Candid Drive - Cap Change to cut bass

Ballard Guitar

Ballard Guitar

New member
Hi there,
I am a long time user of the Barber Direct Drive, including many of the models & revisions. My favorite version, still, is the big box V2, because it has trim pots inside to adjust the bass and presence settings. I recently built the Candid Drive, and it sounds great. However, the compact versions of the Direct Drive seem to be less intended to be pushing a tube amp at gig volume, and instead, are optimized for use as stand alone tone generators, with a more neutral, pedal friendly rig. The Candid Drive, IMO, has enough low end (and high end) to sound a little boomy (and a maybe a little fizzy) with my amp.
So... I'm hoping to build a second one, and swap a cap or two to trim a little low end, and possibly also trim a little high end. More concerned about the lows, though. Please share your advice, regarding where in the circuit I might be able to tweak some values to get a leaner version of this great sounding pedal. Thank you very much!
 

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A lot of the Barber drive pedals share a common topology (especially the recovery section at the end). See the Tater Tot schematic as an example.

In the case of the Candid Drive, the bass trimpot would be in place of R13.
 
R13 and C12 make up the bass filter in the final gain stage. I've built the PedalPCB Sliver, which isn't a Direct Drive, but shares a very similar topology. See the schematic in the build doc. At least with the Sliver circuit, to me, the bass trimpot doesn't offer a huge adjustment. It's noticeable for sure, but depending on how much trimming you want to do, it may not be enough. That said, it should be pretty easy to wire 50k trimpot in place of R13 on the Candid board. Roughly the middle position of the pot would be near stock. If that gets you where you need to be, then either leave the trimpot where you like it, or remove it and solder in an equivalent resistor.

If you want to make more dramatic changes, then you'd look at the RC networks tied to the gain switch. I.e., C5+R6 and C6+R7, and/or C3+R4 and C4+R5. Here you can try smaller caps for more pre-gain bass cut... but this will also have a greater effect on the overall voice/tonality of the pedal compared to changing R13/C12. So you could cut bass but also make the tone not to your liking. This is really where you'd ideally breadboard the circuit and tweak until it sounds right. If you don't want to do that, then I would probably just pick one side of that tone switch, and socket the four components (two Rs and two Cs). Or go crazy and socket all eight components. Either way - swap one component at a time and take notes.

FWIW, I also built a Candid Drive a while ago. I really liked the overall tonality - I think David Barber has a great ear. But I didn't keep it because I also thought it was a bit too bass-heavy for my purposes. You might also consider the AionFX Tachyon (my build) - it has a similar character, but I prefer its EQ to the Direct Drive.
 
MattG said:
R13 and C12 make up the bass filter in the final gain stage. I've built the PedalPCB Sliver, which isn't a Direct Drive, but shares a very similar topology. See the schematic in the build doc. At least with the Sliver circuit, to me, the bass trimpot doesn't offer a huge adjustment. It's noticeable for sure, but depending on how much trimming you want to do, it may not be enough. That said, it should be pretty easy to wire 50k trimpot in place of R13 on the Candid board. Roughly the middle position of the pot would be near stock. If that gets you where you need to be, then either leave the trimpot where you like it, or remove it and solder in an equivalent resistor.

If you want to make more dramatic changes, then you'd look at the RC networks tied to the gain switch. I.e., C5+R6 and C6+R7, and/or C3+R4 and C4+R5. Here you can try smaller caps for more pre-gain bass cut... but this will also have a greater effect on the overall voice/tonality of the pedal compared to changing R13/C12. So you could cut bass but also make the tone not to your liking. This is really where you'd ideally breadboard the circuit and tweak until it sounds right. If you don't want to do that, then I would probably just pick one side of that tone switch, and socket the four components (two Rs and two Cs). Or go crazy and socket all eight components. Either way - swap one component at a time and take notes.

FWIW, I also built a Candid Drive a while ago. I really liked the overall tonality - I think David Barber has a great ear. But I didn't keep it because I also thought it was a bit too bass-heavy for my purposes. You might also consider the AionFX Tachyon (my build) - it has a similar character, but I prefer its EQ to the Direct Drive.
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Thank you! 👍
 
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