Harmonic Percolator

New version as of August 2022

Rare and sought-after box of confusion. Is it OD? Is it distortion? Truth is the Harmonic Percolator has a pretty unique tone of its own.

Famously used by the one and only Mr Steve Albini. Can't promise you'll nail his tone, but its a step in the right direction.

Supplied with the same 2N404 as used in the original units. Lovely gold-legged cans of mojo.

The pots are board-mounted pot for minimal wiring and simple enclosure mounting. We've added clipping options as they can make a big difference to the tone of this beast. Kit is supplied with germaniums as standard, but you can add a toggle switch to select a second set of diodes instead. If you go for this option we'll supply 1N4148 and 3mm red leds. Go nuts and select a three-way on-off-on toggle switch to have the circuit run with no clipping at all in the centre position. Boosty!

Last option to mull over is the circuit version. The original trace values, or those reportedly in Steve Albini's personal unit.

If you want the PCB without parts there's a link for that at the bottom of the page.

Partial kit: PCB, all board-mounted components), pots.

Full kit: As above, plus footswitch and appropriate daughterboard/components for your selected bypass type (see Downloads section for details of those), jack sockets, DC socket, battery snap, hook-up wire, LED.

Enclosure (pre-drilled) is available as an option with full kits, and can take a battery if desired with footswitch positioned 22mm higher, closer to the controls. Knobs are not included.

Builds are only available with full kits including enclosure. Please choose appropriate knobs.

Inspired by: Interfax Harmonic Percolator

Difficulty: Easy

PCB size: 50 x 27mm

Knobs required: 2

Enclosure: 1590B

Direct-Connect compatible (4-way)

Download the INSTRUCTION PDF

Product Code: HarmonicPerc

Brand: Pedal Parts

Weight: 85.0g

Product Condition: New

Kit type* Version* Ribbon connector?* Diode switch?* Allow for battery?* Pre-built (UK Only)?*

£40.80 inc. tax

£34.00 ex. tax

? Tax based on United Kingdom.

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Customer Reviews

10 review(s) posted (write review)

Easy and booteek
"One of the easiest builds i have done in a while, albeit with expensive booteek NOS parts. And it sounds ok, more aggressive without diodes, i suppose i have to get out of the bedroom to get it to sound gnarly like Albini! Look forward to the Albini version dropping!" Ozzie Battla - 16 May 2022

Absolutely perfect
"What a great build! This was my first kit from Fuzzdog and it went nearly perfectly. I originally got the optopuss switching but I burnt the optocoupler. I emailed asking for help, and they replied quickly (I m across the ocean) and sent me another with my next purchase. Then I ruined the trace on the optopuss board. Haha! I m not great at this. Lol. But after I got everything finished, normal switching, it worked exactly as it should. Shipping was impressively fast. 10/10 would and have purchased from fuzzdog again." Will W - 25 September 2020

Allot of fun to mod
"As i would never do this to an original. I had fun coming up with some fun mods. Namely increasing the bias to 2 62k and changing to a 2n5088 and a MN165 soviet style. Slight increase from 100p to 120p i jist wanted to use them up tbh. The 47u taunt i changed to 100u eltrilyte for more gain and then just the 100n to polys and the 47n input cap an ERO. Left the clipping diodes off as the input and output pots are plenty. It then really benefited from an 18v charge pump. Simple pcb to have allpt of fun with to try out your germanium transistors." Hex - 21 April 2020

Even order goodness
"Easy to build. Great sound. My only knock is mine can get a bit hissy when the "balance" is turned up past 1 o'clock." Rich - 22 March 2018

Very. Subtle. Death. / Bodies. Stink. In. Graves. / Uncovered.
"Niiiiiice. Very subtle. Kind of sweet sounding. With spikes. If anything, I like this best used with a fade pot, like on a mixer using the FX send, where u can fade in the amount of signal. Just tip it in the signal lightly. Synths really scream thru this. Easy build. Not at ALL what you think a FUZZ should be. Like I said... subtle. LOVE IT!!!" damnedcat777 - 20 May 2017

What. The. Actual. F##k!
"Get this pedal!! This has got to be the nicest sounding distortion I've ever used. I'm not messing about, it actually sounds beautiful. You're gonna think I'm a bit weird, but it's sort of, erm, friendly sounding. Told you. But it does! Honestly gorgeous sounding. I did accidentally blow my face off though, it's actually got a very high output. I had my amp volume low cos it's half nine or so and got a bit of a shock when I hit the switch. Well, Steve Albini said just have both controls at maximum. Don't do that. Not at first. Don't get evicted. Get this pedal, I shit you not, it's fantastic sounding. Thanks Lee. Wow." Mick Jones. - 17 March 2017

Great Pedal.
"Little did I know, when the Mrs asked me what I wanted for christmas, did i expect to actually get a HP(albeit one I would have to build). I've never built anything like this before and it was really straight forward due to the fantastic instructions and great PCB. I'm really pleased with the pedal, its way more interesting and dynamic than most normal overdrive/distortion pedals. I've just ordered a filth fack, got the bug. Great site, great products. Thanks Poodle." Charlie - 03 January 2014

Another addition to my pedalboard
"Fantastic sounding kit. Very, very dynamic to your pick attack but as noted in other review can sound very different depending on type of pickups used. I'm using it with the diodes removed (via the switch), this gives a load more output from the pedal and a gorgeous overdrive sound regardless of guitars used but its still a very distinctive sound. Great stuff!!" Simon - 09 May 2013

Harmonic Percolator Kit
"I'm a very happy customer. My kit arrived very quickly, and working at a very leisurely pace, took me around 5 hours to complete (could probably be done in an hour and a half if you were working quickly). There are two main reasons I decided to go for this kit - the fact that it includes the same rare, out of production transistors the original used (and at such a good price), and because you can select the 2n404's hFE (within small ranges). The hFE of both transistors (but particularly the 2N404)have a significant effect on the tone of this pedal, and the only other place I've found 2N404's available is ebay, all of which are both untested and expensive, which in my books is a recipe for wasting money. I opted for a 2N404 in the 181-200 hFE range and I'm very pleased with it. I'm also very impressed with the quality of the pcb, I never really understood what was so special about double-sided pcb's until I started soldering on this one - I found it much easier to consistently make lovely shiny joints. The pcb is also very compact, which is big plus. One important thing to note is that the nature of this circuit means that it is very sensitive to transistor hFE's, input impedance and output impedance. With the stock components even original HP's made in Milwaukee will sound uninspiring with some guitars, but amazing and totally unique with others. You can compensate for this by installing sockets and swapping different components in and out. I'm an insatiable tw" Taylor - 11 March 2013

Harmonic Percolator.
"My kit was the "old" vero board kit - the new PCB kits should be even easier to make. Great kit, with great instructions. Had to email about orientation of the transistors, and got a quick and detailed reply. Worked first time and makes my Tele sound super-mean! Superb service all round. I have just ordered the F zz F actoy kit." Mark - 20 February 2012