Tech Talk - Gibson GA-90 (1956)

A "Revelation in Rythm" - the GA-90 was introduced alongside Gibson's first electric bass - the violin-shaped EB-1. Finished in dark brown "buffalo-grained" leatherette.

The amplifier features six 8 inch speakers, strangely enough it may seem. The confined throw of a speaker from that period combined with a small cone area makes it less appropriate for deep bass reproduction. Just adding more speakers won't do the job. This amp was designed by Seth Lover to rid the problem of the large single coil pick-up for the new bass guitar

that "would make a god-awful hum" when it got to close to the amplifier. Later he would try solving this problem by designing the "humbucking" pickup. Top mounted preamp with control panel and a bottom mounted chassis for the main amp. 25 watts output.
Speakers 6-8"
Inputs
(instr. + mic.) 2+2*
*hi-gain sw. 2
Channels 2
Volume Controls 2

Bass, treble
for ea. ch. No
Tubes 8
Preamp. 2-6SJ7 2-5879,
Phase splitter 6 6SL7
Output (5881)
Rect. 5V4 5Y3
Watts Output 25