Marshall’s JMP-1 preamp was a classic little unit. Packing real valve tone into a single rack space unit with MIDI programmability, it was often paired with a Marshall EL34-based rack mounted power amp (and sometimes even Marshall’s JFX-1 rack mounted effects processor) into a formidable rig of doom. Racks eventually fell out of favour in deference to combos and heads, but Marshall’s new JMD:1 is intended as the logical successor of the JMP-1, this time available in head and combo versions.
The key to the JMD:1’s tone is its digital preamp, designed in partnership with Sweden’s Softube (if you’re anti-digital you should know it’s paired to a Marshall EL34 power amp). There are 16 different models here, painstakingly modelled on actual Marshall amp rigs. Left to right, the head’s controls are master volume and presence; reverb; delay level and delay adjust; modulation depth and modulation adjust; volume, treble, middle, bass and gain; then the 16-position pre-amp selector pot.
Below this array of knobs are several buttons: manual; channels 1, 2, 3 and 4; modulation; delay/tap tempo; external FX; compare; and footswitch/MIDI program. You can store unique sounds if you use just the amp itself, bump that up to 28 by using 6-button the footswitch, or 128 if you’re using a MIDI setup. If you’re playing in a band that uses a sequencer live, you could conceivably program the sequencer to do all your preset-changing. Cool! Delay has four modes: hi fi, analog, tape and multi, and cycling the knob through the range of each setting changes the rhythm of the repeats in multiples of the tempo (as set by the tap tempo control). Similarly, aside from the noise gate setting which relies solely on the mod depth control, the mod adjust control ups the speed of either chorus, phaser, flanger or tremolo.