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Jamo MT

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  • Jamo MT

    Back in November, I bought a bunch of Jamo close-out drivers, 6 of 20306
    5 1/4 mid/woofers and 4 20452 1" dome tweeters for about $6.00 per driver.
    To make a long story short, I ran into many problems tops among them was there was no published specs for either driver. I thought I could do some measurements of the drivers but measurement is another can of worms. I was stuck. I had a nice cabinet but a few trys with crossover design led nowhere. I shelved the preakers for a number of months but kept reading and thinking I'd give it another go.

    A couple weeks ago, Zilch referenced a crossover design site that he thought would help rookies,"". This has been a breakthrough for me. I followed Elliott's method of crossover design, and the first crossover I designed using his method was shocking. Far and away better than anything I had come up with, not perfect but on the right track. I made 4 more changes and I gotta say holy crap, I have a speaker! The sound is incredible for a little .28ft^3 enclosure ported with 4-7/8" long 2" port. Wide deep soundstage, amazing bass for such a dinky system, nice smooth mids (piano is real with nice overtones), a non fatiguing high end. I can't get over them.

    LP: 2nd order, using Gonzale's number of .35 for baffle step. L1 = .5mh, c1=2.4uf, zobel r=6ohm, c= 48uf.

    HP: 2nd order with impedence compensation and L-pad. c2=3.5uf, L2=.35uf.
    CLR filter: c=22uf, L=.35mh, R=7ohm. L-pad Rs=3ohm, Lp=4ohm.

    The next project is to use the drivers in an MTM cofiguration.
    Attached Files

  • #2
    Re: Jamo MT

    thats pretty cool. goodferya.
    " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

    Quote Originally Posted by hongrn. Oct 2014
    Do you realize that being an American is like winning the biggest jackpot ever??


    • #3
      Re: Jamo MT

      Just goes to show there is more than one way to relieve a feline of his skin
      Don't listen to me - I have not sold any $150,000 speakers.


      • #4
        Re: Jamo MT

        What I find interesting about ESP's method is the importance of controlling the driver's impedence, and the order in which the crossover is developed. Another interesting idea is he dosen't rely on TS parameters, he measures voltages and DC resistance of the driver, constructs impedence compensation filters, remeasures voltages to construct the x-over and L-Pad. He also has a nice calculator that's easy to use.

        I was able to use my WT-3 to tweek the Zobel and get the actual Z @ Fc for X-over development without voltage measurement. Much easier to me than wading through all of the measurement and simulation software, SPL Trace, etc. Now this only works for two way systems but this method is easy. I can see using this method with drivers with published specs, constructing the x-over and loading the values into PCD for further refinement.

        This has definately produces success on my part and brought my level of understanding up 2 notches, and I can explore more complex structures. Now I want to bring my little Jamos to a DIY event and hopefully not be blown out of the water!


        • #5
          Re: Jamo MT

          I'd like to read that...have you got a link?
          "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy." --Winston Churchill


          • #6
            Re: Jamo MT

            Hey Rob Google "Elliott Sound Products" and then scroll through the articles, of which there are a bunch, to "Crossovers, Filters and Signal Processing" and go to "Passive Crossovers".