Essex A-30

Based on the Vox® AC-30 with top boost


(it has his own cut tone control, no mid, no presence, no master)

With four EL84s generating around 36 watts vs the AC-15’s two EL84 at 18 watts, the AC-30 was originally designed simply as “twice an AC-15” for British pop bands that needed the power to take them to the larger venues (and stadiums) that this new music was reaching. Through the course of the early ’60s, however, this soon-legendary combo evolved into something very much its own. The EF86 pentode was dropped from the preamp early on, replaced by another 12ax7 ECC83, but the most distinguishing factor arrived in 1961 in the form of the highly interactive “Top Boost” tone circuit. First available as a back-to-factory modification, Top Boost became a standard option in 1964, and amps from that era—with a pair of Celestion alnico Silver Bell (G12) speakers—represent the archetypal AC-30s in the minds of most players. With a broad, blooming, three-dimensional tone and volume levels that belie its 36-watt rating, the AC-30 has been a cornerstone of tone for The Beatles, The Shadows, Tom Petty & The Heartbreakers, Brian May of Queen, Peter Buck of R.E.M., and many, many others.

Model is based on* a Vox® AC 30. Music was changing in the early ’60s and guitarists were asking for more brilliance & twang. So the Jennings Company, makers of Vox® amps, decided to add Treble and Bass controls (and an extra 12AX7 gain stage, incidentally) in addition to the Treble Cut knob it already had (which in actuality was a sliding bandpass filter that always seemed like it was working backwards); this additional circuit became known as Top Boost.

The AC 30 with Top Boost was the amp made famous by many British invasion bands. Much of the unique character of the Vox® sound can be attributed to the fact that Class A amps overdrive in a very different way than Class AB. Brian May of Queen, Mike Campbell of Tom Petty’s Heartbreakers, and The Edge of U2 have all used classic AC 30s to make their music. Although usually played fairly clean, a cranked AC 30 has a great saturated lead tone, a la Brian May on the early Queen albums.
On this Amp Model, the Middle control acts like the original Cut knob on the AC 30. We plugged into the Hi gain input of the AC 30’s Brilliant channel when creating it.

An AC30 has no power amp feedback so it doesn’t have presence controls. It has a “Cut” control which is basically an adjustable snubber on the phase inverter.

Starting Point: Master 10, set Drive to taste, Mid 5 (50%)
Instead of turning up Drive, try boosting the input signal before the amp.
Cabinet suggestion: Alinco Silver Or use (or combine with) Marshall greenbacks (4×12 20w or 25w). Alternative: Red Wirez Vox and Marshall greenbacks, Ownhammer Blue and greenbacks

Reference Videos

Room recording

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