Transistor Specs for Tone Vendor Mk II?

M

MobyOctopad

Active member
Hi all, I've tried combing through old posts here, as well as on diystompboxes, looking for some guidance on gain and leakage specs for a TB Mk II build, and hadn't really had much luck other than finding out at least Q1 needs to be leakier than what you'd use in most other circuits. Until, that is, I read through the build docs for AionFX's Deimos where they recommend the following gain and leakage:
  • Q1: hfe 50-100, high leakage (150-300 µa)
  • Q2: hfe 50-100, low to medium leakage (100-200 µa)
  • Q3: hfe 100-120, low to high leakage (50-300 µa)
Does this largely track with what folks have used on their TB MkII's? I'm particularly thrown off by such a broad range on Q3's leakage.

I was planning on paying an additional testing fee on some ge transistors and wanted to make sure something along these lines worked. Thanks y'all!
 
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If I'm reading the schematic right, I could go with 70/70/100 hfe and just play with the values on R2, R5, and R7 to get the desired voltage, is that right? And would the voltage laid out in the Aion docs still be useful?

• Q1: Collector -8.5V, Base -0.05V, Emitter 0V
• Q2: Collector -0.15V, Base -0.07V, Emitter 0V
• Q3: Collector -8.5V, Base -0.15 to -0.35V, Emitter -0.1V

This is helpful, thanks y'all!
 
If I remember correctly Q3 should be leaky or else the circuit will sound a lot more gated and splatty at max guitar volume. That being said rolling off the volume knob on your guitar should clear that up, socket that Q3 and go for what you like best ^^
 
Those are normal looking TBMKII voltages but seriously don't get super hung up on any particular gain/leakage/voltage measurement. The original ones are all over the place and unless you're trying to do a forensic reconstruction of ONE particular pedal, just shoot for a pedal that sounds rad and you like playing.
 
Those are good voltage readings to aim for. You can swap resistors to get there or go through a stash of transistors leaving the resistors stock.
 
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