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The Blues Buster pedal (variation of the Marshall Blues Breaker) schematic shows a B250K drive pot with a rather small 3K3 fixed resistor in parallel. Is this correct? Most BB- type circuits use a B100K drive pot, or a B250K value for a drive range boost. I haven’t built my Bles Buster kit yet, but I’m trying to understand why it calls for a 250K pot with 3k3 across it. Resistors in parallel equation would indicate the equivalent resistance to be about 3260 ohms. What kind of drive range can you get with this seemingly small value? If anyone could explain how this works in a Blues Buster circuit, I’d greatly appreciate the help. Thanks.
Greetings Wayne. This is not a circuit I’ve built myself and your interpretation appears right regarding the pot value in question. My suggestion is first that the circuit is correct as it stands because the brains trust here tests them before they go for release. Perhaps try breadboarding it to see (hear) what’s going on. Sorry I can’t offer you a better explanation but I regularly breadboard circuits to see whether or not they’re appropriate for my setup.
Hi there.
This is indeed a typo. The value we decided on for the parallel resistor (R6) should have been 330k and not 3.3k
This would give you a pot value of 140k roughly. We felt that 250k (the next available pot value) was too much.
That said you can use a 250k pot and leave (R6) the parallel resistor empty, (no jumper). If you think it is too much then you may put whatever value works best for you.
Thank you very much for pointing this out. The build document has been updated.
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