About the GA-40

So what is all the fuss about?



Well the GA-40 was an amp sold by Gibson in the 50s as part of a matched set with its flagship solidbody electric guitar, the Les Paul. 4,810 of them were made between 1954-59.

Surprisingly, given the full on rock world that awaited the Les Paul, the GA-40 was not a high power amp. It is not a 40 watt amp as the name might suggest, rather it uses a pair of lower-powered 6V6 output tubes and has a conservative 14 to 16-watt rating.

The GA-40 has an unusual "pentode" preamp section - meaning it has five functional elements other than the three of the standard 12AX7 dual-triode—called a 5879. The 5879 sounds nothing like the familiar 12AX7, and has a higher gain and a fatter, thicker overall tone. This higher gain doesn’t necessarily mean that this tube itself distorts more easily, but rather that it pushes a firm, bold signal onto the next stage, whihc is easier to push to distortion if you want to.

It has two channels, eahc of which are voiced differently: Channel 1 (designated Instrument/Microphone) is hotter than Channel Two (designated Instrument). You can patch them together (by plugging into Input 1 of Ch1 and running a jumper cable from Input 2 to Input 1 of Ch2, or vice versa) to blend the two voices together all the time.

Channel 2, the Instrument channel, has its own little treat in store in the form of what is regarded as one of the most delectable tremolo circuits available. Powered by a single 6SQ7 preamp tube, the GA-40’s tremolo is deep, thick and lush, and provides anything from a throbbing, swampy wobble to a machine-gun staccato.