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Alembic F2B fet adaptation help

Started by garfo, May 17, 2015, 01:41:25 PM

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garfo

Hi, I'm thinking of building this schematic.. It is a Fet version of the legendary Alembic F2B bass preamp. Should I scale down the tonestack for lower noise?
Such as:
C3- 2.5n;
C4- 1u;
C5- 470n;
R5- 10k;
Bass/ Treble- 25k pot; Mid: 1k Pot!?!

Here's the schematic


HamSandwich

You're correct.

Dead Astronaut on DIYSB did a bass preamp that's the same thing with scaled down Tonestack.

garfo

Quote from: HamSandwich on May 17, 2015, 02:28:11 PM
You're correct.

Dead Astronaut on DIYSB did a bass preamp that's the same thing with scaled down Tonestack.
Nice, thanks.
By the way, should those trim pots and volume pot also be scalled down?
I ask this because from what I understand, this is the Tube original schematic but with fets, and maybe the fets don't need those 100k res for biasing as well as the 1M vol pot is too much before the second Fet...?

HamSandwich


garfo

Thanks, I think I'll leave them the same. By the way, the output cap, shouldn't it be 10x bigger?