Actually, that conversion wouldn't be too tough to do at all. You'd have to change some component values and then make one significant connection change on the PCB. Here's how to do it:
- For the resistors, R1 and R3 values stay the same (470K & 10K), while R2 and R4 change to 100K and 220R, respectively.
- For the caps, C1 (the lower cap) is decreased from 100n to 47n while C2 (the upper cap) increases from 100n to 470n. For the added cap, C3 (which is mislabeled on the Pregain schematic as C2) you will need a 220pf ceramic cap.
- Everything then mounts the same on the PCB EXCEPT R1 and C3. Here's how to mount them:
- Twist each lead of the ceramic cap around opposite leads of the R1 resistor so that they are connected in parallel. See example image below. Solder the leads together on each end and trim off the cap leads leaving the resistor leads at full length.
- Solder one lead of the resistor/cap pair into the R1 PCB eyelet closest to the Q1 transistor.
- Standing the resistor/cap pair on end, bend the top resistor lead down and wrap it under the lead of the already-mounted R3 resistor immediately above it. Solder in place and trim the excess lead. You may need to bend the resistor/cap pair over a bit if it's too high, but it should fit under the pedal backplate without contact.
That should do it!
Attachment:
rez-cap_parallel.jpg [ 31.37 KiB | Viewed 877 times ]
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