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KRaper/Choke cymbal woes

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  • KRaper/Choke cymbal woes

    I've been lurking these boards for a while now, as I cobble together my a to e conversion from everyone else's awesome ideas. Aside from the setbacks with my rack and clamps, I'm at my wits end with making my Crash choke-able. First, a run down of my parts.

    (1) Pintech plastic crash/frisbee
    (1) KRaper circuit (found here: http://www.vdrums.com/forum/showthread.php?t=33816)
    (2) Piezos, 27 or 35 not sure which
    (1) Alesis Trigger I/O, configred (I think) for PS on channel 8 (Crash)
    (0) Using Mainstage to process midi signals

    I believe I have wired the circuit all correctly, though I am unsure how to test it. What I get in testing it through Mainstage is a normal Crash sound when tapping the bow piezo, and a softer crash sound tapping the edge piezo. It does not choke the sound if I hit only the edge piezo during the bow piezo noise.

    What I'm looking for is either: a way to test for what the problem is in the wiring or alesis setup (ex. wiring improperly like so will give you the following sounds etc), OR an explanation how to setup mainstage to interpret the already correct midi signal for choking. I'm pretty stumped at this point, and in need of sagely advice from the vdrum wizards.
    Last edited by boobavon; 10-07-08, 09:53 AM.

  • #2

    Welcome to the boards and the exciting (and frustrating) world of DIY edrums. I'll take a stab at your question but I believe you will hear similar responses as mine.

    The main problem you are having is that you are confusing the purpose of the Keith Raper circuit which is to fool your module into thinking that the second piezo is a switch. When connected up correctly and "tuned" properly and the second piezo is struck in conjunction with the first piezo, the output of the circuit mimics that of a switch closing momentarily hence you get an edge sound. In order to get a cymbal to choke, the module expects the switch to be closed for a longer period of time which is impossible to do with a piezo. Choking needs to be achieved via some other means like using an actual switch.

    There are several posts in the DIY section that show various edge switch designs. Look for ones by Hellfire, Gastric, and Sarge201. I think all of them have made edge switches for choking. There have even been some tries at making an edge switch that acts as a choke and a trigger for the edge sound thus eliminating the problematic KR circuit altogether.

    Hope this helps and I also hope that I am not too far off-base with my simplistic explanation above. If so, I am sure someone else will chime in with corrections.