Friday, February 20, 2009

Hammond Tone Cabinets (HTCs)

These old Hammond Tone Cabinets used to be the lowest item on the totem pole. If I didn't have enough room inside the shop/warehouse, it would be the HTCs that would have to spend the night outside on Death Row. People always seemed to want Leslie Speakers with their Hammonds, and the HTC would be just another extra to haul away and take up space. When too many piled up I used to give them away to a local Hammond Nut, who would make bookshelves out of them.

All of that is now changed!

I've been having more calls for rebuilt HTCs lately from some of my local churches. Not every church needs or likes the animation provided by the Leslie Speakers. I used to say that if a HTC is working, it will work for a long time until it dies. But if the electrolytic capacitors are still original, they are in horribly bad shape now. They all need to be replaced with new ones. The reverb return wire usually has a rotted out center core, and is shorted in several places. The speakers might be blown to shreds or in perfect shape. Anyway, I've got another church that needs another HTC to replace their worn-out one. Problem is, these monsters aren't easy to work on. So I have to psyche myself up and tackle yet another HTC next week.

HTCs are self-powered speaker systems designed for the Hammond Organs from 1936 to the end of the run. Most of them have vacuum-tube amps (valves, for our UK friends). They usually have reverb (invented by Hammond) and two or 3 channels for bi-amping purposes. The cabinets are almost all open-back types, meaning they are not tuned for sound-enhancement purposes.

I've often thought about designing and building a front-end for the Hammond Tone Cabinet. It would be a preamp built into a "Box of Knobs" for use as a Guitar Amplifier. The preamp would simply plug into the 6-pin male connector on the HTC. It could be used on any 6-pin HTC. If any of my readers have an interest in a product like this, leave me a comment and I'll raise it up my list of priorities.


  1. Hi, I would be interested in a HTC mod like what you describe. or to learn how to covert to audio use, say a sub woofer?

  2. The simplest way to use the HTC for guitar is to find a good guitar amp that has a Line Out on the back. I can make a dongle that connects the Line Out from the amp to the 6-pin connector on the HTC. There also has to be an a/c power cord to that 6-pin connector, or else the HTC will simply sit there with tubes colder than a mackerel. Let me know if you are interested!