The JAM Pedals "Achenbach" Harmonious Monk mk.2 is a limited, hand-painted artwork version of the Harmonious Monk mk.2, an all-analog harmonic and amplitude tremolo pedal created by JAM Pedals with That Pedal Show1. It offers two tremolo voices in one box: Harmonic mode, which JAM Pedals describes as creating "rich, phase-like movement," and Amplitude mode, which provides traditional volume modulation1.
The Achenbach edition is electronically identical to the standard mk.2. What sets it apart is the finish: it is the Harmonious Monk mk.2 "reimagined through the artwork of The Simpsons artist John Achenbach," and every limited artwork pedal is a one-of-a-kind hand-painted piece, so each one differs in detail from the photos1.
The Achenbach artwork version is listed by JAM Pedals as sold out2. It was a limited hand-painted run, and the same circuit remains available in other finishes, including the "Relic" Harmonious Monk mk.2.
What the Achenbach Harmonious Monk mk.2 does
A tremolo modulates your volume, and the Harmonious Monk mk.2 gives you both classic approaches. Amplitude mode is the familiar one: the whole signal's volume rises and falls at the set rate. Harmonic mode instead splits the signal and modulates the treble and bass against each other, which JAM Pedals describes as "rich, phase-like movement," closer to a slow phaser or Uni-vibe sweep than to a choppy volume pulse1.
The mk.2 keeps the original Harmonious Monk's all-analog circuitry and tone while adding features, and That Pedal Show describes it as built to be "even more useful and functional on guitar, keys and anything else"4. Input and output are in phase, and internal Treble, Midrange and Bass trimmers shape the effected signal, so the wet path can be voiced to suit the instrument rather than fixed for guitar alone1. JAM Pedals pitches the Harmonious Monk line as "offering vintage pulse, modern control and a remarkably wide range of movement"5.
Players named on JAM Pedals' own pages include Matt Schofield, listed among the guitar players using the Harmonious Monk mk.22, and Alex Feder, quoted on the Achenbach page saying: "The Harmonious Monk is, hands down, the best tremolo I have ever played in my life"1.
The controls and footswitches
Four knobs handle the core settings, and three internal trimmers voice the effected signal1.
| Control | What it does |
|---|---|
| Speed | Sets the rate of the tremolo |
| Depth | Sets the intensity |
| Level | Controls output |
| Mix | Blends dry and wet signals |
| Internal Treble trimmer | Shapes the effected signal |
| Internal Midrange trimmer | Shapes the effected signal |
| Internal Bass trimmer | Shapes the effected signal |
The Mix control is worth noting for anyone who has used an older harmonic tremolo: blending dry and wet lets you keep body in the sound at deep settings instead of committing fully to the effect. The pedal has two footswitches, one of which is the ON/OFF switch. The default startup state is off; to change it, disconnect power, hold the ON/OFF footswitch and reconnect power1. That means you can set the pedal to come up already engaged if it lives switched on in your rig.
Power comes from a 9V DC center-negative supply, with an isolated supply recommended, and the maximum current draw is 145 mA1. That draw is on the high side for an analog tremolo, so plan your power distribution accordingly.
History, versions and the Achenbach artwork
The Harmonious Monk is an all-analog harmonic and amplitude tremolo created by JAM Pedals in collaboration with That Pedal Show1. The mk.2 line includes custom artwork versions, among them the "Achenbach", which reimagines the pedal through the artwork of The Simpsons artist John Achenbach, with the same sound as the other artwork versions ("Arachnid", "Beast", "Cactus Totem" and "Relic")1. Each limited artwork pedal is a one-of-a-kind hand-painted piece, so every unit differs in detail from the photos shown1. The "Achenbach" mk.2 is sold out4.
The Achenbach is one of several custom artwork versions of the mk.2. JAM Pedals has offered the same pedal as the "Arachnid", "Beast", "Cactus Totem" and "Relic" editions, all with the same sound and differing only in paint6. The Achenbach version carries artwork by John Achenbach, an artist known for his work on The Simpsons, and because each pedal is hand-painted, no two are identical1.
The regular price was £334.00, tax included, and UK orders were shipped DDP with 20% UK VAT and all duties included, so there were no extra charges on delivery1.
Videos
That Pedal Show
JAM pedals
JAM pedals
Questions
Is the Harmonious Monk mk.2 true bypass?
Yes. JAM Pedals lists the bypass as true bypass, so with the pedal off your signal passes through without active buffering. The default startup state is off, and you can change that by disconnecting power, holding the ON/OFF footswitch and reconnecting power.
What power supply does the Harmonious Monk mk.2 need?
It runs on 9V DC with a centre-negative plug, and JAM Pedals recommends an isolated supply. Maximum current draw is 145 mA, which is high for an analog tremolo, so check that your power brick has enough headroom before daisy chaining it with other pedals.
Does the Achenbach edition sound different from the standard Harmonious Monk mk.2?
No. The Achenbach is the same harmonic and amplitude tremolo circuit as the other artwork versions of the mk.2, such as the Relic, Arachnid, Beast and Cactus Totem. The difference is the finish: each limited artwork pedal is a one-of-a-kind hand-painted piece by John Achenbach.
Can the Harmonious Monk mk.2 be used on keys or bass?
Yes. That Pedal Show describes the mk.2 as designed to be useful on guitar, keys and anything else, and internal Treble, Midrange and Bass trimmers let you shape the effected signal to fit the instrument. Input and output are in phase.
Is the Achenbach Harmonious Monk mk.2 still available?
No. JAM Pedals lists the Achenbach artwork version of the Harmonious Monk mk.2 as sold out. It was a limited hand-painted edition, so units do not come back once the run is gone. The standard Harmonious Monk mk.2 circuit continues in other finishes.
Sources (6)
- “Achenbach” Harmonious Monk mk.2, JAM Pedals (www.jampedals.com)
- Harmonious Monk mk.2 B-stock, JAM Pedals (jampedals.com)
- JAM Pedals Harmonious Monk mk.2 Review, Premier Guitar, 2024-01-21
- Harmonious Monk Mk.2, That Pedal Show, 2023-04
- Harmonious Monk, JAM Pedals (jampedals.com)
- “Relic” Harmonious Monk mk.2, JAM Pedals (jampedals.com)
