Vox had obtained a bit of experience in solid state design during the development of the Continental Organ. One of the members of the Vox Continental engineering team, Les Hills, created a radical new solid state power amp concept that was incorporated into the T.60. Unlike tube amplifiers that required a heavy output transformer, Les Hills design coupled the output transistors directly to the speakers. Eliminating the cost, size and weight of the output transformer would help to create a trimmer amplifier package. Additionally, as solid state amplifiers did not have the high voltage and current demands of a tube amplifier, the power transformer could be modest in size, reducing weight and bulk from the final product.

Dick Denney once told me Vox tried to make their amp heads no larger than the size of a "lunch pail" whenever possible. That certainly was true in the case of the small box AC-100, small box AC-50, and T.60 heads.

The completed design for the Vox T.60 amp head used a pair of germanium output transistors that were capable of about 30 to 40 watts RMS and 60 watt peak output power. The amp had two inputs and three controls. A rotary voltage selector allowed the amp to be adjusted for the mains voltage anywhere in the world. This same chassis also powered the "AC-30 Solid State," a 3 x 10" amp offering from this period.

The compact, closed back speaker cabinet designed to match the T-60 head had one 50 watt Celestion 15" bass speaker and one 15 watt 12" Celestion Alnico Blue speaker. A crossover capacitor filtered the lowest bass frequencies from the 12". The cabinet sides and bottom were constructed of 3/4" baltic birch plywood; the baffle and back were 1" thick.

It is worth noting that Vox also built a version of the T.60 speaker cabinet that had two 50 watt 15" Celestion speakers. This was called the "AC-100 Bass Cabinet." This was the cabinet that Paul McCartney powered with an Vox AC-100 amp head during the touring years of the Beatles. Many people call this 2x15" cabinet the "T.100," a name Vox never officially used. However, Dick Denney refers to this cabinet as the "T.100" enclosure in his 1992 book, "The Vox Story."

Paul McCartney played a Vox a T.60 amp and cabinet briefly with the Beatles, but not for long. His amp head failed repeatedly and at first Vox couldn't understand why. After the release of the amp, Vox found that failures of the T.60 amp head were all too common.

Eventually, Vox discovered the problem causing the large number of T.60 amp head failures. The power amp design for the T.60 amp head was prone to go into high frequency oscillation. In simple terms, the amplifier continuously generated an extremely high pitched squeal at full power that was above the range of human hearing. This drove the power amp section past the safe design limits for the output transistors, causing meltdown. A successful solution to this output transistor failure problem was never implemented.

The T.60 was discontinued in 1966 with the introduction of the next generation of Vox bass amps, the UL430, UL 460 and UL 4120. The UL Series amplifiers had solid state preamps but the output amp stage was tube powered. Due to the problems with the T.60, Vox was not yet ready to introduce another amp with a transistorized output amplifier.