Hands-On Review:For the tone freak who must have them ALL!

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By Phil Montoya

The idea sounded intriguing. But after all the hype around amp modeling and super-hyper-above-and-beyond amp modeling in the last few years, I was skeptical. My skepticism has been smashed. Randall is definitely romping all over the premium amp market with the RM4 system.

A blinding light
Like most brilliant ideas, this one is very simple. Rather than modeling classic tube amps with varying degrees of digital deception, why not build actual, tube/analog recreations of the distinctive classic pre-amp sections and incorporate them as modules into a plug-and-play unit? After a whole lot of research and engineering, Randall has pulled it off... beautifully.

Click To EnlargeThe RM4 rack unit contains 2 - 12AX7 tubes to buffer the effects loop, and 1 that works as a pre-amp tube with the 2 tubes contained in each module. Four 7" x 5" x 1-1/2" modules at a time fit in the RM4. The modules are interchangeable tonal replicas of classic tube pre-amp sections, and so far Randall has designed 11 of them. The RM4 master unit also features a series effects loop, a parallel effects loop with front-panel control, front- and rear-panel inputs, pre and post loop outputs, a ground lift, MIDI in/through, and a master volume control.

The unit operates like a four-channel pre-amp but each channel is actually a module pre-amp unto itself. You simply plug the modules into the slots-even while the amp is on, switch to the channel corresponding to the module you want, and you're good to go.

A world of options
Click to enlarge.The modules have identical front panels and they each incorporate a pair of 12AX7s. There are gain and master controls plus a 3-band EQ and bright switch on the front of each. The bright switch added noticeable presence to most of the modules and just seemed to pick up the high end for a few others. Most similarity between the modules ended there. The pure analog circuit boards were visibly quite distinct, and the sounds were much more so. Each module sounded entirely unique and responded to knob tweaks in its own way. Even the output levels of the modules varied greatly. Randall sent along 9 modules with the RM4 they sent me for review. I played them all through headphones then through a Randall RT2-50 stereo tube power amp (which is a whole other amazing story in itself) through a 4 x 12 cab.

Recto-designed after the Mesa/Boogie Dual Rectifier, this module produced fabulous harmonics and a very ready, heady distortion-thick and rich. Through the RT2-50 it was a stadium-ready screamer. Plexi-designed after the classic Marshall, this one evinced a lighter body with surf-like distortion and glassy clarity without a brittle high end. Clean-a Randall original, this amp lived up to its name and sported a lot of body. It produced a great jazz tone with plenty of low end but good definition and lively response. When I cranked the OD it became very ballsy but not too distorted.

SL+-designed after the Marshall Super Lead, this module was really eager to crank. It distorted at the drop of a hat and responded dramatically to pickup changes. It was very robust for hot blues leads ala Billy G., especially on the neck pickup. The bridge pickup brought it closer to Clapton in his stadium mode. Blackface-designed after the Fender classic, it is what it is. Through the tube power amp it sounded so much like its namesake that it was scary. It delivered glassy clean tones when the OD was down and chicken-scratchy old-time blues sounds with the overdrive cranked. Modern-another Randall original, this one was extremely easy to distort and produced a smooth and less raw distortion with a very full midrange. With the gain cranked I was reminded of Robin Trower. It produced very heavy overtones, perfect for guys who like to swim in distortion-drenched sustain.

Click to enlarge.Tweed-I had to look in the mirror to be sure I hadn't suddenly transmuted into Neil Young. Aside from the original Randall designs, this one caught the total feel of the original better than any of the others (though all of them where pretty darn close). Deluxe-like its Fender namesake, this module sported a very full, clear rhythm sound. With the gain cranked it produced warm and gravelly distortion and was very responsive to tone changes. With the gain and treble backed off, it put out some seriously sultry jazz tones. This is one I could definitely find myself leaning on as my old standby. Ultra-this is an original whose sound typified the screaming, complex, and heavy distortion that put Randall on the map. On the cleaner settings it produced great heavy metal crunch, but it was always itching to get into the real insane noisemaking.

Analog glory
The sounds of all the modules changed radically depending on the pickup and tone selections of my guitar. I didn't realize how much my digital effects were drowning the character of my guitar until I got back to a pure analog/tube signal path. Likewise, the stark dynamics of the
RM4 modules reminded me of how much digital sound flattens out a guitar signal.

For the guitarist with an obsession for pure tube tone who really likes to use a lot of radically different sounds and/or dupe classic sounds but doesn't want to lug around a bunch of amps, the
RM4 is a godsend. It would also shine as a studio piece, saving lots of room while still delivering a huge range of fantastic tones.




Features & SpecsAll pre-amp modules
  • Chassis holds choice of up to 4 pre-amps from Randall's 11 modules
  • Connects to any power amp
  • Tube-buffered effects loop
  • Parallel effects loop with front-panel mix control
  • Series effects loop
  • Front- and rear-panel inputs
  • Pre/post loop outputs
  • Ground lift
  • MIDI in/through
  • Master volume
  • 2 - 12AX7 tubes
  • Gain
  • 3-band EQ
  • Master
  • Bright switch
  • Mounts into RM4 with card-slot connector and thumbscrews
Optional MIDI programmable footswitch available.