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A105 Percussion Discussion

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  • A105 Percussion Discussion

    Hi guys,
    I heave a Hammond A105 and as you have probably seen by some of my other posts, I'm inspired to finally get some issues sorted out with her.
    Got the Leslie 251 hooked up and it appears to be working great. (with the exception of pops when changing speeds)

    The percussion only seems to work on the upper manual when the last black preset is selected. AND it sounds really thin, tonally. When the any of the other left side presets are selected the Percussion switch has no effect.

    I don't know what is supposed to happen when selecting percussion. Does it only work for the top keyboard? or is it supposed to effect both?

    Were should I start to pinpoint this problem? I have read some stories about using 3 9v batteries to fry off metal particles etc. Not sure I understand the idea.

    I did check the AX7 tube on the upper preamp and swapped that out with a few other tubes. No change. I also checked the long-standing percussion note with all of the drawbars "in" and adjusting the perc pot on the preamp. Seems normal.
    There also appears to be voltage of 24v+ on that (was it green?) wire... on the pre amp...?

    Anyways, just looking to see if anyone else has had this weird waning percussion issue.

    Thanks for any help and guidance..
    Getting closer to perfection!

  • #2
    Hi Sparky -
    It's hard to determine if you really have a problem.
    Much of what you describe is normal.
    Please watch this video and then come back with an additional post.
    https://www.youtube.com/watch?v=C0-MyNdunGQ
    Thanks.
    Roger Memphis
    C-3 with O-M, 145, 122RV, 2 PR-40's, PSR-36
    CV with HR-40, 2 B-40's

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    • #3
      The video passes over certain points rather quickly.

      With the organ configured as shipped, the percussion feature only works when the upper manual B preset is depressed. To isolate what the percussion does, push all the drawbars in for the second group, depress the B preset, and turn the firs percussion switch on, or tilted forward. You should hear a distinct plink that fades away. If you hold that key down and try to play other keys, there will be no sound.
      You must play detached, or releasing each key as you play. You can mix the plink sound with the left most brown drawbar se at 8,and if you play in 5ths, it will sound like a marimba.

      Moving to the fast decay tab, the plink will go away faster.

      The third harmonic yields a higher pitched plink, which when mixed with the first 3 drawbars pulled to 8, yields the wildly popular jazz setting.

      The volume soft tab makes the plinks softer.

      There is a procedure for adjusting the percussion but I have forgotten the precise details.
      Larry K

      Hammond BV+22H+DR-20, Celviano for piano practice
      Retired: Hammond L-102, M-3, S-6, H-112, B-2+21H+PR-40, B-3+21H, Hammond Aurora Custom, Colonnade.

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      • #4
        It is normal that when the percussion is turned on, the overall volume of the manual drops. IMHO this sucks. Fortunately this drop can be easily eliminated by removing the can from the matching transformer, bridging (with a piece of wire) the bottom left resistor, and putting the can back on.

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        • #5
          Originally posted by Tim_at_Jonas View Post
          It is normal that when the percussion is turned on, the overall volume of the manual drops. IMHO this sucks. Fortunately this drop can be easily eliminated by removing the can from the matching transformer, bridging (with a piece of wire) the bottom left resistor, and putting the can back on.
          Actually, the drawbar volume only drops when the percussion is set to normal volume, but not soft. As for modifying, I deal with a lot of players in the gospel scene. I find most organs with the percussion set so that it does reduce the DB volume, in other words, set to normal volume. Seems they found a way to use it as it is, so I don't change it.

          Geo

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