API 312 gain Pot

[ilfungo]

Hi
I want to build a API 312 Stepped gain pot (25k rev log)
I've serched anywhere ut I can't find any info about,
could someone help me?
Thanks!!!

 

[CJ]

those amps have a sweet spot for best tone and least noise.

to find it, put a pot in the feedback path and listen.

then replace with fixed resistor and pad the front end.

 

[ilfungo]

Thanks CJ
I must replace R3 20 k with pot?
And after attenuate the input signal ( t pad could work?)
thanks!!!

 

[Whoops]

I want to build a API 312 Stepped gain pot (25k rev log)
I've serched anywhere ut I can't find any info about,

there's info on that on the API 312 main thread, a lot of people did their build with stepped gain switch (not pot like you said)

easiest thin is to buy the CAPI switch and PCB, everything already done for you:

https://capi-gear.com/catalog/product_info.php?cPath=51_133&products_id=237

you can also do it yourseld , by following Hybrid 312 values:

https://web.archive.org/web/20160705022551/http://www.schwenkleraudio.com/hybrid312/


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I'm really not a fan of fixed gain preamp like CJ suggested, I like and need the variable gain.
With variable gain you can also decide to drive the preamp harder, or into distortion if you need.
With variable gain you can still have it in your own "sweet spot" if you want, but keep the flexibility for other uses, with fixed gain you can't

 

[ilfungo]

Thanks!!!