anyone help with an explanation of that, the use of the parallel diode and why that part of the circuit is connect to B+ and B- though 22k resistors, which I am presuming is the +- power rails??
Thanks for any help with this - sorry for the newbie questions...
Cheers Tom