In April 1967, the Defiant cost £194 and 5 shillings (pre-decimal). In today's money, that would be around £3,200 according to the Bank of England inflation calculator.

Its general format: a "Super Twin" solid state guitar amplifier, that is to say separate amp and speaker cabinet, 50 watts output, twin channel, with reverb, tremolo and distortion operated by a three-button footswitch. The normal channel had the tremolo along with switchable top boost. The treble channel had the distortion and a mid range boost effects network. Reverb could be switched between the two.

The speaker cab was a 2x12" containing two Celestion T1279s (8ohms each) wired in series, and a Goodmans Midax horn - see the examples below, on this page. Side stands enabled amp and cab to tilt backwards. The latter could be fixed to the former with a chrome tongue and bracket arrangement.

The Defiant's analogue in the solid state bass range was the " Foundation Bass", which shared the same power section (ie. also 50W), but had a different (bass) preamp.

From most angles, the amp section of the Defiant closely resembles a Supreme - the same number of vents on top, same size box, and so on. The clearest indications of type are naturally the serial number plate, and the small runner, lower right, bearing the name DEFIANT.

If both those are missing, taking the back panel off should provide the clue: two main power transistors, instead of the four of the Supreme.

General characteristics of the early amps

• DIMENSIONS - Amp: 23 1/2" wide, 9 1/2" high, 11" deep. Cab: 32" wide, 21" high, 12" deep. Covers were provided for both amp and cab, the latter being extremely rare these days.
• Production of the amps on this page began c. April/May 1967 and ran through to around June.
• The earliest amps are termed "ST50R" - Super Twin 50 Reverb - on the serial number plates, not "Defiant".
• At first, the serial number is given solely as four digits xxxx. The sequence begins at 1001.
• After the first forty or so amps, the form of the number is given as ST..xxxx. As has been mentioned, "ST" stands for "Super Twin", indicating that cab and amp are separate.
• The first control panels are generally deep black. Later batches are, or have become, brown/bronze.
• Fixings for the preamp are present on top of the wooden cases in the early amps (at front, near the corner protectors).
• Jack input sockets are at first metal and of open construction. Surrounds are white. Black plastic inputs superceded these.
• Logos initially simply state "VOX". Lettering is in silver. Later the lettering is in gold, and then "VOX. Solid State".
• Back panels are cloth covered and have angled corners. Post-JMI panels have square corners.
• Two indicator lamps are present - one for mains supply, one for the standby circuit. The standby lamp was done away with later.
• The schematic for the preamp is OS/136, the power amp OS/134.

Contrary to myth, the Beatles did not use Defiants at any time - only Conquerors (see this page) - but Freddie and the Dreamers did:

Above, Freddie and the Dreamers, RAF Wethersfield, 4th July 1967. Defiants just visible on stage. Pics from this thread.

Later Defiants made in the Vox Sound Equipment Ltd era (early 1968 - late 1969) and subsequently by Vox Sound Ltd (late 1969 - c. 1972) are registered on this page. The serial numbers of those run from 2000 - 2900.

Below, a register of surviving amps. If anyone knows of early Defiants that have not yet been included, do let me know.

Serial number 1012 - currently in Sweden

The amp previously here, incorrectly registered as 1012, is immediately below. Its number is probably close however. Above, the Defiant that correctly and uniquely has the number 1012, along with its speaker cabinet. Note that the model of the amp is given as a "ST50R" = "Super Twin 50 Reverb" and the speaker cab as a "ST50". The back board of the amplifier is missing its grille cloth, but everything else is in place. The original footswitch survives. Amp and cab are in full working order. Thanks to Peter for the pictures.

Updated

Serial number unknown

In good general condition, the footswitch still surviving. The speaker cabinet has its original drivers - Celestion T1297s - and Midax horn. The missing green lens of the amplifier section has been replaced with yellow.

Serial number 1018

Good external order. Defined on the serial number plate as an "ST50R". A jack socket (preamp line out?) added on the flat of the control panel.

Serial number 1022

The cab, a Vox Sound Ltd unit which had Celestion greenbacks, was sold separately from amp.

Serial number 1026 - currently in Germany

Bought new in Holland - presumably in 1967 - currently in Germany. The speaker cabinet and the power section of the amp are fully original, no changes, no repairs. Note though that while the amplifier section is given as a "ST50R", the speaker cabinet is given as "Defiant", not "ST50". Click on the buttons below for further images. Thanks to Ed.

Serial number 1031

A good early amp. Pictures of the cab, which at some point in its life had been regrilled with Selmer cloth, are immediately below.

Sold on ebay UK in June 2016 - just a few pics from that auction. Preamp chassis no. 01233. The latest Lemco capacitors in the preamp has the date code "YB" = February 1967. A set of pics of dated components inside the amp are now on this page.

Cab probably originally from 1031 - currently in the UK?

Evidently a working unit for many years, the recovering and regrilling themselves showing signs of much wear. The new tolex covers the holes for side stands and mounting hardware on top of the cab. Inside, the original speaker wiring diagram and original speakers, though one was blown, along with the Midax horn. The cab is termed, as in the case of the cab above, an ST50.

NEW

Serial number 1050 - currently in the UK

Thanks to Tim, pictures of Vox Defiant amplifier section serial number 1050 with a Vox AC100 speaker cabinet from late 1965 / early 1966. The two were purchased together in the late 1970s. Note that the Defiant, being early, is termed "ST50R" on its serial number plate = "Super Twin 50 Reverb".

Serial number 1055 - currently in the USA

"ST50R" on the serial number plate. A good early Defiant with a later cab ("Solid State" in the logo) - the side stands are repros, designed for an AC30, but do the job. On the amp, indicator lens replaced, and the Belling Lee mains input socket adapted as a cable pass-through.

Serial number 1090 - currently in the USA

NEW

Serial number 1092

In excellent condition. The amplifier section and speaker cabinet retain their 1960s shop labels - "Music Inn Instruments" in Nottingham (which is still in business). The speaker wiring diagram survives on the side wall of the cabinet. Thanks to Paul for the pictures.

Serial number 1100 - currently in the USA

Amp alone. All effects in order.

Serial number 1102 - currently in Australia

A full rig in almost unbelievably pristine condition - complete with hang tags dated April 1967, and covers. The cab is designated an "ST50". Thanks to Paul for the pictures.

Serial number 1108 - currently in the UK

Brown control panel, input jacks with white surrounds, and screws to secure the preamp by the upper front corner protectors. A bit of wear and tear externally, but apparently otherwise in good order.

Serial number 1117 - currently in Europe

Serial number 1126 - currently in the USA?

Images from two different auctions, the first with a reproduction Defiant cab (bearing a 7-series style logo). The amp is complete with its cover, mains lead, and footswitch.

Serial number 1135 - currently in the USA

Serial number 1151 - currently in Germany

The shop plaque on the fore-edge of the cab.

Serial number 1157 - currently in the USA

Needing some remedial work. The power section may be missing.

Serial number 1180 - currently in Europe

A nice amp, cabinet mounting hardware still in place. Original Celestion drivers still in cab. Also present, the guarantee slip with the type of amp stamped on, and the serial number hand written.

Serial number 1184 - currently in the UK?

Preamp chassis 1173. Power amp 1225. A nice Defiant with a Foundation Bass cab. Thanks to Steve for the pictures.

Serial number 1198 - currently in Spain

PRE/AMP.T SER. No. 1729. One of the red CCL filter capacitors has the date code "A7" = January 1967. Inside the amplifier cabinet, the manufacturer's sticker - Heslop and Co., which was based in Raleigh, Essex. Along with Vox (JMI), Heslop was a member of the Royston Group of Companies. Thanks to Juan for the pictures.

Serial number 1204 - formerly in Europe, now in the UK

Defiant serial number 1204. Preamp chassis no. 1315; power amp chassis no. 1776. Signal path capacitors are still the yellow Lemcos - date codes "XL" and "YB", respectively November '66 and February 1967. The power amp chassis has red CCL caps dating from 1966 and early 1967. The latest component date codes visible are February 1967.

Serial number 1212 - currently in Europe

The black cloth faded to brown.

Serial number 1216 - currently in the UK

A first set of pictures from the auction in 2012. The seller notes the serial number as being ST1216.

A second set of pics from the amp's re-sale in 2014. No evident changes.

Serial number 1217 - currently in Germany

Currently here. Ignore the now standard fantasy about Defiants being used by The Beatles in the "Hello Goodbye" promo.

Serial number 1219 - currently in the UK

Serial number 1226 - currently in Germany

Good cosmetic condition. Sold in Germany in 2019.

NEW

Serial number 1272 - currently in the UK

Thanks to Jeremy for the pictures.

Serial number 1277 - currently in Japan

Thanks to Chris for the pictures.

Serial number 1296 - currently in the Netherlands

Superb condition, complete with original covers. Both amp and cab have plain silver VOX logos. The cab retains its original drivers and wiring diagram.

SERIAL NUMBERS UNKNOWN

Serial number unknown - currently in France

Sold on Leboncoin (France) in 2016. Original speakers remain. Rope carry handles added to the speaker cabinet. The screw threads for the side stands appears to have sheared off. The presence of "DEFIANT" on the cab's plate, rather than "ST50", suggests a serial number for the amp above 1100.

Serial number unknown - currently in the UK?

Brown control panel, preamp fixings on top of cabinet.

Serial number unknown - currently in the USA?

Brown control panel, preamp fixings on top of cabinet.

Serial number unknown - currently in France

A good Defiant rig. Still metal jack sockets and top fixings for the preamp. Note the large hoods to the castors, also found in some Conquerors of the same period. Also, see the two Defiants at the foot of this page. It may be that these entries will have to be moved.

Serial number unknown - currently in the UK

A nice rig. The cab is in a repro trolley (for which it was not intended) - note how low it sits in relation to the top bars.

Serial number unknown - currently in the UK

Sold on ebay.uk in early 2014. Probably an early amp. White surrounds to jack sockets. "VOX" in silver, no "solid state".

Serial number unknown - currently in Scandinavian

Possibly an early amp. "VOX" in silver, no "solid state". Hard to tell, but probably white surrounds to jack sockets.