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  • Hammond chop adding drawbars suggestions

    Hi!

    Some time ago I bought a hammond L-100 series organ. I've played it for a while now and I completely fell in love with the instrument. I really want to take this organ with me on the stage but as (at least for me) it's quite a big and heavy instrument to transport, I've never really had the opportunity to take it with me to a gig. After opening up the organ and taking a quick glance in the schematics, I decided its quite a fun piece of gear to experiment with. Not soon after I started building a new housing for the organ to make it portable. As the organ is in pieces now, it seems like a great time to upgrade it a little bit! In the service manual, I saw there were open spaces for extra key contacts. I decided to buy another donor keyboard to take extra keycontacts out of to add to my lower manual. It has 6-7 contacts per key instead of the 9 used in the upper one, it seemed to be an interesting idea to expand it to 9 as well, adding a couple of extra drawbars. But as I opened the keyboard up there appeared to be space for 10 keycontacts per key instead of 9 (I think I misread the manual).

    Now I have decided to go with 10 voices per key. The new contacts are added and I am already rewiring parts of the keyboard. (I know I dont have all the right frequencies in my tonewheel generator but the remaining frequencies will be made with sine wave tube oscillators).
    I'm using the standard set of hammond voices ofcourse:
    Root
    Fifth
    Root
    Root
    Fifth
    Root
    Third
    Fifth
    Root
    and........

    Now the 10th one... What do you guys think I should add?
    I was thinking of maybe adding a seventh between the last fifth and root, trying to complete the harmonic series. Or what about adding an extra lower root or fifth?
    Any suggestions would be helpful!

    Yours faithfully,
    MvD



  • #2
    MIDI encoder?
    Tom in Tulsa

    Fooling with: 1969 E100, 1955 M3, 1963 M100, Leslie 720

    Comment


    • #3
      Wow really? I wouldn't have thought there'd be room for 10 key contacts on the lower manual of an L100 since there are only 7 drawbars without modification. I'd definitely be interested in some pictures! Anyway, in the case of you adding a tenth drawbar, there was a specific reason they left out the seventh harmonic, because the actual wave frequency of a 7th harmonic is 30% different from it's place on the 12 tone scale which they thought was too much of a difference and would make it sound off. However, it might be cool, I just wouldn't recommend it. Laurens Hammond did a lot of studying of pipe organs and sound for building the Hammond, and decided to leave it out and instead add subharmonics, which is why you see the first two drawbars being the octave under and fifth above the fundamental. I don't think you're going to get very much out of adding a tenth drawbar. Now if you mean adding in the seventh of that note, as opposed to a seventh harmonic, I would not recommend that either and I don't think you'll like the outcome as it will be dissonant, but hey I have never seen that so maybe it will be cool. You also start to get really far away from the fundamental as you add these voices, which is why I don't think you'll get much out of it, and most of the keyboard will be folded back, and folded back again on other drawbars, which I imagine you've already done a lot, so you'll just be increasing the volume of some other harmonic. If anything, I'd probably just add a root.

      I learned this from this site in which it talks about how the organ works and many other cool factoids! Maybe you can find this useful as to what you may want to do, what I was talking about is talked about on pages 5 and 6, I hope that whatever you do works out alright!

      http://www.nshos.com/HAMMOND7.htm
      1949 Hammond CV w/1960 Leslie 45 (converted to 145), using H-1 and Leslie 25 amp
      1958 & 63 Hammond M3
      1963 Hammond L100 with 70s Leslie 120
      1979 Rhodes Piano

      Comment


      • MVD
        MVD commented
        Editing a comment
        Hey! thank you very much for the article, its actually a very interesting source
        At the end of page 6, the writer appears to state that some models appear to use 7th harmonic?
        I'm very curious to listen to how it sounds now... I wasn't really able to find a demo with such a drawbar... For that reason I decided to just add that 7th harmonic and try! Worst case senario, I'll just end up with 9 useful drawbars like the average hammond organ :-)

        I'm trying to add some pictures of the project and the keyboard but I appear to get an error message...

    • #4
      If you have the upper manual rear panel opened and are thinking of adding in the extra contacts, why do you not just do the standard addition of foldback and upper octave tapering? That seems an obvious place to start. Adding MIDI could be useful but I have never tried that yet. Attached are a couple of pics that show L100 modified for foldback and tapering
      You may only view thumbnails in this gallery. This gallery has 2 photos.
      1966 C-3 / 925
      1965 M102 / 145
      1967 M111A / 330

      Comment


      • MVD
        MVD commented
        Editing a comment
        Hey! Thats one neatly modded keyboard!
        I've been thinking about midi too, but I don't think its that desirable in a spinet model organ... If I gig or stay at home, I'll probably take a nice fullsized keyboard with me as an extra :P
        As for the foldback, I've built some tube oscillators to add the higher frequency sinewaves to the mix! I might not have all the tonewheels, but I did have some ecc83 tubes laying around from an old project. No foldback needed!

    • #5
      Originally posted by MVD View Post
      Now the 10th one... What do you guys think I should add?
      I was thinking of maybe adding a seventh between the last fifth and root, trying to complete the harmonic series. Or what about adding an extra lower root or fifth?
      Any suggestions would be helpful!
      If you add a lower root and fifth, you could "sort of" play left hand bass. That's how I rewired two drawbars on my M100. Along with the pedals, I find that this works well for a typical organ-guitar-drums gig, where the lower manual and pedals take care of the bass role.
      Otherwise, yes the seventh would be the next logical step. The Hammond X77 has both a seventh and a ninth in its extra drawbars, but I can't say I use them all that much...

      A100, X77, M3, M100, E100
      Leslie 147, 145, homemade road Leslie
      My youtube channel

      Comment


      • MVD
        MVD commented
        Editing a comment
        The lower root and fifth are already added! That was the main idea of the project. I just happened to notice there was some space for 10 keycontacts per key instead of nine... Its funny to do some experimentation with an extra set of contacts, hence I was asking for some suggestions whatever to do with the 10th set of contacts :)

    • #6
      try going up and add the 1 1/7' Drawbar
      Last edited by Ben Madison; 04-22-2019, 05:08 AM.
      Instruments:
      22/8 Button accordion.

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      • #7
        Originally posted by Ben Madison View Post
        try going up and add the 1 1/7' Drawbar
        That sounds painful to have to listen to.

        Comment


      • #8
        Ooh, ooh! Retrofit a 70's rhythm unit. Usually the lower manual would have optional snare and hihat while the pedals got kick drum.
        No, perhaps not. I loved the seventies, but some things were evolutionary dead ends.

        BUT Wait!! sure there's the midi idea, but why not install an actual analogue synth kit??? I bet they were never pressure sensitive, being on/off switches like the organ.

        My own chop is currently operating as a clothes rack, proof that getting TOO tricky with things can be a handicap and cause delays spanning YEARS.
        However, getting into the manuals becomes second nature once you've done it a few times, so those spaces will still be easy to get at when you DO have a dead-cert idea.
        -1958 Hofner 550 archtop guitar -1959 C3 and PR40- -1964 Busillachio Harmonium- -1964 M101-
        -1967ish Leslie 122- -1975 T500 (modded..chopped, and reassembled!)-
        -DIY 760 FrankenLeslie/rat hideout-
        -1980 Electrokey Electric Piano- -Yamaha electric Harmonium (early 80's?)-
        -1990 Jansen GMF150 amp- -1992 Korg 01W/fd- -1992 G&L S-500 geetar.

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