Dating fender speakers
Per Blue Book and Fender Consumer Relations Department.
There are other ways but the above is a more accurate method.
In such cases we tend to favor British voiced speakers to give us a throaty and meaty tone where the treble is tamed and compensated for.
Such speakers may not be well suited for crystal clear and soft clean tones, but they match perfectly with our blackface AB165 Bassman with jumped channels and lots of preamp and power amp distortion.
We use it to describe a “natural” tone, meaning a relatively flat frequency response.
Speakers can have different frequency response depending on materials and construction design, like cone shape, magnet weight and coil size.