Monolith Oracle stock and with input gain mod

[johnk]

Stock (with useless gain control):





and with input gain mod (IMO, much better!):

[boratto]

I got some AC125, can i use them without much damage to the original?

[rocket88]

as long as you're using PNP transistors you should be fine. just play around with them and see what works. in mine, i have russian mp41's with hfe ~85 and it sounds incredible.

[boratto]

If you say it ROCKS, i believe in you! Importing ten Mp41 from bulgaria

[rocket88]

it really does. with the density all the way up, and the tone bypass engaged mine sounds like the apocalypse is coming. i've used it with both my basses and guitars. it even handled open C tuning for both with ease. it's moved up to my top 5 fuzzes.

like i said, both the transistors i used have are mp41a hfe ~85. i'm not sure how many you'll get with that hfe by ordering only 10. i have something like 100 or more of them to pick from. most of them were closer to 60-70hfe, so not sure how similar it will be to mine, it might not matter. socket the transistors an give them a try, you got nothing to lose. if you don't like them, just swap them for something else.

i'm in the us, and found a guy in canada that has a huge stock pile of ac128's, and he sorted through and picked 2 that had ~100hfe for me, as well as a few others from some fuzzface's. but, i have yet to try them in the oracle.

i have ordered mine directly from russia to with great luck, but some people haven't been having as good of luck as me. so far out of 400+ russian ge transistors, all different kinds, i have only had one bad one. also, all of mine seem to have usable hfe's, i've only gotten a few, something like 20 or so, 30hfe or below. also, all of them are super low leakage.

what are the hfe are your ac125's?

[boratto]

I will grab then at the shop, the specs talk about ~75. I will work to find a matched pair. It seems to be a mean pedal. I can´t resist to build these evil things. I am looking for a perverse high gain distortion... (i need at least one, to pair with the fuzzes) but i still do not find something that get my attention.. Many times i find them too tinny sounding. Any suggestions?

[rocket88]

check out the dr. boogie, or the wampler triple wreck. both are on my list to build, and if you check out diystompbox forum there are tons of threads on mods you can do to the good dr. if you play with the input and output caps by increasing them you can let more bass into the circuit and out respectively, not to mention increasing the coupling caps. i plan on doing this, and also plan on playing with the values in the tonestack. i'm sure if johnk were to chim in he could give an even better idea, as i know he's built both.

[johnk]

I modded the heck out of my Dr. B but for me (stock or modded) the tone changes quite a bit as you raise the distortion level. it's a lot better now but still not my cup of tea. (and neither are boogie amps for than matte r)

[boratto]

Thank you guys. I uploaded more 3 high gain options too, that seems very interesting. The schematics are at the request section.