Howdy!

I did not really need this amplifier, but recently picked it up in a Craiglist package deal with yet another amplifier and speaker cabinet. I had forgotten what a great amplifier the Gallien-Krueger 400RB is.


Gallien-Krueger was started by a couple of HP engineers back in the early 1970s and became one of the most popular bass amplifier manufacturers in the world. They were pioneers in lightweight high-power solid state amplification. Their first iteration of the 400RB was introduced in 1982 as a scaled-down version of their 800RB amplifier.

These amplifiers were hugely popular back in the day, and I still see them regularly at gigs. They are reliable, loud and sound pretty nice.

This 400RB amplifier weighs in around 15 pounds, and measures approximately 17.5" wide by 4" high by 9.5" deep. You can mount it in a standard size rack if you replace the amplifier end caps with rack ears. For its weight the power output is good, with 200 watts at 4 ohms.

The 400RB is a classic-looking amp, with a crinkly-finished metal case. There is a handle mounted to one end of the case in case you decide not to go with a rack case. The front is uncluttered, with a neat line of controls. There is one ¼” input jack (a 10db cut switch is included) and a volume control. Tone controls include 3 filter switches (low cut, mid cut and high boost), and a 4-band equalizer. On the output side there is also an adjustable footswitch-controllable boost circuit with its own input jack and a master volume knob.

The back of the case is very simple with a direct out, an effects loop and two ¼” speaker outs.


I opened this one up to see what was inside. The wiring is tidy and nicely routed, and there is a huge transformer. Gallien-Krueger eschewed a cooling fan and went with a great big heat sink on the back of the chassis instead.

Through my Ampeg cabinet (with an EV 115L) or my Genz 12-inch cabinets the 400RB amplifier is amazingly loud for 200 watts. It has a very smooth tone and has a lot of character that I do not usually associate with older solid-state amplifiers. It also has great lows and low-mids. I had planned to sell it, but have kept it around because it has a different tone than my Genz or Ampeg amplifiers.


In nice condition, Gallien Krueger 400RB bass amplifier sell for $150 to $200, but you should keep in mind that there were some changes to these amplifiers over the years, and they do not all have the same features. The one that I have is a Series I amplifier that was built in 1989.

The original Series I amplifiers required a footswitch for the boost function to work and had a permanently attached power cord.

The Series II was the same amplifier, except the boost worked without a footswitch (a footswitch could still be used, though), and it had a detachable IEC power cord.

The Series III was a new design with increased power output as well as new features including: variable voicing filters for contour and presence, a tuning mute switch, a cooling fan and an XLR balanced direct out. These amplifiers put out 240 watts at 4 ohms.

Series IV was the final production version of the 400RB with the same features as Series III and 280 watts of output at 4 ohms.


They are all good amplifiers, but I prefer the sound of the Series I best. Try one out if you get a chance!