The brown 6G2 Princeton Amp is often described as sitting somewhere between Tweed and Blackface Fenders - both sonically and of course chronologically. However, it does have a voice of its own: for instance, it has significantly more midrange roar than the Blackface era amps - actually it sounds very angry indeed when pushed hard. It also won't sag as much as the cathode-biased 5E3 Deluxe when you hit the low strings hard. My amp has been recapped and the original handle has been replaced first with a no-name strap and recently with a genuine current-production Fender leather handle. The tremolo footswitch is missing, but otherwise there's little to complain about.
The brown Fenders weren't that popular in the past while everyone was after the Tweed and Blackface era amps. Lately, however, they have started to get the recognition they definitely deserve. The lack of "mainstream success" until recently has one definite upside: these early 60's tone machines can be found in astoundingly good condition - most of them having been lying in garages, attics or storage rooms for decades while their black and Tweed counterparts were being lugged all over the world. I'm not saying mine is an example of a museum piece, but realizing it's a 50-year old piece of musical gear, I've seen worse. Much worse.
As far as official sources go, there is no such thing as 6G2-A. There's a hand-written "A" on the tube chart of this amp, but I doubt it is a sign of a revised schematic as the last Princetons of this era were manufactured in 1964 and there's no sign of a "-A" suffix in those amps - or any other suffix for that matter. All "6G2-A" Princetons seem to have been made in early 1962. In discussion forums people have found one common denominator to most (if not all) 6G2-A amps (or whatever you wish to call them): they have an Alnico Oxford 10JB-14 speaker instead of the much more common ceramic Oxford 10J-4. This has led to one plausible theory: maybe the "A" implies Alnico speaker. Who knows? At least there are several examples and mine is one of them.
The tremolo in this amp is downright delicious. It's not the pitch-shift-warble kind of thing that a Fender Bandmaster and several other amps of the same era have. While that lush chorusy vibrato is fantastic, sometimes you'll want something that can actually be called simply a tremolo: that is, a fluctuation of the volume rather than pitch. This amp does it exactly the way I want a tremolo to be: it's strong - almost hypnotizing at extreme settings - yet it kind of steps away especially when playing lead parts with percussive, fast notes. Theoretically you could leave it on all the time if you just want to spice sustaining notes and chords with it and otherwise play staccato melody lines... to a certain degree of course. One interesting thing is that the Brownface Princeton has almost exactly the same circuit as the Tweed Vibrolux - another classic Fender amp.
This amp has been fully seviced in November 2012:
Specifications
Tube configuration
Serial numbers:
Chassis: P01560
Tube chart: LA (January 1962), Production #6, "A" hand-written after "6G2"
Mains transformer: 125P1A, 606146 (1961, week 46)
Output transformer: 125A10B, 606204 (1962, week 4)
Speaker: 465-133 (magnet) - denoting Oxford, 1961, week 33; P4474-1 (speaker cone)