Documenting another Bell & Howell amplifier conversion - this time I'm going to try replacing the EF37 pentode preamp, with a 6SL7 octal dual triode, with a Fender style one knob tone control. 

While it has a different model number and a shiny red faceplate, it's the same amp as the 621 and others in the series.  Quite often, the model number has more to do with the projector than the amp.

BELL & HOWELL 622 PROJECTOR AMPLIFIER

Stock - the infamous rats' nest.

Now with the unnecessary parts removed - although there is still more work to do.