Very little seems to be known about the alnico G12 speakers from the 1940’s and 1950’s. Examples do turn up online from time to time, and I’ll share some of the ones I have seen here.
Every speaker is a piece of the jigsaw, so if you have any really old Celestion or Rola G12 speakers, especially B024 or B025 model, that you would like to contibute to this page then please email me, and I will update it and share the info.
*Big thanks to everyone who has donated information and photos so far*
Pre-1956 Date Codes
We already know from existing date code charts that the year code for 1956 is the letter A. I think it is safe to assume that Celestion were using the same A to M cycle before 1956. So working right back to the letter A would give us the table shown below.
|A = Jan||A = 1944|
|B = Feb||B = 1945|
|C = Mar||C = 1946|
|D = Apr||D = 1947|
|E = May||E = 1948|
|F = Jun||F = 1949|
|G= Jul||G = 1950|
|H= Aug||H = 1951|
|I/J = Sep||I/J = 1952|
|K = Oct||K = 1953|
|L = Nov||L = 1954|
|M = Dec||M = 1955|
For example “09EF” would be 9th May 1949.
The date codes were printed on the outer rim of the metal chassis, at least until Feb 1951 (H year code), then on the front gasket from at least April 1952 onwards (I/J year code).
The months codes went from A to M, skipping the I. Any instances of the letter I are typos and should be a letter J.
The Celestion P44 (model number 1335) is a 10w alnico speaker with 3 Ohm impedance and 1.5″ voice coil. Although these speakers are similar in appearance to guitar speakers I would not recommend using them for guitar, they were built for use in radiograms and other audio equipment.
The Celestion brochure for the P44 describes it as “a lightweight, relatively inexpensive speaker possessing the full bodied bass response normally associated with more costly 12″ speakers, together with a particularly clean and smooth upper register. This model can advantageously replace a 10″ speaker in most radiogram applications”
The 27LH date stamp on this P44 may indicate 27th Nov 1951. It was sold on UK ebay recently with another speaker dated 19MF, which could take production of these speakers back to December 1949.
Notice the ‘POB’ cone stamp, which was probably a cone made in house at the Thames Ditton factory – similar to the ‘RIC’ stamped cones. The date stamp and circular inspection stamp are printed on the rim of the metal chassis.
Here we have a later P44 in excellent condition. The ’27DK’ date stamp on this speaker translates as 27th April 1965. Notice the cone is now a pulsonic with 9/830/00 stamp. The date stamp and circular inspection stamp are printed on the front gasket instead of on the metal rim.
The celestion P74, model number 1772. Supposedly a higher powered version of the P44, and probably rated at 12 watts. The ribbed cone and larger magnet probably make these a better choice for guitar players than the P44.
The MG date code printed on the outer rim could be translated as Dec 1950.
Here is a very early G12 speaker model 1478, possibly a P74, still carrying the old motto “The Very Soul of Music”. Notice both the model number and date stamp are printed on the outer rim of the chassis. The cone stamp is barely readable.
The 25DF date stamp could indicate it was made on 25th April 1949.
The evolution of the Alnico G12 – model B024 / B025
B025 is a 15 Ohm speaker, and B024 is an 8 Ohm speaker. They are 12 watt speakers originally designed for audio, so are not strictly speaking guitar speakers, but they were used in some early guitar amplifiers.
Shown below are a few examples that have turned up in recent years.
This B025 model speaker turned up on UK ebay a while ago. Notice the model number (B025), date code (30CG), and circular quality control stamp are all stamped on the rim of the metal chassis. The magnet has four small nuts at the top, not the large slot head screws found on later speakers. The 30CG date stamp could translate as 30th March 1950.
A slightly later speaker. The date stamp 26BH could indicate 26th Feb 1951. Notice the Rola label, and the additional C in the cone stamp. ‘RCIC’, instead of ‘RIC’.
The date stamp is still printed on the rim of the metal chassis.
Date stamp now on the front gasket. The HJ date code could indicate August 1952. RIC cone stamp.
04LL could be translated as 4th November 1954. Date stamp on the front gasket of the speaker, notice the circular quality control stamp is still on the rim of the frame. Rola label.
A very similar speaker to the previous one with Rola label. The date stamp 13GM could be translated as 13th July 1955. This speaker also has a RIC1 cone.
01DD translates as 1st April 1959. Notice the magnet now has the large slot head bolts in the back. Unfortunately we dont know if this speaker had a Rola label or a Celestion label. The circular inspection stamp still on the rim of the speaker.
Here we have a B025 from 11th April 1962, now with the Celestion logo on the label instead of Rola. Both the date stamp and the circular quality control stamp are on the front gasket. Large slot head bolts in the back of the magnet.
A similar B024 speaker dated Jan 1963. Celestion now using pulsonic cones. The owner of this speaker has since been in touch with me and confirmed it has the H1777 stamp.
A model B025 dated July 1965, also with the pulsonic H1777 stamped cone. The most recent B025 speaker I have seen and possibly one of the last ones to be made.