LARGE BOX AC50s - SOLID STATE RECTIFIED
Serial numbers in the 6000s
Amps assembled primarily at the Burndept factory (note the presence of the stamped chassis number).
The brimistor is the norm. Transformers are now the black-topped units made by the company that produced the transformers in AC100 mark 2s.
The warning plaque is red, and the serial number plate is three-line.
These are the standard features of late AC50s, that is to say of amps with serial numbers from the 5000s - 8000s.
Red Lemco capacitors, which first make their appearance around serial number 5739, persist in the preamp until around serial number 6300 (see below). Blue Hunts cathode bypass caps follow in step.
Speakers in the Foundation Bass cabs are either Goodmans Audiom 91s, or Celestion T1279s. Speakers in the guitar cabs are likely to be Fanes.
Below, a register of amps. If anyone knows of others that have not yet been included, as ever do let me know.
Serial number 6018 - currently in the UK
Control panel faded to green/back, as is the case with a number of other later AC50s.
Serial number 6023 - currently in the UK
Chassis number 2634. Pot codes are "EN" = May 1966.
Serial number 6028 - currently in Japan
Chassis number 2505. Thanks to Kenichirou Fujimura for info on this amp.
Serial number 6090 - currently in Germany
Serial number 6100 - currently in Belgium
Serial number 6115 - currently in Europe
Serial number 6168 - currently in Australia
Bought in Manchester in 2001, now in Tasmania. Thanks to Steve for the pictures.
Serial number 6171 - currently in the USA
Serial number 6172 - currently in Europe
Serial number 6234 - currently in the USA
Serial number 6238 - currently in Sweden
Chassis 2561. Repaired in Goteborg in 1976. A complement of green Plessey (?) filter capacitors added on the upper chassis, along with a fan. A red warning plaque, in Swedish, probably supplied early on, can be in the last picture. I think the text is something along the lines of "Make sure the device is unplugged from the mains before removing the back panel".
Serial number 6253 - currently in the USA
Chassis 2911. Pot codes are "FN" = June 1966. Pictures kindly supplied by Tom along with the history:
"My friend's dad bought it new and used it for his Fender Rhodes Piano. He bought the Head, 2-12" guitar cab, and 1-18" Foundation Bass cab. He stopped using it sometime in the early 80s when it was put in his attic.
"November 2010, friends dad was cleaning out his attic and asked me if I wanted the rig. I said sure and asked how much money he wanted for it. He stated he wanted nothing for it, just simply wanted it out of his attic. I took it home and cosmetically it was in rough shape. At some point the grille cloth was replaced with carpet! It was filthy. I was surprised it worked! One of the 12" speakers had been replaced with what I believe to be a Jenson, the other appeared to be a Goodmans 12" that I believe to be original. Only the Jensen was working...barely. The Goodmans Midax horn was in the cabinet, however not working. I took the head to a Valve Amp repair shop in my area. Had it cleaned internally, retubed, and biased. It needed a couple caps replaced but otherwise was in great condition."
"I ended up putting 2 new Jensen 12" speakers in the cabinet with the horn, but left the horn disconnected. The Foundation Bass cabinet still has its original Celestion 18" in it. It was in pristine condition inside once I opened the cabinet up...everything was like new!"
Serial number 6298 - currently in Europe
Grille cloth faded to brown (as sometimes happens). Nice amp.
Serial number in the 6000s - currently in Europe
Chassis number 2718. A new mounting plate for the XLRs has been provided on the back panel (necessitating the moving of the warning plaque). Original blue Hunts capacitors still in place in the preamp. The cab is an AC30 cab in an original early Super Twin trolley - note the basket top for the amp.
Double-pin corners first come in at around this point
Note, however, that a good number of amps that follow still have single-pin corners. It is not until we get into the high 6000s - in the 6800s so far as one can tell at present - that double-pin corners become the norm.
Serial number 6471 - currently in Belgium
Serial number in the 6000s - currently in Europe
Serial number in the 6000s - whereabouts unknown
Serial number 6474 - currently in Germany
Chassis no. 3001. A replaced mains transformer, but otherwise in great condition.
Serial number 6552 - currently in the UK
Serial number 661x - currently in Europe
Serial number 6680 - currently in the UK
Serial number 6690 - currently in the UK
Serial number 6757 - currently in Italy
Accompanied by its Foundation Bass speaker cab (with Celestion T1108). Red Lemco capacitors in the preamp. Note the inspection tag at the mains switch end of the preamp board.
Serial number 6760 - currently in the USA
Thanks to Gene for the note on the existence of this amp.
Serial number 6798 - currently in the UK
Accompanying a 1980s V125 cab.
Serial number 6824 - currently in Europe
A Foundation Bass rig.
Serial number 6884 - currently in Europe
Accompanied by a solid state Vox Sound Equipment Ltd. Foundation Bass cab. Probably exported originally to Germany or the Low Countries - a metal shop badge (rare in England and the US) can be seen on the top front edge of the cab.
Serial number 6911 - currently in Europe