Argentum 1212 biasing and info
- Thread starter Jachiro
- Start date
Robert
Reverse Engineer
It uses the standard 4-knob template.
Ok. So I just finished putting everything together and there’s some things I’m unsure about since there’s no documentation available.
I assume the trimpots are for biasing the J201 transistors? Since there’s a TC1044 in the circuit, I take it that VDD=18V and the bias voltage for the transistors will be around (VDD/2)=9V. Is that assumption correct?
Also if anyone who has built this pedal has info on what control each pot on the board corresponds to, that would be great. Having that is a lot better than me having to turn pots and guess.
If anyone has a schematic and/or layout of this circuit and pcb that would be great too. Thank you!
I assume the trimpots are for biasing the J201 transistors? Since there’s a TC1044 in the circuit, I take it that VDD=18V and the bias voltage for the transistors will be around (VDD/2)=9V. Is that assumption correct?
Also if anyone who has built this pedal has info on what control each pot on the board corresponds to, that would be great. Having that is a lot better than me having to turn pots and guess.
If anyone has a schematic and/or layout of this circuit and pcb that would be great too. Thank you!
mralanmorgan
Member
The build doc is up. The 2 b1m are for bass and treble, volume a100k, gain a1m. Also yes, 9v for each j201. I started at 9 on all and then did minor tweaks by ear. Have fun playing this pedal, it's fantastic.
Is there a recommended gain and volume setting at which we bias the transistors?
mralanmorgan
Member
Using a multimeter you bias the jfets to 9v each. From there you may be able to tweak a little bit too get a touch more volume, but I wasn't able to achieve much more drive.
Sorry, I misunderstood the question. No. The pedal needs power, but it doesn't matter where the knobs are at.
temol
Well-known member
Volume - no.
Gain - I'd set gain to max and short the input to GND. You don't want any signal going through the pedal while measuring voltages.
I just built one and found that 9V sounds best to me. I'm getting very close to exactly 18V from the charge pump. Interesting sound! I kinda like that it doesn't sound like everything else. It makes a killer boost for a Strat into another OD but can get quite sludgy with HBs.
