This Single-channel Tube Amp is a Real Quick-change Artist!
The Randall MTS RM20B packs a ton of tone into its 15-watt, 1 x 12" combo package, and its modular preamp section gives you a staggering array of tube-powered sounds. Though it's a single-channel amp, the MTS RM20B has a couple of tricks up its sleeve: a footswitchable Tube Boost function lets you dial in more gain or volume, and a series effects loop adds to its tonal versatility. Density and Presence controls, an XLR Mic Eliminator direct output, and rear panel bias panel are also included on the MTS RM20B.

Randall MTS RM20B 15-watt Tube Compo Amplifier at a Glance:
Tube Boost function
Silent XLR output option
MTS modules
Tube Boost function

A big part of what makes the Randall MTS RM20B so cool is its modular approach to preamp tones. But that's only half of the equation! The RM20B uses Ruby EL84 tubes in the power section to give you quick transient response to playing, as well as great power-amp overdrive capability. The RM20B is a single-channel amp, but its footswitchable Tube Boost function takes advantage of these tubes to give you some extra overdrive and volume level capabilities. The RM20B can take a lower to mid-gain module from pristine clean to sustaining lead tone at the click of a switch by simply activating the included tube boost function. Use the tube boost gain control to add a desired amount of additional saturation then adjust the boost level control for the desired boost volume. For all modules, especially the higher gain tones, the tube boost function can be used as a volume boost without adding additional saturation by simply rolling out the boost gain and adjusting the amount of boost volume.

Silent XLR output option
For such a compact, easy-to-transport amp, the MTS RM20B packs an impressive punch. Its single 1 x 12" Celestion Greenback speaker is well-matched to the amp section, and a semi-closed-back cabinet design lets it pump out a tight, convincing low end. If you're looking for some late-night playing options or studio recording alternatives, the RM20B features an XLR Mic Eliminator direct output circuit as well as a speaker on/off Standby switch for silent recording. Now you can lay down real authentic tube guitar tracks without disturbing the neighbors.

MTS modules
With fourteen MTS preamp modules to choose from and more in the works, having a new amp is as simple as plugging in a new module. Start with as few as one, or install up to four, and you'll have all your favorite tones right at your fingertips. All modules can be used for the RM4 preamp and utilize the same panel layout. Here's an overview:

Ultra: Extreme hi-gain, with tight low end and liquid sustain. This one exemplifies the Randall tone, and is perfect for any classic to modern metal tone.

Treadplate: Based on the preamp circuit of a Mesa/Boogie Dual Rectifier. Cutting tone with strong mid-range. It has defined the modern day rock and Nu-Metal tone.

UltraXL: A modern version of Randall's high-gain tone, the Ultra XL has massive amounts of liquid gain combined with huge bottom end and cutting upper mid-range.

JTM: Based on the preamp circuit of a classic Marshall JTM45. Classic mid-gain amp with good bottom end.

SL +: Based on the preamp circuit of a hot rodded Marshall Super Lead. Randall give the classic Super Lead circuit a bit more gain and punch.

Plexi: Based on the preamp circuit of a classic Marshall Plexi. You can take it anywhere from Page, to Angus, to Gibbons.

Top Boost: Based on the preamp circuit of a Vox AC30TB with a little more kick in the front end. Chiming high end that will handle anything from classic Petty, to Brian May to modern Lenny Kravitz.

Tweed: Based on the preamp circuit of a '59 Fender Bassman. Great for all blues tones with a huge bottom end and nice bite in the gain circuit.

Blackface: Based on the preamp circuit of a Fender Blackface Twin. Legendary clean tone with cutting mid-range and sparking highs.

DLX: Based on the preamp circuit of a Fender Blackface Deluxe. Tone that bleeds country music. Great mid-range and top end spank, with more bite than the Blackface.

Clean: Very warm and round. A perfect clean tone for the jazz and blues guitarist, or any guitarist looking for a smooth, robust, clean sound.

Modern: Modern Hi-gain distortion. This one takes you from modern rock to nu-metal rock tones.

Brown: Classic high-gain brown sound. A basic hot-rodded Plexi with great mid-range sustain. Great for early EVH and 70's rock as well as dirty tone from early 90's grunge.

XTC: Based on the preamp circuit of a Bogner Ecstasy red channel. An all around great hi-gain tone with tight low end and cutting mid-range. It will cover any rock to metal tone.