Vintage speaker dating
The 6 digit code indicates what manufacturer made the speaker and when it was made. Here is a list of some of the speaker manufacturers and their EIA codes: So, the speaker in the image above would have been made by Jensen (220) during the 27th week of 1951 or 1961.The year is confusing because it is only a single digit.Some manufacturers also attached other letters to the end of the date code to indicate day of the week, work shift, serial number, lot number, etc.The EIA only specifies manufacturer and year/week code.In later years, the EIA converted to a 4 digit date code so the year could be easily identified.There are 2 acceptable methods of displaying the EIA date code, with or without a hyphen between the manufacture code and the year/week code.It'd be awesome if you could upgrade to a modern browser, especially Chrome and Firefox as that is the best out there right now. You might find some of the information useful in determining which speaker would be best suited to your application.The picture is a section of the basket rim of a speaker.
In most cases the first letter represents the month, and the second letter represents the year.From 1986 onwards a two digit number is normally used instead.The code beginning with the letter ‘T’ is the model number of the speaker, for example ‘T1281’ represents a 55Hz 16 Ohm G12H.The small circular stamp with ‘insp’ text or a letter ‘P’ inside it, is a quality control stamp.It is an important stamp to look for to authenticate old ‘pre-rola’ speakers.