Vox AC30: copper and grey panels, Celestion blues and silvers
Mid 1964: serial numbers in the 15000s
Serial number 15665 T, amp model and number machine stamped, voicing (T = Treble) hand-stamped.
Continued from the page on AC30s with serial numbers in the 14000s. So far no Super Twins with stray numbers in the 14000s have come to light.
Throughout the 15000s, as in the case of amps with numbers in the 14000s, one finds three models: the "Treble", designated with a "T" on its serial number plate; "Normal" voicing designated by an "N", and Bass designated "B". All three had their own schematics, in order: OS/056, OS/065 and OS/057. Some notes on the treble circuit, which was new in 1964, can be found on this page.
"TB" - also stamped on the plate - indicates that the amp was fitted with the Top Boost circuit (Treble/Bass Boost).
A growing collection of documents relating to the AC30 in 1964 can be found here.
Significant component date codes in amps on this page are mostly of mid 1964: June for a main filter capacitor made by TCC (serial number 15041); second quarter of '64 ("B/64") for Mullard "mustard" caps.
Transformers are Albions and Parmekos. At this point, Woden (hitherto used more or less exclusively by Burndept) was designing a simplified and cheaper set of transformers for JMI - see this page. Existing stocks had presumably been used up.
Celestion silver alnicos - the T1088 - designed for JMI in the Spring of 1964 did not wholly supercede the Celestion blue - the T530 - at first. Amps with serial numbers in the 15000s occasionally still have blues. The earliest date codes known for Celestion silvers are from the middle of May.
New grey control panels, which are also to be found sporadically on amps with numbers in 12000s-13000s, occur with increasing frequency in amps with numbers in the high 14000s and 15000s.
Most Twins have Burndept-made chassis; those produced by Westrex were generally alloted to Super Twins.
As mentioned at the head of this page, serial number plates are normally machine stamped. The voicing - "N", "T" or "B" - is still hand stamped, however.
If anyone knows of further amps that should be incorporated on this page, do let me know.
Serial number 15041 T - currently in the UK
Copper control panel. Basketweave vinyl. Black vents. A mixture of Mullard mustard and WIMA coupling capacitors in the preamp. The main preamp filter cap has the date code "VF" = June 1964. Speakers are Celestion silvers - T1088.
Serial number 15050 T - currently in the UK
Much as serial number 15041. Copper control panel. Basketweave vinyl. Black vents. Wima and Mullard mustard capacitors in the preamp. Celestion silvers.
Serial number 15098 T - currently in Europe
Celestion blues in this one, perhaps replacements as the wiring looks new.
Serial number 15241 T - currently in the USA
Serial number 15257 T - currently in the UK
Copper panel, brown grille cloth. The original black cover survives. In the preamp, mustard capacitors with date codes "A/64" and "B/64" = first and second quarters of 1964.
Serial number 15325 T - currently in the UK
A refurbished cabinet. Copper control panel. Celestion silvers.
Serial number 15344 B - currently in the UK
Copper panel, Celestion silver alnico speakers.
Serial number 15405 T - currently in the USA
Copper control panel. Basketweave vinyl. Black vents. Celestion silvers.
Serial number 15600 - currently in the USA
Existence recorded by J. Elyea.
Serial number 15640 - currently in the UK
Grey panel, integral top boost. One of the original Celestion blues remains (note the orientation of the label), the Celestion silver probably a replacement. Textured (non-basketweave) vinyl.
Serial number 15641 T - currently in the UK
Sold on ebay in 2010. Grey panel, Celestion silver alnicos.
Serial number 15687 T - currently in the UK
Grey panel. The chassis is probably later, however (i.e. replaces the original one). Note the dome voltage selector.
Serial number 15724 B - currently in the UK
Serial number 15888 TB - currently in Sweden
Grey panel with integral top boost, Celestion alnico speakers. In accordance with Scandinavian legislation, the voltage selector has been removed and the numnber of cycles excised from the serial number plate.