March 20, 2020 at 6:29 am #11754EdParticipant
Hi all, The pot values for this build differ between what’s shown in schematic and what is shown in parts list (some of the resistor values differ as well). See here. Example: tone is A1K in schematic but A50K in build list. Vol is A100K in schematic but B50K in list. Etc. What are the real values I need to use? Thanks!March 20, 2020 at 7:20 am #11755BillyModerator
The values in the parts list are what I’d use
The parts list is drawn up specifically for GPCB improved circuitsMarch 20, 2020 at 4:00 pm #11759
The tone control is an A1K pot. We changed those values based on Mod reports. I should not have changed them honestly.
I will fix those inconsistencies.
The Volume control is as per the BOM is an A100K and Tone is a 1K.
That said either of these value changes in either of the potentiometers does not matter much seeing how they are dividers and either would work similarly due to the nature of the circuit. The Taper would only slightly change the feel.March 20, 2020 at 4:54 pm #11762CybercowModerator
Barry – the BOM states B50K for Volume, but the schematic shows A100K. Which is it please? B50K or A100K? (I suspect A100K.)
And to be clear, the schematic shows A1K for Tone, but the BOM shows A50K., So go with BOM for that one?March 20, 2020 at 5:10 pm #11763
The Volume is A100K.
The Tone is A1K.
My point above was we have used both values and both tapers many years ago with not much sonic difference. We probably should not have bothered. Unfortunately when a value was finally decided upon I forgot to check for consistency at the time.
That is what I meant to say above and again apologies for the confusion.
Build document has been updated.March 20, 2020 at 5:36 pm #11764CybercowModerator
Barry – one final point . . . (and I know this is not as vital as the other two pots) – what about the BIAS trimpot? The schematic for the trimpot does not match the BOM either.March 20, 2020 at 5:59 pm #11766
Uggg. This also slipped through the cracks from 2010. Probably our 5th board offering ever.
The Bias Trimpot would also work with either. That said since we are now using J113 instead of MPF102 I would probably go with a 10K trimmer.
I will update that as well.March 20, 2020 at 6:13 pm #11769
OK Build Document has been updated to address the Trimmer value discrepancy.
Thank you for bringing this to my attention.March 21, 2020 at 12:13 am #11772Bruce RModerator
I’m updating the kit BOM at Pedal Parts and Kits to reflect these changes.March 24, 2020 at 12:55 am #11848huli50Participant
FWIW, I’ve built this recently and did a lot of research on the original pedal that I believe inspired the Killer Bee. I actually think the A50k tone and the B50k volume is more consistent with that original pedal. It’s the way my kit was supplied and it works just fine IMO.
Also, the kit came with a 5k trimmer which also worked fine biasing the J113 to 6 volts with little difficulty. I’m guessing a 10k trimmer would work just the same; maybe just a little more sensitive than the 5k.
Not trying to make a big thing here. Just trying to emphasize the point made here that either values for pots and trimmers would likely work equally well.
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