Vox Vox AC100

The AC-100 was the largest all tube model produced by VOX. All the major touring groups of the mid sixties utilized the amplifier, but the AC-100 is a very unstable amplifier and tended to blow up when pushed hard. It was the first 100 / largest amp to be produced at the time. It is purported that The Who initially got their stage act of smashing guitars and amplifiers because of the AC-100's tendency to malfunction. The Who would take their frustration out on their equipment but when it became apparent that the audience enjoyed the spectacle, amplifiers were then smashed as part of the show as much as out of shear frustration.

The AC-100, initially named the Supreme in England, was soon renamed and the Supreme moniker was given to the 120 watt model in the solid state line. The AC-100 was originally released as the AC-80/100 (Cathode Biased) and then as the AC-100 MkI and finally as the AC-100 MkII. The AC-100 MkI had the front cabinet routed which made the cabinet thinner in appearance than the MkII model. The cabinet in all other dimensions was the same as the MkII. The MkI usually had brown fret cloth and a black control panel whereas the MkII was normally a gray control panel amplifier with black fret cloth.

The AC-100 MkII was the third variation of AC-100's. The MkII, while physically the same size as the MkI, no longer had the routed head and came in black with black grill cloth. AC-100's came with open back speaker cabinets, but closed back cabinets were available at extra cost.

The vertical VOX speaker logo on British amplifiers came in two types; one was a vynide covered wood badge with solid plastic VOX letters and the other an plastic injected mold plate.

On close examination, you will notice that the thickness of the head cabinet is about half the thickness of the speaker section's cabinet thickness. The head was routed out in the area where the fret cloth baffle sits, but the cabinet is actually the same thickness as the speaker section and the head/speaker components of the AC-100 MkII.

The AC-100 was a single channel amplifier with a volume, bass and treble control. Two inputs; one high and one low sensitivity. The output plug is a Amphor XLR type connector and the mains input is a Amphor four pin XLR type connector.

The Midax high frequency horns included with a number of English and American amplifier models was actually a midrange horn and was manufactured by the Goodman Speaker Company. The best this horn could pass is about 5kHz. The English and American amplifiers had an oil filled capacitor wired in series with the horn and the capacitors' value was changed as the impedance and speaker configuration demanded.

The following was excerpted exactly as written from an original 1960's MIdax Horn advertisement;

Mid-range Driver MIDAX H950 - When the

major advantages of a horn loaded middle

register loudspeaker are required, the Midax

H.950 is the correct choice - giving freedom

from distortion, complete smoothness of re-

sponse and extreme efficiency. The total

frequency range covered by the Midax 950 is

from 650 c.p.s. to 8,ooo c.p.s. Crossover fre-

quencies should be at 950 c.p.s. and 5,ooo c.p.s.

to allow proper overlap. Sturdy die-cast

exponential horn with wide flange for easy

fixing. The self-centering diaphragm can be

readily replaced without special tools.

System Power Handling Capacity: 25 watts

(British rating), 50 watts (American rating).

Specification:

Impedance: 15/16 ohms

Baffle Hole: 5 5/8" x 2 9/16" (14.3 cms x 6.5 cms).

with 5/16" (0.79 cms.) radii at corners.

Fixing Holes (Horn Flange): 6 holes, 0191" diam.

(5 mm.)

Overall length: 9 15/16" (25.2 cms). Weight 4 1/2 lbs.

Four pin XLR design was utilized for mains or A/C connections. This connector is very unsuited for the purpose of delivering 120 or 240 volts of alternating current and would have difficulties passing modern day consumer protection listings.

The UK VOX logo varied from the US logo because of the VOX diamond background motif and the raised letters in the VOX logo.

VOX usually used an Amphenol rectangle shaped XLR jack on their speaker cabinets. This connector is very similar to the modern day Switchcraft XLR connectors

Typical VOX speaker and mains connecting hardware was provided to VOX by Amphenol. VOX utilized a round three pin design for amplifier to speaker connections as above; a round four pin configuration for mains connections and a rectangle shaped three pin configuration on the speaker cabinets proper. All of these XLR jacks are compatible with the modern day Switchcraft versions, but physically have little resemblance. Vox also utilized a tip-ring quarter inch plastic connector on other amplifier models.

Features

Output Power 100 watts

Tube Compliment ECC83, 12AU7 (x2), EL34 Quartet.

Channel One Two inputs,

one volume,

one bass,

one treble

Speaker(s) Four Vox Celestion Alnico 12" speakers

+ two Midax HF horns.

Size (Head) 7" H x 19" W x 11.5" D

Size (Speaker cabinet) 40" H x 27" W x 12" D

Accessories Cover, Chrome roller stand, Foot pedal.

All AC100's that I have seen all have come with the Gray bulldog Alnico Speakers. Not to say that it never came through with the more common Bule ones.

I have bought one of these rare examples. It set me back $5,000 but well worth it. I am a Vox collector. I have Many other amplifierst along with Super Beatles, Beatles, AC50's and many more. My AC100 is a 1965 MKII. It is a beatiful sounding and looking amp. I have finally got that Beatle tone I have been looking for.