Hammond distraction

[Doc B.]

I mentioned in another thread my latest hobby project, the restoration of a Hammond Model E concert organ from about 1942. This thing is rather monstrous, about 441 lb. for the organ and about 160 lb. each for the two D-20 tone cabinets. This weekend I did a major step in the restoration, the replacement of 43 capacitors on the main tone generator. These caps are part of an LC filter that reduces the upper harmonics produced by the tone wheels to give a more pure sine wave tone. Unfortunately the wax paper caps tend to absorb moisture and swell over time, which raises their capacitance value by as much as 100%. That in turn lowers to filter frequency, making the organ sound really dull and meek. Recapping made an amazing improvement, just about doubling the output of the tones that were affected by the filters and bringing it quite close to the original spec. Also managed to get the chorus generator hooked back up and now all the effects on the organ itself work (the chorus sounds quite nice).  Last step is getting the preamp out of the organ and replacing a couple caps in the tone control, at which point it should be possible to hit the spec levels quite closely.

Later Hammonds use mylar caps, so I thought that would be an appropriate type of cap to use for replacement. Here's some crappy iphone pics of the recapped tone generator, the old caps, and a shot of the keyboard after a lot of cleaning and a quick touch up of the cabinetry with some Old English:

[xcortes]

And who's gonna play it?

[Doc B.]

I had a B3 when I was a kid, and took lessons for a couple years. So unlike a guitar I can actually fall back on some faint memories and play a bit of tune here and there without feeling completely lost. After the time investment in making this amazing contraption work I certainly want to give it the old college try and plan to start practicing as soon as I get it buttoned up.

The organ belonged to Jacqui Naylor's dad. It had been sitting unused for many years, and I suspect from the heavy wear on the cabinet and the fact that it has signs of a few repairs it came out of a church. Since it isn't a B3 none of Jacqui's musician buds were interested in it, and she asked me if I'd like to take it on. My hope is that I can get Jacqui and husband Art Khu up here from SF some time in the not too distant future and hear Art play it. The guy can really blow on a B3.

[mchurch]

Doc;

Just as a matter of interest are the caps all the same, or are they each different? It may be a dumb question but I have never seen the inner workings of and organ like this. My last experience was a pipe organ when I was a young-in.


Cheers

Mike

[Doc B.]

Doc;

Just as a matter of interest are the caps all the same, or are they each different? It may be a dumb question but I have never seen the inner workings of and organ like this. My last experience was a pipe organ when I was a young-in.


Cheers

Mike

The different tone wheel frequencies get different low pass filters. There are 83 tone wheels, but only six get a .27uF cap and thirty seven get a .1 uf cap. Yeah, patience is a virtue when changing these out. These are coupled to coils of various inductance values to create a custom filter for each tone wheel. Has to do with keyboard tapering, Hammond's attempt to reduce "key click" - the noise made when a key is pressed and the various contacts from the different drawbars are closed rapidly in sequence, creating switch bounce and a sort of "fft" sound at the beginning of the note. This was deemed a bad thing when Hammonds were invented with the idea of emulating pipe organs and is more prominent at the higher notes (thus the tapering of the output levels at higher notes), but nowadays it is considered an important part of the Hammond sound. There is a fair amount of interesting info on the web about how these amazing machines work and how to fine tune them. If you want to see a truly amazing Hammond invention look up the Hammond Novachord - the first polyphonic analog synth, made in the late 30s. 178 tubes or something like that.

[Chris]

Beautiful Doc, and REAL ivory keys also? what a piece of engineering... THIS kind of history, just HAS to be restored....  AND It will be perfect for Halloween midnight, when the good Doc sits down and plays a rendition of the organ in  The Ghost and Mr. Chicken while laughing profusely.... I not sure about anybody else, but that would scare the begeeezes out of me and I am sure a few kids to boot.....

[Grainger49]

I had a professor in college who was restoring an organ.  These pictures and Doc's explanation gives me greater appreciation for what he was doing back then.

Please post more!

[dbishopbliss]

This is the Bottlehead forum after all.  With product names like Foreplay and S.E.X., where are sexual innuendo jokes?  Doc just lobed a softball and nobody is at bat.  In honor of the return of Beavis and Butthead to MTV, I will have to step up...

Doc said his organ is "rather monstrous".  Xaivier wants to know who's going to play with Doc's organ.  I thought that was the Queen's job, but looks like Doc is going to let Art play with it as well.  Not that there is anything wrong with that.

Ha!

[Doc B.]

No ivory, just 1930s plastic, presumably a bakelite type material. Aside from those funky waxpaper caps and a few drifty carbon comp resistors the materials used in these instruments were pretty amazing. Palladium wire for key contacts, oil filled filter capacitors that still read to spec, amazing attenuators on the expression pedals that are stepped but sound continuous, an oiling system for the rotating parts that uses threads to constantly wick oil to the bushings, they even spent some time figuring out how to mouse-proof the thing as much as possible.

Colin and I got the second tone cabinet running last night, which has this crazy oil filled reverb unit in it. A separate tube amp drives springs that are damped in oil filled columns, and a Rochelle salt pickup sends the reverb signal back to the amp to be blended with the main signal. Sounds pretty funky, virtually no treble in the reverb, but I was amazed that the crystal pickup hadn't dissolved over the past 70 years. I have a newer spring reverb tank to install, which is what Hammond did to update these cabinets. Will try both ways, but I may just stay with the bizarre old oil one. How's it sound? Imagine sitting in the ball park listening to Take Me Out To the Ballgame

Re the organ jokes, you can imagine the response I got when texting Jacqui as I described looking inside her huge old organ for the first time and seeing lots of dust and corrosion. On the bright side, all of the important parts still seemed to be there.

[ironbut]

Wow,.. sounds super cool!

I'd love to see some of those eq circuits (sounds Pultec like on a grand scale!).
It looks like Jacqui found the right man for the job.
Have fun!

[Armaegis]

Very nice. I purchased a 1905 piano a couple years ago for $100 but did not have the ability to restore it, so I had to pay for someone else's expertise. On the plus side, real ivory!

[Chris]

Yes, in response to dbishopbliss...  the project can be titled, "Doc's Newly ENHANCED Organ?"...... ok , I will get out of the gutter now.....

[R.Mackey]

Your organ is a thing of beauty...  :0

I'm curious what your listening impressions are after the fix is complete.  I had an old M-3 for years, until it expired, and hope to move up to a B-3 variant in the next few months.  Wonderful sound out of those things, even when they're wheezing their last.  I don't think I've ever heard one that wasn't at least 40 years old, so don't really know how they sound new, except for my old records from The Nice.

Took the innards out of the M-3 after it died.  Maybe one of these days I'll make a 6L6 stereo SET out of it, if I can find some matching iron.

[Chris]

Yes, we could all make beautiful music with Doc's organ...... ok I will officially stop now...

[Doc B.]

Your organ is a thing of beauty...  :0

I'm curious what your listening impressions are after the fix is complete.  I had an old M-3 for years, until it expired, and hope to move up to a B-3 variant in the next few months.  Wonderful sound out of those things, even when they're wheezing their last.  I don't think I've ever heard one that wasn't at least 40 years old, so don't really know how they sound new, except for my old records from The Nice.

Took the innards out of the M-3 after it died.  Maybe one of these days I'll make a 6L6 stereo SET out of it, if I can find some matching iron.

When we had our B3 my best friend had an M3. An M3 thru a Leslie is very close to a B3. The B3 we had when I was a teenager was probably 15-20 years old at the time. I don't know if it had wax or mylar caps, I never even looked in the back of it. This Model E now sounds as I remember the B3 to sound and based upon this experience I can't say that I would be in the camp of "oh, don't change those nice old caps, that's what makes it sound so good." The E's output levels were terribly uneven note to note and the thing was very weak and dull sounding before the recap.

There is no doubt that this E is a different beast than a B3. One could remove the strange tremulant mechanism and install a vibrato scanner, thus making it a "Model EV" rather like the model BVs. The old school chorus generator really sounds nice, and I think I like it better than I remember the later chorus setup on my B3 sounding. I hope to get a Leslie 31H, which is a period correct predecessor of the 122. It's sort of a giant economy size version. That will certainly add a little more of the classic sound. The one thing left to add to make it able to do more of a B3/M3 sound would then be percussion. I have acquired a set of percussion switches from an M series organ, and I am thinking of picking up an AO-29 amp just for the transformers in the percussion section. I think I could probably build the percussion circuit into a chassis and put in the switch panel in a manner that would be reversible. The combo of the old and new bits and three tone cabinets (the 31H and the existing D-20 and DR-20) could make for a pretty versatile, exceptionally non-portable rig.

I had a fun experience last night - after struggling to figure out how to ( badly) play a guitar for the past couple years I sat down at the organ and in just a few minutes of head scratching managed to read and play a recognizable version of Take Me Out to the Ballgame, which seemed most appropriate for the way this organ sounds. Pretty cool that some wee bit of muscle memory remains after not playing for something close to 40 years.