GK RB`s

[Fourstringsonly]

How many watts was the 400RB & 800RB? Also...what about the GK400B? I saw a Fleabay auction saying "the amp that John Paul Jones made famous"... whats the best one? Are all three the same sound?

[sevdog]

GK made John Paul Jones famous? That's interesting since the 800rb came along in the early 80's and I'm pretty sure that there were some pretty big Zeppelin albums in the 60's and 70's.

...the 400rb is 280 watts while the 800rb is a bi-amp head...you should do a search on the 800rb

[Dugachug]

the 400 is 280 watts into 4 ohms the 800 i am not sure but i think it's not in production anymore, but the rb700 is 480 watts. Great sounding amps, Flea of rhcp and Justin Chancellor of tool use these heads.

[dhsierra1]

the 400RB I and II had 125 watts at 8 ohms and 200 watts at 4 ohms, the later versions had different cosmetics and specs as mentioned above.

The 800RB has two amps built in and was biamp-able. 200 at 8/300 at 4 for the "low range" amp, and 100 at 8 only for the "high range". Could run these at full range as well which is what most people seem to do.

Both are excellent amps, the classic GK sound. I have both and use them constantly.

JPJ did use an old GMT amp in the 70s on occasion. GMT then changed it's name to GK.

[B-string]

The 400B was rated at 200 watts as was the first 400RB. I don't remember if it was the series II or III that saw the bump to 280 (more like 300) watts. The 800RB is two amps in one head, one 300 watts @ 4 ohms and one 100 watt @ 8 ohms ONLY. The 800RB's amps can be used both in full range or a true variable biamp.
The 800RB's were made with a low end cut (high pass) filter built in. The 400 series was/is different from the 800RB.
A voicing change to the 400RB series was made at the III/IV level.
GMT (now called G-K) started in 1969 (out of RAG's garage) when Santana took his newly purchased GMT to Woodstock.