May 20, 2019 chris

The Original Micro Bass Amplifier

The Gallien Krueger MB150S III is quite an anomaly in the landscape of bass amplifiers or amplifiers in general. Going strong in its third generation / installment (that’s what the “III” stands for) you can tell it has been around for quite a while.
Needless to say it’s rare that a model survives that long at all.

Considering the fact we’re talking about a single 12″ / 150 watts combo it’s astonishing this little box became a household name amongst an interest group that usually argues loudly for more watts, more cabinets, more speakers.
“Four 8×10 Cabinets and two 300 watt valve amps are the bare minimum for me!”

What’s going on here?


It’s been 50 years since a young man picked up an amp from a shelf, walked onto a stage and played a show. Not that big of a deal, besides the circumstance that the young man was Carlos Santana, the stage was Woodstock and the amp was designed and build by Robert Gallien. It was this initial spark that put a company on the map which eventuall would become Gallien Krueger.
Whom have, if you believe the story told by themselves, quite a lot of innovative inventions under their belt. Such as the first rack mountable instrument amp (GK 200RB / 1981) and the first internal D.I. (GK 800RB / 1982), both features the are almost mandatory nowadays.

Especially the 800RB was a bestseller throughout the 80s and 90s and almost everybody and his mother had one. Fancy some name dropping?
Radiohead, Helmet, No Doubt, Guns n´ Roses and of course the inevitable Flea of the Red Hot Chili Peppers. Legend has it these amps were even bought by countless schools and colleges to equip their music classes, which of course led to the next generation of musician growing up with them.

It was in 1984 when GK introduced the 200MB to “set the new standard for a studio bass amp”. This combo amp was the ancestor of the MB150S and a roaring success pretty much until today.


If an amp remains the same for 35 years, even while going through different “generations”, there must be something to it. A good tone for sure, but let’s not forget that tone is taste and taste is highly individual.
The best amp in the world is always just the best am for me.

And haven’t lots and lots of good or even great sounding amplifiers been forgotten by maybe 99% of musicians? Did someone say “Acoustic Amps“?

It have to be other, certain, if not unique features a device brings to the table to outwear it’s competitors. Like, in this case, hitting the sweet spot between a small enclosure and a rich sound. As if the stressed marketing phrase “reduced to the max” served as the blueprint.

It’s a small, really small piece of gear (48cm x 41cm x 22cm / 11,8kg) just able to house the 12″ ceramic speaker with a packed but no-nonsense control panel. But when switched on it quickly dispels the concern about working with a toy.
In fact it’s a sturdy apparatus, reliable as can be and simply does what you want it to do.


Often, when dealing with several instruments or models of amplifiers, established over years one might get confused with the names or notations that come up..
To get a few things straight, here’s the “cast” of the play in order of appearance:

Gallien Krueger 200MB
The legendary “grandfather” of our main actor. “Born” in 1984 and sought after until this day.

Gallien Krueger 150MB
The “father”. Not much can be found about this one.

Gallien Krueger 150MBS III
The star of this play. He is the reason for reading this.

Gallien Krueger 150MBE III
The “E” is for “effect”. Comes with an advanced EQ and chorus.

Marshall MB150
A 15″ bass combo amp by Marshall. From 2008. With the same name. An evidently with a 1/4 inch jack input for CDs.

Gallien Krueger MB200
A small and only 900 grams light 200 watts hybrid bass amp head which GK introduced in 2011.


The control panel we’re looking at masters the challenge of “how many things can you fit on a 41cm x 4cm space” brilliantly. A DI out (including groundlift), an input (including -14db pad), lowcut, contour, hi-boost filter, an active EQ, masterlevel, a limiter, the fx-loop and even a headphone output.
That is a lot!

Let’s put aside the regulars and take a closer look at what makes the amp special.


To build a general foundation for your sound you’ll want to use these tiny controls.
LOW CUT helps you to get rid of unwanted mumbling frequencies at the low end, CONTOUR shapes the whole thing from flat to a more HiFi-ish tone by increasing the smiley curve. Less mids and more lows and trebles, so to speak.
HI BOOST can get you into a more thinner and boney territory. Careful here, when you tweak this one all up you’ll end with something that reminds you almost of an old radio or cellphone speaker.


Taking a different approach (just like GK did with their famous RB800) the EQ starts with treble and goes all the way to bass. 12 o’clock setting of the controls means flat to give enough range to adjust.
The important one of course are the HI-MIDS and the LOW-MIDS which give you distinctive access to the relevant frequencies of a bass guitar or double bass.
You don’t need to tweak like crazy. A small adjustment makes a difference. This EQ really works the sound.


More some sort of an insurance than tone shaping. As the MB150, despite its size, can get really loud the limiter protects the amp and the speaker discretely. And limiting a bass (player) seems generally a good idea, doesn’t it?


practice + neighbours = headphones
It just makes sense to outfit a bedroom friendly sized amp with a bedroom friendly feature, doesn’t it?


Maybe it just makes sense to go for a handy amplifier when you have to carry an overtowering instrument such as a double bass. It surely can’t be the only reason though.
But if you get a device that not only supports but also amplifies your signal, helps you to monitor your sound, comes with a DI to go straight into the PA and is a trustworthy partner on stage… that’s a package to talk about.

Truth is we don’t know for sure why so many double bass players over the years feel attracted by the Gallien Krueger Micro Bass amplifier. But there are plenty of reasons why they could or should be…

company profile (a nice read into the company found in the archives)
Double Bass: The elephant in the room (our blog post about the big bad bass)

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