Vox AC30: every version
Every version, how to tell them apart, how to date one, and what to check before you buy. 12 versions, 1960–present.
The AC30 is a 2×12 combo with four cathode-biased EL84s, and it has been built by almost every owner Vox has had since 1960. The JMI amps of the 1960s are dated by their panel colour and covering, the Top Boost began as a bolt-on and became standard, the 1970s and 1980s amps dropped the GZ34 for diodes and moved to circuit boards, and the modern reissues brought the GZ34 back. The rectifier, the panel and where it was made narrow any AC30 down quickly.
The versions, in order
JMI AC30/4 and AC30/6 (c. 1960–1964)
JMI
The first production AC30s: the two-channel EF86 AC30/4, then the three-channel AC30/6 on ECC83s.
How to spot one
- The AC30/4 has two channels with four inputs and an EF86 pentode preamp valve.
- The AC30/6 has three channels with six inputs (Normal, Brilliant, Vib-Trem) and uses ECC83 (12AX7) preamp valves in place of the EF86.
- The AC30/6 was built in Normal, Bass and (from 1964) Treble versions that differ only in a few tone-capacitor values; the version is marked on the chassis or type plate.
- Early amps have fawn covering with brown diamond grille cloth and brass vents; smooth black covering appears from 1962.
- The earliest amps have black control panels; copper-coloured panels replace them from late 1961.
- Twin 12-inch Celestion alnico speakers; the blue-painted Celestion “Alnico Blue” is the usual fitting in the early 1960s.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | GZ34 tube |
| Phase inverter | Long-tail pair |
JMI AC30 Top Boost (and AC30 Bass) (c. 1962–1968)
JMI
Top Boost adds Treble and Bass controls and one more ECC83: first as a bolt-on at the back, later on the main panel.
What changed from the JMI AC30/4 and AC30/6
- The AC30/4's EF86 preamp valve had already given way to ECC83s in the three-channel AC30/6, largely because the EF86 was microphonic.
- The Top Boost circuit (Treble and Bass controls plus one ECC83) was added, first as a rear-mounted add-on and later on the main control panel.
- The control panel went from black to copper (late 1961) to grey (1964); the covering from fawn to black (1962–63).
How to spot one
- Top Boost adds Treble and Bass controls and one extra ECC83 valve.
- On earlier amps the Top Boost is a separate add-on on an L-shaped bracket, with its own small control panel on the back of the chassis; on later amps the Treble and Bass controls sit on the main control panel.
- Copper-coloured control panels run to about 1964; dark grey panels take over from 1964.
- Black covering (smooth, then textured) replaces fawn during 1962–63, and black grille cloth replaces the brown diamond cloth from about 1964–65.
- Speakers move from the blue alnico Celestion to a silver-painted alnico Celestion around 1963–64.
- The AC30 Bass is the same amp with bass-voiced tone values and the same valve line-up.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | GZ34 tube |
AC30 Top Boost and Top Boost Reverb, 1970s (c. 1970–1978)
Vox Sound / Dallas Arbiter
Silicon diodes in place of the GZ34, circuit boards with board-mounted valve sockets, and reverb versions.
What changed from the JMI AC30 Top Boost (and AC30 Bass)
- Rectifier: GZ34 tube → Solid-state (silicon diodes)
- The GZ34 valve rectifier was replaced by silicon diodes.
- The circuit moved onto printed circuit boards with the valve sockets mounted on the boards.
- Reverb versions were added.
How to spot one
- No GZ34: the valve rectifier is replaced by silicon diodes.
- The early-1970s chassis uses printed circuit boards with the valve sockets mounted directly on the boards.
- Top Boost Reverb versions carry two extra ECC83 valves for the reverb.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
AC30 Solid State (Late 1970s)
Solid state
An all-transistor AC30 with no valves, sold alongside the valve model.
How to spot one
- An all-transistor AC30 with no valves, sold alongside the valve model.
Specs
| Rectifier | Solid-state (silicon diodes) |
|---|
AC30 Top Boost, 1980s (1978–1990)
Rose-Morris
Diode rectifier, particle-board cabinets, and Fane speakers on early-1980s combos.
What changed from the AC30 Top Boost and Top Boost Reverb, 1970s
- Fane ceramic speakers replaced Celestions on early-1980s combos, and cabinets went to particle board.
How to spot one
- No valve rectifier: the power supply uses silicon diodes.
- Early-1980s combos use Fane ceramic speakers rather than Celestions.
- Particle-board cabinets instead of the earlier birch ply.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
AC30 Limited Edition (1990) and AC30 Vintage (1990–c. 1993)
Limited Edition / Vintage
A numbered 1,000-amp Limited Edition with a red panel, then the “Vintage” line, all on one circuit board.
What changed from the AC30 Top Boost, 1980s
- Brown diamond grille cloth and a fawn covering option returned; the whole circuit sits on one printed circuit board.
How to spot one
- Limited Edition: a numbered run of 1,000 amps with a numbered plate on the back.
- Limited Edition: red control panel and a return to brown diamond grille cloth, in fawn or black covering.
- Diode rectifier (no GZ34) and the circuit on a single printed circuit board.
- The valve line-up uses an ECC81 and an ECC82 alongside ECC83s, plus four EL84s.
- Made in England.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
| Construction | Single printed circuit board |
AC30TB / AC30TBX Top Boost reissue (1993/94–2004)
Korg-era reissue
The GZ34 comes back in a three-channel Top Boost built in England; the TBX has Alnico Blues.
What changed from the AC30 Limited Edition (1990) and AC30 Vintage
- Rectifier: Solid-state (silicon diodes) → GZ34 tube
- The GZ34 valve rectifier returned, and the Celestion Alnico Blue was reissued for the TBX.
- Production moved to Marshall's factory under Korg ownership.
How to spot one
- The GZ34 valve rectifier returns, with four EL84s, five ECC83s and one ECC82.
- The AC30TBX has Celestion Alnico Blue speakers; the AC30TB has Celestion Greenbacks.
- Three channels (Normal, Brilliant/Top Boost, Vib-Trem) with a Cut control, like the 1960s Top Boost layout.
- Unlike the originals it has a standby switch and larger vents.
- Built in England for Korg by Marshall.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | GZ34 tube |
| Preamp tubes | 5 × ECC83, 1 × ECC82 |
AC30HW / AC30HWH Hand-Wired (c. 2003–2004)
Hand-Wired
A limited hand-wired AC30: one channel with Top Boost tone controls, valve-driven reverb and tremolo, Tone Cut and a master volume.
What changed from the AC30TB / AC30TBX Top Boost reissue
- Hand-wired on tag boards instead of a printed circuit board, with a single Top Boost channel, valve reverb and tremolo, and a master volume.
How to spot one
- One channel: high and low inputs into one ECC83, a Volume control and a Top Boost Treble and Bass stack.
- Valve-driven spring reverb with Depth and Tone controls, and tremolo with Speed and Depth.
- Tone Cut and Master Volume controls.
- Four EL84s and a GZ34 rectifier, hand-wired on tag boards; the AC30HW is the combo and the AC30HWH the head.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | GZ34 tube |
| Phase inverter | Long-tail pair |
| Construction | Hand-wired tag board |
| Channels | 1 |
AC30CC2 / AC30CC2X Custom Classic (2004–2010)
Custom Classic
Two channels with master volume, reverb, tremolo and an effects loop, on a circuit board, with the GZ34 kept.
What changed from the AC30TB / AC30TBX Top Boost reissue
- Production moved to China; the amp became two channels with master volume, reverb, tremolo and an effects loop, and kept the GZ34.
How to spot one
- Made in China.
- Two channels (Normal and Top Boost) that can be linked, plus reverb, tremolo, master volume, Tone Cut and an effects loop.
- The AC30CC2X has Celestion Alnico Blue speakers.
- Printed circuit board construction.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | GZ34 tube |
| Phase inverter | Long-tail pair |
| Preamp tubes | 3 × ECC83 |
| Construction | Printed circuit board |
AC30H2 / AC30H2L Heritage (2007–2008)
Heritage Collection
A hand-wired run pairing an EF86 channel with a Top Boost channel, with a 30/15 W pentode/triode switch.
What changed from the AC30CC2 / AC30CC2X Custom Classic
- A hand-wired, limited run paired an EF86 channel with a Top Boost channel, with no reverb or tremolo.
How to spot one
- Two channels: an EF86 channel and a Top Boost channel.
- A pentode/triode switch drops the output from 30 to 15 W.
- Hand-wired construction; built in China.
- Celestion Alnico Blue speakers.
- The AC30H2L is the limited version in an oiled mahogany cabinet.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | GZ34 tube |
| Phase inverter | Long-tail pair |
| Rated power | 30 W / 15 W |
| Construction | Hand-wired |
AC30HW2 / AC30HW2X Hand-Wired (From 2010)
Hand-Wired
Hand-wired on a tag board: Normal and Top Boost channels, a Hot/Cool switch, and no reverb or tremolo.
What changed from the AC30H2 / AC30H2L Heritage
- The EF86 channel was replaced by a Normal ECC83 channel, a Hot/Cool switch was added to Top Boost, and production moved to Vietnam.
How to spot one
- Hand-wired on a turret/tag board with no printed circuit board; made in Vietnam.
- Two channels (Normal with a bright switch, Top Boost with a footswitchable Hot/Cool switch); no reverb or tremolo.
- The HW2X has Celestion Alnico Blue speakers; the HW2 has Celestion Greenbacks.
- Fawn covering on a birch-ply cabinet with diamond grille cloth.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | GZ34 tube |
| Construction | Hand-wired tag board |
AC30C2 / AC30C2X Custom (From 2010)
Custom
The CC2's replacement: diode rectifier, simpler switching, Greenbacks as standard.
What changed from the AC30CC2 / AC30CC2X Custom Classic
- Rectifier: GZ34 tube → Solid-state (silicon diodes)
- The GZ34 was dropped for a diode rectifier and the switch options were simplified.
- Celestion Greenbacks became the standard speakers.
How to spot one
- Diode (solid-state) rectifier instead of a GZ34.
- Made in China.
- Celestion G12M Greenback speakers; the C2X has Alnico Blues.
- Two channels (Normal and Top Boost) with reverb, tremolo, master volume, Tone Cut and an effects loop.
Specs
| Power tubes | 4 × EL84 |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
AC30 buying checklist
Date it
- JMI serial numbers are only a rough guide to the build date; confirm with the parts' date codes.
- Panel colour dates a JMI amp: black (to 1961), copper (late 1961 to 1964), grey (from 1964).
- Covering dates a JMI amp: fawn to about 1962, black from 1962–63 (smooth, then textured); black grille cloth from about 1964–65.
- A GZ34 valve rectifier points to a 1960s JMI amp or a Korg-era reissue; diodes point to roughly 1968–1993 production or a 2010-on AC30C2.
Check it’s original
- An early Top Boost on the back panel was an add-on unit: check that its part dates match the rest of the chassis to tell a factory fitting from a later one.
- EL84 output valves are the most often replaced part; the original preamp valves and GZ34 survive more often.
- A Korg-era reissue from the 1990s–2000s has a standby switch and larger vents, which no 1960s original has.
- A red panel with a numbered back plate means a 1990–91 Limited Edition, not a 1960s amp.
- Original transformers carry their maker's marking and a date code that should fit the period of the amp.
What usually needs work
- The EL84s run hot; on amps with valve sockets on the circuit board (early 1970s, 1990–93) the heat can warp the board and lift tracks.
- Check around the output valve sockets for heat marks, which are common on 1960s amps.
- Old filter capacitors need replacing on vintage examples, as do drifted resistors and leaky coupling capacitors.
- EF86 channels (AC30/4, Heritage) are prone to microphonic ringing, so valve choice matters.
Questions buyers ask
Did the first AC30s have Top Boost?
No. Top Boost arrived around 1961–63, first as a back-panel add-on and later built into the top panel.
Which AC30s have a GZ34 valve rectifier?
The 1960s JMI amps, the 1990s–2004 AC30TB/TBX, the AC30CC2, the Heritage and the Hand-Wired. The 1970s to early-1990s amps and the AC30C2 use diodes.
Do I need to set the bias when I change the EL84s?
No. The four EL84s are cathode-biased, so there's no bias to adjust when changing valves.
Where were the modern AC30s made?
The AC30TB/TBX in England; the Custom Classic, Heritage and AC30C2 in China; the 2010 Hand-Wired in Vietnam.
What's the difference between the X and non-X models?
The X models (TBX, CC2X, HW2X, C2X) have Celestion Alnico Blue speakers; the others usually have Celestion Greenbacks.
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