Hard Rock Pinnacle Purebred Drive (Chuck D Bones modified Animals Diamond Peak)

MattG

Well-known member
This is pedal is based on a PCB I designed myself, based on the @Chuck D. Bones-modified Animals Pedals Diamond Peak Overdrive, discussed in this thread. I call it the "Hard Rock Pinnacle Purebred Drive". As you can see, I'm late to the PCB party for this circuit. There's a good reason why this circuit has seen so many PCBs made for it: it rocks! I had been watching that thread with interest for a long time, but what finally sold me was @Brett's build report, where he said, "Think of how the Boss BD-2 responds to pick attack, now make it sound good, like really good." I have mixed feelings about the BD-2, but it's a benchmark of sorts. If nothing else, pretty much everyone and their brother has played one, so comparisons to it are a useful common ground. But I've always thought it shines particularly bright in the touch-sensitivity and volume cleanup departments. However, the BD-2 cousin, the OD-3, has been my jam for quite a while. I always wished there was a pedal that had the tone and drive sounds of the OD-3, but with the more open sound and dynamic touch-sensitivity of the BD-2. I won't say that this pedal is exactly that; in fact, the drive sounds isn't really like the OD-3 or the BD-2. But this pedal definitely has phenomenal response to pick attack and volume, and the drive sound is just great.

On top of all that - it's clearly a very flexible, tweakable circuit. I think this is a good one to breadboard and tweak values to taste. For those unaware, this circuit is essentially the same topology as the Aldrin Fuzz, i.e. Skreddy Lunar Module, Screwdriver, Hybrid Fuzz Drive, and the Skreddy/Animals Major Overdrive.

Part of the fun of this circuit is transistor rolling Q2 and Q3, which are low-gain silicon. I used metal can 2n2369 (HFE 59 per my CTT) in one build, and MPSA42 (HFE around 90) for the other. (I used 2n4123, HFE around 94, in my prototype.)

My PCB takes Chuck's effect circuit exactly; the only changes are addition of two trimpots for biasing, and an extra power supply filter cap. Additionally, I added the inverter-based relay bypass circuit I've been using for my last dozen or so builds (see my build report history - I have standalone bypass PCBs with this circuit). I also added solder holes at the bottom for traditional 3PDT bypass.

For those who watch my build reports, the exterior finish continues my recent trend of Envirotex (two-part epoxy resin) over mandala stickers. I tried something a little different this time, I made the mandala sticker cuts bigger, and didn't put the sticker on the top of the enclosure (where the power and I/O jacks are). The jury's out on this - first, this is one of my worst jobs in terms of the resin pour on the sides, and second, make the stickers bigger on the sides mean they're not as smooth, so probably more likely to catch on something and start peeling off (the resin is supposed to prevent that, but combined with a mediocre pour, it might not happen). But I'm not going to worry about it, the pedal sounds too good! (I've actually been rocking my prototype - with three of the pots wired backwards - because it sounded too good to wait on the revised PCB to come in!)

I have a few extra PCBs, I'm happy to send them out to anyone who asks.

Edit: I forgot to add in my initial post, this circuit pairs really well with the Zorkmid!
 

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Awesome job here @MattG! I'm glad that my build report convinced you to build one, it's a lovely circuit.

the drive sounds isn't really like the OD-3 or the BD-2. But this pedal definitely has phenomenal response to pick attack and volume, and the drive sound is just great.
My reference to the BD-2 was based almost entirely on the pick attack and note clarity, as I think you gathered. It's a bit of a different flavor of drive compared to the Boss circuits, and I stand by my statement that it sounds superior to an unadulterated BD-2.

Your board and build look great! Goddamn those are some fat traces...;)
 
Most excellent. Clean build and beautiful box artwork.
I find that 2N2221 and MPS6530 have low enough HFE (71 & 81, respectively) to work well in this circuit. High-voltage transistors, like 2N6517, tend to have lower HFE, so try looking for those too.
 
My reference to the BD-2 was based almost entirely on the pick attack and note clarity, as I think you gathered. It's a bit of a different flavor of drive compared to the Boss circuits, and I stand by my statement that it sounds superior to an unadulterated BD-2.

100% agreement. I think I rambled too much about Boss circuits in that first paragraph. Indeed, dynamics/pick attack/volume cleanup are the selling points of this circuit, much like the Boss BD-2. But the tone of the Diamond Peak is definitely its own thing.

Most excellent. Clean build and beautiful box artwork.
I find that 2N2221 and MPS6530 have low enough HFE (71 & 81, respectively) to work well in this circuit. High-voltage transistors, like 2N6517, tend to have lower HFE, so try looking for those too.

Thank you for the compliments and more importantly, thank you and @HamishR for bringing this circuit to us!

I've attached the BOM and drilling offsets to this post for anyone who gets a PCB. I still have some PCBs left, and am happy to send them out to whoever wants one.

Note that the relay bypass circuit is completely optional. You can build it using only the components for the actual effect circuit, and wire it up to a 3PDT (just like most PedalPCB boards). I tried to make it simple by explicitly indicating in the BOM which components are for the relay bypass (and I also gave those components three-digit reference IDs, actual effect circuit components have two-digit IDs).

The only other quirk I've found is that I didn't put the test points in an intuitive location. Specifically, the right trimpot is for the left test point, and vice-versa.
 

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Here's mine, all ready to box up. I didn't have a 9V latching relay, but a little cut here, a little jumper there and voilà!
I installed S.I.T. resistors in lieu of trimpots and subbed BS170 for 2N7000. Those metal cans are 2N2221.
I might solder the TREBLE & BASS pots from the other side because I want to avoid scorching those pretty WIMA caps.
(yes, I'm going to clean the board)


Hard Rock Pinnacle cb mod front 02.jpg

Hard Rock Pinnacle cb mod back 02.jpg
 
Silver Mica, Baby!

This is what I did on the board. I named the 10K resistor "C116" because it is installed where C116 would go. Since Q104 is not being pulsed, I can use it to drive both the relay and the LED. A 1N5817 Schottky diode is not necessary for use as a flyback diode (D103). Any diode capable of carrying the relay's coil current will suffice. R200's value is selected based on the relay coil voltage and resistance. I cut the trace between pins 1 and 10 of the relay using a drill press. I could have used a knife, but it would have taken longer and not been as pretty. The flip-flop formed by U1D & U1E can power up in either state. For whatever reason, the one on my board powers up with the relay in the off (Bypass) state. We can more-or-less ensure that the relay powers up in the Bypass state by installing a 10nF cap from U1-9 to GND. I say "more-or-less" because if the power chatters on start-up or comes up slowly, all bets are off.

NB: Matt's latching relay drive circuit works just fine. If I had a 9V latching relay, I'd have left the board alone.

CD40106 relay control.png
 
All done!
Found a little problem with my board during bench testing: no gain. Turns out I had Q2 & Q3 installed backwards. The footprint is for BC-type transistors and I installed 2N2221s. I had to pull the transistors and reform the leads. It's all fixed now. Anyone building this board, don't do what I did. Double-check the transistor orientation before you solder them in. Make sure the leads are formed correctly. NB: I do not recommend BC-type transistors because the HFE is too high on all of the ones I have. One more note: The pot spacing is slightly different from the Pedal PCB standard layout. Use the drill guide Matt provided above.

[EDIT]
I also recommend changing R11 to 3.3K to improve Q3's bias adjustment range. I ended up with 5.6K for R11 + the trimmer on this build and 7.5K on the breadboard.

Hard Rock Pinnacle cb mod front 02.jpg

Hard Rock Pinnacle cb mod innards 02.jpg
 
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