12 position rotary switch resistors value instead of 25k ohm rev log in API 312

[marconine]

Hello, I've just realized a couple of API 312 preamplifiers and I'd like to put a 12 positions rotary switch (with resistors) instead of the 25k Rev log pot required for gain control.

Can someone tell me what values should have the resistors?

Many thanks in advance

Marco

 

[ruffrecords]

Use one of the on line tools to work out the values for a log switched pot then simply wire them in reverse.

Better still, select the gain you want at each switch position, work out the value of resistor required from the API schematic. It is probably not a true rev log so you will gain the benefit of more accurate gain setting.

Cheers

Ian

 

[marconine]

Thank you

 

[Ricardus]

Better still, select the gain you want at each switch position, work out the value of resistor required from the API schematic.

Jeff has literally published the values right here:

https://capi-gear.com/catalog/images/build/VP25-26/VP25-VP26-Rev-C-PCB-BOM.pdf

 

[marconine]

Great, thank you!