Gibson’s E-150 / EH-150 amplifiers have long been regarded as the quintessential pre-WWII model, one of the most influential and recognizable amps of all time. This early 1940's amp is a prime example of Gibson's innovation in guitar amplifier design.
Also known as the 4th rendition of the classic EH-150 amp, dated Ca.1941-’42, this model was the final variation which showed up in Catalog BB, dated 1942, with a rearranged control panel, having the tone switch replaced by a potentiometer, ranging from Treble at 0 to Bass at 9, with Normal halfway between. The picture was the once-again retouched version of the ’37 catalog’s shot. A major change in the circuit (that may have occurred earlier) was the tube phase inverter, with a twin-triode 6N7 replacing the transformer. Also new were the 5U4 rectifier and the three 6SQ7 high-mu triodes (amplification factor of 100), with two for the microphone channel and the third common to both channels.
An interesting placement of tubes on the amp, which was not included in the retouched catalog shot, features the power tubes on either side of the rectifier tube, not standard anywhere else in the world of amps, but somewhat logical. Removal of the tubes to satisfy our curiosity revealed marked sockets from the factory, so this apparently wasn’t the result of repairman monkey business. Sadly, the Echo Speaker output was removed for the final 150, possibly to save money on the center-tapped output transformer previously used. By this time, the EH-150 and the previously supercharged EH-185 shared the same circuit design, right down to the schematic.
Our current owner mentions the EH-150 as the “Charlie Christian” amp that morphs into “Jimi” amp without breaking a sweat.
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