Thanks to Eric from J. Rockett Pedals for this blog entry with information from Celestian Speakers.
Good info on the Celestion site about speaker dating. I’m a speaker nut and there’s tons of misinformation out there. I happened to purchase a matched pair of 1968 Greenbacks in mint condition awhile back. Everyone who called on the speakers were reading the date codes wrong so they all passed on them. I knew my date codes and scored both speakers for $400 total and they are worth $500 each since they are mint! Ah, knowledge is power!
So, if you get a used cabinet in check those speakers out as you might have a gem! Know your cone codes as well. Few people realize that Pulsonic cones (the holy grail cone) can be found in speakers as late as 1974 to 1975 and the cone code will be 1777 (75Hz) or 0444 (55Hz). These are often mistaken for Kurt Mueller cones when they are actually some of the last Pulsonic cones. They have more pronounced ribs and are found in creambacks and even early blackbacks. I happen to own four 1975 blackbacks with 1777 Pulsonic cones and they definitely sound better than the pair of 1977 blackbacks that I have with Mueller cones! Check out www.bygonetones.com as everything you ever wanted to know about vintage Celestion speakers is on that site. The dude knows his stuff!
When Was My Speaker Built?
You can use the chassis date codes to accurately pinpoint the age of the driver you're interested in.
One question we're often asked is "how old is my speaker?" And if your speaker is in reasonably good condition, then it is straightforward to find this out for yourself.
Since 1956, all Celestion chassis drivers have been stamped with a date code (two numbers and two letters), denoting exact date of manufacture. The codes are added on the production line and are placed on the speaker's chassis leg, on the front gasket or on a label on the magnet edge.
In recent times this information has also been reproduced on the barcode label stuck to the outside of the speaker packaging.
If you can track down the date code, simply refer to the following set of tables, which provide an accurate record of the date codes used throughout the years.
1956 - 1962
Date codes from 1956 to 1962 are written in the form: Day/Month/Year. For example: 15DE = 15th April1960.
1963 - 1967
Note the loss of the 'I' from the month codes. Date codes from 1963 to 1967 are written in the form: Day/ Month/Year. For example: 19MK = 19th December 1965