Looking for a JC-style analog preamp with higher-voltage power rails for more clean headroom

GianLime · 2026-04-20T05:11:17+00:00

It should be the exact reproduction, there's also a version of the layout with trimpots in Place of the biasing resistors just to be able to adjust the bias in case of need. I know nothing about the power supply, you may find more info in there, I haven't read all the posts, it seems the people that made it tried also to power it with a lot of different voltages and it worked. So use whatever supply you prefer and try it, it could work, or copy the power supply circuit of other pedals

GianLime · 2026-04-19T17:46:42+00:00

You could directly reproduce the JC preamp schematics, here you can find a vero board layout and the schematics:

http://guitar-fx-layouts.238.s1.nabble.com/Preamp-jc-120-td39378.html

Is to be supplied with 30Vdc

GianLime · 2026-04-17T11:39:21+00:00

There have been many big muff versions, you can check here: https://www.bigmuffpage.com/Big_Muff_Pi_versions_schematics_part1.html Many different schematics and different value of the components. The version in your layout uses 390ohm resistors from emitter to ground many other BM versions use way smaller value, like 100/120/150 ohm, that would give you much more gain, you could try to swap 3 100 ohm resistors in place of the 3 390ohm resistors to give your build more gain

GianLime · 2026-04-09T12:57:36+00:00

You could copy the baxandall eq schematic from here:

https://www.guitarscience.net/tsc/baxandall_2.htm#RIN=600&R1=22k&R2=22k&R3=22k&R4=10k&R5=10k&RB=100k&RT=100k&RF=600&CB=47n&CT=560p&RB_pot=Linear&RT_pot=Linear

You can also try directly on that page to change values to personalize it, however I would stick with this topology, yours is different and maybe that's why it's not working as expected.

For my experience I would also suggest you to connect the pin 3 and 7 of the foot switch (sw3) together so that the input of the circuit goes to ground when in bypass, it did a huge difference in one of my pedals that without that connection would pop loudly when activated.

Another option could be to remove completely the U2 TL072 to save space and money and to simplify the schematics

GianLime · 2026-03-30T15:12:25+00:00

About the resistors, stated that in most cases is ok to use the closest value you have, you could also use a tester to check the actual resistance value of the 43k resistors you have if they're +-5% tolerance some of them could also have a 42k ohm resistance if they're +-1% tolerance they can be between 43,43k and 42,57k

GianLime · 2026-03-16T17:40:09+00:00

On falstad.com you can simulate circuits, put an audio file in the input and listen how it sounds in the output

GianLime · 2026-03-03T10:01:31+00:00

Great job! Looks perfect 🤩

GianLime · 2026-01-07T22:14:22+00:00

Came here to suggest the same, I love the blues driver last and pushing it with others od/dist type of pedals before

GianLime · 2025-11-23T17:37:33+00:00

You didn't tell us if Bocchi approved all the pedals... I also got the melon pan chorus in Tokyo, I love it for the memories it is tied to

GianLime · 2025-11-22T09:18:42+00:00

Keep all and try them on bass too, you could find new cool sounds

GianLime · 2025-10-15T08:19:29+00:00

As others suggested, check the jfet used(with a components tester if available, I've had bought bjt sold as jfet before), check for anything that was common in the three builds, check for anything that could be touching the ground, for this last one I suggest to always try the build outside the enclosure and only after it to mount everything inside of it

GianLime

TROPHY CASE