Cathode-biased AC80/100s - thin edged boxes: autumn-winter 1964

serial nos 174 - 199

Serial number 174 - currently in the UK
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Sold on ebay in June 2013. Brown grille cloth. Thin-edged box in good condition. The original Cannon mains connector is visible in picture 2. The backboard has a number of additions - a Bulgin mains connector above the XLR speaker socket, and an inserted panel of jack sockets in a cut-out. The serial number plate is in more or less the same position as that of no. 173 on the preceding page, but the white warning plaque is on the right rather than the left.


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Truly superb condition - a few new replaced caps and resistors here and there (old work), but otherwise all there. Thanks to Martin for the pics - in the last, by the way, Bill Wyman's prototype teardrop bass!

Serial number 175 - currently in Japan

No pictures available.

Serial number 177 - currently in Connecticut
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For years this amp was pictured on Marcus Hardy's Tone Heaven site (the one rather poor image above). The caption read: "The mint example pictured, number 177 was sold to a gentleman in Florida. Apparently, one reason for the lack of survival of these amps was the unreliability of the transformers on this model. This amp was purchased new in 1964 and the speaker cabinet contained newspaper from this era !!!! In the photo, the control panel looks black but in fact was a copper / red colour." The page in question is archived by webarchive.org here. Marcus Hardy found this fine rig in a music shop in Bournemouth, where it had been since the the late 1960s, kept in a back room. He had been asked to locate an AC100 by the "gentleman in Florida" mentioned in his caption, and this is what he turned up.



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Both amp and cabinet have their original brown covers. Newspaper in the cabinet (the Daily Express and News of the World) from September - November 1964, used as dampening, is likely to have been put in by its first owner, probably at a date not too far removed from the date of the latest pages (Sunday 1st Nov. '64) - see the pictures below, the scrunched-up paper now flattened out.


Examination of the amp by its present owner determined that one of the filter capacitors in the preamp had been wired in wrongly at the factory, thereby impairing the amps's functionality. This is probably why the Bournemouth shop had kept it in a back room. However, at some point in its life, the amp certainly had been used. The original Mullard yellow-print EL34s - XF2s with the code B3K4 (4th week of November 1963) - show evident signs of wear. Thanks to Tom for the pictures.


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To judge from its back panel, no. 177 is a twin of no. 178. The mains connector is a Cannon LNE-11, which Vox regularly fitted to its AC80/100s. Such connectors were also used by the BBC and the hifi manufacturer Quad.


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New pictures of amp, cab and the drivers - 15" Celestion T1076, 15ohm, wired in parallel for a total of 8ohms. Extremely rare to find original examples surviving in situ. The grille cloth and logo of the cab are immaculate, thanks no doubt to the covers, pictured two sections above this.

Serial number 178 - currently in the UK
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Above, pictures supplied by the seller of the amp.


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Said to have been refitted with a new mains transformer for a Mk 2 fixed bias AC100 at the Vox factory in 1965/66. Due to the higher rating of the secondary - after rectification 470V instead of 450V - the cathode resistors were raised to 400 ohms. The output transformer is a later replacement again, possibly 1970 or 80s? The amp probably originally had a Cannon LNE-11 mains socket, as on 177 above. The bass control was wired to work forwards, ie. in the conventional manner, clockwise. The bass in 173 and many others, on the other hand, works backwards. Pictures 9-12 show the volume and tone pots (in order, volume, treble, and two of bass).


Last four pictures: the amp tidied up - a shroud and bracket have been fitted to the output transformer; 100 ohm plate resistors reinstated; and Cannon LNE-11 mains socket installed.


The amp was acquired (ie. came back to the UK) from Japan, where it had been for some years. The first four pictures were supplied by the seller. It seems to have been one of three brown-fronted thin-edged amps that passed, though not with any great regularity, to and fro among Japanese collectors (serial nos 175 and 184 being the others). Prior to Japan, no. 178 may have been in New York. The owner of no. 177 saw a twin of 177 in a NYC dealer's premises, but the amp at that time had already been sold and was awaiting shipping to Japan.


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Above, further pictures, 2013, the last two with a Foundation Bass cab that originally travelled with a small-box AC50.

Serial number 182 - currently in the USA
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Reproduced by kind permission of Jim Elyea


Exterior in fine condition. This amp was changed at some point from cathode to fixed bias

Serial number 184 - currently in Japan

No pictures available.

Serial number 185 - currently in the UK (collection: Mike Handley)
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A beautiful AC80/100 - in the second picture atop an original 2 x 15" bass cabinet. At some point the plate resistors flamed out and a section of new tagboard had to be added. One can see the divide between the two pieces nine tags from the left.


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Sold on ebay in September 2015. Note as in some of the amps further up this page, and on the one before, there is no screw on the top edge of the back board. The Amphenol connector is a later (anachronistic) addition.

On to serial numbers 200 - 220



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