Dating vox ac30 top boost

As rock raged through the late ’50s, though, a more powerful amp was needed.

In late 1959, Denney and Jennings first tried using two more powerful EL34 tubes in a short-lived AC30, then simply doubled the AC15’s output stage to four EL84s to give birth to the amp we know and love today.

The AC30/6 was now an amp with three channels, each channel having two inputs.

About this time, the "Top Boost" (or "Brilliance") feature became available as Vox's optional addition of a rear panel-mounted circuit that introduced an extra gain stage and tone controls for bass and treble (as opposed to the single "tone" control of earlier AC30s).

The Vox AC30 is a guitar amplifier manufactured by Vox.

It was introduced in 1958 to meet the growing demand for louder amplifiers.

Early AC30s sound great in their own right, but the model evolved to its optimum form when the Top Boost tone stage was adopted—first as a back-to-factory add on in 1961, then as a standard model option in 1964.

The Top Boost circuit adds another preamp tube to the signal chain, as well as a simple yet powerful EQ stage with Treble and Bass controls that are very active and interactive in use, upping the chime factor and adding a little grind when pushed hard.It is known that it is the 'brilliant' model (or top boost) and it was Edge's earliest amp used to record every U2 album Since the higher output AC30/4 shared its preamplifier design with the lower powered AC15, Vox discovered the high-gain EF86 tube was susceptible to microphonics, or even failure, when exposed to the increased vibration present in this uprated amp.Vox soon tired of the problem so to cure AC30/4 reliability issues caused by the troublesome EF86 preamp tube, in late 1960 Vox redesigned the preamp circuit, replaced the EF86 with an ECC83 (12AX7), and released this new design as the AC30/6.The AC15 was powered by a pair of EL84 tubes, an EF86-driven "Normal" channel, an ECC83-driven "Vib-Trem" channel, and rectified by an EZ81.The original first-generation AC30 used a GZ34 tube rectifier, three ECC83s (12AX7) for the Normal channel and the tremolo/vibrato oscillator/modulator circuits, one ECC81 (12AT7) phase inverter, and EL34 tubes in the power amplifier circuit.The first AC30 Twins used two Goodmans Audiom 60 15-Watt Speakers, followed by Celestion G12 alnico speakers.

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