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Thread: Vertical alignment of speakers

  1. #31
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    Quote Originally Posted by Dr.db View Post
    @Tod: The question still remains: where about is the threshold for this being audible for the human ear??
    If you saw the spectra for two speakers and one was obviously smoother than the other, wouldn't you want to go with the visibly smoother pair even if you didn't think you could hear a difference? I know that I would, and do.

    Remember that there is no way to A/B/X something like this unless you created a speaker that could instantly shift to two different drivers mounted in the two positions. So sometimes I have to trust my eyes, rather than my ears, to optimize what's there.

    You can optimize a car for the 1/4 mile, but unless you have timing equipment to make the most of it, your butt isn't going to feel a couple 10ths of a second difference. Same thing.

  2. #32
    Member jmpsmash's Avatar
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    Quote Originally Posted by toddalin View Post
    Remember that there is no way to A/B/X something like this unless you created a speaker that could instantly shift to two different drivers mounted in the two positions. So sometimes I have to trust my eyes, rather than my ears, to optimize what's there.
    what would that experiment involve?

    ie. if there is a way to shift 2 drivers horizontally with respect to each other, what do we measure?

    I have 2 2123H (which covers around 300Hz to 3kHz) that are mounted on separate open baffle that I can move around. They are driven by DSP crossovers and identical amps. They can act as tweeter/midbass with the appropriate curves. I also have a couple of minidsp measurement mics.

    If we can come up with the right experiment, I can try to make some measurements.

  3. #33
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    Actually, I was thinking that there is a way to at least A/B it with the current set up as the 10" and Heils are separate from the 18"s and a simple double throw switch could be used to select which 10"/Heil plays, either the one vertically aligned, or the one next to it.




    But to me, with the ability to vertically align things and from what I've seen on the RTA, there is no reason to change things here.

  4. #34
    Junior Member ditusa's Avatar
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    vertical alignment of speaker

    it is call mutual coupling effect same as the 4435 studio monitor both woofers side by side 2" spacing.

  5. #35
    Senior Member DavidF's Avatar
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    Quote Originally Posted by Dr.db View Post
    I have been told it is allways favoured to vertically align the individual woofers and drivers on a baffle.
    As I understand this is to avoid lobing and getting the individual sources to match up better and improve imaging.

    A speaker like the JBL S9900 follows this aproach, but the JBL Everest DD66000 or DD67000 doesn´t.
    The Everest speakers only use one of their 15" woofers to run up high to the horn. So the center of the "midrange-woofer" isn´t vertically aligned with the center of the horn. It is offset by about 8".
    I wonder how this affects the overal presentation?
    Is this considered to be a major tradeoff in this speaker-layout or is the offset of such small amount that it doesn´t really affect the sound?

    Best regards,
    Olaf
    You will get interference with drivers separated in distance that manifests in lobing and radiation tilt. The acoustic response will vary depending upon things like crossover alignment, the number of drivers, driver phase characteristic and the bandpass range involved. I suspect is just easier to deal with the response deviations having the drivers on, or nearly on, the same vertical plane. Especially in a multi-way system.

    So the woofer does not have line up on-center to the mid range as long as you know what is happening to the response around the crossover frequency.
    David F
    San Jose

  6. #36
    Senior Member Ian Mackenzie's Avatar
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    Hi Olaf,

    If you have a look at the DD67000 user manual and specifications JBL specify the mid woofer should be placed on the inside for correct imaging.
    JBL also mention the system can be used with the enclosures far part such as room corners with the enclosures aimed towards the centre of the room.

    Perhaps an over looked virtue of the midrange horn is the wide 100 degree horizontal dispersion and the physical width of the midrange horn. This wide horizontal directivity means horn dispersion will closely match the dispersion of the woofer and load the compression driver correctly at the lower end of its operation range. These properties make the transition from the woofer to the horn subjectively less sensitive than a horn with a narrower dispersion.

  7. #37
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    Thanks a lot all of you.

    The reason for my initial question came up with an idea for a diy-speaker a year ago:
    Name:  3-Wege Hornlautsprecher Olaf Frontansicht.jpg
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    It would use the following parts:
    JBL 2405
    JBL 2441 on 2397 horn
    JBL 2123
    TAD 1603

    If all compontents would be lined up vertically, the 15" woofer would be right at the bottom of the enclosure. A woofer that close to the floor would interacts badly with the room-acoustics and the bass gets boomy... To avoid this I thought I could mount it much higher on the baffle, but therefor I would have to offset the 2123 off center. This can be seen in the illustrated drawing...

  8. #38
    Senior Member Ian Mackenzie's Avatar
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    Have you trialed that woofer in your listening environment?

    You are making too many assumptions in an attempt to settle on a design before you cut timber.
    It doesn’t work that way. You can’t avoid doing some real work yourself before finalising a design. A Yabba fest on a forum is not an alternative approach to refining a loudspeaker project. It’s opinions and insights but that’s all.
    If you can do that simply build a Jbl clone. The work has been done.

    Try the woofer out in several positions and at several baffle heights. The same with the 2123 under the horn.

    I would not compromise or complicate the baffle layout without doing some fact finding practical trials.
    Do a test and learn trial with that baffle. Have you considered mounting the 2123 above the horn and placing the tweeter lower at ear height. Try a few different driver layouts and see what works best for you.

    You can move the enclosure, raise the enclosure slightly or if a real problem exist use some for of EQ. You can also tune the enclosure to account for room boundary proximity. Connect it you with a cheap Minidsp crossover to see how well it all works.

  9. #39
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Dr.db View Post
    If all compontents would be lined up vertically, the 15" woofer would be right at the bottom of the enclosure. A woofer that close to the floor would interacts badly with the room-acoustics and the bass gets boomy... To avoid this I thought I could mount it much higher on the baffle, but therefor I would have to offset the 2123 off center. This can be seen in the illustrated drawing...
    I’m not sure you have to worry about the woofer becoming boomy just because of the proximity to the floor. If you were making a three-way, getting the woofer up a bit will help with the mids, but in your case that isn’t as important.

    As Ian suggests, there really is nothing like building test mules when creating a new speaker from the ground up. You can follow all the rules and do everything right and still end up with a stinker, or you can make a number of compromises and hit it out of the park. (American baseball reference)


    Widget

  10. #40
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    Both of you are absolutly correct, in the end I have to try it.

    Currently my listening room is very small and the speakers are very close to the sidewalls and the listening position. I can´t really judge anything under these bad room acoustics to be honest. Right now I´m using another much smaller speaker for dailly listening (1,3" Audax softdome, 6" Audax mids, 12" PHL) as the big speakers won´t work in this room.
    But I´ll be moving in a bigger place next year, so I started plans on the big speakers

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