JMP Experience – Electric guitar pedal – Marshall-Style 2203, JCM800 Overdrive

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All audio clips are recorded with a Marshall JCM900 head set on an extremely clean tone.


Fender Stratocaster HSS (equipped with Fender Texas Special single coil at neck and middle, and DiMarzio Paf Pro humbucker)
Gibson Les Paul Standard (equipped with Seymour Duncan Alnico 2 humbuckers)

Clean sound, no effects added

Clip 1
Guitar: Gibson Les Paul Standard (bridge pickup)
Pre Amp Gain: 8/10
Power Amp Gain: 8/10
Tone: 6/10
Volume: 4/10

Clip 2
Guitar: Gibson Les Paul Standard (bridge pickup)
Pre Amp Gain: 4/10
Power Amp Gain: 3/10
Tone: 6/10
Volume: 4/10

Clip 3
Guitar: Fender Stratocaster HSS (neck single coil)
Pre Amp Gain: 10/10
Power Amp Gain: 5/10
Tone: 5/10
Volume: 4/10

Clip 4
Guitar: Fender Stratocaster HSS (bridge humbucker)
Pre Amp Gain: 9/10
Power Amp Gain: 4/10
Tone: 7/10
Volume: 4/10

JMP Experience is a distortion pedal inspired by the guitar tones of the first Marshall Master Volume heads called JMP 2203.

An old story…
It was 1975 when Marshall’s first foray into the world of Master Volume amplifiers. Before that, the 30, 50 and 100 watt Super Lead “Plexi” heads were the go-to amps for rock guitarists and beyond, responsible for the era’s iconic sound, imitated and replicated in every way possible, becoming a true guitar reference on which we also made a products called Plexi Breed pedal. As glorious and gritty as the sound of a loud “Plexi” is, the guitarists of the mid-70s were no longer satisfied with the sound of the amp alone, without the help of a fuzz pedal, distortion or overdrive, they just didn’t produce the desired amount of distortion. Also, due to the fact that these amps lacked a master volume control, the only way to produce that famous “Plexi” sound, was to turn it up so that those power tubes (usually EL34, but also KT66 and 6550) could literally create magic. However this solution to generate distortion for most guitarists was a big problem due to the high volume produced by these powerful amplifiers. Anyone who has ever been in front of a maxed out Marshall Super Lead knows firsthand exactly why the great Jim Marshall was called “The Father of Loud”.

The introduction of Master Volume
With the arrival of the JMP 2203 head in 1975 a master volume pot was implemented, something normal nowadays, but at the time it was a real revolution; the 2203 obviously also boasted a “Pre Amp Volume” (often known as “Gain”) control. Gain allows the guitarist to dial in the amount of distortion in the preamp section while keeping the overall volume of the power amp, and therefore the amp could be set low. The overall output level is determined by the Master Volume control, hence the logical name “Master Volume”.

Improving perfection
Due to the growing demand for more distortion and sustain at lower volume levels, Marshall came forward with the Master Volume series in 1975. “That amp came about because guitarists of the day wanted the Marshall tone, but very often, they found themselves losing engagements and jobs due to the unmanageable volume, those amps were too powerful and lowering the volume was not a compromise to consider as the overall sound changed radically.

Essentially, Marshall’s designers took the 100 watt (1959 model) and 50 watt (1987 model) Super Lead heads and cascaded the preamp gain stages, correcting bias and settings on the second stage, then added the much desired Master Volume control at the preamp output. Two new heads were born: the 50 watt 2204 and the 100 watt 2203. Both were a success, especially the 2203 model which soon became legend.

JMP or JCM800?
Way back in 1966, not only did the England soccer team win the World Cup, but Jim Marshall signed an international distribution deal with a company called Rose-Morris Agency. Unfortunately, the exorbitant 55% price markup on exports meant that Marshall amps purchased outside of England were hardly cheap. So, when that contract finally expired in early 1981, the JCM800 line was born.

Since the JCM800 line has been around for the entire decade it dominated, many would logically assume that the “800” was a nod to the 80s, especially when the 900 series followed in the 90s! In truth it was pure chance! The letters “JCM” stand for Jim’s full initials – James Charles Marshall. As for the “800” part? Here’s the real story in the words of Jim Marshall:

“I wanted a new name for the amps, but every idea we came up with was dreadful… then, one day, I looked at the number (license) plate on my car and immediately thought, ‘That’s it — that’s what we’ll use.’ It was staring me right in the face all along!” – Jim Marshall

The pedal and the inspiration
The JMP Experience exploits the same principles of the aforementioned heads (2203 and 2204) to generate that typical tone character which unlike most pedals on the market, includes the possibility of simulating (always in a totally analog way) the saturation of the power amp through the exclusive Power Amp Gain control, to offer every type of response in terms of compression and resonance.

“The idea of making this pedal came from the will to emulate the guitar sound of one of my favorite heavy albums of all times, let’s talk about “Piece of Mind” by the British band “Iron Maiden” from 1983. I discovered this album when I was a teenager, I already played the guitar and for many years it was my reference guitar tone, especially for rhythms, so I tried to find out about the type of equipment used to record this wonderful album; the Internet was not yet widespread in those years, poor info and only a few documents talked about this, I had to wait years before learning what Dave Murray and Adrian Smith were using. The info came by accident but it came: they were using a couple of Marshall JMP 2203 heads. So I set to work.” – Luca Colombo

The controls
The pedal features 4 simple controls:

Pre Amp Gain: controls the amount of preamp distortion;

Power Amp Gain: controls the saturation of the virtual power amp, higher values give the typical sag of a high volume amp;

Tone: works on the frequency response of the distortion, low values offer a darker and warmer tone, high values give more bite;

Volume: sets the main output volume offering a boost of approximately 20db.