MB Series Bass Heads

MB 200

With it’s substantial 200 watt output power, tiny footprint and incredible 2 pound weight, the MB200 is the ultimate in grab and go amplification. Featuring a 4 band active EQ and contour, XLR output, headphone/line output, auxiliary input and Speakon output, the MB200 is the ideal solution in the studio or on the stage.


MB 500

Weighing in at less than 4 lbs. and taking up less than one rack space, the MB500 delivers 500 watts of power in a package that will easily fit into your gig bag. Featuring GK’s legendary four band active EQ and contour control, the MB500 allows you to tweak your tone before hitting the digital power section. In addition to the generous tone shaping capabilities, the preamp section also features a foot switchable boost channel with independent volume control to dial in just the right amount of grind and level boost when needed.


MB 800

Continuing the evolution of the MB series, the MB800 features incredible output, increased functionality and a completely discrete FET (field effect transistor) driven preamp. With 800 massive “GK watts” of power, the MB800 can handle even the largest venues without breaking a sweat, and at 4.9 lbs. neither will your roadie. All of the controls of the MB800 are lit to indicate the current operating status including; input clip, tuning mute, Gain A, Gain B/Level-B, power amp clipping, limiter enable and EQ/Contour settings. The same FET technology used to create the legendary boost (G.I.V.E.) circuit found in all GK amplifiers for over 30 years is used in every stage of the MB800 preamp. Using FET devices to drive the GK four band active EQ, Contour and Gain allows the MB800 to transition seamlessly from a full, warm, clean tone to full on GK growl.



MB Fusion 500

The MB Fusion combines the all tube preamp of the Fusion series (without motorized controls) with the ultralight power amp found in the MB500. In addition to the identical tone shaping capabilities of the Fusion series, two foot switchable gain and master volume controls make the MB Fusion the ultimate in portability, tube tone and functionality.



MB Fusion 800

The MB Fusion 800 is the newest and next logical step in the MB series of bass amps. The preamp of the the MB Fusion with the power and control of the MB800.




What customers are saying about MB heads

Just wanted to let you know I bought the new MB500 bass head you guys just put out and I have to tell you from the minute I started playing, the amp gave me nothing less than an outstanding performance! The tone was clear and punchy and there was plenty of volume without pushing the amp. I especially liked playing it with the pad on. I enjoyed the compressed sound and when I needed the boost it was right there and then some. It gave my bass a fat tone and I can’t say enough about the size and weight. A bass player’s dream!! I have been a GK user for the past 20 years and I have to say the MB500 is the best amp I have ever played. It sounds great in any situation. Keep up the great work! – Ceaser Monitto

I purchased an MB Fusion about 5 months ago and just wanted to pass along the credit I think you deserve. I have never owned a GK amp before and I was interested in this model because of the tube pre-amp. The reviews were good and I expected a lot but so far it has surpassed all my expectations. This is one beautiful sounding amp with an aggressive nature that I just love. I have been playing bass over 40 years and have used almost every brand of bass amp at one time or another but this amp seems as though it was designed personally for me as it has everything I need in an amp and not a lot of junk I don’t need. I like the simplicity of the tone controls and it is such an easy amp to set up and get a good sound from. So far this has been my favorite head I have ever used. Thanks for coming out with the perfect amp. – Dave

Well, I have had my MB Fusion 800 for a few weeks now and used it on a few gigs. I think I’ve died and gone to heaven. WOW! Thank you all for your recommendations and help. This new rig is so versatile, good for ANY size venue. It has the best tone quality of bass rig I have ever heard or played through. Just amazing, this setup (NEO112, NEO212 and the MB Fusion 800) ROCKS! I can’t say Thank You enough. – Bruce P

Hi, I’m a UK bass player and wanted to drop a quick note to say I really love this amp! I’ve been playing bass since 1974 and have been pro since 1982, so as you can imagine I have tried almost every format and flavor of bass gear. I wish I’d found GK much earlier in my career, as the sounds coming from this little guy suit me down to the ground. The MBFusion 500 is my go-to amp. Such harmonic complexity, detail and clarity, yet with seemingly endless heft and authority and it fits in my bass case! I can get my entire rig in my tiny British car, and in one trip! – Mark J. Smith

I was struck by the richness and depth of the system (the MB500 with a NEO212 and NEO112) where nice loud bass never got distorted. It projected power without being overbearing or ‘hyped’, even when Brandino kicked in the octave divider effect, the low bass frequencies were still tight and punchy. The mids were lush and sweet and the highs were crisp. When the string was popped, the sound was never harsh, but stayed very musical, with a sort of natural compression on the transients that sounded natural and not overly limited. Tonally it complemented the drums without hiding the kick, and blended well with the richness of the Hammond organ tones, without overwhelming them or being overwhelmed. Overall, I was very impressed. That may have been the best balanced bass tone for a modest club setting that I have ever heard.

– G. Radai, Audio Engineer

I recently purchased an MB200 amp. I’m not a bass player, nor have I ever pretended to be. I am however, a pretty fair pedal steel guitarist. I started playing steel in 1975. In my steel playing career, I’ve owned numerous ‘Standard Of The Industry’ steel amps, several of which, despite being from the ’70s & early ’80s, are still favored by a lot of players. Unfortunately, they are also on the heavy side. Great when I was younger but now, not always a good thing. Especially true when you play a ‘not so lightweight’ pedal steel. Add to that, I generally have to carry a second amp for most gigs as I double on guitar. I’m a member of The Steel Guitar Forum & came across numerous posts regarding the GK MB200 amp. You guys really seemed to nail exactly what a lot of us steel players were looking for. Adding an outboard reverb unit (which is a steel guitar essential), the tone is just incredible. Lately, I seemed to be fighting my amp for the tone I was hearing in my head. Not any more! This amp has delivered everything I was after at a comfortable price and in an extremely lightweight package. The low end is clear and the individual notes within a chord have unbelievable definition, no muddiness at all. The mids do not get honky or harsh. The highs are sweet and clear without being piercing. I’m running this with just a 112 cabinet and absolutely love the tone. A lot of players like to experiment with different speakers & cabinets. This amp gives us the flexibility to do that with ease. I will be using it out tomorrow for the first time and can’t wait. Since I first hooked it up on Thursday, I find myself going back time after time to turn it on and listen just one more time. This amp is just the greatest! Please, don’t change anything about it. I’m planning on buying a second one as soon as funds allow. Thanks for a truly wonderful product! – Bob Poole

The MB Fusion is, without doubt, the best amp I have played. I’ve spent a lot more money on far bigger amps from other brands but have not got anywhere near the tone I was looking for until now. I’ve always liked the punch and general sound of GK amps, but factoring in the light, natural drive I can get with this one just takes it that one step further that I needed and blows everything else I have played out of the water. The fact it is packaged in such a small and light shell just makes it my perfect amp (I play in a bar band so the less big, heavy gear we have, the better). I don’t usually write to companies after buying their product, but I felt I should this time just to thank you for producing this amp and giving me the sound I have been looking for since I started playing.
– K. Imray

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