Monday, April 06, 2009

Inside the Hammond L-100

After more playing and reading, I decided I really needed to get those drawbars working properly. There are numerous resources on the web with a wealth of information on Hammond tonewheel organs; this page describes what I did tonight.

Nearly all of the drawbars were really noisy when moved, and for a handful of them sound would drop out entirely on some settings. As I mentioned yesterday, the fundamental tone for the upper manual was one of these. It worked OK at lower settings, but from about 6 to 8 it would go silent unless I pushed down on the drawbar. Typically that drawbar contributes much of the tone of whatever my right hand is playing, and since my left hand is nearly useless, this was not a good situation.

So it was off to Radio Shack on my lunch hour to get some spray contact cleaner/lubricant, and tonight I opened up the organ once more.

It's a pretty complicated machine, and you can't even see the most complicated part of all, the guts of the tone generator.

Here's the back of the tone generator. Inside are dozens of gears and wheels and coils and magnets.

The spring reverb.

The synchronous motor, which is synchronized to 60 Hz AC power, and the reason these things never go out of tune. Note that it's attached to the tone generator via a spring; apparently the motor pulses a little, which would affect the sound in a bad, 60 Hz kind of way. The spring takes care of that. In some Hammonds, there's a second starter motor on the opposite end of the tone generator. Those models have two power switches that have to be turned on in a particular way; the L-100 just has the one.

Glowing vacuum tube goodness!

Here's the business end of the drawbars. I sprayed a little contact cleaner/lube in each of them, and worked the drawbars a little to clean them out. They work much, much better now. There's no noise or dropouts.

As far as I can tell, everything except the A flat pedal works now, though the mysterious "brilliance" tab doesn't seem to do a thing. I'm not sure what it's supposed to do; add brilliance, I guess. If you heard me play, you'd know that I could use a little brilliance.

Sunday, April 05, 2009

A new instrument arrives

On Friday an old Hammond L-100 organ took up residence in our library. Grandma Thvedt saw an ad in the local paper and thought we'd like it. Grandpa and I went to look at it several days ago, and it was in pretty good cosmetic shape, and it functioned well, too, so Grandpa bought it as a gift for the kids. I think it was a pretty good deal at $25. We planned to come back later and wrestle the thing over here, but by Friday I'd thought better of that plan -- it weighs a ton -- and called a local moving company. It cost more to move it than to buy it, but I'm still well pleased with the bargain.

Since the arrival I've had a little time to read up on Hammond tonewheel organs, and to try all of the available settings. It has a few problems, but nothing really serious. The worst is probably the non-working A-flat pedal, but even that's not so bad. The pedals cover only one octave anyway, so they're already pretty limited.

Today I opened it up to do a little maintenance. They're meant to be oiled once a year. On the inside of the back panel, somebody had noted two dates when it had been oiled -- once in 1988, and once in 1992. I don't know for sure, but this organ probably was built some time in the first half of the 1960s. I'm a little curious about the care it's had over the decades.

Some of the drawbars, which are pretty much the whole reason you'd want an old Hammond, need their contacts cleaned, including most especially the one that controls the fundamental tone for the upper manual. I'll be opening it up again in the near future to tackle that job. I'll try to remember to take some pictures of the inside -- it's really something.

We're really having a lot of fun with it. I caught Thomas making some wild sounds on it by turning it off and on while playing. I put the kibosh on that. I read that Keith Emerson used to do the same thing on his L-100, but he also stuck knives between the keys to get sustained notes and some other pretty crazy things.