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Old 12th March 2013, 05:19 PM   #11
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Join Date: May 2010
Location: Scottsdale, AZ
I am working with an existing system with three different Behringer models, at varying output power levels.
I haven't had problems, other than knobs not corresponding with similar positions on the same model, etc. Since I set the gain structure using measurement that isn't a big deal. The more aggravating issue is the DIP switches used to configure the input/bridging/pairing schemes. Those switches need a magnifying glass to be seen and read accurately!
If the client had Crown or other brands in that class, I'd be just as happy.

They say you can't "hear" an amplifier. What I'm hearing with these things doesn't impress me.
Caveat Emptor...
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Old 30th March 2013, 04:48 AM   #12
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Join Date: May 2010
Location: Scottsdale, AZ
Progress Report:
The drivers are now being selected for impedance curve matches/resonant frequency similarities.

Here is a question for the group: What about using a Zobel? The array is not going to employ any other driver. It's low frequency augmentation will come from the "Mid" speaker (which also serves as the "Speech" source).
A Zobel when there is nothing but the correction of the impedance tail?
Let's start what could be an argument: Will there be an audible result?
Testing begins next week to determine the aggregate polar behavior - comparing the use of one row of drivers all facing the same direction, vs. a second row along side and behind facing the opposite, providng better high-frequency dispersion - while still being out of polarity.
Bring on the experts on Zobels!
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Old 31st March 2013, 12:40 PM   #13
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Join Date: Oct 2012
the plot thickens!
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Old 4th April 2013, 09:25 AM   #14
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Join Date: May 2010
Location: Scottsdale, AZ
An array panel was raised today. It was hung about 16 feet above floor level. The mic was moved from center aisle to outer seats along the front row, on either side to sample how the "front side" measured compared to the "back side" in corresponding seats. Tomorrow we do some simple EQ to make the curve easier to track, from inner to outer seats.
This is different than doing a polar response, as the distance from seat-to-louspeaker is going to change. We are looking at the change in level, along with the roll off in high frequency response as we move from seat to seat.
What we saw this evening was encouraging enough to proceed with the double-row panel, based on the rolled-off high frequency response from the back side of the array.
We will also bring "test" music to the venue and "play" the panel in Difference Mode (basically sideways) to see what reflections from the platform/stage walls do to whatever imaging might result.
The next step, probably next week, will be to finalize which version of the two-row panel we like best and start cutting plywood and stretching grille cloth.
There is evidence of a very narrow "null" down the center aisle, but the seats next to the aisle have surprisingly listenable response curve,ergo, time to listen to music...

More to come!
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Old 5th April 2013, 02:59 AM   #15
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Join Date: Oct 2012
LamGeezer
would you be able to upload any pictures of your array and the location?
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Old 5th April 2013, 07:11 AM   #16
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Join Date: May 2010
Location: Scottsdale, AZ
I just came from the venue, where I spent most of the afternoon. Currently we have been working with a piece of OSB with five drivers on it. We hung it in the approximate location we intend to put it, to allow us to see how the acoustical environment affects the imaging - which heretofore we were uncertain about - and to see what the front/back differences were like out in the main space.
If you look at the Galaxy S5N8 5 1/4" driver on the Parts Express or other webpages you can see the likely impediment for rearward energy radiation. Add to that the hole in the 3/4" panel surrounding the rear frame and you end up with a ring radiator. Our documentation of the resulting behavior has been pretty casual - we went out into the seats and "walked the space."
We found, by just listening that the sphere of energy thrown from the front of the driver sounded different than that thrown to the rear.
But, not much.
There was enough high frequency in the rear "balloon" that the expected Difference information was discernible. When the "mid" speaker, the existing center mounted speech-optimized device, was added with some care in balancing the levels - the spooky clearly directionally noticeable information began to form out in the space. This "cloud" of sound seemed to form around and above, as well as behind the listener.
This is unlike the image you get from loudspeakers placed ahead and above the seating plane in the traditional Left-Center-Right kind of arraying often used. Amorphous isthe best description i can come up with at this point. Once I get a more finished and representative device built I will work on posting some pictures. Today was fun and exciting, but we have a ways to go and there are some corners in the route to completion. I like to look around them and make sure we're still going in the overall direction we intended!

More information follows...
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Old 8th April 2013, 06:06 AM   #17
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Join Date: May 2010
Location: Scottsdale, AZ
The problem with this kind of project is that it is inevitable that there are protracted (!) periods of observation required while each contributor drags in their reference material, in order to assure all the participants that a consensus is being developed as each step is taken.
The bigger problem is that the process is getting to be more fun than efficient!
This week I am documenting here that the goal is to test the double row panel and get it and the respective drivers into the shop for final construction while the issue of low frequency up to about 250Hz is addressed - preferably in a dipole whose directivity will "knit" with the panel in each opposing sphere.
We experimented with using the low frequncy potential in the center speaker to "fatten things up" a bit - without the result for which I was looking. We could have driven the center woofers a bit harder, compromising the intelligibility goals toward which the design of the center was being driven.
A question to the group:
I'm thinking about four OB 15" woofers mounted"face-to-face" in a pair on either side of the respective panel, driven so-called Isobarik -style. While the budget is geared to meeting needs, wants will be entertained and the usual "value-engineering applied, at least to the point where the Designer steps in, and reminds the folks why we're pursuing this project less than two years after the original installation!
Suggestions are welcome, along with the accompanying engineering justifications, respectively! :-)
Pictures are being taken and will follow once the issues "in the air" have been further addressed.
Your patience is appreciated, mine is getting frazzeled by the desire to hear how it all comes out!

Cheers!
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Old 21st April 2013, 04:23 AM   #18
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Join Date: May 2010
Location: Scottsdale, AZ
The latest:
We ran a 100 Hz test tone through the face-to-face Eminence Gamma 15's we're using as the low mid component in this array. The modal behavior of the venue is bizarre! Every six-to-eight feet you walk on the sanctuary floor there is a major shift in the perceived level of the tone...
We did, however, note that, when playing music through the woofers the modal pattern is not so obvious.
The ten-driver panel was raised to the position where it will finally hang. There will be some separation from the woofer set-up which will be closer to the ceiling.
The face-to-face array of woofers is also operating in "push-pull" dipole mode. We do have some options to move the woofers up and down - some.
Because of the scheduling conflicts of two people working on this project there are very narrow time windows in which the work is being done. Still, it proceeds.
Stay tuned - the pictures are being taken as we go...

Cheers!
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Old 21st April 2013, 01:00 PM   #19
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Join Date: Oct 2012
LAMgeezer
being that your dipole is going to behave omni like your modal behavior could simply be the product of distance to boundary reflections a simple change of position and running the same tone during your next window of opportunity would confirm that.
i guess i still have to be patient for pic's...
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Old 21st April 2013, 09:10 PM   #20
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Join Date: May 2010
Location: Scottsdale, AZ
We rotated the woofer array and moved it around the platform a bit to be sure. Many of the dimensions of the space are either identical or exact multiples of each other. Tuning and regulating the organ pedal division is kind of a bizarre exercise, as you might imagine.
There is one additional feature - all the glass (what there is), resonates far above the frequencies where it might "leak" and provide some relief.

Oh well...

Turk, hold on!

Cheers
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