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Is a resistor necessary for piezo tweeter ?

Discussion in 'Amps and Cabs [BG]' started by Kevinlee, Oct 26, 2005.


  1. Kevinlee

    Kevinlee

    May 15, 2001
    Phx, AZ..USA
    I just put a Leson piezo tweeter in a 410 cab, wired in parallel. Should I have a resistor and cap in there as well or is it ok to just have it wired in without them?

    If so can someone draw a simple diagrarm of how the cap/resistor should be wired..

    Thanks
    Kevinlee
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Not all piezos are wired in the same fashion and you should obtain the manufacturer's recommendation. Most piezos do not use caps and resistors are optional, but I can't speak for LeSon.
     
  3. haujobb

    haujobb

    Dec 16, 2004
    Wallaceburg
    IFAIK almost no piezo's need a cap. Most companies will recommend a 10 ohm resistor though, the reason being that as the frequency rises, the impedance continues to drop on a piezo, and piezos have the ability to go up in the 100Khz range. So by wiring a 10 ohm resistor, you prevent the impedance from dropping too low and also help to match the efficiency of the tweeter to the woofer.

    Like bill said, check what the manufacturer recommends for that specific model.
     
  4. Kevinlee

    Kevinlee

    May 15, 2001
    Phx, AZ..USA
    How do I wire the resistor in? A simple diagram would be much help.

    Thanks
    Kevinlee
     
  5. Doug Parent

    Doug Parent Supporting Member

    May 31, 2004
    San Diego, Ca.
    Dealer Nordstrand Pickups.
    SWR uses a simple cross-over network with thier LeSon equipped cabinets but I have no idea how its put together. It includes a resistor for sure, the LeSon is an efficient little squaker. You'll want perhaps a volume control (L-Pad) to balance it with the woofer.
     
  6. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    You have to find out from LeSon. Piezos are not all the same. Most use resistors, some don't. Some use filter caps, most don't. What LeSon needs LeSon knows. I don't.
     
  7. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    The Leson is VERY different from most piezos.

    Every LeSon I am aware of uses a coil and capacitor crossover network. That's part of their patent.... and why they sound better and louder than most piezos.

    The coil is inside. You provide the capacitor, which sets the crossover frequency. I believe most use something between 2.2 and 4.7 microfarads, but you need to get the exact info for your type from your parts source (they had better know).

    It absolutely REQUIRES an external capacitor, which varies by type and crossover frequency. If you don't use the cap, the piezo will probably just melt, because you will heat up the coil severely.

    As far as resistor, you can use an attenuator, like an "L-pad", or resistor network, but a plain resistor won't work as well.....

    Make sure you use a "non-polarized" capacitor... meant for speaker crossovers.

    If you can't get info from your sources, PM me and tell me the type you have, I do have data on a lot of those speakers.