Is The MD 100DFX Combo, Amp Review True?

Posted by: Daniel R. Lehrman Posted in: Guitar Amps

Mourn not Marshall’s Valvestate amps, those wonederful vintage amps that defined guitar amplifiers, for now the company has added to their successful old series with the AVT and MG models. The MG series is the new doorway into the Marshall-driven rock dream, promising classic looks, decent build quality and, hopefully, a worthy dollop of that trademark tone.

Marshall MG100DFX Combo

Marshall MG100DFX Combo

Unlike the Valvestates, though, the MG series does not include a real valve in the circuit: instead the designers have developed FDD, aka Frequency Dependent Dampening, a form of speaker emulation that mimics the way valve amplifiers interact with loudspeakers. Marshall deserves due recognition for this: amp designers often concentrate their efforts on preamp distorsion, neglecting the influence of the power stage on feel and playability. FDD creates a “larger than life” illusion from the speakers-and, as a bonus, you get a speaker-simulated line input for low-volume home recording and easy connection to a PA system.

If you like the way Marshalls look-textured vinyl covering, plastic corner protectors, that big white plastic logo-you will like the MG100. it’s a 100 watt, two channel combo with a single 12″ Celestion speaker, an effects loop, an emulated headphone/line output and a jam along CD input on the front panel. there are four digital effects (reverb, delay, chorus and flanging) and a channel swithing/effects activating footswitch. It weighs in at 52 pounds and is solidly constucted from 3/4″ chipboard. It’s a solid 23 1/4″W x 22″H x 11″ D.

A master volume controls both channels but each has it’s own Gain control and EQ. The clean channel has Bass, Middle and Treble plus a Contour control to shape the mid frequency range to vary the tone from vintage and woody to scooped and aggressive. There’s also an OD1/OS2 switch-the second option providing obscene levels of gain.

The Digital FX Preset/Adjust control is dual purpose, allowing you to select one of the four types of effect: chorus abd delay together, delay: chorus: or flange. As you sweep the control, each different effect became active in different regions of the knob’s travel range. For instance, in the chorus/delay section, the knob controls the delay time from a short rockabilly or surf-style slapback to long, atmospheric “stadium’ echoes ( though, the idea of anyone trying to play surf music with a Marshall seems pretty strange to me-a bit like playing Barney Kessel lines on a B.C. Rich) Anyway, the number of repeats sensibly decreases as the delay time shortens. This knob also controls chorus speed and flange speed.

The digital FX level control allows you to mix the effects with your dry sound-very sensible. because you’ll never be stuck with an effect you like but with an excessive volume level. The reverb is also digital.

Most guitarists place their effects between their guitar and their amp, but the MG100’s effects loop allows you to place them between the preamp and power amp. This can result in improved signal to noise ratio because, unlike the guitar signal, any noise generated by by the effects unit does not pass through the whole amplifier. It also provides a wider pallete of sounds. because a flanger or chorus in front of an amp only acts on a clean guitar signal: the distorted signal passing through the effects loop will contain more harmonics, so that effect is more potentially radical and extreme. Higher fidelity is another benefit, because a preamp will distort any effect that passes through it. Placed in the effects loop, the effect is applied to the distorted guitar but stays relatively clean as it passes through the power stage.

The MG100 has a -10 dB/+4 switch to match levels to pedals or rack-mount effects and an Effects Loop Mix control for blending in the required amount of the effect place across the effect loop. In practice, though, it didn’t work as well with standard stomp-boxes. As the effects loop signal was faded in, the overall volume of the amp came in dropped, reaching it’s minimum when the dry/effect mix was 50/50 then rising again as it moves towards 100 per cent wet. If your effects loop has a dry/wet balance parameter, it should be set at 100 per cent wet internally. A polarity flip button would be a sensible, cheap solution, but as matters stand, the functionality of the Effects Loop Mix is somewhat compromised.

The FDD button, of course, switches on the Frequency Dependent Dampening circuit. Marshall is obviously please with its FDD technology and surely the only reason that switch is included is to demonstrate what the MG100 would sound like without it! However, I can’t imagine that anybody would use this amp with the FDD switch disengaged.


The clean channel sounds pretty good. I fired it up against a favorite of mine, a Peavey Classic 30 I have had for a while and found the MG1oo’s playing response very valve-like, with a softer, rounded off quality to the front of the notes. The tone is reasonably warm and bluesy and a wide range of is available via the tone controls. With a Strat I was able to get funky and also coaxed a little SRV clean but fat tone out of it. Driving the clean channel less happy results, though.

I was all set to be fully impressed with the clean channel until I activated its Crunch switch. Instead of the classic overdriven Marshall tone I was expecting, I was almost blown thru the wall by, less tone quality than expected, but very acceptable. The upper harmonics left something to be desired also. However nothing about the sound was a turnoff.
Writing an un-biased review and having said a mouth full about its good and bad points my overall impression and verdict is that it is a great, although large practice amp and reasonable gig amp. It has a lot of power. For the die hard tube/valve amp lovers this amp would not do the job. For someone looking for ultra durability and a great overall presence with lots of versatility, you just found out what hi tech solid state electronics can deliver.

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4 Responses to Is The MD 100DFX Combo, Amp Review True?

  1. I think power tube saturation is much to important to think that tube amp sound can be acheived by pre- amp tubes alone.

  2. Alline Pietryga

    Can I take guitar lessons for beginners in my panties?

  3. I picked up one of these quite by accident,a musician friend needed airfare back to NYC so I picked up the amp for 200 bucks.My main rig is a half stack TSL.I wanted a more portable rig.Two mods were immediate,my computer tech replaced the fan,the stock fan is very cheaply made.Next the speaker,I do not like celests,my fave is the vox bulldog,I did the same in my 4×12 cab,you can really push a bulldog around and they like it.The lifeless tone of the amp in the crunch/od1/od2 so bemoaned by many is due to the speaker itself.This is the first solid state amp I have ever had,I am a stone tube guy but I like this amp alot.And the fact it is written off as an ugly duckling makes it even better.It works well stand alone with a small combo yet it is designed really to go direct into a PA.And the PA is what…solid state.So onstage you are just crusing the amp,dialing in the tones and the FOH/foldback mix is laying down your output.

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