Celestion 1777 Cone Prefixes

[BRMSlash]

I've got a couple of different versions of the Classic Lead 80 and noticed they have different cone codes. They also sound slightly different. Just wondering if any one knows what the codes refer to or is there some reference we can look up?

Fore example: One cone has D31 1777 stamped on it and another has D10 1777. I found the D31 version to sound much better, but unfortunately I had to get it re-coned due to a voice coil rub due to use in an open back cab (i.e. I probably exceeded its excursion limits). Going off the date codes, the D31 version was produced two months after the D10 version (i.e. 16JN and 25GN date codes). Maybe an improved recipe?

I also have some new Heritage G12-65's that have a cone code of 1 32 1777 that sounds fantastic. Maybe the 1777 prefixes that are in the 30's are the better sounding ones?

[Scumback Speakers]

In the previous cone versions used by Celestion (Pulsonic, Kurt-Mueller, R/C, etc) that two digit code was the week of the year the cone was made.

So a 29 102 003 Pulsonic cone was made the 29th week of the year the speaker was made.

[BRMSlash]

Thanks, that's useful info. However, the numbers for that purpose would seem a bit redundant in this case, as the speaker frame has a more exact date code specifying the actual day/month/year. I guess the cone and the frame could be manufactured on different dates, however the cone code wouldn't specify the year.

[Scumback Speakers]

That's correct. The cone code is probably irrelevant as far as the date it was made. I've seen discontinued 102 014 cones in rare T1460 G12H30 55hz 8ohm speakers with 1974 date codes.

Yet the 102 014 cone is rare to find past 1972 in a 16 ohm model (T1281).

I learned to accept that there are date code guidelines for Celestion speakers...but not absolutes. And there are long transition periods between changes.

[BRMSlash]

Just received a direct reply from DrDecibel:

It’s a date-code the cone manufacturer uses for quality control purposes. Same reason we put the date-code on our speakers. It tends to come and go and not all of them have it but we like to see it.