In terms of what went out for sale, the first runs of the new split-front AC30/4 overlapped with the last of the AC30s in TV front cabinets. Serial number 4414 TV front; number 4401 (below) new split front.

From a practical standpoint the new cabinets were a marked improvement on the old - three carrying handles instead of one, and three vents in the top to allow air to circulate better around the chassis (at least that was the theory). Backboards were stouter. Cosmetics changed too: a new type of beige covering (sometimes called "fawn" or "tan"), and two lines of gold piping around the body of the cabinet.

The circuit and control panel of the AC30/4, however, remained much the same as for the TV front amps. The legend by the fuse continued to have the Greek alpha rather than an "A", and the two tone controls, "Brilliant" and "Bass", held their place.

From mid 1960 production of the AC30/4 went side by side with that of the AC30/6. All preamp chassis were drilled for six inputs, though two were naturally blanked off by the control panel of the AC30/4:

"Melody Maker" magazine, 19th November, 1960. The AC30/6 is 89 guineas; the AC30/4 is 85 gns. There is also an AC30/4 Bass model at 89 gns.

A detail of the chassis of AC30/4 serial number 4715, the middle two holes (of the six) blanked off by the control panel.

Initially all AC30 chassis (AC30/4s and AC30/6s) were made with only a thin aluminium lip at rear, normally with a drop of 1/4" to 3/8". The screws holding the upper back board of the cabinet in place were screwed straight into the metal, often with consequences that can be seen above - holes that are ripped or torn.

In the spring of 1961, however, a new type of chassis with a deeper lip at rear and inset cage nuts for the back board screws was introduced - and reserved for - the AC30/6. AC30/4 chassis continued to be made in the original way with thin lips at rear, and with holes for six inputs, two as ever blanked off.

On serial number plates "N" stands for "Normal voicing", and "B" for "Bass". Often in the lower compartment of the plate, there is a "4" in the upper panel (to indicate the AC30/4), and a "W", indicating assembly by Westrex - see this page. An early AC30/4 chassis (for a TV Front AC30) still has its blue Westrex tag.

Further images of AC30/4 serial number 4669, BASS voicing, "W" to indicate the chassis had been assembled by Westrex.

The explicit designation of the amp as a "4" on the plate (something not found on the TV front amps) was a means of making record keeping easier (the registers kept of sales and despatches). Since AC30/4s and AC30/6s had serial numbers in the same sequence (in the range low 4200s to low 4700s), one could not tell simply from the number alone whether the amp was of one type or the other. Black panel AC30/6s (Twins and Super Twins) continued on their own from the low 4700s to mid 4900s.

The speakers chosen for the split-front cabinet were largely the new Celestion "blue" - G12 alnico T530, sprayed Jennings blue - as depicted in the page from the brochure below.

Note that the brochure illustrates a control panel for the new circuit of the AC30/6.

It is clear, however, that a number of AC30/4s were fitted with Celestion CT3757s or early T530s (hammertone/oyster finish, as the CT3757, no "bell" dust cover) - see this page. Numbers of TV Front AC30/4 Twins are likely to have had these speakers too.

By October 1961, Jennings was signalling the phasing out of the AC30/4. See the documents on this page. Orders for the AC30/4 were honoured though at the old price of 95 guineas (£99 5s). For a limited time, one could purchase the AC30/6 at the special price of 100 guineas (£105).

Components, assembly, etc.

Chassis in the main were assembled at the Vox works at 115 Dartford Road. For pictures of the site and the factory, see this page (on the Vox AC100 website). In Spring 1961, Westrex took over the assembly of AC30/6 chassis too. Runs of AC30s - of both varieties - are likely to have been assembled at Dartford Road too.

Notes on how to read component date codes, are available here.

The transformers for both the AC30/4 and AC30/6 were made by Haddon ("Haddon Transformers Ltd." of South Ruislip), the choke by Radiospares.

Haddon mains transformer of AC30/4 serial number 4401.

so far as one can tell at present, Bulgin chickenhead control knobs were standard on AC30/4s regardless of the type of cabinet, ie. common to chassis in both TV front and split front cabinets. Anything else is likely to be a later addition/replacement. Circular knobs seem only to have been fitted to AC2s, AC10s, AC15s, and AC30/6s (AC30/6s for a short time only in Spring 1961). Any exceptions to these general rules of thumb will be signalled if and when they arise.

The schematic for the AC30/4 is JMI sheet OA/032 (drawn 29th April 1960, and registering a change dated 7th Feb. 1961).

Information panel of circuit diagram OA/032, the AC30/4, 29th April, 1960. Changes for "Bass" models are noted in the diagram with asterisks.

On the introduction of a new capacitor into the circuit in February 1961 - marked C42 in the diagram - see also this page.

Addition, top right-hand corner of the diagram.

The circuit of the AC30/4 Bass differed only in the values adopted for six coupling capacitors (C3, C6, C10, C7, C9, C11). Most are of a higher value to reduce the amount of treble admitted.

Detail from a JMI brochure of early 1961 prepared for "Musicland" in Bexleyheath - principally guitars, but the AC30/4 Bass is mentioned (even if the wattage is given incorrectly).

In general outline, the preamp of the AC30/4 goes hand in hand with that of the AC15 (schematic OA/31) - an EF86 as V1, three ECC83s (V2, V7 and V9), and an ECC82 (V8). The output section is of course doubled up: four EL84s (V3-V6) instead of the AC15's two.

The EF86 which added so much to the sound of the AC30/4 was unfortunately also its weak point - EF86s can be extremely sensitive to vibration and prone to microphony. The AC30/6 with its complement of ECC83s was much less troublesome.

Jim Elyea's book, "Vox Amplifiers. The JMI Years" (California, 2009) is again a wonderful repository of info on these amps and other AC30s.

"A Service Engineer's Guide to the Vox AC30 Valve Amplifier" by Stephen Grosvenor (2006), gives excellent schemas of the circuit boards and electronic layout. His site is here.

A page on AC30s with speakers of known date can be found here. Speakers consistently have the latest date codes - ie. later than those on the electronic components in the chassis of the AC30.

If anyone knows of further early new-style black panel AC30s that should be incorporated on this page, do let me know.

Just to note that some of the stray/rehoused chassis illustrated at the foot of this page may originally have belonged to TV front AC30 Twins. Known serial numbers of late TV front Twins (from 1961) - 4322, 4373, and 4411 - show that sales overlapped with the new split-front amps for a good while.

Serial number 4250

Westrex-made chassis. Fawn covering, split front. Belonged to Chas McDevitt. The amp arrived as the fulfilment of an order for AC15s placed in May 1960. But when the amplifiers (one for Shirley Douglas, number 4270 below), arrived some months later they were new AC30/4s. The amplifier was later recovered in black and a top boost module fitted. Existence noted by J. Elyea, p. 624.

Serial number 4270

Fawn covering, split front. Belonged to Shirley Douglas. Existence noted by J. Elyea, p. 624.

Serial number unknown - currently in the UK (?)

Old, old pictures, but a reasonably intact AC30/4 chassis and its rather battered cab. The drivers are Goodmans Audiom 60s, 15 ohms each. The cab is probably later - note the rounded corners to the back boards and the presence of new-style plastic handles. Are the speakers the originals from the original cab? TV front or split front?

Updated

Serial number 4290N - currently in the USA

Westrex-made chassis. An old picture of serial number plate 4290N, taken in 2006, showing it (with what look to be the original screws) on a cabinet finished or refinished in bright red vinyl. The cabinet in question may be the one pictured - split-front, Celestion blue speakers, AC30/4 chassis - but the serial number plate on the back of that when photographed looks to be of a later type and probably a repro. The plate stamped 4290N was evidently passed on at some point and refitted on a TV front amp (circuit said to be AC2/30) in light grey illustrated on this page. "N" signifies normal (rather than bass) voicing. More on the amp in red below, serial number in the 4500s.

Serial number unknown - currently in the UK (?)

Old pictures from ebay. One can just see the four inputs on the control panel. The serial number plate has distinctive wear. Speakers are hammertone/oyster T530/CT3757.

NEW

Serial number unknown - currently in the UK (?)

Chassis and speakers go together; the cabinet is significantly later. In all likelihood the original had a TV Front (those being relatively fragile and prone to damage), but it is just possible - hence its inclusion here - that it was an early split front. The speakers, as in the entry above, are hammertone/oyster T530/CT3757. The pink and yellow wiring is original. The long run is generally more typical of TV Front amps it should be said though.

The Phantoms, a popular band from Yorkshire, pictured in late 1961 with two of their three AC30/4s, bought from Barratt's in Manchester at some point close to the beginning of the year. Thanks to John Weatherby, the band's bass player.

AC30/4s with Celestion blues - early 1961 to late 1961

The amps below for the most part have Celestion T530 blue speakers. The earliest known to be original to speaker cabinet or serial number plate, are those that belonged to serial number 4447N, date code "27DF" = 27th April 1961.

Serial number 4304 N (?) - currently in the UK

A copy of this entry has also been placed - just in case - on the page on black panel AC30/6s. The serial number plate, apparently deliberately scratched, is currently on a refurbished beige cabinet containing a copper panel chassis from 1962 / 1963. The hire purchase card accompanying the amp - certainly from 1961, said to be from Hessy's in Liverpool - seems to have become wetted or rubbed in such a way as to obscure the serial number. The photos of the card that have been posted are slightly indistinct.

NOTA BENE - it is evident from pictures posted on FB that the chassis, or perhaps one newly slipped in, now sports a control black panel.

Serial number 4322 - currently in the USA

Likely to be a (rare) genuine TV Front AC30 Twin in a standard cabinet (standard size, back boards with cutaways, diamond-pattern rexine covering).

Serial number 4347 B - currently in the USA

Westrex-made chassis. Pictures from some time ago (the three smaller ones from 2005). The date code on the TCC capacitor by the choke is "RD" = April 1960. The detail of the plate has been blown up a little beyond its natural size to show the number better. A relatively rare early instance of a bass voicing.

Serial number 4400 - currently in the USA (?)

Existence noted by J. Elyea.

Serial number unknown - currently in the USA

The green TCC filter capacitor in the preamp has the date code "RC" = March 1960. The Hunts Tropydur capacitors have been replaced.

Updated - serial number plate a repro

Serial number 4401 (?) - currently in the USA

The serial number plate looks to be a repro. No component date codes known at present. Chassis is good and clean. The cabinet has holes on top for new-style plastic handles, all carefully filled up now. The Celestion blues have RIC1 cones, pink and yellow wiring original. Sold by Artisan Guitars in 2016/2017.

From this point "AC30 4" often appears on serial number plates

Serial number 4402N - currently in the UK

Westrex-made chassis. One Goodmans Audiom 60, one Celestion blue. The top edge of the back panel has three rather than two fixing points. Thanks to Richard for the pictures.

Serial number 4430 - currently in the USA (?)

Existence noted by J. Elyea.

Serial number 4447 N - formerly in the UK

Westrex-made chassis. Spring 1961. On the tone pot in the third picture, the date code "CI" = March 1961 for its manufacture. Further pictures of the amp can be found here and on this page.

Serial number 4495

Existence noted by J. Elyea.

Serial number 4530

Existence noted by J. Elyea.

Serial number in the mid or higher 4500s

Recently parted out in the UK (2024) - chassis, speakers, and cabinet sold separately. The surviving original speaker has the date code: "29EF" = 29th May 1961. Although the chassis had pretty well been "shotgunned" - almost wholesale replacement of certain classes of component - many of the originals had been retained (in a bag). The Hunts caps had date codes "HAY", "TYY", and "TIY" - respectively the 29th, 40th, and 41st weeks of 1960 for their manufacture.

The chassis is evidently now set in a new cabinet, control panel facing forward low down on the front, Marshall style. Cosmetics of the cabinet mimic Vox.

Serial number 4570

Existence noted by J. Elyea.

Updated

Serial number in the 4500s (?) - formerly in the UK

Square corners to the cabinet's backboards. The serial number plate that appears in the right-hand image is a repro.

Thumbnail images from Rob's old website.

Owned in the early 2000s and perhaps beyond by Rob Livesey (Manchester, UK). Noted as having original components with date code March 1961. The choke in this amp was made by Radiospares. Mains and output transformers are Haddons. The chassis was completely dismantled, cleaned, and reassembled with many new components.

It is not known what the cabinet (covered with non-original red vinyl) has to do with the chassis - original or perhaps from another source? The serial number plate in the second picture is of a later type and probably a repro.

Late 2024 / early 2025 - the amp has been presented online in two different locations in the USA.

Serial number 4586 N - currently in the UK

Sold in the UK in 2018. Westrex-made chassis. A nice example. Haddon transformers, the output transformer marked on its underside "0H083". Note the green Welwyn ceramic 80ohm cathode resistor in the second last picture. On the serial number plate the "N" for normal voicing.

Serial number 4606 N - currently in the USA

Westrex-made chassis. "AC30 4W" "4606 N" The "N" for "Normal voicing" was stamped over a "B" for "Bass". The cab is later - from 1964, with rounded corners to the backboards, basketweave vinyl, and black vents.

Date codes "16FF" and "29FF" = 16th and 29th June, 1961.

The amp does not survive, but its serial number plate and speakers, which travelled together, do. Given the date of the speakers, the amp will probably have been ready for sale in July 1961. Thanks to Chris for the pictures.

Serial number 4615 N - currently in the UK

Front now a single piece of non-Vox cloth. On the control panel a couple of later rocker switches have been added. In the preamp an additional gain stage (or top boost stage?) has been fitted on an aluminium bracket/panel. Speakers are ceramic Celestion greenbacks.

Serial number 4627 B - whereabouts unknown

Westrex-made chassis. No pictures of the amp at present.

Serial number 4633 N - currently in Europe

Westrex-made chassis. Said to be in Italy, but it may be elsewhere by now. The pictures, supplied by a potential seller (caveat emptor, as always), actually come from an ebay auction.

Number corrected

Serial number 4642 N - currently in Europe

Original split-front cabinet and serial number plate ("W" for "Westrex" after the model designation in the upper panel of the plate). The chassis is now a Burndept-made Top Boost from early to mid 1964.

Serial number 4669B - currently in the USA

Westrex-made chassis. A number of original black WIMA Tropydur capacitors survive in the preamp, one visibly with the date code "70" = July 1960 for its manufacture in Germany.

Serial numbers unknown

Serial number unknown - currently in the UK

Excellent condition. The Westrex-made chassis is not original to the cabinet however (note the screw holes along the preamp lip), and the serial number plate belongs to the cabinet, not the the chassis. Good shots of the Haddon transformer label, and the RIC cone code of the alnico blues - "RIC 1FY". The choke, which is probably a replacement, has a Drake Transformers code: 292-426. The chassis is also pictured in another box refurbished with modern beige vinyl.

Serial number unknown - currently in the UK

Westrex-made chassis - the "W" visible on the serial number plate. The original black WIMA Tropydur signal capacitors have been renewed throughout.

NEW

Serial number unknown - currently in the UK

The green TCC capacitor in the preamp has "RJ" = September 1960 for its manufacture. The date code on the tone pot ends in "H", so some month in later 1960 seems likely also. The Celestion blue speakers - note the original pink and yellow wiring - indicate the amp was made ready for sale in early 1961. Two picture pages - thanks to David - can now be found here, the second page linked at the foot of the first.

Serial number unknown - currently in the USA

Two sets of pictures, one from Plexi Palace days long ago, the others slightly more recent. The output transformer is a Radiospares unit. The shrouds of the choke and mains transformer have been painted blue in place (note the brackets on the mains transformer) shrouds. The speakers are likely to be Celestion CT3757s.

Serial number unknown - currently in the USA

Distinctive in having one large round black control knob (the first on the panel), and five smaller (normal sized) ones. At some point in or after the mid 1960s, the electronics were overhauled - visible mustard capacitors have 1964 date codes.

Serial number unknown - currently in Australia

Superbly restored, the Celestion B024s from a Hammond Organ, circular control knobs from another source.

Serial number unknown - currently in the UK (?)

Note the cigarette burns near the outer handles. Grille cloth possibly renewed.

NEW

Serial number unknown - currently in Europe

Cabinet covered in black vinyl, two of the three original brass vents present, thick brown leather handles with stubby metal end clasps added later. The chassis has circular knobs with gold trim at the edges on top. These are also additions, probably from some radio.

Chassis - currently in the USA

An AC30/4 chassis with replaced control knobs - now American "cooker" style - in a later AC30 head cabinet. Sold by Cream Street Music. The serial number plate on the cab belongs to the cab not to the amp. Haddon transformers in place; no visible date codes on components.

Chassis - currently in the UK

The aluminium preamp has been drilled for six input jacks (see the last picture, top left corner), the centre pair blanked off by the control panel. The Lemark transformer is a replacement.

Chassis - currently in the USA

Voltage selector set to 115v. The box, with its black basketweave covering and plastic handles, is later.

Chassis - currently in the USA

Voltage selector set for 115v. The fuseholder is a replacement.

Chassis - currently in the UK

A knocked-down AC30/4 chassis - the "Brilliant" and "Bass" tone control legends just visible - sold on ebay some time ago along with a selection of parts. The panel is interesting. The control legends and outer decorative band look normal; but compartments marking off the pairs of control are lacking, and there are instead incised markers.

Chassis - currently in the UK

Thanks to Steve, pictures of a black panel AC30/4, for the time being exterior only. The cabinet may be the original, but reworked (and recovered) in the 1970s. The speakers are Goodmans Audiom power range, red label, 8 ohms apiece.

Chassis - currently in Germany

Out and about recently on ebay.de (October 2023), an AC30/4 chassis in a new cabinet. The mains transformer has been replaced, and some of the original hardware is lacking (pots, fuse holder, voltage selector, knobs, and input jacks), but the Haddon output transformer is still present along with the Radiospares choke and - ununusually - a good spread of the original WIMA Tropydur capacitors, some with "70" date codes = July 1960. Normally these were the first things to be replaced by servicemen.

NOTA BENE - the chassis was sold again in Spring 2024 with certain things added and the original output transformer and choke removed.

On to black panel AC30/6s.

Copper panels appear in the high 4000s, see this page - AC30s in beige cabinets, copper panels.