Dating hiwatt amps
Nothing will trash an output transformer like NOT doing this.
Be nice to your Partridges and they'll be nice to you.
( The two-digit prefix in these serial numbers seems to indicate the year made, and in the latter example, which was seen on a DMI-Sound City F115 bass cabinet, it appears the model number might have been included in the serial number as well.
For the earlier Dallas Arbiter-era Sound City products, however, the best you can legitimately determine is a range of years during which an amp or cabinet was made based on the eras in which these products appeared.
It's awesome, everything is done using the simplest solution possible and it sounds great. Thanks for breaking it down in to such easy to understand terms. Very similar sound to the older Orange/Matamp 100 watt heads.....
I always knew baxandall's had a much broader range than FMV's but I never realized just how elegant the controls in this amp are. They made the pix only heads from 1972 to early 73 only...
It's much worse (and potentially fatal for the OT) if you have a speaker cable plugged into the head but not the speaker.
Unlike solid state amps, tube amps are much happier with their output shorted then open-circuited."So, always, always, ALWAYS turn on a tube amp ONLY when there is a speaker cable connected between the amp and a cabinet!
To a great extent, condition, originality, and, especially, model determine price.Following is a listing of each era: Among the cosmetic and model-naming changes along the way, most of the Mark 4 models have what many refer to as an "active preamp." The exceptions to this are the Mark 4-era 50R PA, 50 PA, 50 PA Plus, and 120 PA, all of which have passive preamps. If your amp still makes sound when you turn up the volume control(s), you have a passive preamp.