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Discussion in 'Amps and Cabs [BG]' started by rawlsjk, Jan 2, 2004.

  1. I believe I've blown my tweeter in my SWR bass cabinet. I took apart the cabinet and noticed that the tweeter didn't have a crossover circuit. I'm looking to install a new tweeter myself, but I'm wondering exactly what type of circuit must I build to obtain a normal operating tweeter? I am rewiring the cabinet to have a load of 4 ohms (if that has any effect on how the tweeter circuit should be built). Thanks a lot for any help that I receive.

  2. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    The only type of tweeter that wouldn't have a crossover network would be a Piezo type...is that what you have?

    I thought that piezos couldn't burn out because there is no voicecoil or moving parts... A piezo tweeter is capacitive in nature and will show infinite ohms on an ohmmeter. Are you sure that it's blown???

    You'd need to design a crossover around the ratings of the new tweeter...impedance, minimum usable frequency, mfr's recommendations for a crossover point, etc. The impedance of the woofer section doesn't have an effect on this.

    What type of tweeter are you using?

    I presume that the SWR cabinet in question is the 4x8 in. cabinet that you mentioned in your profile. What is the impedance of each woofer?
  3. BruceWane


    Oct 31, 2002
    Houston, TX
    The Workingman's series bass cabs do use a piezo tweeter, thus no crossover.

    If it's not a WM series, the "crossover" is probably just a single capacitor on the positive side, most likely right on the tweeter, between the terminal and the voice coil lead. This gives a 6db per octave rolloff of lows below a certain frequency, depending on the uF of the capacitor.

    The woofers are fed a full range signal. So technically, you don't have a "crossover", but actually just a high pass filter on the tweeter. Which is pretty typical in 10"+Tweeter cabs.
  4. You may have just blown a fuse. I did that on my Goliath Jr. and SOB with the tweeter attenuator control off. I now run the control at 7, aproximately 9 o'clock, with no problems.

    Remove the input panel and check the fuse. It's a 3 amp fast-blo.
  5. Finger Blister

    Finger Blister

    Jul 8, 2003
    If it's a Piezo...
    Just replace the tweeter.
    A piezo from SWR cost me $12 and 3 minutes
    of my time. Just make sure to match the 2 wires

    My Henry 8x8 doesn't have fuse protection either.

    With replacement piezo tweeters so inexpensive,
    why bother with a circuit that only adds
  6. Thanks everyone for all your help. The tweeter in question is a piezo tweeter (so, I guess that I don't need a crossover circuit). So, if I'm reading this right, all I have to do is purchase another piezo tweeter, and connect it properly? Now, connecting it properly, is that positive (signal) to positive (tweeter) or positive (signal) to negative (tweeter)? I really appreciated all the replies. I learned a lot from each post. Peace!

  7. Finger Blister

    Finger Blister

    Jul 8, 2003
    Ignore what you think is positive or negitive
    as far as wiring goes.

    Match the old one with the new.
    One wire at a time.
    Don't guess.
    There is a + & - stamped into the piezo.

    Use your Noggin.
  8. Petebass


    Dec 22, 2002
    QLD Australia
    I've used piezo's on some of my home-made cabs. While it may not need a crossover, I found i was able to get them to distort without one.

    Can I suggest you whack a capacitor on the positive terminal of the tweet to block the low frequencies from getting to it. Is shouldn't cost you more than a few bucks and could prevent this happening again. A capacitor with a value close to 10uF (that's 6dB/ octave at 4K). The frequency is high but the slope is shallow, so the tweet should still sizzle.