Harmonic Percolator

From the vendor

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.

We're now all out of our stock of vintage 2N404, so we supply the closest Russian units we've found, which sound just as awesome.

To add a bit of mojo we're now supplying T0106 black-cap 2N3565 as standard, and while stocks last you can opt for vintage 1N695 diodes rather than Russian units.

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