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Marshall JMD:1 100-Watt JMD102 Combo Amp Review

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Marshall JMD:1 100-Watt JMD102 Combo Amp Review

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Legend has it that Who bassist John Entwistle enlisted drum shop owner and teacher Jim Marshall to build a bass amp loud enough to be heard over Keith Moon's drumming. A short time later, Pete Townshend walked into Jim Marshall's shop asking him to build a guitar amp so he could be louder than Entwistle. And the rest is a rock and roll history. So, when the grimacing FedEx guy abandoned on my doorstep a 70+ pound box emblazoned with the iconic Marshall logo, I knew that whatever lay inside should be very loud indeed. And it was.

Turns out that what lay inside was a Marshall JMD102, the latest in hybrid amp technology from the most iconic amp builder in the history of loud. The JMD102 is a 2x12 100-watt combo from Marshall's new JMD:1 line that also includes a 100-watt full stack, 50-watt half stack, and 50-watt 1x12 combo.

Future and Past Come Together
Under 28" wide, 21" tall, and only 10" deep, this 2x12 100-watt all-in-one amp is only slightly larger than many 1x12" combos. Powered by four EL34 valves (I'm going with the British term since this is a British amp), it has plenty of raw analog muscle, which the Eminence AX75 speakers handle exceedingly well. While Marshall may have taken it on the chin when they went down market and started dabbling with solid-state circuits, they are still kings when it comes to focused output derived from valve power, and this amp shows off that legacy. What may give pause to some Marshall and valve power purists is the JMD:1's digital preamp and onboard effects. The digital preamp is Marshall's foray into amp modeling, and to make sure they got it right, they collaborated with Swedish DSP company Soft Tube, relying on their "Natural Harmonic Technology" for the 16 different digital preamps found in the JMD:1 series. Given the many classic Marshall tones throughout the company's history, adding simulations to any amp with the Marshall brand had to be daunting prospect, so they were wise to leave the simulations to experts in the field via Soft Tube while Marshall focused on what it does best—loud, proud, classic valve power and tone.

The sixteen preamps included in the JMD:1 series are, of course, based primarily on classic Marshall amps, including the 1959 Plexi, the holy grail of rock JCM800, and more recent models like the JVM series and Haze 40. A few Marshall's stompboxes and their MIDI-controlled rackmount digital preamp are also represented.

Controlling the Beast
The preamps are accessed from a single knob that breaks down the tonal palette into four categories: Clean, Crunch, Overdrive, and Lead. Marshall's standard set of controls for EQ and volume all respond differently based on the selected preset. This makes sense since, for example, the EQ knobs of a Marshall 1974 behave differently than the EQ controls on a JMP-1. Likewise for gain staging. So dialing up a preamp setting is like dialing up an amp, since all the relevant knobs will behave accordingly. The JMD:1 manual does an excellent job of explaining this along with the gain staging and signal path of each preamp setting.

The amp's front panel includes five LED push-button switches to store four amp presets. The fifth button (technically the first on the panel) puts the amp in manual mode (what you see is what you get). While only four amp presets and one manual setting are available from the front panel, there are 28 different amp presets available—seven banks containing four presets each. These are accessed using the included 6-way foot controller and are also available via MIDI. The foot controller is smartly designed and easy to use. LEDs tell you what preset you are on. The first four footswitches call up the presets of the current bank, and the two remaining footswitches allow you to increment/decrement through the seven available banks. Again, LEDs on the controller tell you what bank you are currently in. If for some reason you don't plan on using multiple banks of amp presets, you can change the foot controller to act as a universal controller for the amp. This mode, called Switch Mode, lets you assign each footswitch to a button on the amp's panel. So, for example, you can use three switches for different preamp tones such as clean, distortion, and lead, and use the remaining three to manage the JMD1's onboard effects and an external FX loop. Kudos to whoever thought of that!

The back panel of the JMD:1 has everything you'd expect from an amp, with some feature implementations worth noting. The FX Loop has a switch for +4/-10 dbv I/O, and has a Wet/ Dry knob. It can also be turned on and off via the amp's front panel of, if assigned, the foot controller. The emulated speaker line out uses a balanced XLR connection, and Headphone out, Line in, and Preamp out are also available via 1/4" jacks.

Okay, I'm dying to get to the tone, but, for the sake of due diligence, I need to mention that the amp has the standard Marshall controls, Gain, followed by EQ (Treble, Middle, Bass), followed by preamp volume, followed by a bunch of knobs and buttons for the effects—more on that later—followed by the standard Marshall Master Controls Presence and Master Volume. Got it? Let’s move on to the good stuff.
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