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Thread: Fast Bass, Slow Bass - Myth vs. Fact, Max dB with Doug Blackburn Back Issue Article

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    Fast Bass, Slow Bass - Myth vs. Fact, Max dB with Doug Blackburn Back Issue Article


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    I believe that has been posted before. This is the part that jumped out at me:

    "To avoid comb-filtering effects that cause "beating" (reinforcement) and "cancellation" effects in the sound (both are usually partial effects), it is imperative for the phase, time domain, amplitude and frequency performance of the woofer and midrange driver to be "aligned." Get the midrange or woofer a little ahead of or behind the other driver, and comb filtering starts. You can do things to minimize it, but you can’t stop it with certain combinations of driver and crossover. It is fearfully hard to integrate a dynamic woofer with an electrostatic panel because the two drivers are so different from one another. Your absolute best shot is using an active crossover with infinitely variable phase/frequency, polarity, time domain and amplitude adjustments. Play with it long enough and you could dial in the response of the dynamic woofer and electrostatic panel to achieve perfection in their integration. Achieving the same thing using a passive crossover is incredibly difficult. Some designers are getting better as they learn from years of trying, but it is still one of the hardest things to do in audio that I can imagine. Just getting a dynamic midrange and dynamic woofer to integrate perfectly is enough of a challenge. You can hear even small errors show up as speed problems in the bass or midbass. These are the kinds of "character" that will remain with the speaker no matter where it is used."

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    Quote Originally Posted by 4313B View Post
    I believe that has been posted before. This is the part that jumped out at me:

    "To avoid comb-filtering effects that cause "beating" (reinforcement) and "cancellation" effects in the sound (both are usually partial effects), it is imperative for the phase, time domain, amplitude and frequency performance of the woofer and midrange driver to be "aligned." Get the midrange or woofer a little ahead of or behind the other driver, and comb filtering starts. You can do things to minimize it, but you can’t stop it with certain combinations of driver and crossover. It is fearfully hard to integrate a dynamic woofer with an electrostatic panel because the two drivers are so different from one another. Your absolute best shot is using an active crossover with infinitely variable phase/frequency, polarity, time domain and amplitude adjustments. Play with it long enough and you could dial in the response of the dynamic woofer and electrostatic panel to achieve perfection in their integration. Achieving the same thing using a passive crossover is incredibly difficult. Some designers are getting better as they learn from years of trying, but it is still one of the hardest things to do in audio that I can imagine. Just getting a dynamic midrange and dynamic woofer to integrate perfectly is enough of a challenge. You can hear even small errors show up as speed problems in the bass or midbass. These are the kinds of "character" that will remain with the speaker no matter where it is used."
    I am pretty much in agreement there, absolutely tiny amounts of delay and phase differences can have large subjective results, let alone what the graph shows.

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    Senior Member frank23's Avatar
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    I once read, maybe it was at Linkwitzlabs, that the acoustical centres should be aligned at 1/16 of the wavelenght at crossover. I have achieved this from mid > high by doing an impulse measurement, it took 11cm of moving the 2344 forward relative to the 2123. From low to mid 1/16 would be give me a allowable difference of about 6cm with my system, this is enough not to have to bother moving the 2123 backward in comparison with the E145.

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    All Cones or All Horns

    My conclusion from this artical is use all cones or all horns

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    Quote Originally Posted by Fort Knox View Post
    My conclusion from this artical is use all cones or all horns
    I thought the conclusion was to buy an iPod with earbuds.

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    My conclusion from this artical is use all cones or all horns
    Nothing wrong with cone/horn combinations. Ever see the step response of a 4344?? Looks like crap however that doesn't stop the system from sounding good. The long midrange horn path of the 2307 really goofs things up. What you want are shallow horns where the physical offsets are more manageable or a step baffle or no baffle solution where you can line things up.

    Rob
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    Buds

    Quote Originally Posted by 4313B View Post
    I thought the conclusion was to buy an iPod with earbuds.
    I got 6 Buds in the ice box

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    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by Fort Knox View Post
    I got 6 Buds in the ice box
    Thanks but I prefer good beer ... Stout usually ...

    or did you mean smokeable buds?
    2ch: Oppo, JoLida 502CRC, JBL L212, 18ti,240ti; Heath AS101, Von Schweikert VR4
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    Administrator Robh3606's Avatar
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    did you mean smokeable buds?
    In the fridge??

    Rob
    "I could be arguing in my spare time"

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    Comb-filtering has nothing to do with beating which has nothing to do with ...

    To avoid comb-filtering effects that cause "beating" (reinforcement) and "cancellation" effects in the sound ...

    Comb-filtering happens when sound of different frequencies is delayed by a constant time, and thus by a frequency-dependent phase. The early reflections from the room's walls which add to the direct sound produce comb-filtering.

    For bass waves in a room the wavelengths are too large for the effect to happen.

    Beating happens when two waves of slightly different frequencies f1 and f2 are added. The beating frequency is | f1 - f2 |, so actually anything but beating in the usual sense.

    You can experience beating on many large ships such as ocean ferries, when each 10 seconds or so a rattling goes through the ship.

    Ruediger

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    Quote Originally Posted by Robh3606 View Post
    In the fridge??

    Rob
    Buds do keep fresh longer when chilled ...
    2ch: Oppo, JoLida 502CRC, JBL L212, 18ti,240ti; Heath AS101, Von Schweikert VR4
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    Comb-Filtering Freak

    [QUOTE=Ruediger;340235]To avoid comb-filtering effects that cause "beating" (reinforcement) and "cancellation" effects in the sound ...

    Comb-filtering happens when sound of different frequencies is delayed by a constant time, and thus by a frequency-dependent phase. The early reflections from the room's walls which add to the direct sound produce comb-filtering.

    I prefer a slightly live listening room...and I'll even throw in some surround-sound-reverb......
    So what does that make me..

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    Quote Originally Posted by hjames View Post
    Buds do keep fresh longer when chilled ...
    So this is where all the hippies went!

    It would be fun if you all posted pictures of yourselves from the late sixties :-)

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    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by more10 View Post
    So this is where all the hippies went!

    It would be fun if you all posted pictures of yourselves from the late sixties :-)
    he he - dose daze are gone - but the memory survives!
    And the way laws have been changing in the US of A,
    it jest might be legal by the time I retire ...
    Heck, who'd a thought Colorado would make it legal?
    2ch: Oppo, JoLida 502CRC, JBL L212, 18ti,240ti; Heath AS101, Von Schweikert VR4
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