cdwillis
Well-known member
- Build Rating
I messaged Chuck D Bones about making a tweaked OCD clone with a baxandall tone stack a few months ago. The project got put on the back burner, honestly because I had a lot going on and not enough time to breadboard it properly. Recently I've been working with Eagle and laid out a new version of the circuit then ordered some PCBs from JLCPCB without bothering to test it on the breadboard. Like the other PCBs I've laid out I used the pot layout from the PedalPCB drilling template/jig to make things easy. Chuck suggested I use a single op amp for the first stage so it would be easy to try other single op amp since the dirt character is going to be influenced so much by the op amp itself clipping. I think I'm going to make a second version of the PCB with that arrangement so I can try out a CA3130 op amp in the first spot.
It sounds pretty damned good if I do say so myself. There are a few tweaks I have in mind for the next build though. I plan to change the 4.7k/68nf (the schematic still has a 47nf cap there, but I used a 68nf) high pass filter in the first op amp section to 3.3k/100nf for a little more maximum drive, along with the 4.7k minimum gain resistor to 3.3k to match. The HPF frequency is around 500hz so it still sounds decently thick without getting too bloated and farting out. With that much low mids coming through I'm going to swap the 220pf caps to 100pf to let a little more high end harmonic content through the circuit. With the OCD you've got a 1khz HPF there, so the 220pf caps tame some of the high end that's more evident with the bass being cut. I wanted to make it a little thicker than that or a typical tube screamer type 720hz bass cut.
I think the volume pot would work better as a linear pot so at noon it's a little louder. I'd like to be able to put the level, bass, and treble pots at noon with the drive at minimum and achieve a nice always on type of tone sweetener or clean boost. It works this way already, but with the logarithmic pot I have to turn it to about 1 o'clock to get unity volume or slightly above. I was testing it on my Marshall and it sounded good then I tried it on the Orange OR-15 which can be funny about drive pedals. With some tweaking I could find different ways to use it on both and still make it sound pretty good. I have a few more of these boards if anyone is interested in building one themselves.
It sounds pretty damned good if I do say so myself. There are a few tweaks I have in mind for the next build though. I plan to change the 4.7k/68nf (the schematic still has a 47nf cap there, but I used a 68nf) high pass filter in the first op amp section to 3.3k/100nf for a little more maximum drive, along with the 4.7k minimum gain resistor to 3.3k to match. The HPF frequency is around 500hz so it still sounds decently thick without getting too bloated and farting out. With that much low mids coming through I'm going to swap the 220pf caps to 100pf to let a little more high end harmonic content through the circuit. With the OCD you've got a 1khz HPF there, so the 220pf caps tame some of the high end that's more evident with the bass being cut. I wanted to make it a little thicker than that or a typical tube screamer type 720hz bass cut.
I think the volume pot would work better as a linear pot so at noon it's a little louder. I'd like to be able to put the level, bass, and treble pots at noon with the drive at minimum and achieve a nice always on type of tone sweetener or clean boost. It works this way already, but with the logarithmic pot I have to turn it to about 1 o'clock to get unity volume or slightly above. I was testing it on my Marshall and it sounded good then I tried it on the Orange OR-15 which can be funny about drive pedals. With some tweaking I could find different ways to use it on both and still make it sound pretty good. I have a few more of these boards if anyone is interested in building one themselves.
