When we acquired our 1913 Mason & Hamlin upright T-100 (red)
Welte-Mignon it had a single speed Holtzer-Cabot 110 volt, 1/8 hp,
60 cycle, 1150 rpm motor.
The pulley set up resulted in the pump operating at 40 strokes per
minute, with the result that the reservoir would empty and the wind
motor would slow when loud passages were played.
I changed the set up to a 2-speed 110 vac GE motor, GE Model
5KH49SN3048 (Grainger # 2K707A-H300), mounted on a Overly-Hautz #601
motor base (to provide ease of belt tension adjustment), which in turn
was mounted on 1/2" of firm felt.
The GE motor has a 5/8" diameter shaft and provides 1/4 hp at 1140 rpm
and 1/10 hp at 850 rpm. I use Browning OKxx pulleys with 5/8" bore.
I currently use an OK17 pulley which gives 34 strokes at low speed and
45 strokes at high speed. For "normal" play I would use an OK22 pulley
which gives 38 and 51 strokes per minute. For "concert" play I would
use an OK25 pulley which gives 42 and 56.5 strokes per minute.
I find the motor quiet although it has ball bearings. However I do
notice that the lamp which shares the wall outlet dims when the motor
goes to high speed.