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Thread: SR pros on this forum

  1. #1
    Senior Member JuniorJBL's Avatar
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    SR pros on this forum

    I have a church with 4 SR4735x FOH mains.
    I know that room has a lot to do with how it will sound but I only have what I have to work with.
    HF is way down on the RTA with almost none at 16k and MF is very muddy. The room is a fan shape and holds about 600-700 people.
    The speakers are in the ceiling right over the front edge of the stage.
    The stage is shaped like:
    \______/

    With steps around all three sides.
    There ar 2 4735's in the center and 1 on each side. They are at about a 25 degree angle. Does anyone have some ideas as to what aproach I should take to get some clarity to this system? Should I add some UHF drivers, more horns maybe 2" throat horns.
    The room is about 150' deep and about 250' wide. Eveything is powered by crown and we use a Soundcraft sprit live 24 and a DBX Driverack 260.
    Thanks for all of your input.
    Shane

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    RIP 2014 Ken Pachkowsky's Avatar
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    Quote Originally Posted by JuniorJBL
    HF is way down on the RTA with almost none at 16k and MF is very muddy. Should I add some UHF drivers, more horns maybe 2" throat horns.
    The room is about 150' deep and about 250' wide. Eveything is powered by crown and we use a Soundcraft sprit live 24 and a DBX Driverack 260.
    Thanks for all of your input.
    Shane
    It is normal to have severe HF rolloff 15 to 20+ db at that frequency. Its beyond what most people can hear. I think I read somewhere most of the population can't hear above 15K. As far as adding 2 inch horns, I am not sure.

    I would post a message to BO or JBL Dog or others. These guys are FOH engineer types and could be of much greater assistance. It would appear you have decent gear so I am sure thats not the issue.

    Hopefullly one of them will help you out.

    Ken

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    Moderator / Treasurer/Marketplace Czar boputnam's Avatar
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    Quote Originally Posted by JuniorJBL
    ...we use a ... DBX Driverack 260
    How...?

    ----------------

    (ps: My first fiddling, would be to bypass that, completely. Take it OUT of the signal path. Not that it is misbehaving, per se - it maybe doing exactly what someone told it to do - but maybe it is not doing what is needed...)
    bo

    "Indeed, not!!"

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    Senior Member JuniorJBL's Avatar
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    like this

    Quote Originally Posted by boputnam
    How...?

    ----------------

    (ps: My first fiddling, would be to bypass that, completely. Take it OUT of the signal path. Not that it is misbehaving, per se - it maybe doing exactly what someone told it to do - but maybe it is not doing what is needed...)
    Running in mono providing eq/crossover and delay out of the board. It would be hard to bypass this piece.
    I could remove it and run them by themselves but the system is tri-amped.

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    Moderator / Treasurer/Marketplace Czar boputnam's Avatar
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    Hi, Shane...

    This will be tedious to diagnose, so let's go slow - we need to understand the signal path.

    Some background:
    A. Is this a new problem?
    B. When did it develop, and what was it like, before?
    C. The Live 4x2 - is it in good condition? Are you certain you are giving a full-pass signal (non EQ'd) to the driverack?
    D. Any reason to suspect the 4735's are not working properly?
    E. If you send a full-pass signal (low gain) to each component of the 4735, what does it sound like? Do the cabinet elements work when the dbx is bypassed?
    F. Is there a chance you have crosswired the tri-amping TO the speakers (ex the dbx)? Sorry, but my roadygoofs love to cross-wire my mains, just to tease me at soundcheck...

    Now:
    Check each of the band passes, separately. My understanding is, the:
    LF is good
    MF muddy
    HF low gain

    1. Double check all the settings on the driverack - make sure you know what it is doing.
    2. Ensure it is not in "auto" mode.
    3. Use the driverack merely as a crossover, and keep all gains at unity.
    4. APPLY NO EQ (either parametric or 28-band).
    5. Ensure there is no C/L on.
    6. Ensure the Feedback Eliminator is OFF.


    Basically, use the dbx thingy as a crossover ONLY as a start.

    How does it sound?
    bo

    "Indeed, not!!"

  6. #6
    Senior Member JuniorJBL's Avatar
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    Hi Bo

    A little more background on this system:

    I thought it was tri-wired but it is bi-wired.

    A: This is not a new problem
    B: it has always been a tough room to make sound good
    C: as far as I could tell it should be full pass out to the driverack and the live 4x2 is in good shape no dead pots or functions.
    D: Not to my knowledge
    E: I have not done this yet.
    F: Possible


    Yes:
    LF is fair to good (a little hollow sounding)
    MF is muddy and loud
    HF low gain and muffeled

    As far as the driverack is I did undo all eq/c/l and fe
    Started with flat muted the sub
    To my ear WAY to much mid and the rta shows about +12 in the 1K area with a Q of wide so in other words mild slope within a few K above and all the way down to about 200-160Hz

    Next:
    This is what I think has to to with some of the problems in this room.

    1: speakers are 2 in the center and 1 per side.
    The sides are vertical w/MF/HF plate vertical as well.
    Centers are mirror image MF/HF plate to the center running vertical and the cabs are horizontal.
    When you walk down the center isle it sounds like you are spinning around as you walk. Phasing is horible. I used the driverack to run the centers out of phase 90 degrees and that made a semi-big difference.

    My thoughts were to move the center speakers out to the edge of the center and move sides over next to them to form a \__ __/ like that. (I did not look to see that may BAD diagram in my first post made know sense).

    It would seem that this would give better seperation Please correct me if I am wrong because to move these beasts is rather tough. They are about 22' in the air and you can only get a one man lift in the room so you need rigging so that 2 people on the floor can control them.
    I will be back over there in about an hour so I can try some other things.
    Also after changing the phase I ran the rta w/pink noise and did a "by ear and eye" eq tring only to cut with the eq and it did sound somewhat better but still struggling in all areas for clarity.

    Thanks again for your input.
    Shane

  7. #7
    Senior Member Akira's Avatar
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    Quote Originally Posted by JuniorJBL
    My thoughts were to move the center speakers out to the edge of the center and move sides over next to them to form a \__ __/ like that.
    a picture would mean everything.

    in live reinforcement placement is everything. we have a saying in the industry "1 in the air is worth 2 on the ground'
    without seeing the installation, my guess is you hit it right on the nail...
    PLACEMENT PLACEMENT PLACEMENT
    Generally, when doing a hall, a single point source array in the front center of the room is the way to go. ie: "the Grande ole Oprey" or Albert Hall or any Turbosound installation

    the shape you drew above should be modified so that the two front speakers are not in the same plane, thus cancelling each other out. They should be arc'd using the identical splay as the side speakers, forming an unbroken continuous wave front. The result is a "point source array" which is perfectly in phase as you walk around the perimeter of the room.

    p.s. for this to work all speakers must be identical. In this case you must align all MF/HF plates so that all boxes are in a vertical line array.

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    Moderator / Treasurer/Marketplace Czar boputnam's Avatar
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    Hi, Shane...

    Maybe you and Akira are on the right track.

    I do worry about lobing, and phasing, but, I'm not convinced - yet - that the signal is ready for you two...

    Before you move anything around, can you isolate, and run only the centers? And, then only the sides? Is there any difference / improvement? If there is, and you like the sound of one over the other, then you two are on the richt track.

    If not, then there remains, IMO a signal quality problem we have not yet gotten to.

    I think it's important you run the Live 4x2 straight through to the power amps, bypassing the dbx. This will only require a couple of (long...?) XLR cables. I'd loan you some but we are not near enough... Switch the SR4735x to fullrange (use the internal passive xover). Then, input into the Live 4x2 some souce material - use one of the stereo strips with EQ (rather than a line or tape input). How does it sound?
    bo

    "Indeed, not!!"

  9. #9
    Moderator / Treasurer/Marketplace Czar boputnam's Avatar
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    Quote Originally Posted by JuniorJBL
    I thought it was tri-wired but it is bi-wired.

    A: This is not a new problem
    These two thoughts concern me.

    You have inherited this system, correct (someone else put it together)? If so, there is very likely an issue with the bi-amp wiring - this is VERY common, and could be an easy fix.

    Try my suggested passive full-range, non-dbx trial first. If that works, my friend, you may only have a bi-amp wiring issue...
    bo

    "Indeed, not!!"

  10. #10
    Senior Member JuniorJBL's Avatar
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    Pics

    Here are some pics of where the 4735's are.
    Attached Images Attached Images  

  11. #11
    Senior Member JuniorJBL's Avatar
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    maybe...

    There are some thoughts as to bi-wire problems.
    This system has been built over a 10 yer period. The amps were just replaced from old crests to the Crown CT series. I did not install the amps or speakers but I can tell you getting to the speakers is a pain in the @ss. I can do this sometime this week.

    I did redo all connections at the board and yes it would be easy to bypass the DBX.

    As you can see from my pic they are behind the screens and very hard to get to. I also hate working high in the air trying to move a 250lb object.

  12. #12
    Senior Member JuniorJBL's Avatar
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    BTW

    Sorry for not posting in the right area

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    Moderator / Treasurer/Marketplace Czar boputnam's Avatar
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    WOW!! Glad for the pics. Beautiful place. Anyway...

    Yea - let's answer all signal-path questions possible, first. Obviously, any moving of cabinets is an extreme solution - although it may be the one.

    Question - are the cabinets sitting on their heads (horn, down?).

    Anyway, when you can get up there and run the cabling into the passive network, and completely bypass the dbx, we will be most interested in the report.

    With those long cable runs, there easily could be cross-wiring issues. Make notes of the cabling colors / labels before your ascent, and verify what is in the loft. TAKE A LOT OF NOTES, and some pictures. It may be worth experimenting on your own with some intentional cross-wiring down at ground level, and just see if there is any improvement. Things could be mighty scrambled. :dont-know Anyway, it won't hurt anything...
    bo

    "Indeed, not!!"

  14. #14
    Senior Member JuniorJBL's Avatar
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    Question

    Horns on the sides are up.

    Cabs are horizontal in the center. and the horns are in the middle w/horn on top.
    It looks like we might get the lift out on wed night.

  15. #15
    Moderator / Treasurer/Marketplace Czar boputnam's Avatar
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    Quote Originally Posted by boputnam
    It may be worth experimenting on your own (before the ascent...) with some intentional cross-wiring down at ground level, and just see if there is any improvement. Things could be mighty scrambled. :dont-know Anyway, it won't hurt anything...
    Give it a try...
    bo

    "Indeed, not!!"

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