Mirror image line array

Re: Mirror image line array

Greg Huber said:
Hi again all -

The way we have been describing what we are hearing is "it seems like there are more highs house left". It can be heard when listening to both sides at the same time, or A/B-ing quickly.

I agree measurement can probably show us what we are hearing, but I'm liking the advice of a trusted colleague best so far..."Flip the ******* and see what it sounds like" - that's my style, too.

I've restacked a few PAs in my day - I remember fondly the first time I worked for Peter Yarrow. It was around 1979, I was a very young MON guy, and my boss didn't get the LF "crunchers", metal MF JBL horns with 2441/2482, and 2402 HF up high enough to begin with. I worked with Peter many more times over the years, and when the artist comes in and tells you your PA is stacked wrong, you get to restack it. Peter pays attention to those things, and he is always right.

(Art, if you're reading this - that wasn't you - it was Willie! Heeheehee!!)

Thanks - more to follow!
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Greg,

Steve DuBuois had to go through the wringer with getting the monitors right for Peter at the Northrup in 1984 too ..

The center to center distance between the mids and the highs in the EVXLC127DVX is more than 1/4 wavelength (it is well over one complete wavelength), so it results in an off axis null in the crossover region.
Since the acoustic crossover between the mids and the highs are probably not identical in rolloff, the off axis nulls won't occur in the same line on the left and right of the two hangs.

Since the cabinets are not symmetrically hung, instead of a definitive center "sweet spot", you get two sets of humpty dumpty peaks and dips, if you listen one side of center it will sound different than the other side of center.
Even from left to right the width of your H3000 desk will sound wonky, if you flip the one side so both mids are center, at least the FOH area should be pretty even.

The ******* that did not hang them symmetrically ****** up.
Flip the ******* and at least the ****** up off axis dispersion will be symmetrical at FOH.

Hope to see you at the STS reunion party!

Art
 
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Re: Mirror image line array

I could be wrong and would have to check with EV but I do not believe The XLC DVX is designed to be inverted with out some modification. If someone here knows differently and it is an approved EV modification or recommendation I would be interested in the documentation.
 
Re: Mirror image line array

Art Welter said:
Flip the ******* and at least the ****** up off axis dispersion will be symmetrical at FOH.
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And still messed up everywhere else.

So often when people are talking about "sound quality" what they are really talking about what is good at FOH and don't give a damn about everywhere else. You know-for the people who PAY MONEY to attend and make it possible for the FOH guy to have a paycheck. Yeah-they don't matter-as long as the FOH guys gets the "toys" he wants he is cool.

I personally believe that you should try to get the coverage as even as possible for EVERYBODY.

Flipping the array upside down only moves the issues to a different spot. Yes it is now symetrical-but what about the people who are in the nulls? Tell them that. OH if you had purchased seat G27 it would sound better---------------------------------------
 
Re: Mirror image line array

Ivan Beaver said:
And still messed up everywhere else.

So often when people are talking about "sound quality" what they are really talking about what is good at FOH and don't give a damn about everywhere else. You know-for the people who PAY MONEY to attend and make it possible for the FOH guy to have a paycheck. Yeah-they don't matter-as long as the FOH guys gets the "toys" he wants he is cool.

I personally believe that you should try to get the coverage as even as possible for EVERYBODY.

Flipping the array upside down only moves the issues to a different spot. Yes it is now symetrical-but what about the people who are in the nulls? Tell them that. OH if you had purchased seat G27 it would sound better---------------------------------------
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The measurement session I proposed would verify/eliminate the asymmetrical component layout as the culprit at FOH and give some insight into the speaker/room interactions. I guess that's too much.
 
Re: Mirror image line array

Bill Hinds said:
I could be wrong and would have to check with EV but I do not believe The XLC DVX is designed to be inverted with out some modification. If someone here knows differently and it is an approved EV modification or recommendation I would be interested in the documentation.
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I think the fact that there are two logos on the front turned 180° relative to each other is a very strong proof that they are designed to be inverted and be deployed in a symmetrical manner.
As for why speakers need to be deployed symmetrically, I'm sure that the reasons are obvious to everybody, and there would have to be very compelling reasons to do it differently for an asymmetrical deployment to make any sense at all.
 
Re: Mirror image line array

Per Søvik said:
I think the fact that there are two logos on the front turned 180° relative to each other is a very strong proof that they are designed to be inverted and be deployed in a symmetrical manner.
As for why speakers need to be deployed symmetrically, I'm sure that the reasons are obvious to everybody, and there would have to be very compelling reasons to do it differently for an asymmetrical deployment to make any sense at all.
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I wonder how we've gotten along all these years with vertically asymmetrical speakers that have woofers on the bottom and highs on the top.

Mac
 
Re: Mirror image line array

mackerr said:
I wonder how we've gotten along all these years with vertically asymmetrical speakers that have woofers on the bottom and highs on the top.

Mac
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Obviously very well because such an arrangement is symmetrical in the horizontal plane, and not only symmetrical, but in most cases indistinguishable from single point sources because our hearing's vertical source resolution is not very precise.
 
Re: Mirror image line array

Per Søvik said:
Obviously very well because such an arrangement is symmetrical in the horizontal plane, and not only symmetrical, but in most cases indistinguishable from single point sources because our hearing's vertical source resolution is not very precise.
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Not obviously. We live with it because that's the way it is. Yes our hearing has better resolution in the horizontal, but as you walk through the sound field the lobes are just as obvious. At any given location the asymmetrical speaker will "in most cases be indistinguishable from a point source" as well. It is only when you move around you are aware of any differences. Just because no one but Ivan talks about the lobes caused by the driver offset doesn't mean they aren't there, and that they don't affect the sound. There just aren't a lot of easy solutions, and we are used to it.

Mac
 
Re: Mirror image line array

mackerr said:
Just because no one but Ivan talks about the lobes caused by the driver offset doesn't mean they aren't there, and that they don't affect the sound. There just aren't a lot of easy solutions, and we are used to it.
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Taking that concept to another level are speakers with rotatable horns as many do not consider that rotating the horn changes the driver interaction through crossover and thus potentially the resulting response and pattern. And there are a lot more products with horns that can be rotated than there are ones that provide data for the box with the horn in the 'standard' and rotated orientations.
 
Re: Mirror image line array

Brad Weber said:
Taking that concept to another level are speakers with rotatable horns as many do not consider that rotating the horn changes the driver interaction through crossover and thus potentially the resulting response and pattern. And there are a lot more products with horns that can be rotated than there are ones that provide data for the box with the horn in the 'standard' and rotated orientations.
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And once you consider how small many of the "rotatable horns' are-rotating them only affects the top octaves-and does nothing down into the midrange area.

But as long as the user "believes" that the pattern is changing-then it "must"-never mind the physics---------------------------

If users would pay a little bit more attention to what is actually happening and not what the "marketing dept" says-their might be more products that actually worked the way they were intended.
 
Re: Mirror image line array

Hey all...

The hang SR is flipped. MF cones are onstage, both sides. Two easy hours.

The PA sounds much closer to the same left to right, especially at FOH. The SR side has somewhat more LF now, probably because now the 12s are next to the staircase. It is not anywhere near as noticeable as was the upper MF bouncing around offstage right. We may try some acoustic treatment on the side of the staircase, but I don't think that will make much of a difference.

The cabinets are definitely designed to hang both ways, and I would recommend that anyone flying these cabinets invert one side as a rule.

Thanks for all the thoughts and braining -

Greg
 
Re: Mirror image line array

Ivan Beaver said:
And still messed up everywhere else.

I personally believe that you should try to get the coverage as even as possible for EVERYBODY.

Flipping the array upside down only moves the issues to a different spot. Yes it is now symetrical-but what about the people who are in the nulls? Tell them that. OH if you had purchased seat G27 it would sound better---------------------------------------
Click to expand...

Actually, this rig covers our room very well and very evenly. In fact, that's what it seems to do best. Its coverage is more even than any other rig I've heard in my 30+ years down here.

Using 120 degree boxes makes stuff a little washy, not in your face like the old point source boxes we used to make sure to aim one of at FOH. It's a pleasure to watch a FOH engineer walk upstairs and hear something that sounds like what he's hearing on the floor and at FOH for a change.

I've read a few things about the Danley boxes, I'd love to hear one in in this room!
 
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Re: Mirror image line array

Greg Huber said:
Hey all...

The hang SR is flipped. MF cones are onstage, both sides. Two easy hours.

The PA sounds much closer to the same left to right, especially at FOH. The SR side has somewhat more LF now, probably because now the 12s are next to the staircase. It is not anywhere near as noticeable as was the upper MF bouncing around offstage right.
Greg
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Greg,

You can easily turn the SR LF down a dB, but there is no substitute for symmetrical dispersion.
Glad it worked out!

Art
 
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