Cathode-biased AC80/100s - late copper panel amps:

Autumn to early Winter 1964

Serial nos 200 - 230

Thin edged boxes at first, then thick (serial numbers 221-230). For a comparison of thin versus thick, . The change to thick-edged boxes in terms of amps that were actually issued certainly came by October 1964, perhaps even earlier. It seems likely, however, that amps in thin-edged boxes with serial numbers in the very low 200s continued to be issued in the last few months of 1964, i.e. the type of box that amp went out in was for a time a matter of chance. By the end of 1964 almost all the thin-sided boxes (note the qualification) are likely to have been used up.

Pictures taken on behalf of JMI before the end of October 1964.

The shot below of Gene Vincent on stage at the Empire Pool, Wembley, 20th Nov. 1964, shows a thick-edged amp on top of the SDL cab and trolley:

Gene Vincent and the Londoners with Vox loan equipment, November 1964

The pic is also at the head , and given . The trolleys of the AC50 and AC100 (AC80/100) provided for the bands on that day are of an early type with a rectangular "basket" for the amp. Note that the AC80/100 has no corner protectors.

Serial number 225 below, discovered by Mitch Colby in Denver, may at one time have been a JMI loan and demonstration amp, as the one pictured above presumably was. Note that it also lacks corner protectors.

If anyone knows of any early AC100s that have not yet been included, please email me at click here for the address. This page will be updated, so please come back to look from time to time.

Serial number 202 - currently in Japan (collection: Kazutoshi Nakashima)

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An AC80/100 that has travelled for some years with a Super Foundation Bass cabinet (2 x 15) from the late sixties. The amp was probably sent back to the Vox factory for a new box in 1967 - note the double-pin corners, and the carefully re-attached serial number plate and white warning plate. In the sixth picture one can see the three Woden transformers through the grille. In good condition internally - perhaps the nicest condition of all the amps on this page. No. 202, the 101st AC80/100 off the "production line", was probably made in the <late> summer of '64.

Serial number 206 - currently in Denmark

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Box in immaculate condition; internal power section components have been renewed, and a few too in the preamp; but all else, including the Woden transformers, is original.

February 2024: - serial number 206 is probably the amp used by the Swinging Blue Jeans in Sweden in mid October 1964. Compare the alignment of diamonds on the grille cloth - a sort of DNA. Grille cloth was fitted by hand, and is extremely rare to find two amps fitted out in the same way.

Serial number 212 - currently in the USA

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A great amp. Original Woden transformers and hardware. The 270ohm cathode resistors, still in place, have the code "VA" - as in all other copper-panelled AC80/100. The grille cloth of the box (with no scrim / gauze behind it) is black.

The amp has travelled with an AC100 cabinet and trolley since 1990 and possibly before. The lower pair of speakers have date codes in 1964. The upper set are later however, having connecting points between the spokes rather than on them. The "DG10" and "DG18" stamped on the frames apparently do not correspond with any possible - they should mean 10th and 18th April 1974. But there are often anomalies in Celestion stampings. Thanks to Jeff for the pictures.

Serial number 215 - currently in the USA

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Pictured on the voxshowroom site. Some replacement components, but otherwise in good condition. The output transformer is an early replacement. The amp's original box with serial number plate survives, pictured above. Thanks to Mike for the info. The amp currently lives in a repro box with repro serial number plate.

Serial number unknown - currently in the UK

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Serial number unknown. Perhaps originally in a thin-edged box, as these were more fragile and prone to damage. Now in a reproduction NCM cabinet with a repro serial number plate and a later red warning plaque. The original transformers are in place and the preamp in good order, but the underside power section substantially rebuilt, the original tagboard and components doubtless having gone up in smoke, a fate that almost befell some of the amps further up on this page.

200s?

Above, amp and cab at the Philadelphia Guitar Show, 2006 - grille cloth on the amp matches exactly. .

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Above further pictures of the amp after its arrival in the UK, with details of the power section. The volume pot has the code "AL" = January 1964, as in the case of serial number 173 below. Note that the Bulgin knobs are dark brown, as those on serial number 202.

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Above a new board destined for incorporation in the amp. Some components have been left out for the time being to allow access to the fixing screws. The board is actually two pieces made by Radio Spares (RS) joined together (the second pic shows the join). Standard RS board is 18 solder tags long. AC80/100s require 19. The boards came from ebay. The replacement pictured above may require some adjustment as the holes do not line up with the chassis fixing points (spacing is different). The 5W cement resistors came from Partridge Electronics, and the capacitors and other resistors from ebay. The Mullard BY100 diodes were sourced from a radio repairman in Southampton.

200s?
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2013: the new board installed



Transition to thick-edged box by serial number 220

Thick edged boxes were advertised as early as September 1964 (below) and seen definitively in public by November. See the image at the head of this page.

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"Melody Maker" magazine, 12th September, 1964.

Detail of a photo of The Kinks on "Top of the Pops", either 16th November, or 12th December, 1964. Note that the trolley of the AC100 SDL is of the early basket-topped type - Type 1. For a surviving example, see serial number 225, below.

Serial number 220 - currently in the UK

A thick edged box with its original serial number plate (0220). Thanks to Neal for the info.

Serial number 221 - currently in the USA

Thick edged boxes were advertised as early as September 1964 and seen definitively in public by November. See the image at the head of this page.

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Serial number 221, sold on ebay in 2007 after having gone round a couple of times. Images .

Serial number in the 210s-230s - currently in the UK

Illustration from "The Vox Story", David Petersen and Dick Denney (1993), p. 54.

with the blurb: "A rare EL-34 powered Vox AC100 head with black, not brown cloth, and copper control plate. Early examples had a thin edge to the cabinet."

Serial number 225 - currently in the USA (collection: J. Elyea)

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Below, a shot of the preamp from Jim Elyea's book. There are two things of note: (1) the grey 0.05mfd Radiospares "snubber" capacitor over the mains switch. These were fitted at factory to many AC100s and AC50s produced with a view to export to the USA. The option of the cap. was never registered in circuit diagrams.

(2) the English-made Daly capacitor at the right-hand end of the tagboard has the date code "WE" = May 1965. Perhaps one of the spare/replacement components supplied to Thomas Organ by JMI?

That the amp was in California by April '65 seems clear: a photo of it appears in the first issue of Thomas Organ's "Teen Beat" magazine, printed while Marv Kaiser's first Vox "Battle of the Bands" competition was still in progress (see the page linked below).

AC100 serial number 225.

Detail. "WE" is May 1965. Solder joints look old.

This amp travelled for years, perhaps from the time of its manufacture, with a Mark 1a cab. The rig was found in Denver c. 2003 and bought by Mitch Colby, who subsequently sold it to Jim Elyea. The second picture is from the old Colby Amplification website. The lower four images, with a different cab, reproduced by kind permission of Jim Elyea - illustrated in his book, Vox Amplifiers. The JMI Years.

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"Teen Beat" magazine, vol. 1, no. 1, April 1965. A version of this picture was produced in the 2000s (common on the web) with added header and text.

The set is likely originally to have been an early demonstration piece. See further . Note the promotional picture above for the Brothers Grim: the amp has no corner protectors; the logo is composed of single letters; the basket top of the trolley is just visible, jutting out from the bars to its left and right; and at its base, the trolley has ball casters. The set may also be the one featured in the black and white photo of Dick Denney at the Frankfurt Music Fair, March 1965, but details are too indistinct to be sure.

Serial number in the 200s - reported by "325-at-2pm" - probably no. 225 (above)

On a Vox Talks thread (09/10/2002, now gone) - a complete rig reported by "325-at-2pm". The speakers of the cabinet were said to have had date codes of November 1964. Very probably this is serial no. 225. On another thread the grille cloth was said to be brown.

Serial number 226 - currently in the USA

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Probably made for export to the USA in the last quarter of 1964. Note the presence of the (original) Radiospares capacitor above the fuseholder - unspecified in the AC80/100 schematic but added to amps destined for the USA. See also serial number 392. The capacitor reduces arcing across the mains switch.

In company with serial number 225 above, the thick-edged box has (and had) no corner protectors. The grille cloth has been changed, and a new US-style logo applied. Two of the runners that support the chassis inside the box have been renewed (and fixed in from the underside of the cabinet). The Woden transformers have date codes "LU" and "MU" = respectively November and December 1963, but the amp is unlikely to have been ready for use or sale until the last quarter of 1964. Preamp electrolytics have been replaced, so too the resistors and capacitors of the cathode bias circuit underchassis. These take a lot of strain in the AC80/100 circuit.

Serial number 231 - currently in the USA

Only the amplifier section box survives. The chassis - either copper or black panel (which is not known) - is long gone. The box is thick edged. That its grille cloth is black suggests that the amplifier was issued as part of a SDL set. There are at present no details bearing upon the question of when the box (and/or amp) found its way to America however.

Serial number 254 - currently in the UK

Detail from the Vox advert in "Beat Instrumental" magazine, December 1965 - (scroll to the foot of the page).

The amp was never provided with a logo, nor the holes for one. Compare the distinctive diamond pattern of the grille cloth.

The chassis - two fans added in the US. Further pics will be posted in due course.

The amp belonged to JMI until it was sold (presumably in late '65 or '66). It was not used on stage or otherwise by the Stones. But Bill W. certainly stood beside it. Thanks to Tom for picking the amp up in Brooklyn and arranging for the shipping. Further details and pictures to follow. Some can be found on the updates page - .

28th August: new pages on the amp can now .

By serial number 236, panels changed from copper to black. See this page. If the cab that accompanies 236 is original to it, then the change of panel colour probably corresponded with a change of trolley type - from Type 1 to Type 2.

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