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Thread: JBL Synthesis - Room Design and Treatment

  1. #121
    80sKid
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    Quote Originally Posted by JBL 4645 View Post
    ...I was fascinated with the treatment in the VUE at London nice soft spongy like fabric as pictured in the VUE pictures I took last year of one two THX screens fully rigged with JBL.

    It was layered with white fabric over the front I’m guessing its one of two types behind fibre or other

    This is typical movie theater sound treatment -- seen round the world in thousands of theaters. It's rigid fiberglass, or mineral wool, panels attached to the wall and then covered with acoustically-transparent fabric that is pleated and mounted over the panels.

    The fiberglass panels shouldn't represent a health concern for anyone once they are mounted and behind the fabric. Firstly, the rigid panels are quite dense and only shed when brushed against. And all the loose fiber gets shaken out during installation. Plus the fabric on top keeps in any remaining fibers. As long as you take precautions for installation (or have someone else handle that) and clean up the space thoroughly before "moving in," you should be fine.

    But then, as others have mentioned, there are alternatives. The most popular being cotton panels that are made from recycled blue jeans.

  2. #122
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    Quote Originally Posted by JBL 4645 View Post
    Oh, I humbly agree one can not have too much.

    Al, have you ran frequency sweep with free software like REW at the sweet spot to clarify this?
    No. I don't ever get caught up in measuring this and that. My ears are the judge! If there is a flat spot half a metre from where my feet are I don't care. My feet don't have ears.

    Allan.

  3. #123
    JBL 4645
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    Quote Originally Posted by Allanvh5150 View Post
    No. I don't ever get caught up in measuring this and that. My ears are the judge! If there is a flat spot half a metre from where my feet are I don't care. My feet don't have ears.

    Allan.
    You have point there. That is true the floor doesn’t have ears. But what if its in null in the chest area that is several inches below our ears what then?

  4. #124
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    surprise!

    well, we ran into another snag with the room. The designer wanted the countertop and base removed from the corner of the room. It sounded hollow, so no problem, right?

    We popped the top off in preparation for demolition.
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  5. #125
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    Okay, let's look inside. Wait, What's that?
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  6. #126
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    Okay, it's the d@#%ed footer. It's not going anywhere, and it continues around underneath the shelving to the right.

    The stub wall is bolted to the floor. The studs would have to be cut out, and then we'd only gain 4". Not worth it.
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  7. #127
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    So, the room is now officially a "problem room." It's thwarted me in every effort to make it a better place for the Synthesis® gear.

    My thought process is something like this:

    1. Put the Synthesis® gear in the room in a temporary install, with
    no more physical changes to the room so it can be returned to regular
    use.

    AND

    2. Save up for a year or so and finish the unfinished basement area
    and install the SynthesisR system permanently in there. I have a bid
    for about $28,000 for the primary construction.

    OR

    3. Sell the Synthesis® system and recover some of my money, plus end my grief.

    Chris Neumann talked me down from the ledge (as in, "Wait, don't jump! Things aren't that bad.") and agreed to work with me on a temporary install, which hopefully will go quickly. Even at that, it should be a night and day improvement over the beautiful Performance Series system that was in there.

    There will be more as the saga continues.
    Out.

  8. #128
    Senior Member rdgrimes's Avatar
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    What's the problem with the shelf and base? I don't get it. If it's the sound of the dead space, why not stuff it full of insulation?

  9. #129
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    The plan called for an S1S-EX to be placed there, along with a bass trap. The S1S-EX would have been inset part way in the wall. Doesn't work as intended if it's 30" off the floor.
    Out.

  10. #130
    Senior Member rdgrimes's Avatar
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    What if you make a corner notch and place the S1S-EX at a 45' angle back as far as it can go into that space, leaving the remainder of the existing boxed area so the S1S-EX just sticks out a bit. You might be able to hammer out some of the footing to allow more room in the corner.

    What 1st struck me about the corner is that the boxed area is perfect for a custom sub install. Take out drywall, install particle board and a corner-angled baffle, create the appropriate sized space behind and add cross-bracing and ports. You can take all the measurements off the S1S-EX and use it's driver and even the grill and port tubes? Looks like the tubes are removable from the cab.

  11. #131
    Senior Member louped garouv's Avatar
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    Quote Originally Posted by Titanium Dome View Post
    So, the room is now officially a "problem room."
    .....
    There will be more as the saga continues.

    aren't they all.....




    I recently laid some laminate flooring down after tearing out all of my carpets, only then did i realize nothing is 'square' in the place....


    be well....

    i trust everything will work out for you....

  12. #132
    Senior Member BMWCCA's Avatar
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    Your mom probably told you, "Nothing worth doing is ever easy!"



    Hang in there. It'll sound fantastic!
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  13. #133
    Mike Ronesia
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    That's too bad. It's not the first time I've seen one of those nice details hiding something that messes up the plans.

    Though it will cost more I'm guessing the basement HT would end up being a better solution with not as much compromise and 3 years from now you'd be glad you did it.

  14. #134
    80sKid
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    Personally, I would move forward with the room and make it as good as is practical / affordable.

    I would stuff that gap behind that half-wall completely with fiberglass (and I would pack it firmly, not loosely). Plus double up the drywall, by adding another layer to the outside.

    I would still put the surround speaker in the position you originally intended (as far as lateral positioning is concerned). Make its installation heigh immediately above the half-wall.

    I'm confident the sound won't suffer much by having the surrounds up a few inches higher than originally planned. In my experience, surrounds being above ear level is BETTER.

    Of course if you, or the JBL guys, feel strongly otherwise (which should really only be if you are going to do a significant amount of multi-channel MUSIC listening), the solution could be to flip the surround speakers upside down.

    This will put the high frequency drivers close enough to ear level to get the job done. (Note that this will likely require positioning these surrounds the opposite of how their installation labels indicate -- i.e.: the end that is indicated should be towards front of room, should be towards back of the room.)

    You will need to put an acoustically aborbent material or object on top of the "shelf" that is created by this half-wall, to absorb the first reflections from the surround speaker. You could even use cushions for this purpose, if that look matches the decor of the room.

  15. #135
    Senior Member Valentin's Avatar
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    Quote Originally Posted by Allanvh5150 View Post
    Hi Ash,

    I can definately say there are no nulls in my room. One sub is under the plasma as you have seen and the other is about 1.5 metres behing the listening position. 1000watts per cab and tuned to 27Hz. Serious overkill but one can never have too much.

    Allan.


    There is definitely nulls in your room
    one thing is that your room is dead in the upper frequencies and another is in the bass region

    not even the big anechoic chamber in harman is free from reflexions at 40 hz

    230 usd of fiberglass is not going to do the trick

    besides you do not want to kill all the room reflections not for listening pleasure

    here is an anechoic chamber in Mexico city were i have done some tests and its good to 80 hz with wedges of 110cm to go down too 40hz you would need 215cm long wedges


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