Here’s what the Phat Phuk is: A germanium/JFET booster. A unique sounding pedal which adds a beautiful sheen to your bass’ top end and a bit of grit to the overall tone. It’s a fantastic pedal for situations where you want a lift in your overall level, during a chorus or bridge for example, with a bit of bawdy bump via the germanium transistor.
The exact germanium transistor is a Chinese PNP on the originals, but others can be used. Shoot for around 90 hFE. On originals there is a trimmer that is essentially a gain control. I've laid it out so that you have the option for a trimmer or external board mounted pot on the same board. So if you want the pot externally, don't populate the trimmer and vise versa. Here's the schematic for reference.
I've got a question, the new version of the Phat Phuk B (called Suppa Phat Phuk), beside the external Bias pot like in this layout, got an extra "phatness" (tone like) control, any hint to how to mount that extra pot in this layout (if possible)?
ReplyDeleteI would assume it's a pot that goes between 2 different caps going into the germanium section. I'd wire it with a 100n cap and 10µ (negative side) replacing the 4.7µ cap, then the 100n cap to lug 1 of a B100k pot, the positive side of the 10µ to lug 3, and then lug 2 going to the base of Q2. Most of that you'd have to wire off board though.
DeleteThanks!
DeleteA question:
ReplyDeleteDo you have the same circuit for guitar (silver pedal)?
Thanks!
I don't, but I would guess the main difference would be smaller cap values.
DeleteOoops! The circuit it's very similar to CRIMSON DRIVE, posted in your blog here:
Deletehttp://effectslayouts.blogspot.com.es/2014/12/earthquaker-devices-crimson-drive-2.html
Thanks!
Verified.
ReplyDeleteI used a J112 for Q1, since it is just a buffer. For Q2, I used a TI 2404A from Small Bear that came in a bag marked "38", which I would guess is the Hfe since it came from a low-gain <40 bag. I left out the tantalum cap, but the noise level is not bad.
Like the demo video says, this boost sounds like a nice pre-amp and adds a little liveliness and grit to your sound. I could see this being an "always-on" pedal for some people. The bias knob crackles when turned and I did not like the overdrive you could get with it. Personally, I would just go with the trimmer or a fixed resistor after finding the right bias. My build did not have a whole lot of volume available, though still enough to be useful. A transistor with more gain would probably have given me more volume. The build reports on the tagboard site indicate that a wide variety of Ge transistors work in this circuit, so use a socket and try whatever you have on-hand.
Would I be able to substitute the 2K linear pot for a 1KB or 5KB?
ReplyDeleteCheers!