Not too long ago we looked at several amplification systems of this kind: small tube amps that give us the full warmth of the big amps, but for situations where we don't need excessive power. The product we're reviewing today is certainly quite feisty and aggressive, and it yells louder than its small size suggests. Looks can be deceiving. Even though it's one of the smallest in the family, this is a pretty scrappy amp. Although its wattage is moderate, it can deliver serious muscle.

Obviously, its effectiveness (in terms of volume) will depend on the context in which you need the amp. Many guitarists need tools that really sound. Tired of so much modeling, they want the real deal, good old tube grit. Without belittling modeling, which gets us out of so many jams, finding something manageable, portable and aggressive with tubes is a goal for many. This head may be the definitive find for many musicians with these needs.

Front Panel
With a nice finish that lets you see its tubes from both the front and the back, we have a small but complete head. Black with feisty red details. The front panel provides a ¼" TRS input, a switch, bass, mid and treble EQ, and a master volume.

Now we come to some peculiarities of the little Krank. This little buddy has two switchable channels: the Kleen Channel and the Krank Channel. With the boost switch, we increase the gain quite forcefully on both channels. At the end of the panel there's a curious pot called sweep. It acts on the EQ in a very peculiar way. So much so that the flexibility we get by combining the possibilities of both channels, the boost, the EQ and the sweep turns the RV JR into a machine with a wide variety of tones.

Rear Panel
Few surprises. Its eye-catching tubes, the power inlet, the fuse, a voltage selector, a line out, the speaker output, an impedance selector (much appreciated) for 8 and 16 ohms, a switch to engage the effects loop, send and return and, finally, the effect level control.

The Tests
I connected this little monster first to a single-speaker cabinet, then to a rather large one: a 4x12". I wanted to see what the overall result was. I carefully tried all the Rev JR's options, gaining some body when I used the big cabinet. It felt like I was playing through a serious beast (with many more watts). In any case, the choice of cabinet is up to the user, since it depends on your needs or, better, your priorities: portability, thick sound, several cabinets, tight sealed sound, open back, etc.?

As I mentioned a little earlier, having two channels and the boost helps a lot in setting up a large number of clearly differentiated sounds. I got good results clean, at crunch and especially at higher-gain settings. Personally, I think it's an amp built for burning off adrenaline. Playing in that last area with a bass boost on its EQ and adding the magic of the sweep pot, you can get truly crushing results.

This little critter certainly surprises.

Conclusions
A lightweight head, moderately priced considering its quality, but not especially cheap. And in saying that I'm not saying it isn't worth what it costs; I'm only saying there are cheaper things, surely of different quality. It's well equipped and versatile, with two channels and a boost. It has authentic tube sounds. Very portable. Suited to cleans and medium saturation, and highly recommended for heavier stuff.

In short, for the 700 euros it costs, plus a cabinet, you can already look at quite a few things. Though with the quality of this one, I don't think you'll find cheaper ones. Whether it suits you or not will come down to your style and what your “ears” are after. Try it, crank it, run through both channels, squeeze everything out of it and decide.

Good luck.