Vox AC30
Characterised by its "jangly" high-end sound it has become widely recognized by British musicians and others, such as George Harrison and John Lennon of the Beatles, Bill Wyman of the Rolling Stones, Brian May of Queen, Dave Davies of the Kinks and Hank Marvin.
Vox initially offered a 1×12" version but subsequently introduced the 2×12" AC30 Twin, which solved the volume problem at larger venues.
The new cabinets featured a different covering known as fawn Rexine, which was a sort of beige leathercloth with a subtle printed grain.
Ventilation was provided by three small brass vents on the top of the cabinet, and the TV-front's single suitcase type handle was replaced with three leather straps.
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.
[citation needed] The Rose Morris company, who owned the Vox name through the 1980s, sold Vox to Korg in the early 1990s, who then manufactured a reissue of the early '60s AC30 Top Boost, correcting previous inconsistencies ranging from the correct style grille cloth to the GZ34 rectifier tube.
These AC30 amps were mostly offered in the traditional black Tolex/brown diamond grille configuration, but were also available in limited numbers with purple, red, or tan tolex.
In the mid 1980s, a company in Marlborough, MA, called Primo, imported and began re-distributing the AC30s in the U.S.[citation needed] In 2003, Vox created the "AC30 Heritage Handwired Limited Edition" amplifier (AC30HW).
According to Vox this was far more labor-intensive, but it allowed for easier repair versus circuit boards because there were no copper tracks to burn.
The article specifies details of the amp, including price, and its control layout: "The AC30 HW ($4,000; head $3,250; 2×12 cab $1,350), which was developed with input from boutique amp designer Tony Bruno, features the famous Top Boost preamp, but has a control that is quite different from the standard model.
At the 2010 Winter NAMM expo Vox introduced the Custom series; these models were updates to the 2004 Custom Classic series amplifiers and featured two channels (Normal and Top Boost) with two inputs for each channel (High and Low), more akin to the original AC30/4 layout released in 1958.
[citation needed] Introduced in 2010, the amp featured Hand-wired turret board construction (against cheaper PCB construction), Birch-ply cabinets featuring solid bracing and a natural high frequency diffuser (versus MDF cabinets and no high frequency diffuser); All-tube design (different from the Custom series tube pre/power amp but solid-state rectifier); ECC83/12AX7 preamp tubes (×3) EL84 power tube quartet; (AC30 models); EL84 Duet (AC15 models); GZ34 rectifier (AC30 models); EZ81 rectifier (AC15 models); came factory-fitted with matched Ruby Tubes to provide extended dynamic range; maintained the traditional VOX two-channel design (Top Boost and Normal.
[citation needed] The Heritage series 50th anniversary models incorporate the classic EF86 pre-amp tube, which although subject to failure in the late '50s had been re-introduced and improved.
The classic EF86 pre-amp tube is remarkable for its high gain and for the notable harmonic overtones it produces and feeds to the power tubes when driven into distortion, providing the creamy distinctive VOX sound of the early hand made amplifiers produced by Jennings of Dartford.
The Heritage series 50th anniversary model stands alone as either the AC15 or AC30 with this distinct circuitry not found in the current VOX line-up.
As the amp is designed to replicate May's tone, there are no controls on the amp except for a single volume control, though a switch enables the user to halve the number of output valves (therefore reducing the output to 15 watts as well as the volume, making it more suitable for home use), and there is a boost function operated from the included footswitch.
[12] As of 2006, a company having licensed the name JMI (Jennings Musical Instruments) began manufacturing period correct, British made AC30 "copy" amplifiers, available in both black and beige.
Since this incarnation of JMI has never owned the Vox brand, their official website lists the disclaimer "JMI amplification are in no way affiliated with Vox amplification (Korg)", and the models are listed as 30/6 (6 input) and 30/4 (4 inputs, sans "Brilliant" channel).
The high bias condition is believed by some to be the source of the amplifier's famous immediate response and "jangly" high-end, though the lack of negative feedback, minimal preamp circuit, simple low loss tone stack, and the use of cathode biasing on the output stage play at least as large a role, if not larger.
