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Thread: Time alignment

  1. #1
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    Time alignment

    Hi guys,

    I often see mention on the forums about various speakers being time aligned due to slanted baffles, adjustable modules, etc. Most of these speakers are anything but time aligned.

    To verify if a speaker is time aligned, you want to look at the step response. For instance, look at this Dunlavy:

    http://www.stereophile.com/content/d...r-measurements

    The output of the drivers arrives at the microphone simultaneously -- it is a time-aligned design. Stereophile uses an impulse response to derive the step response and therefore is a good source for verifying this information.
    Jeffrey W. Fritz
    Editor-in-Chief
    The SoundStage! Network
    www.soundstagenetwork.com

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    Addicted to Best! Robh3606's Avatar
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    Hello Jeff

    OK that's true very few speakers are time aligned. The real question is does it matter??

    Rob
    I could be arguing in my spare time

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    Quote Originally Posted by Robh3606 View Post
    Hello Jeff

    OK that's true very few speakers are time aligned. The real question is does it matter??

    Rob
    The research I have done says no. Would be interested to see what Jeff has to say....

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    Member Sponsor Addicted to Best! rockitman's Avatar
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    Wilson X-2's and Maxx 3's are time aligned. I would imagine so is Alexia. It does make a difference as these wilson speakers can be adjusted optimally for distance back and ear height. Most speakers can not be adjusted in this way.
    Christian

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    Addicted to Best! cjfrbw's Avatar
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    Can't remember exactly, but I think it was Linkwiz who stated that if he had his druthers, he would choose phase coherence over strict time alignment.

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    WBF Technical Expert (Speaker & Acoustics) [Technical Expert] Mark Seaton's Avatar
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    Quote Originally Posted by Jeff Fritz View Post
    Hi guys,

    I often see mention on the forums about various speakers being time aligned due to slanted baffles, adjustable modules, etc. Most of these speakers are anything but time aligned.

    To verify if a speaker is time aligned, you want to look at the step response. For instance, look at this Dunlavy:

    http://www.stereophile.com/content/d...r-measurements

    The output of the drivers arrives at the microphone simultaneously -- it is a time-aligned design. Stereophile uses an impulse response to derive the step response and therefore is a good source for verifying this information.
    Claims related to "time" are most certainly some of the biggest abuses and loosest definitions. Figure 5 in the linked Dunlavy measurements is the most telling. IMO the arrival of the sound at/through the crossover is what matters much more as it also can play out in the spacial response. Put another way, the time discontinuities at crossover and then the phase response/group delay are what really matter. Of course you will get different sets of priorities from different designers.

    In the past it was common to talk about "time alignment" in terms of aligning voice coils. Unfortunately this approach is thrown out the window once you add anything more than a 1st order crossover any low pass filter delays a driver. In most cases it simply made predictions with textbook crossovers easier as you were equidistant from the drivers. The fore-aft adjustment does certainly change interactions, but simple visual alignment is rarely optimized.
    Mark Seaton

    Seaton Sound, Inc.

  7. #7
    VIP/Donor [WBF Founding Member] ack's Avatar
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    Isn't time alignment only meaningful at the listening position, and for which the drivers may have be adjusted back or forward, a la Ascendo, Wilson and some others?
    Sources: mod. VPI Aries 3;mod. JMW 10.5i/Ortofon A90;mod. Pass XP-25;Spectral 3000SL xport/mod. Alpha DAC;mod. Magnum Dynalab Etude;mod. Revox B-77II Amplification: Spectral DMC-30SV/DMA-400RS Speakers: Heavily mod. MartinLogan (custom Mundorf xover, cabling, woofers; structural mods);mod. REL Cabling: MIT Oracle 50ic,MA-X/Oracle 90.1 Power: MIT Z-Strip, Magnum Z-Trap; Shunyata Black Mamba CX HC cords, Typhon Tweaks: EAR Isodamp c1002 References: Live unamplified music
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  8. #8
    WBF Technical Expert (Speaker & Acoustics) [Technical Expert] Mark Seaton's Avatar
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    Quote Originally Posted by ack View Post
    Isn't time alignment only meaningful at the listening position, and for which the drivers may have be adjusted back or forward, a la Ascendo, Wilson and some others?
    What arrives at the listener's ears is what matters, although the terms often thrown around use no qualifications until a salesman has to make them up on the fly when asked.
    Mark Seaton

    Seaton Sound, Inc.

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    Member Sponsor [WBF Founding Member] Mike Lavigne's Avatar
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    when asked about time alignment relative to my MM7 main towers and bass towers here is what my speaker designer said;

    While it is true that the lower frequencies have much larger waves, getting them to integrate in phase with the main tower is really not much of an issue when it comes to room placement, meaning you will not experience much if any wave cancellation. However, the wave launch, when having the towers perfectly time aligned to the listening chair is needed to provide a tighter presentation with greater impact, and also to align the harmonic series from top to bottom to produce a seamless and tonally lifelike presentation. This is not to say that you can not move the towers around, because you can.
    so for him optimally you would have perfect alignment; but it's not essential, simply desired. there are other issues which may be more important in particular situations.

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    Quote Originally Posted by rockitman View Post
    Wilson X-2's and Maxx 3's are time aligned. I would imagine so is Alexia. It does make a difference as these wilson speakers can be adjusted optimally for distance back and ear height. Most speakers can not be adjusted in this way.
    http://www.stereophile.com/content/w...r-measurements

    http://www.stereophile.com/content/w...r-measurements

    On the other hand, this is:

    http://www.stereophile.com/content/q...r-measurements
    Jeffrey W. Fritz
    Editor-in-Chief
    The SoundStage! Network
    www.soundstagenetwork.com

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