Name: Steve Kennedy
Email: steve@pacair.com
Subject: Dating Music Man amps...
Thread: 48
Time: Wed, 18 Apr 2001 00:05:26 GMT
I haven't found a corellation between serial numnber and date of manufacture. Usually, you can find the dat of manufacture by removing the amp chassis from the cabinet and looking for a sticker or a grease-pencil date written on inside on on the side panels of the chassis. It can be written any number of ways and you might have to decode it.
It is easier to decode the tube complement. If it uses 6CA7/EL34 output tubes it is earlier than 1980. If it ALSO has a 12AX7 phase splitter tube, then it is most likely 1977 or earlier.
This isn't gospel, but when the amps were introduced in 1974, they all had that 12AX7. After a few years, the 12AX7 was replaced with a solid-state driver board. Many amps from this period have covers over the hole in the chassis where the tube socket for the 12AX7 would have mounted and the solid-state phase splitter board mounted inside.
I have two 410-65 amps. The one with the 12AX7 is dated 1974 on the end-panel of the chassis in green crayon or grease-pencil. The 1979 model has the solid-state driver board and the cover plate.