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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!
Mahalo!
a question----i have two Behringer BX1200 cabinets that i use with my gk rb400(1988 series 1), and each one is rated at 4 ohms. they are 1 x 12 inch soeakers. It sounds pretty good when i use both cabinets, but since they are both 4 ohm, is this a mis-match with the head, or not really? thanks, rick in ohio
ReplyDeleteHi Rick. Running both speakers at 4 ohms will hurt the amplifier. It can run one 4 ohm speaker or two 8 ohm speakers. Thanks! Rex
ReplyDeleteBack in the days I used to have two of them Series I - 400 RB, every of them firing up a 215 and a 212-cab. Each fullstack was standing on a side of the drumriser. I had to "defend" the low end against 4 Marshall-fullstacks. Wow. lots of hauling, but the sound was sweet.
ReplyDeleteUwe, from germany.
Hi Just read this and am wondering about my old Series I 400RB - not working and a reputable local tech said it needs a power transformer (Australia 240V)He quoted me $350AUD to repair which seems excessive to me, so I am wondering if there is a "drop-in" replacement available? There is a local transformer rewinding business but I am unsure whether they would do the job or not.
ReplyDeleteAny thoughts on options available?
Thanks - Andrew - Melbourne, Australia
It seems like you could buy another used one for less than the price the want to fix yours. GK might still stock transformers, as they are a common part. I would email hem, and maybe check with another amp repair shop. Thanks!
ReplyDeleteWould this amp work okay with a single 8 OHM speaker cab w/max power of 700W? I'm thinking about buying one of these GK heads but don't want to damage the cab or the head by mismatching the ohmage. Let me know if you can. Thanks!
ReplyDeleteHi Swede!
ReplyDeleteIt will not damage anything, but it will not be as loud as it could be with a 4ohm speaker. I hope this helps, and have a super weekend!
Rex
Hi i just bought a GK 400rb Serie 11 and it was missigng the rakmount kit (brackets or ear's) do you happen to know where i can find these? I've check with GK website but they don't have any more rackmount kit's in stock for these old models... So i'm searching everywhere!!!! Thank's And GK Rock's big time!!!
ReplyDeletePatrick
Hey Patrick! Just make your own out of 1” aluminum angle. I bought mine at Home Depot.
DeleteIs it easy to destinguish between the different series?
ReplyDeleteThe transformers have a heat sensing resistor wrapped IN the transformer that can go bad making it seem like the transformer is dead. Its easy to unwrap jump the resistor to test it and then replace the resistor.
ReplyDeleteI have a new 400RB and GK NEO 1x12 cabinet. I am looking for a cabinet with less bottom end more mids. Any suggestions. I play swing jazz.
ReplyDeleteRex,
ReplyDeleteWhere in Hawaii are you located? My family and I vacation there once a year because my father-in-law has a place on the Big Island.
I have an RV 400 series 2 running through a Cerwin Vega B-36 MF cabinet the cabinet's contains a 18in woofer and a 12in crossover at 400 HZ. At 4 Ohms. Sounds unbelievable I will not sell this to anybody for any amount of money. You can't buy a B-36 MF anymore either. You don't need a million Watts of power to sound good. 200 Watts with the right Speaker Cabinet is all you need. I run the input volume at 12, boost at 12, and the master at 3 o'clock and I get a super loud full sound out of it.
ReplyDeleteI had an Ampeg SVT and B-15S and Fender Tube bass combo but sold them because I didn't like the muddy tone and back breaking weight. I also had a Gallien Krueger 200MB and 400RB. Still have them. Their tone is clean yet warm. They have been reliable. I now also have a DNA800 which also has beautiful clean, warm tone, weighs even less and has no hum when turned on idling. Time will tell if it is as reliable as my Galliens. Over the 40 years I have owned bass amps it has been the Galliens I have never wanted to sell.
ReplyDeleteIf I run a 4 ohm 2-10 cabinet and a 8 ohm 4-10 cabinet, will that be ok with the gk 400rb ?
ReplyDeleteHey Rex. Love your site.
ReplyDeleteI have a 400rb first series. Would like a foot switch. But checked online and found one rf-1. Asking $98. That's a lot. Any idea if I could use another better priced?
I have a series I and am really pleased with it but sometimes the sound cuts in and out. I run it into a 4ohm peavey 215. Was wondering if you had any insight?
ReplyDeleteWill my rb400 sound goth with SWR goliath III 2x10's
ReplyDeleteMy stepfather has so much stereo equipment 4 massive sspeakers couple amps, besides this one I have. Out of curiosity does anyone know (ballpark) I can sell it and.get my.Mom and I some $ back for what the funeral home.
ReplyDelete