The Fender Tremolux was a guitar amplifier made by Fender. It was introduced in the summer of 1955 with a rated power output of 15 watts, cathode bias, two 6V6 output tubes, and a 5V4 tube rectifier. The Tremolux was the first Fender amp with a built in effect, tremolo.
In 1957, the rated power output of the Tremolux was increased to 18 watts when it changed to a fixed bias design and a 5U4 rectifier. In 1961, the Tremolux was changed from a 1x12 tweed-fabric covered combo amp to a piggyback amp with oxblood grillcloth, covered with cream tolex. Its rated power output was increased to 20 watts, its output tubes were a pair of 6BQ5/EL84 (the only Fender amp of that time feature them) and they were operated at voltages in excess of their rated maximums and under fixed bias, but was soon changed to 35 watts and a pair of 6L6GC power tubes with a GZ34 rectifier (circuits 6G9-A and 6G9-B.) There were 10", 12" and 2-10" speaker cabinet configurations (the 2-10" being the majority of amps produced). In 1963, the grillcloth changed to gold colored. In 1964, the cream tolex was replaced with black tolex and the circuit was changed to AB763, which used an optoisolator to couple the tremolo effect, replacing the earlier direct bias-modulation circuits. In 1963 and 1964, the Tremolux shared the same circuit as the Fender Vibrolux, with the Vibrolux on a 1x12 combo as opposed to a piggyback configuration. The Tremolux was discontinued in the summer of 1966.
The early or first Tolex made 6G9 Tremolux Amps were the 6BQ5/EL84 amps starting at Serial Number 100. There were about 179 total 6G9 Tremolux Amps ever built. There was one change in the circuit during the 6G9 EL84 amp lifespan. The latest serial number known is 279, this would make 179 EL84 amps known. If anyone has seen a serial number later than the 279 please post it here. Update: #314 has surfaced. Update: #354 is here in Germany.This is one of the most rare amps that Fender had ever made. The EL84 Tremolux did not have professional printed tube charts, but instead they have a typewriter-written tube chart that was copied in a blue-ink mimeograph machine.