Hammond Tonewheel Organs

Early in 2008, I was bitten by the Hammond organ bug, resulting in the acquisition of a 1962 Hammond M-111 spinet. Like all Hammonds of this vintage, it features an electro-mechanical tone generator, harmonic drawbars, and a vacuum tube amplifier. Here I document the work I’ve done to get this organ back into shape and to keep it that way, enhancements I’ve made along the way, and my discoveries about the operation of this piece of musical history.

Musical Theory and Techniques

• On the Nature of “The Hammond Organ Sound”
• The Science of Hammond Organ Drawbar Registration

Repair, Maintenance, and Modifications

• Adding a Rotary Speaker to a Hammond M-111 Organ
• Adding Foldback to the M-100 Series Spinet
• Hammond Organ Tonewheel Generator Capacitor Replacement and Calibration
• Overhauling and Improving the Hammond M-100 Series Vibrato System
• Overhauling the AO-29 Amplifier in the Hammond M-100 Series
• Presets for the M-100 Series Spinet
• Rebuilding a Hammond AO-29 Amplifier from the Ground Up
• Retronome – A Versatile Analog Drum Machine for My Hammond Organ
• Window Seat Bookcase Tone Cabinets for a Hammond Organ

Related Projects

• MusicRack – A Digital Sheet Music Display System
• Oh, the Noise! Noise! Noise! Noise! – Stringz’n’Thingz Revisited
• Rejuvenating and Expanding a PAiA 1550 Stringz’n’Thingz Synthesizer