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Thread: Hammond B3 Help: Low Frequency Hum: Newbie

  1. #1


    Hammond B3 Help: Low Frequency Hum: Newbie

    Hi everyone, first post here.

    I recently acquired a hammond B3 and a 21H. I'm getting a very low frequency hum when I play it (only when a key is a pressed) when no keys are pressed the organ is silent. It doesn't matter what register the note is in, whether its high or low, i still get the low frequency hum; it comes out of the bottom speaker of the leslie. At first I thought it was a leslie issue; I replaced tubes and the crossover thinking it was that; but still had same problem. Then spoke to a repair guy and he said it would be a b3 issue not a leslie issue ( he has me try the G/G ground trick on the preamp and that changed nothing)

    Any ideas what it could be? Thanks so much

  2. #2
    Senior Member geoelectro's Avatar
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    Hum while playing keys is to some degree normal. However, I have seen it very bad. The thing is, I'm not sure what the cure is. Of course always tighten the grounds around the preset panel etc.

    I have two installations where we have Hammond's that were perfect in our shop, but have this "hum while playing" problem after they were delivered. In one case we determined it was the location in the building. After years of putting up with the hum, a flood from Hurricane Ike wiped out the organ. (A-100/147a) We replaced the organ and guess what, the hum was now in the replacement! After a few minutes it was explained that they now wanted to organ on the opposite side of the pulpit. Hum went away! So, something related to that location was inducing hum into the organ.

    We just replaced a C-3/122 in one of the last church's hit by Ike and they used to have this hum problem as well. The replacement had it to a lesser degree as the pulpit area was completely remodeled placing the organ slightly more toward the congregation. Still, it was there and not present in our shop.

    One last story is a church that moved their Hammond C-3/122 into the fellowship hall while the sanctuary was being remodeled. There was an awful buzz which got louder when played. I couldn't find anything wrong but suddenly noticed the recessed lighting looked like those curly florescent light bulbs. I asked if they could turn the lights off and all the noise went away.

    So, you may want to check to see if there could be something about the organ's location that allows it to pick up hum that is external.

    Geo

  3. #3
    Senior Member Clarion's Avatar
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    Quote Originally Posted by geoelectro View Post
    Hum while playing keys is to some degree normal. However, I have seen it very bad. The thing is, I'm not sure what the cure is. Of course always tighten the grounds around the preset panel etc.
    My brand new Hammond H100 was delivered way back in the early 70's with prominent Hummmmmm . . . Hammond in their last stages of gasping for air, declared that they designed it that way!!? Yeah right . . . . and wouldn't do squat in an effort to correct it!

    All it took to fix it was adding a couple of electrolytic capacitors to the power supply B+. I sent them a copy of the bill, and they sent a refund of $6.50 for the full cost of the capacitors.

    If an organ manufacturer ever deserved to die, it was Hammond! Eight years later, I gave the foul sounding instrument away for $0.00! And I still feel guilty to this day, that I overcharged the recipient.

  4. #4


    thanks for the replies. The hum has occurred in 3 different locations. at a church, at my home, and at my studio. I doubt this hum i'm getting is on purpose. It's like rediculuously loud, and unlike other hammonds i have owned. i appreciate the replies; keep em coming. I will try to post a recording of it on youtube.

  5. #5
    Newbie Ken Knapp's Avatar
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    Are you locating the Leslie on the left side of the organ and fairly close to it? If so, hum from the motors could be induced into the transformer for the manuals. Solution is to move the Leslie farther away or move it to the right side of the organ (looking from seated at the organ).
    Ken

    www.tonewheeltech.com
    A member of MITA International (Secretary)
    www.mitatechs.org

  6. #6


    Hi Ken,

    If you are sitting at the organ as if you were playing it, the leslie is on the right hans side, directly next to the organ. I will try moving the leslie farther away and see if that helps. Thank you

  7. #7
    Senior Member Hamman's Avatar
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    Kens right...I had my Leslie set up right next to the organ's left side and had a low hum when i depressed any key. Also would be there only when the Leslie was in the chorale mode. When in the fast mode....no hum! Moved the Leslie (122) away fro the organ and the hum disappeared. Also I once recently was getting a crackling sound through the Leslies and it frustrated me to no end since I had just rebuilt my AO-28 preamp extensively. It had ran great for a few months till...................I got a ne Droid phone and had sat it up on the music rack. Yes the phone was the culprit....who knew?? By the way I found the solution to that problem by picking up the phone to answer a call...........then I noticed no more crackling! The phone issue only happens on my organ with the 122's not the other with 251 ??! Both A105's
    Allen, Conn, Hammond, Rodgers

  8. #8
    Moderator Brendon Wright's Avatar
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    Also, couldn't there be some effect from the RC filters failing?
    Our 59 C3 didn't have RCs on the generator and it has this delicious low harmonic (hum about two octaves lower than the 16' note) under some of the high-mid notes when they're played. Made the organ quite fat.
    The T500 didn't have it because the RC's filtered all of these spurious harmonics out so I bypassed 'em.
    -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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