The amplifier chasis was housed in the bottom of an open backed cabinet with the two control knobs mounted on the amplifiers faceplate.
The amp just did not have enough power for those low frequency bass notes. Bass players of the day complained. Not only did the speaker and tubes distort, the baffle board that held the massive speaker fluttered.
|Note the brace on baffle|
But bass players were not at all satisfied with this Supro amp.
However, as a guitar amp, the Thunderbolt was a something else. That raw tube distortion combined with the heavy bottom of the Jensen 15 sounded huge.
Airline was Montgomery Wards brand name for musical instruments. Valco created a similar amplifier for them known as model 62-9020A, which is the same circuit as the famed Supro Thunderbolt.
|Airline "Thunderbolt" 60-9020A|
By 1967, Valco merged with Kay. However, this was end of the line for Valco.
The merged company went out of business in 1968.
Now the Supro brand name has been revived.
Zinky went on to produce high quality boutique amplifiers under his name. Recently Zinky acquired the rights to the Supro name and is now producing high quality updated replicas of former Supro amplifiers and guitars.