Celestion Silver Alnicos - T1088
Link to list of date codes on the Celestion site.
The Celestion register of speaker types - the "T" book - is printed in extenso (insofar as it relates to 12" speakers) by Michael Doyle, "The History of Marshall" (1973), appendix 1, pp. 136-142. Some of the relevant pages are available on Google Books
Also see Jim Elyea's wonderful, "Vox Amplifiers: The JMI Years" (California, 2009), esp. pp. 264-276; and the numerous posts in the Vox and Speaker fora of the Plexi Palace.
Rola G12 B024 and B025 - 8 and 15 ohms
The Rola G12 B024 - the 8 ohm version of the B025 (below). Alnico magnet. 1940s through to mid 1960s. Aluminium voice-coil. There seem to be three basic types (1) small nuts on the cap, date code stamped on frame; (2) small nuts on cap, date code on gasket; (3) large screws on cap, date code on gasket. See the excellent comments on this Plexi Palace thread.
The Rola G12 B025 - the 15 ohm version of the B024 (above). Date code "16BH" stamped on frame = most likely February 1950.
A later BO25 (with large screws on the cap) has been posted on the Plexi Palace - code 01DD = 1st April 1959. The speaker below it on that page with code 04LL on gasket, but small screws on cap, is probably from November 1954.
The Celestion 74 - (15 Watts) - 15ohms
An uncommon type of Celestion alnico. The one pictured above is a late example, with date code "04AJ" = 4th January 1964. The lightweight version of this driver was the Celestion 44. Pictures from this page. Note that in common with the Rola G12 above, the 74 has nuts on the top cap instead of screws found on the CT3757 (further down this page).
A nice pair of P74s. The date codes are 01MG, which is impossible (a wrong stamping) and 14LG, which is 14th December 1962.
The Hammertone CT3757 (15 Watts) - 8 or 15ohms
A type of G12 alnico made for Vox. In the example above the code - "3757" - stamped on the gasket, along with the date code - "08JE" - 8th October 1960. The cone code is stamped on the cone itself - " RIC 1 FW".
The Celestion Blue - T530 (15 Watts) - 8ohms
The T727 was the 15ohm version of the T530, used in Vox T60 bass cabinets.
Logged in the Celestion register on 19th Jan. 1960: "As CT.3757. Fitted with cover H1668. Finish sprayed blue". On the left, the classic blue, used extensively in AC30s. On the right, a pair, cones up: T530, date codes 10 and 11BJ - 10th and 11th February 1964.
A late unit with the code 28DJ = 28th April 1964.
A pair of blues. One designated T530 and with the code 10GH = 10th July 1963; the other called a T1088 and coded 30MJ = 30th December 1964. If the gasket of the latter is original, this is a very late "alnico blue".
The Westrex-made T530 / T565 (15 Watts) - immediate precursor of the "Celestion Silver" T1088
Assembled by the Westrex company, on which see this page.. This speaker type was registered in the Celestion log book on 8th Sept. 1961. The model number, slightly indistinct in this instance, can be seen on the outer cork gasket; the cone type - "Ric 2 UR", which sets Westrex-made units apart - is stamped on the cone itself. The date code of this example is 28CH (also stamped on the cork gasket) = 28th March 1963.
THE CELESTION SILVER - T1088 (15 Watts with light doping) - 8ohms
cone made by Pulsonic, the British manufacturer, code H1777
Entered in the Celestion log book, 27th May 1964: "As T530, sprayed Poly Grey". T1088s were probably present in the large AC50 speaker cabs used by the Beatles at Stockholm in July 1964. They were certainly employed in the AC100 cabinets given to Lennon and Harrison in August of that year.
For a selection of surviving cabs - click here
In some respects though, the Celestion T1096, a 15 ohm version of the T1088 also made exclusively for Vox, might have been better choice for the new 4 x 12 cabinets, as a 15ohm load would have taken some of the strain off the output transformers of the Beatles' AC80/100 amplifiers.
One possible reason for the use of T1088s rather than T1096s, however, was the drive to keep the cabinets as trebly as possible (Midax horns et al. - see the examples here). 16ohm speakers are said to be "darker" or bassier than their 8 ohm counterparts.
Above, sold on ebay in late 2013, a T1096 from 23rd May 1964 (code 23EJ). The T1096 was entered in the Celestion log book on 27th May '64 along with the T1088 and other speakers.
One sometimes finds that T1088s are reported as being capable of 20W or even 25W - utter nonsense. Even with the heaviest doping possible, Vox knew that the T1088 was just capable of 17W. See the wiring diagram in the Conqueror cab below:
Early Conqueror with two T1088s from April 1967.
Notwithstanding the entry date for the speaker given in the Celestion log book (27th May 1964), one from 28 April 1964 (!) has been reported - the code presumably being 13DJ.
Other speakers predating 27th May also survive - at least one from 20 May 1964 (code 20EJ: - reported here. Another (if it is another) immediately below:
Code 20EJ - recently on ebay.
Code 02FJ = 2nd June 1964. Pulsonic H1777 cones, as below.
Date code 09FJ = 9th June 1964.
Code 17FJ = 17th June 1964 (ie. 21 days after this type of speaker was logged in the Celestion register). Note that the profile of the cover is more cylindrical than bell shaped. There are three screws around the drum. The cone is a Pulsonic H1777.
Codes 23 and 24FJ = 23rd and 24th June 1964.
Code 30FJ = 30th June 1964. One of a set of three sold on ebay in 2012 - the other two were reconed. Cone code H1777. A small amount of doping visible around the edge of the cone.
Code 17HJ = 17th August 1964.
A pair of blues, one with no cone and a damaged gasket. The other has the date code 18JJ - 18th September 1964 - and the designation T1088, not T530.
Date codes 08 and 09KJ = 8th and 9th October 1964.
A certain someone with a Vox AC30 with silver Celestions. Picture from the fabulous Mirrorpix archive.
Date code 24JK = 24th October 1965.
Solder terminals still on the chassis spoke
Revamped and reconed, but date codes known to be January 1966 - see the last image.
Date code 07BL = February 1966. From a Super Beatle amp.
Two early Super Beatle amps (V1141) with T1088s
An AC100 assembled by Triumph Electronics (rather than by Burndept). In the upper compartment of the cab - two speakers with solder tags on the spokes of the frame, one (perhaps a replacement, as the others are earlier) with the code "30HL" = August 1966. Further pictures of the amp are available here.
Solder terminals on a board between the chassis spokes
An instance apparently with a date code indicating 10 December 1964 (10MJ) is reported by Jim Elyea. This must be a mis-stamping for 10JM = 10th September 1967. Celestion were certainly not immune from errors of this sort.
Date code 23CL = 23rd March 1966. Note that the terminal board is light grey, as below.
The right hand speaker of the pair in the first image. Date code 19EL = 19th May 1966.
Codes 09JL and 12JL = 9th and 12th September 1966.
T1088s made for Thomas Organ
A Celestion T1088 made for the American market (for the Super Beatle speaker cabinet). Date code 19EM = 19th May 1967. Also note the Thomas Organ part code on a sticker: 33-5070-6-B. Terminal board is black.
Code 14LM = 14 December 1967. From a Super Beatle cab.
Speakers in English Vox solid state cabs to go here.
Date codes and model number now stamped on the metal frame
A pair from mid 1969 - codes EB7 and EB22 = 7th and 22nd May '69.
A very clean pair from late 1975 - code KH16 = 16th October 1975. The label references both Vox Sound Ltd and Vox Sound Equipment Ltd. The address of Vox is given as: Elm Road, Vanguard Way, Shoeburyness (Essex).
A pair of speakers from an AC30 with the code CJ19 = 19th March 1976.