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Mordaunt-Short MS3.2 tweeter replacement...

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  • Mordaunt-Short MS3.2 tweeter replacement...

    One of the tweeters for my 27 year old MS3.2s seems to have lost a bit of its output capability. The tweeters are Audax TW6 drivers with removable custom flanges. PE does have a replacement that should work (once the flange is changed) - https://www.parts-express.com/advent...-iii--299-2002. However, as I'm planning to redo the x-over anyway, should I go with a more modern tweeter?

    ​I found two on the PE website that have dimensions that suggest that they might fit without extensive modification to the speaker box:

    Dayton Audio ND20FA-6 - https://www.parts-express.com/dayton...eeter--275-030

    Peerless by Tymphany NE19VTS-04 - https://www.parts-express.com/peerle...eter--264-1006

    ​I'm basically limited to choices that have a flange that's 60mm or less in size, and the mounting diameter has to be 46mm or less.

    ​Should I go for the upgrade, and if I do, which tweeter do you suggest I use?

    The second picture shows the response of one of the speakers with and without the tweeter.
    Brian Steele
    www.diysubwoofers.org

  • #2
    How audible is that drop? Does it jump-out at you?

    I'd use a different tweeter just because the stock tweeter looks rather uninspiring.

    I know, hardly scientific.

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    • #3
      Originally posted by philthien View Post
      How audible is that drop? Does it jump-out at you?

      I'd use a different tweeter just because the stock tweeter looks rather uninspiring.

      I know, hardly scientific.
      ​I sometimes noticed a difference, but now I've measured the difference, I notice it all the time, LOL.

      LOL - "uninspiring" is quite a fitting term. The original tweeter is also surrounded by an additional rubber flange, and the 27 years have not been kind to it. I'm really stuck on if I should just take the lazy route and replace the original tweeters with what essentially are likely to be plug-in replacements, or go with a solution that's going to involve a bit more customization, knowing my carpentry skills (or lack thereof).

      ​Another possible solution presented itself - the SEAS 27TFFNC/G, available off the other DIY site. These are actually pretty good and I use two in my car, but at $40 a pop seem a bit expensive for this particular project.
      Brian Steele
      www.diysubwoofers.org

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      • #4
        Just a quick update - I purchased the Advent replacement tweeters, and as I suspected, the drivers were removable from the flange, and they matched what I had in the Mordaunt-Shorts. Measured frequency response was pretty close too (to the original working tweeter). I redesigned the x-over a bit to flatten the response (basically take down the output a bit around 3~4kHz and fill in a dip between 5~8kHz. The original x-over was a simple first order electrical with some padding on the tweeter. The replacement is second order electrical on both drivers, at basically the same x-over point. Not only does it smooth the total response a bit, now there's a bit of extra protection for the tweeter at low frequencies.

        ​It's not a total success though. One of the tweeters is showing a spike in distortion at 3kHz (and again at 6kHz). Grr. I'm going to take a good listen to see if I can hear any audible impact of that spike, but I may end up having to order another pair of these replacement tweeters.

        Brian Steele
        www.diysubwoofers.org

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        • #5
          Here's the THD of the problematic tweeter. I've seen this type of distortion profile below - looks like it may be an issue with the dome.
          Brian Steele
          www.diysubwoofers.org

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          • #6
            Another that might work for you is the Wavecor TW022.

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