Hybrid Fuzz Driver Deluxe

MattG

Well-known member
Build Rating
4.00 star(s)
Here's my take on @Chuck D. Bones's Hybrid Fuzz Driver Deluxe. A long time ago, I built the Skreddy "Holy Trinity" using PedalPCB's Aldrin Fuzz PCB: The Lunar Module (Aldrin Fuzz stock), Hybrid Fuzz Driver, and Screwdriver. I've done a lot of builds using this core topology. One of my longstanding, all-time favorites is Chuck's modified Animals Diamond Peak and more recently a tweaked Animals Pedals/Skreddy Major Overdrive, the Old Fashioned.

Looking back to when I built the Hybrid Fuzz Driver, I really liked the drive/clipping character, but I was never quite satisfied with the EQ. I've long since parted with that build, but when Chuck worked his magic on the circuit, I knew it was time for another look.

The actual effect circuit is faithful to Chuck's schematic. I just added my standard overkill features of P-MOS reverse polarity protection, extra power supply filtering, and buffered electrical bypass. For the buffer, I used a bootstrapped NPN BJT (aka the "Cornish buffer").

Everything worked on first power-up. I biased Q3's collector at 5v (or at least I thought I did), per Chuck's suggestion. As I started playing, I was somewhat disappointed. The drive character wasn't anything like I remembered; the overall tonality was very brittle - overemphasized highs, spiky, unmusical clipping. And I initially thought I wired the bass and treble pots backwards. But then I realized the pots were wired correctly, it was the enclosure labels that were swapped. This isn't the first time I've done this. Anyway, I kind of put it aside for a day or two. Today I thought I'd mess with Q3's bias again, to see if that improved the sound. The first thing I noticed: bias was actually 8v! I'm not sure how that happened. So I set it to 5v, and wow! that's the Hybrid Fuzz Driver mojo I remembered.

Edit: I should mention, Q2 and Q3 are the "money" transistors: I used low-gain silicon here, metal can 2N2369. I can't remember what HFE they are, but I think they are around 60. These are my favorite in the Diamond Peak, so they seemed a safe bet for the HFD Deluxe.

The enclosure itself is a bare aluminum 125B. I used 180 (I think) grit sandpaper and an orbital sander to do a bit of "polish" on the front face. Art and labels are a Sunnyscopa film-free laserjet decal. This is one of my best transfers ever. I went back to the original "W1+" glue, rather than using the GW1-PRO glue that's given me so many problems. Despite being one of my nicest finishes, I might still sand it down and re-apply, since the bass and treble labels are swapped.

Anyway - this a great circuit, and worth your time if you're a fan of YASF (yet another Skreddy fuzz). I have spare PCBs I'm happy to give away, just PM me if you'd like one.

Edit2: I posted the Gerbers and other supporting docs below in post #9.
 

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Very cool. I recently discovered that I like the HFD after I initially misunderstood it and then spending an unusually long time for me trying to dial it in
 
Holy hell clean build with everything being so tight in there. Glad you finally got your Hybrid Fuzz Driver where you like it!
 
Sick build, my man. What does this do to the supply voltage compared to a 1N5817?

A couple hundred millivolts. Not enough to make a difference. It's clever and all, I'm not knocking it. Other builders do it.

Yes, it's extra optimization where none is needed. But I like to say: anything worth building is worth overbuilding.
 
I had some requests for the Gerber files. So attached here is:
  • Schematic
  • Drilling template / potentiometer offsets (not the same as PedalPCB!)
  • Annotated BOM
  • Gerber files I submitted to JLCPCB
  • Grim reaper enclosure art (with bass and treble labels fixed)

Note: all files are either PDF or ZIP, but the forum software doesn't allow those extensions as attachments. So I added a ".txt" extension to all files. You'll have to download the files, then rename (strip away the ".txt" part).

Also: I had populated the PCB for this build before I learned that the 1M VREF bias resistors I'm using around the CD4053 are arguably sub-optimal. See here for a terse summary, or see here for all the details.
 

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