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6.3 ohm drivers in an mtm?

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  • 6.3 ohm drivers in an mtm?

    This has probably been asked before but I couldn't really find the clear answer. I have 5 tang band w-4 1320sif that I really want to use for something. I've seen the bandit build for them and that's about it. I have them stuffed in some unfinished boxes and really have just confirmed that I really don't use surround sound much if ever.

    I'd like to put them in an mtm with a Dayton ND16FA and a simple cap. Can a power amp that's 4 ohm stable handle the resulting load? Any advice

  • #2
    Likely not a problem at all. On a side note, if you ever decide to sell off any of them please let me make you an offer.
    Craig

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    • #3
      Pm sent

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      • #4
        Those are 8 ohm drivers, the DCR is 6.8 ohms.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

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        • #5
          Originally posted by billfitzmaurice View Post
          Those are 8 ohm drivers, the DCR is 6.8 ohms.
          Drc is 6.3 the newer neo versions are 6.8. I was under the impression 8 was nominal or like an average and drc was more of an indication of how the speaker will be seen. If I am wrong I wouldn't be surprised though since every time I think I have a grasp on things something new gets thrown in.

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          • #6
            Z is a nominal figure, based on DCR. On average DCR is about 0.7 to 0.8 times Z, although there's no precise definition. Amps are rated for minimum Z, but amp designers know that what really counts is DCR, so if an amp is rated for 4 ohms Z, for instance, it's probably intended to handle DCR of 2.8 ohms.
            www.billfitzmaurice.com
            www.billfitzmaurice.info/forum

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            • #7
              Excellent. Thank you for the explanation

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              • #8
                Take a look at that W4's spec. sheet. Resistance doesn't vary w/freq. Impedance does.
                The blue curve shows you that the -1320's impedance is only 8n(ohms) around 350Hz (and also beLOW 20Hz - which isn't on the plot). It probably drops to the DCR value (6.3 or 6.8n, or whatever) down close to a freq. of ZERO Hz.
                It's also around 10n near 25Hz, 200Hz, and again around 1000Hz. It runs above FORTY ohms near it's Fs (free-air resonant freq.) at just over 70Hz.
                Putting the (any) driver in a box will alter that blue impedance plot. In a closed box, the freq. of the "hump" will go up, although the value (impedance) of the hump will drop.
                Putting it in a vented box will give a plot that looks like you pushed down on the top of the hump w/your finger, pushing it all the way down to (maybe) 12ohms near 70Hz (if that's where you tuned the box to). A ported box results in a "valley" between a pair of humps (which might peak around 16n, or so).

                WinISD ( linearteam.org ) will model these (in-box) impedance changes so you can look at them.

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                • #9
                  I've modeled them ported. I'll take a look

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