Whether you realize it or not, we are in the middle of a revolution. Over the past few years, bass amplification companies have been using new technologies to bring more compact bass amplifiers to the market. These “micro amps” are outfitted with relevant, useful controls, as well as efficient designs, and they pack a punch with wattage output similar to their bulkier old-school cousins. Today’s smaller, more load-in friendly amps have carved a deep niche for themselves in a very short period of time.

Gallien-Krueger has been building bass amps for more than four decades now, and it’s already solidified its place in history with the legendary RB series. Further, in many ways, G-K is arguably one of the companies that’s been downsizing heft while increasing quality and practicality for the longest. Always moving forward, G-K has now augmented its line with the MB series and its flagship MB800. Featuring a discreet, FET-driven preamp and a backsaving weight of just under 5 pounds, this little beast delivers 800 watts at 4 Ω—pretty incredible for something no bigger than a history textbook.

The Lighter Side
We’ll get to the impressive output of this amp in a moment, but for now let’s talk construction: The MB800 is housed in a metal, fan-cooled chassis that’s the height of a single-space rack unit, and about half as wide. Though the slenderness of the amp allows you to carry it in a laptop bag or the like, there are screw holes for optional rack ears. Because the knobs are made of a lighter plastic and the housing isn’t super heavy-duty in order to keep the MB800’s weight down, the option to rack the amp for protection against road wear is a welcome and wise option.

Even with its small footprint, the subway- friendly MB800 possesses many of the same features generally found on larger (and heavier) amps. There are two available gain modes, a -10dB pad, mute switch, contour control, and a 4-band EQ. Other features include a level control for gain B, as well as a master volume and a push-button limiter. The back panel boasts a balanced DI, dedicated tuner output, effects-loop jacks, and a switchable line out/headphone jack.

Front-panel controls are illuminated, a boon to any player stuck on a dark stage. Not only that, the knobs’ lights actually change color to indicate operation status, as well as whether the amp is clipping or overloaded. This isn’t just something that makes life a lot easier—it’s something every amp manufacturer should look into. Big thumbs-up to G-K for this smart touch.

Beef Aplenty
When powering up the MB800, the first thing you’ll notice is that it’s a powerful, powerful amplifier. The skeptical side of me wondered if such a little amp could move air. Not only did I quickly find that it could move air, but that it could get the dust out of the rafters as well! The MB800 generated the kind of dBs that make your neighbors call. One person shouldn’t have this much power, but it is nice to have. But how does it sound?

Hopping between a Warwick 411 Pro 4x10 and a Warwick 115 Pro, I put the amp through its paces with both passive and active basses. Starting with the 4x10 cab, I used a ’78 Fender P and a ’75 Jazz reissue to test the MB800 with passive electronics. I set all controls to 12 o’clock, and while the tone wasn’t especially inspiring at that starting point, it began to take shape after rolling off the treble and hi-mid knobs. After an A/B test with the 1x15 cab, I found the amp really liked to be paired with the 4x10—it produced punchy, modern tones that could work for just about any genre of music. The amp nicely maintained the character of each passive bass, while providing just a little of its own color.

With a ’76 Music Man StingRay and then a StingRay HH (both of which have active electronics) plugged in, the MB800 really came alive—the voicing was fantastic! Again, starting with the controls at noon, I found the amp to be bright, yet solid—great for slap and fingerstyle playing alike. Switching to gain B mode (by hitting the footswitch or pressing the front-panel knob), yielded higher input gain, which really brought out the G-K mojo. When I dug in, the signal would break up just enough to get gritty and mean, but without fully distorting. This controlled chaos was, for lack of a better word, perfect— especially with the StingRays. And the tone maintained its dignity while pushing the envelope at the same time.

But the real secret of the MB800 is its contour control. This effective feature decreases mids while boosting high and low frequencies. It’s a great one-knob tone-shaper that can take you from thin to beefy in one turn. The beauty of the contour is that it enables you to, say, smooth out a bass that’s throaty and midrange heavy. And when pushed to 2 or 3 o’clock, it scoops out all the mids in a way that will make any funketeer rejoice.

The Verdict
I’ve used G-K amps in backline situations over many years, and frankly, it wasn’t until now that I was truly impressed. The MB800 has raised the bar in micro-amp technology, and has pushed itself into a new classification. With its impressive features and extremely compact package, this amp has few equals. If you read the specs on this amp before you lay eyes on it, you will be impressed. When you see its small footprint and hear this monster roar, you will be amazed. The MB800 packs the punch of Tyson, the power of a Mack, and the grit of an asphalt sandwich. So if your back is tired of carting around a huge amp head, your search for a lighter alternative may have ended here.