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Thread: Do you time align your drivers ?

  1. #76
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    Is this too simple?

    I run a 4 way active system using a Marchand active crossover. All units are moveable so I time align by putting a signal through at the crossover frequency and check the response on my lapp top software DB meter. This I find works well for a particular listening position. Just lining up the speaker fronts the system sounds horrible.
    I notice some quality speakers also Time Align.http://www.wilsonaudio.com/product_mezzo_tech.shtml

    Dave

  2. #77
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    Quote Originally Posted by Mr. Widget View Post
    The Altecs and Tannoys are not really time aligned since the compression driver is so far behind the woofer. Of course with a simple delay they can be brought into alignment... group delay and all notwithstanding.



    Widget
    I'm assuming your referring to the Altec 511 being so "far behind the woofer"..
    as I measure the 811's @ 3.5" further foreword and @ a mod. (corrected) alignment w/woof....
    (the 2" and 15" diaphragm align. got factory juggled around (I'm assuming 'cause of the phasing plug
    and 828 horn anomalies.....) (but my eq no's show only a negligible correction @ x/o

  3. #78
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    By measuring

    I time align my 5 way system by using Holmimpulse / calibrated mic to measure the 1st peak positive transients, comparing each driver in turn.
    Since I went Najda 4 way DSP X/O I can time align even the bass tapped horns, these are some 9ms behind the rest, that's probably about 12 or more feet they'd have to be nearer than the others - not phyically possible in most rooms
    I do the lower 4 channels in DSP delaying the 3 above the tapped horns suitably. The tweeter is physically time aligned to the upper mid horn by moving it.
    At 11000Hz you only have to move the tweeter very small amounts as the wavelength is so short.
    Aligning the mid bass to mid horn we are talking moving many inches by comparison. Getting things roughly aligned phyically apart form the tapped horns helped make the alignment in DSP easier.

    I like this diagram to explain what needs to be achieved with physical time alignment



    What does it sound like once aligned then? Well for me, it's just sound right. The upper frequencies kind of get things to snap into focus better.
    With the lower frequencies it is timing and smoothness - I guess as things are aligned and not interfering / cancelling.
    I realise there that many reflections going on in a normal room too of course, but I can dep hear the difference between aligned and not aligned.

    I suppose aligning with 2nd or 3rd peak would be better than trough against peak. Perhaps some systems do this to be sort of more right?

  4. #79
    Senior Member Lee in Montreal's Avatar
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    Aligned diaphragm for diaphragm, source for source. Fostex system pictured.


  5. #80
    Senior Member Mostlydiy's Avatar
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    I think you are on the right path there Steve. When me and More10 used his filter on my system we also used holmimpulse to measure all the driver to properly delay all the horns/drivers. The result was very good. I use to have a little dip between the midbashorn and the mids prior to this adjustment but afterwards it disappeared. If you are to go even further I would recommend trying to adjust the phase of the system with a FIR filter. More10 has made a FIR filter of his own using pos Rephase software, that we used and the result night and day. Especially in the bass region. Multiway horn systems benefit alot from this treatment since the horns turn the phase on their own.

    /Mostly

  6. #81
    Senior Member jblsound's Avatar
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    I just time aligned my custom212s. Being they only have 8" MB the recline tilt is only 1.25". I cut out tapered wood doughnuts for mounting the 052Ti tweeters to keep them vertical.
    The result is a more coherent sound.
    Living in the Land of the Sun

  7. #82
    Heather [Senorita member] hjames's Avatar
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    Share the pictures -everyone would like to see!

    Quote Originally Posted by jblsound View Post
    I just time aligned my custom212s.
    Being they only have 8" MB the recline tilt is only 1.25". I cut out tapered wood doughnuts for mounting the 052Ti tweeters to keep them vertical.
    The result is a more coherent sound.
    2ch: Oppo, JoLida 502CRC, JBL L212, 18ti,240ti; Heath AS101, Von Schweikert VR4
    7.1: Oppo BDP103D, B&K, UREI 809A, JBL B460

  8. #83
    Senior Member frank23's Avatar
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    I time aligned my 2123 / 2420+2344. I measured it using pulses. It took about 11cm that the 2344 needed to be put forward in comparison to the 2123 baffe to get the time alignment right. In the end, I liked my sound better with the 2344 mounted on the baffle so to have a smoother radiation surface. I read that widget also thinks that smooth radiation might be more important than time alignment.

  9. #84
    Senior Member jblsound's Avatar
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    Quote Originally Posted by hjames View Post
    Share the pictures -everyone would like to see!

    When they are completely done. Still rebuilding the wrap-around grilles.
    The avatar is from the mid '90s as they looked with the 066s.
    For 12 years I only had a face grille, being they have black ash veneer all around.
    And I got the urge to go back to the original look, with black speaker cloth all the way around the boxes. I actually found speaker cloth down here that looks quite similar to the original L212 cloth. A textured weave.

    Two years ago I replaced the ageing 066s with a pair of 052Ti. Wish I had done that back when the 052Ti was first available. Far superior.
    So anyway, this is the final upgrade.
    The total package: mirror imaged, time aligned boxes, Biased XOs (with upgraded components), 052Ti, 2105 midrange.
    Only original part, 112A MB driver.

    I could have sold these many times over. But imo, I would then have to buy something along the lines of the Revel Salon2, JBL M2, JBL Arrays, maybe the Revel Studio2 to have something better. Those all carry huge price tags.
    Living in the Land of the Sun

  10. #85
    Senior Member Ian Mackenzie's Avatar
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    Have a look at Drew Daniels project for his comments on time alignment.

    I think the term is a generalisation for a number of technical related problem in loudspeaker design.

    For example people talk of group delay when crossing over a woofer below 100 hertz with certain filter types.

    In practise the woofers need to be physically moved 10 feet forward unless a digital delay is incorporated.

    What is interesting is that subtractive filters do not demonstrate the same group delay as typical filters.

    At much higher frequencies from 1000-4000 the human ear is acutely sensitive to time domain artefacts.

    Theses artefacts are often impulse related to diffraction of the baffle, driver transient performance and filter transient performance.

    When these artefacts are superimposed on physical time alignment things start to get complicated.

    Some designers like J Dunlavy used simple first orders crossovers and good Dynaudio drivers on symmetrical stepped baffles with acoustic foam on the baffles to minimise these artefacts and minimise time alignment

  11. #86
    Senior Member jblsound's Avatar
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    Quote Originally Posted by hjames View Post
    Share the pictures -everyone would like to see!
    OK, the last upgrade. Took longer to do the cosmetic changes than the time aligning. Rebuilt the grilles to original wrap around style, removed the ash veneer from the top/sides and painted them red.
    And really went retro with blue cloth....much like my old '73 L55s.
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    Living in the Land of the Sun

  12. #87
    Senior Member Doctor_Electron's Avatar
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    Quote Originally Posted by 4313B View Post
    Actually the improvements are measurable. The breakdown occurs when people are asked whether or not they care. Yeah, they can hear a difference... So what!? Then they go back to listening contentedly to their iPods...
    LOL !!! +Chuckle, guffaw etc. etc. Just TOO real!

    Could there be a higly lucrative, esoterics-driven market for Time-Aligned Ear Buds?

    Wait, wait, don't answer that!

    And I wish the best of the holidays' cheer and joy to all Lansingers, "DE"

  13. #88
    Senior Member SEAWOLF97's Avatar
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    I used to think that time alignment was a gimmick. Then I got my Walsh F's . The factory describes them as coherent drivers and almost everyone who hears them are astounded by the different experience.

    here is the explanation:

    The voice-coil and magnet are located where you'd expect them—at the apex of the cone (see fig.1). As the apex of the cone is compressed or stretched, the area around the apex radiates a soundwave into the surrounding air at the speed of sound or about 1127ft/s. At the same time, the vibrations ripple down the cone toward the rim with a propagation velocity characteristic of the cone material. For a typical paper cone the radial velocity through the midrange frequencies is in the range 400–800ft/s. Is it possible to vibrate the rim of the cone exactly when the airwave from the apex is directly over the rim? Such synchronism would guarantee the propagation of a time-aligned coherent wavefront toward the listener, but obviously requires the cone vibrations to travel faster than the speed of sound in air. Walsh showed that this was possible when the cone is engineered with the proper angle and materials.



    Forty years ago, the Ohm F speaker was a game-changer; it still is

    The Ohm Acoustics F omnidirectional speaker was such a radical advance in 1972 few 21st century speakers can match its sound.

    http://www.cnet.com/news/forty-years...r-it-still-is/
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  14. #89
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    Ohm speaker

    those conical sp. sound ok 'till the vocals start
    then everything gets vary weird

  15. #90
    Senior Member SEAWOLF97's Avatar
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    Quote Originally Posted by Fort Knox View Post
    those conical sp. sound ok 'till the vocals start then everything gets vary weird
    IF your opinion was more valid regarding the design, none would have ever been sold.
    In fact , many have ..by Infinity, Ohm & the uber expensive German Physiks
    (maybe you should notify them that they don't work on vocals ?)

    Have you EVER heard a good working pair of Walsh drivers ?

    It's really strange how NONE of the reviews agree with you

    Ohm Walsh F Floorstanding Speakers

    4.81/5 (27 Reviews)

    http://www.audioreview.com/cat/speak...3_1594crx.aspx

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