REVIEW: Marshall JMD:1

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.

Around the back you’ll find the speaker outputs (two 8Ohm and one 16Ohm); serial/parallel FX loop with level and mix controls; pre-amp out for using an external power amp; 1/4″ stereo line in jack for connecting external audio devices; headphones output with power amp, speaker and microphone emulation; emulated line out on an XLR jack with the same processing applied as the headphone output; single 1/4″ footswitch jack (that’s right, the footswitch uses a single, regular guitar cord to carry the signal); and finally the MIDI in and MIDI thru jacks. Marshall quite successfully implemented MIDI control in its JVM series but it all goes even further in the JMD:1, with the amp remembering your exact settings for every channel, right down to the mix level you’ve selected for the effects loop.

So what you really want to know is what the models are, right? Ok. They’re divided into Clean, Crunch, Overdrive and Lead, and are based on the 1959 (or Plexi); 1974 combo; JCM800; JCM2000; JVM; JMP-1; Haze40; Guv’nor distortion pedal; Bluesbreaker II overdrive pedal; and the Mode Four. Here’s where it gets tricky: some models combine two amps, or even amp/pedal combinations. And they do it with incredible accuracy. You see, what sets the JMD:1 apart from the vast majority of modellers is that usually they attempt to replicate the end tone, whereas the JMD:1 simulates the whole freaking signal path by reconfiguring the preamp topology digitally, as well as reconfiguring the analog circuitry in the power amp to optimise it for whichever amp model you’ve selected. For example, let’s look at ‘Crunch 8. Full,’ based on the 1974 combo. The digital preamp topology changes to combine a 1974 ECC83 pre-amplifier stage with original 1974 treble and gain controls followed by a newly designed EQ with the midrange set at 650Hz and the Bass controlled using a variable capacitor, fed into the original 1974 phase splitter and its EL84 push-pull power amp with no feedback, feeding into a 1960 speaker load.

So how does it sound? Great, especially when you turn it up and get the EL34 power section working. The tones range from sparkly acoustic-like clean, to hard-hitting grunty country twang, to intricately responsive warm blues, to a very Def Leppard-like rounded and compressed pop rock tone (no surprise, as they use the JMP-1 extensively), to classic and hard rock to modern downtuned metal. Some of the channels sound better than others, but especially impressive is the JCM800 model, which maintains incredible note separation even on very complex chords containing tricky voicings like major 2nds, which modelling amps sometimes sound a bit unnatural with.

The effect in general is of a well maintained, well-behaved tube amp – sustained chords decay steadily and smoothly, and this could throw you off if you’re used to a more battered amp that sustains a little unevenly. If you have golden ears and an extensive track record of tube amp experience you might be able to discern, at certain settings, a little bit of that something indefinable that lets you know that you’re not rocking a full tube amp. But 95% of the time the JMD:1 sounds and feels pretty damn accurate.

In the process of writing this review I recorded myself noodling on each channel, using my Ibanez RG550 with Seymour Duncan Parallel Axis Trembucker at the bridge and a DiMarzio PAF Pro in the neck position. Wanna hear?

The effects are quite musical, especially the analog delay which sounds downright studio-quality with the level control at around 6. The reverb is good, but since we’ve already gone this far it’d be nice to have control over different types of reverb. Also, as a JCM2000 series owner myself, I’d prefer if there was a way of turning off the tone-shaping buttons that have been programmed into the JCM2000 models – I wasn’t able to dial in my JCM2000 tone simply because the way I set the Tone Shift and Deep buttons is the opposite to how they’re configured in the models. But the JMD:1 sounds incredible and there’s such a huge range of tone available that I really can’t fault Marshall and Softube for something as minor as choosing to turn on a virtual Tone Shift button in one amp model.

The JMD:1 is a great sounding amp with an unprecedented number of authentic Marshall tones packed into a deceptively simple unit. Digital no longer needs to be a dirty word, and let’s not forget the fact that all that very accurate digital tone is filtered through a true analog, valve power amp. It looks like a Marshall, it sounds like a Marshall and, just as importantly to many players, it feels like a Marshall.

LINK: Marshall

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