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Eminence Co-ax Anyone?

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  • Eminence Co-ax Anyone?

    Anyone using these with low powered tube? APT50 or PSD2002 horn driver? After looking at the suggested boxes, the 10" seems to have the best bass extension and smoothest response. 3.5K seems a bit high, what is the horn's low frequency cut off? Or would a Beta 10 and a separate horn crossed over at 1.8K work better? Any thoughts appreciated.

  • #2
    Re: Eminence Co-ax Anyone?

    I'm surprised that no one has looked into the Eminence Acoustinator 8 yet. It's an 8", but it has decent sensitivity (91dB), reasonable bass extension and a low Fs (57 Hz), and a poly cone with a rubber surround. The response curve looks well-tamed to begin with, at +2.5/-1dB, and the poly cone won't have the 'cone cry' (aggressiveness) in its top end that an untreated paper cone will. On top of that, it will take exactly the same compression drivers that the Beta coaxes will. Qts is low-to-mid, at 0.39, which will enable tuning a little below Fs (by 5-10 Hz). For a more compact coaxial system, it's probably a better choice than a Beta 8. Looking at the FR plots side-by-side, it's much smoother than either the 8" or the 10", and *might* even be able to handle a first-order LP filter because of the well-controlled rolloff. The lone peak at 1k isn't nearly as narrow or tall as either the Beta 8 or Beta 10, which suggests much nicer behavior in the time domain (resolution!) than either of the two Betas, and the Acoustinator begins very naturally rolling off around 2200 Hz.

    http://www.parts-express.com/pdf/290-890s.pdf

    This is one to watch, and I suspect the reason it hasn't gotten enough attention before now is that it's buried in the 8" Musical Instrument Speakers page (intended for acoustic guitar amplification). Were I to do a coax, I'd make this my driver of choice.

    Ditch the Eminence APT50 and go with a better 1" driver like the BMS 4550ND if you can afford it ($129 a pop), which will take a 1900 Hz crossover point and provide extension to 30 kHz(!), which ought to complement the Acoustinator's performance nicely. (Extension beyond the audible range means less distortion in the audible range.) The annular (ring-radiator) Mylar diaphragm of the BMS driver also greatly reduces ringing concerns.
    Best Regards,

    Rory Buszka

    Taterworks Audio

    "The work of the individual still remains the spark which moves mankind ahead, even more than teamwork." - Igor I. Sikorsky

    If it works, but you don't know why it works, then you haven't done any engineering.

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    • #3
      Re: Eminence Co-ax Anyone?

      http://www.diyaudio.com/forums/multi...r-cabinet.html

      BMS 4550 (not ND) is bolt-on, as is 4552ND, and would require a throat adapter. 4540ND would be a better choice, but we tested that, as well. Beta 10 CX has "issues," which a read of the thread reveals.

      O.K. for P.A. only....

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      • #4
        Re: Eminence Co-ax Anyone?

        Originally posted by Taterworks View Post
        I'm surprised that no one has looked into the Eminence Acoustinator 8 yet. It's an 8", but it has decent sensitivity (91dB), reasonable bass extension and a low Fs (57 Hz), and a poly cone with a rubber surround. The response curve looks well-tamed to begin with, at +2.5/-1dB, and the poly cone won't have the 'cone cry' (aggressiveness) in its top end that an untreated paper cone will. On top of that, it will take exactly the same compression drivers that the Beta coaxes will. Qts is low-to-mid, at 0.39, which will enable tuning a little below Fs (by 5-10 Hz). For a more compact coaxial system, it's probably a better choice than a Beta 8. Looking at the FR plots side-by-side, it's much smoother than either the 8" or the 10", and *might* even be able to handle a first-order LP filter because of the well-controlled rolloff. The lone peak at 1k isn't nearly as narrow or tall as either the Beta 8 or Beta 10, which suggests much nicer behavior in the time domain (resolution!) than either of the two Betas, and the Acoustinator begins very naturally rolling off around 2200 Hz.

        http://www.parts-express.com/pdf/290-890s.pdf

        This is one to watch, and I suspect the reason it hasn't gotten enough attention before now is that it's buried in the 8" Musical Instrument Speakers page (intended for acoustic guitar amplification). Were I to do a coax, I'd make this my driver of choice.

        Ditch the Eminence APT50 and go with a better 1" driver like the BMS 4550ND if you can afford it ($129 a pop), which will take a 1900 Hz crossover point and provide extension to 30 kHz(!), which ought to complement the Acoustinator's performance nicely. (Extension beyond the audible range means less distortion in the audible range.) The annular (ring-radiator) Mylar diaphragm of the BMS driver also greatly reduces ringing concerns.
        I've pondered the 8" many a time... Wanna do a duo-design? ;)

        NK
        I'm just that guy. www.sru.edu Rock Solid.

        "It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion."

        L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

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        • #5
          Re: Eminence Co-ax Anyone?

          I couldn't find anything in that link about the Beta 10CX. Could you elaborate on the issues? As to the Acoustinator, not enough db's for a watt and a half.

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          • #6
            Re: Eminence Co-ax Anyone?

            It's all in that thread, measurements with 5 different compression drivers, D'Appolito's review, a German publication review, what we did with it to make it half-*** work, how it performed at Burning Man and Burning Amp, appearance on Linkwitz's site....

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