Marshall cab serial number dating
Very nice sounding speakers – louder than the G12M and more ‘boomy’, but less compressed and more fluid. Similar speakers are the T1862; as T1234 but no plastic cover, and T1279; as T1234 but with the VOX/JMI colouration and label The date of entry into the Celestion log book shows 6th May 1966, however I have owned several examples earlier than this, and I know they date back to at least Feb 66 (see photo below).
Originally they looked very similar to the T1134 with just the gold Rola Thames Ditton labels on the back, but with the standard solder terminals.
Amp manufacturers switched to ceramic speakers, mainly because they were cheaper than alnicos, but they also proved to be a perfect match for the edgy, over-driven guitar sound that was emerging at the time. The ceramic magnets used on Celestion greenback speakers came in four main sizes.
The T1221 was the stock speaker in Marshall lead guitar 4×12 cabinets (1960 model cabs) from the mid 1960’s up until the late 1970’s and was also used by many other brands at the time.
*Power handling increased by 5 watts around late 1967 due to a change in the voice coil design.
The T1134 model was probably the first ‘G12H’ speaker Celestion ever made.
The original speakers had a power handling of 20w and had no doping at all on the cones, really great sounding speakers and it is very rare to find those first ones nowadays.
Over time Celestion made small changes to the specification, probably to make the speaker more durable.