The first amplifiers in this new GA-line had the chassis mounted at the bottom of cabinets. Gibson started to mount the chassis at the top in models introduced in 1950 (with an exception for the Gibsonette introduced in 1952 and a couple of other models that used two-part chassis like the GA-90).
The 6SJ7 small signal pentode was used across the whole line for the input stages and the 6SN7 was mainly used to split the phase of the amplified signal into the output tubes. Allthough, sometimes two 6J5 (medium mu triode) were used instead. Tube holders were suspended in rubber to reduce microphonics.The GA-50 was fitted with a 12 inch and an 8 inch speaker, to improve on the tonal range. Speakers were now of the modern type using permanent magnets instead of the field-coils. Another novelty for this period was „Tremolo“, a feature of the GA-50T and GA-CB.