This was professionally converted from a PA head to a guitar head. It is a MONSTER. Huge, Bismarck-sized transformers. Killer 6L6 output tone from a pair of vintage 6L6GBs. The preamp features a 6SL7 and three 6SF5 octal tubes. The rectifier is a 5U4.
Bogen amps were made in New York. To my knowledge, they never made any amps solely intended for guitar, but just like old Masco PA heads, these Bogen all-tube PA heads are favorites for guitar amp conversions. They are prized by blues guitarists and harp players for their thick, honking blues overdrive when cranked into overdrive, and their good cleans make a great platform for sculpting a sound with pedals.
This amp has two working channels, so if you want to run an ABY switch and have switchable channels, you can. The knobs are: Mic 1 Volume, Mic 2 Volume, Phono Volume (disconnected, good master volume candidate if you desire), 6-Way Tone Selector Switch, and On/Off Switch. Speaker impedance is selectable. There is one 1/4 speaker output jack.
You will not find a cheaper deal on a fully-serviced, 1950s, all-tube, point-to-point, hand-wired guitar amp. Stick a Tube Screamer or Fulldrive overdrive pedal in front of this and LOOK OUT!
These are one of the best kept secrets in the vintage amp world. I guarantee you won't find one at Guitar Center.