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  • blown caps

    I was playing my Korg MS-20 the other day when smoke started pouring out of my vents on the DIY speakers. Whan I removed the back, it appears the the capacitors on the tweek part of the crossovers totally fried. It seems that the tweets themselves are ok. I doug thrrough all the old posts and found all the data for the crossovers, I just can't find the schemetics. Can Anyone help? Below is the data for the crossovers.

    Well, I WOULD run as an MTM, in 1.6cf, but I'd go vented with a 3" long port w/a 2.5" id. They should reach down below 40Hz vented, and will be able to handle more power before excursion issues. Your woofers will be wired in series (for an 8 ohm bass section).

    This should get you pretty close. I'm not sure on BSC, as I think PE has hosed up the sensitivity ratings. They state 96.5 dB at 1w, but on Vifa's spec sheet it's rated 96.5 dB at 2.83v (which is TWO watts for a 4 ohm driver). A couple years back, PE (and/or Dayton) screwed up by changing all their sensitivity specs FROM 2.83v (which is what we need) to 1w. It SEEMS like they're trying to switch back now, but it'll take a while until I can once again trust their specs. THEY ARE WRONG for this Vifa tweeter.

    2nd order HP w/L-pad:
    12uF series cap, then a #20 0.40mH shunt coil (to ground), then the "L" w/a 2n (ohm) series resistor, and a 4n parallel. NORMAL polarity on this tweeter.

    2nd order LP w/Zobel:
    a 1.5mH coil (lower DCR is better, probably an iron core here) WITH a tiny 0.68uF cap in parallel with it to act as a notch filter, then a 5uF shunt cap (to gnd), and lastly a Zobel using a 10n resistor and a 10uF cap.

    This crosses near 1.9kHz, and runs about 88dB. Off you go.​

  • #2
    That XO description is almost certainly MINE !
    How about a pic of your caps?
    You DID use regular XO caps (that could handle the voltage), right?

    Also (just for a "refresh" - so people don't have to go hunting) what tweeter is this, and what woofer(s) (and is it a single, or an MTM?) ?


    • #3
      Isn´t this a bit strange?

      XO-caps usually never fails.

      Perry Mason talking to his dentist:

      "Do you swear to take the tooth, the whole tooth and nothing but the tooth, so help you God?"


      • DeZZar
        DeZZar commented
        Editing a comment
        Definitely strange. Perhaps not using crossover caps??

    • #4
      Originally posted by lasse View Post
      Isn´t this a bit strange?

      XO-caps usually never fails.

      I agree. Most diy use npe caps are at least 50v, and I never even see the 25v common in cheap commercial speakers fail.
      Last edited by dynamo; 12-30-2022, 02:44 PM.