Vincent asks about a 50 to 60 Hz converter for operating his Duo-Art
piano fitted with an original Holtzer-Cabot motor.  I have a few
American pianos fitted with their original motors and I live in Great
Britain where our mains electricity arrives at 230 volts and 50 Hz.

The conversion of the volts to American 115 volts is very easy as there
are many cheap transformers available.  I have never needed to convert
the frequency, although this is possible nowadays with the advent of
solid state inverters which are available to convert any voltage and
frequency into any other voltage and frequency.  The price of these,
however, is very high.

The simple solution is to account for the change in rotational speed by
changing the drive pulley fitted to the motor shaft.  Since the motor
will be running at 5/6 of the design speed all you need is a pulley 6/5
times larger in diameter and the rest of your piano will be rotating at
the correct speed.

One issue that may prevent this course of action is the operation of
the centrifugal switch, as the reduced speed of the motor may not be
sufficiently high to disengage this.  I have never had this problem on
any of my original American motors, and you can hear the switch
disengaging prior to full speed being achieved.  Another effect of
running slower than intended is that the motor will run slightly hotter
but again I have never had a problem with this.

My recommendation is to try using a larger motor pulley before you go
down the road of sourcing an expensive inverter.

With best wishes from GB,
Nicholas Simons