Single tweeter

Discussion in 'Home Theater and Stereo' started by CJ, Apr 12, 2019 at 2:28 PM.

  1. CJ

    CJ Bronze Member Admin Top Poster

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    Why do speakers with many drivers almost always still only have one tweeter? E.g. a tower speaker may have a tweeter, a midrange, and three woofers but aside from some rare designs that are actually notable BECAUSE they have multiple tweeters, you never really see like TTMMWW. Is it just that the excursion demands for a 1" driver to produce such high frequencies really aren't that demanding?
     
  2. DYohn

    DYohn Bronze Member Donor Top Poster

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    Yes, high frequencies require far less power to generate high dbSPL, plus lobbing effects from multiple drivers can be incredibly difficult to handle above about 500Hz. By employing multiple small woofers, the designer can use smaller driers for the same net output as a single large one, resulting in a slimmer tower design. Most systems that use, say, three 7" woofers could achieve the same effect with a single 15, but then the enclosure would have to be 18" or wider.

    If you look at something like a McIntosh system or a line array that uses multiple tweeters, the trick to making it work properly is creating a Bessel Array (different level signals to each tweeter) or using incredibly narrow dispersion pattern tweeters in order to minimize the interactions.
     
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  3. Carl V

    Carl V Bronze Member Donor Top Poster

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    Recently Bryston has begun using two or more. Sony uses three vertically. There’s an it’s Italian design. Back in the day WEGG had an unusually curved array. Tekton has a cluster array. The comb filtering issue, some believe is a measuring microphone problem. Whereas our ear/brain hears it differently and interprets it differently, another audio polemic. PS audio is developing vertical arrays along the lines of the older infinity & genesis. I’ve heard their AN1 prototype. Impressive.
     
  4. CJ

    CJ Bronze Member Admin Top Poster

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    Yeah notably M&K uses three tweeters in a few designs and Tekton uses many tweeters in almost all of their designs from 3 to 7 I believe.
     
  5. Dustin B

    Dustin B Well-Known Member

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    David knows more than I do on this. The only thing I'd add is output capability being an issue depends on crossover frequency. As the crossover frequency gets lower the more trouble the tweeter will have keeping up. So the trade off between lobbing/combing being an issue and output being an issue is part of the balancing act of what to choose as a crossover frequency.
     
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  6. DYohn

    DYohn Bronze Member Donor Top Poster

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    In my opinion the only reason to use a tweeter array in a home stereo speaker is to try and overcome dispersion issues with the driver you are forced to used. Meaning if the driver being used (due to cost or required manufacturer or simple availability) has s directivity issue, you can compensate for this in many cases by using multiple drivers and a properly attenuated crossover. Otherwise there is really no reason to use more than one. (similarly, the only reason to use multiple woofers is if system design trade-offs make it necessary.)
     
  7. CJ

    CJ Bronze Member Admin Top Poster

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    So in this case would a coaxial 15" driver (e.g.) be closer to ideal than a TMWW all else being equal?
     
  8. DYohn

    DYohn Bronze Member Donor Top Poster

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    In theory, yes. A point source is the theoretical ideal, and a coax approaches that much better than a traditional alignment. In practice the differences are small - unless you are listening near-field in which case many people can hear the difference. This is also why audiophile purists claim they like single-driver systems more. If it's one speaker it must be a point source, yes? Of course the tradeoffs of single driver systems are such that they generally only sound good for girl-with-guitar music.
     
  9. DYohn

    DYohn Bronze Member Donor Top Poster

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    A better way to overcome high frequency dispersion issues, by the way, is a technique called "constant directivity." Several manufacturers have approached this, although in practice it is impossible to truly attain.
     
  10. CJ

    CJ Bronze Member Admin Top Poster

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    Yeah, OK so I guess if you could defy physics a full range point source that is incredibly small like a 1" 20-20kHz driver would be perfect. Obviously not attainable.
     
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  11. Carl V

    Carl V Bronze Member Donor Top Poster

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    Theory and practice are never quite the same. Yogi Berra said “In theory, there is no difference between practice and theory. In practice, there is.”

    Then there is the issue of musical instruments don’t act like point sources. Nor do human singers.

    To paraphrase a poem—- we have miles and miles to go before we sleep””

    Enjoy the journey. Smell some roses along the way. We may never reach our perfect destination... but like dr Seuss “oh, what places we’ll go. “
     
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  12. Dustin B

    Dustin B Well-Known Member

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    David do you know if Brian Cheney's VMPS constant directivity claims with the slit and ribbon line array were legit?
     
  13. pillatier

    pillatier Well-Known Member

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    That's deep thought. Emerson and Seuss together!!!!
     
  14. Carl V

    Carl V Bronze Member Donor Top Poster

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    Ah, a controversial design and person. Not everyone agreed or experienced that effect.
     
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  15. DYohn

    DYohn Bronze Member Donor Top Poster

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    VMPS designs were about as close as you can get. He like all evangelists may have exaggerated the effect, but his design worked pretty well as I recall. I only heard it one time though at an audio show, so hard to say in the real world...
     
  16. Mike B

    Mike B Well-Known Member Donor Top Poster

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  17. Carl V

    Carl V Bronze Member Donor Top Poster

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    CBT. Rick Craig of Selah Audio has done some those game changers designs. Pretty good. But still the quality of the individual drivers is of paramount importance.
     
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  18. DYohn

    DYohn Bronze Member Donor Top Poster

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    Line arrays are a different animal, and an acquired taste...
     
  19. DYohn

    DYohn Bronze Member Donor Top Poster

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    FYI since it's been a while and sometimes my memory for acoustic theory that is not complete, I looked it up and a Bessel array (5, 7 or 9 tweeters spaced horizontally) is NOT actually intended to increase horizontal dispersion as much as it is intended to increase power handling and efficiency while simulating a point-source. It was necessary in pro-audio 40 years ago when high-frequency high-power handling was hard to achieve. In today's world there are plenty of high-efficiency high-power tweeters available so there is no real reason to do it other than it looks cool. :sunglasses: So in the interest of being thorough, I thought I'd correct myself.
     
  20. CJ

    CJ Bronze Member Admin Top Poster

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    Interesting as both M&K and Ken Kreisel's spinoff after the bankruptcy and fallout still use tweeter arrays in all of their large speakers. In fact Ken rolled out some new speakers that aren't available yet that put the old M&K 300 and 150 series to shame.

    kk-7000-series.jpg
    kk-3.jpg

    And the new M&K now owned by a Danish company I believe, is making the the 150 and 300 again with new drivers but the same layout with 3 tweeters and 2 woofers.

    Other than horns like Power Sound Audio, Procella, JTR all use, where are you seeing high output single tweeter designs? Or are you talking pro audio.
     
    Last edited: Apr 18, 2019 at 1:00 PM

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