Mantaray horns

[thinking]

Looking for some helpful advice from someone who might have more real-world experience than I do on this particular subject. I have worked before with arraying the Altec mantaray horns to cover larger areas, overlaping the rear of them to align the apparent apexes as noted in some of the altec literature. I ran into someone the other day that was convinced however, that the EAW series AX speakers that were designed to be arrayed, were just the ticket, and, given the marketing hype, would produce near-perfect coverage by just arraying them together. Any comments from anyone that has either looked at this type of a situation, or actually has experience with it?

[LICORNE]

Hello

The EAW coaxial system looks good but this is old tech.Since ALTEC LANSING first introduced it in early 1990's. Available in 12 and 15 " called DTS
DUPLEX SYSTEM.

<font color="#FFFFFF" size="1">[ November 09, 2007 08:22 PM: Message edited by: CONVERGENCE ]</font>

[LICORNE]

I should add. Still available at GREAT PLAINS AUDIO.

http://www.greatplainsaudio.com/

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<font color="#FFFFFF" size="1">[ November 09, 2007 08:18 PM: Message edited by: CONVERGENCE ]</font>

[LICORNE]

Here is a picture of the 16" ALTEC DTS BASS HORN cabinet.The Engine.

There is no comparison with the EAW AX.
The ALTEC model is a professional product.




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<font color="#FFFFFF" size="1">[ November 09, 2007 08:20 PM: Message edited by: CONVERGENCE ]</font>

[Steve Burger]

Sounds like he is in the one size fits all "thinking" mentality. I am not a sound contractor but from what little I know it completely depends on the room.

[thinking]

Thanks for the good info, I finally realized what was bugging me about the marketing of the EAW speakers. Altec has a tech letter no.262, found over in the literature section, that describes the problem of apparent apex. In reading the EAW sales literature, they claimed to have solved the problem of the apparent apex, and then proceeded to say that their cabinets were ideal for mounting in clusters. I finally figured out that they only worked on the problem within a single cabinet, not from cabinet-to-cabinet. Their speaker is really not much better than any other in dealing with the problem of aparent apex in speaker clusters, which is a greater problem than apparent apex within a single cabinet. I say that because within a single cabinet, the problem only occures in the crossover region, whereas, in a cluster, the problem occures at all frequencies. So I'm still opting for the mantarays as the way to go when wide coverage is the requirement, since you can really take care of the problem once and for all.

[thinking]

Thanks for the story, I love stories!
Phasing, ah yes, I did the math on this one to see what the phase cancelation would look like. If you stack two of the Mantaray 90 x 40 horns, you can get the edges virtually touching each other. If you mount two of the previously mentioned one-size-fits-all 90 x 60 boxes for the same 180 degree coverage, the edges will be 20 inches apart. That's going to cause phasing problems for any wavelength shorter than 40 inches, or about 330 Hz and on up. Seems to me that would be a little bit of a compromise in sound quality. I have to rely on the math, since I don't have tons of previous experience to fall back on, which is why I decided to pose the question.

[Todd W. White]

Don Davis, and his sweet wife Carolyn, and I were talking about this one day - it was quite an enlightening discussion.

Much of what Don said was along the lines mentioned above, namely, that people who build boxes that say they have "solved all of the acoustical problems" inherent in everyone else's speaker system ("They also correct for ALL room acoustic anomlies as well, of course", Don said with a glint in his eye and a grin on his face) only do so for ONE unit, NOT a whole system.

What these people who are pushing the "one box does all" concept - the LINE ARRAY people - fail to take into consideration is that when you bolt these things together or hang them in large arrays is this: the speakers DO interfere with one another and EACH ONE really DOES interact with the room in a manner that is uniquely it's own, and when you get all of them going at once, it's can be a real MESS!

Carolyn chimed in with a story about how that a while back she and Don were called in to evaluate a new array that someone was trying to sell a large indoor stadium. The place was pretty big, and had been having problems with it's sound system, and wanted a new one.

Well, the people set up their speakers (from a three-letter speaker company not beginning with a "J"): one large array, which would be indicative of many which would be installed around the perimeter of the seating areas of this large domed stadium, and they began to demonstrate.

"One of the quickest ways you can know if someone has no idea what their doing is if, when they go to demonstrate their sound system to you, the first thing they do is play music through it", Don said.

Sure enough, these people started playing music for the owners. Impressive bass response! Incredible sound pressure levels!

The owner's were ready to sign.

"Stop!" Don said. "Doesn't anyone want to know what this thing sounds like when you TALK through it? After all that IS the main purpose that this system is going to serve, isn't it - to project SPEECH to the fans in the seats?"

So, they drug out a microphone and began talking through the system.

"Decent, but not impressive - I doubt if they had enough articulation to make it through the crowd noise", Don said.

Don was showing them with the TEF how the system equalization could be improved for less loss of articulation (%ALcons - anyone remember that?), impressing everyone, and telling a few stories as he went.

And, since it WAS better than what they had, the owners were beginning to sway when, all of the sudden, Carolyn, who had been wondering around listening to the effects of the array on the room acoustics, called out from across the stadium.

"DON!"

"DON!"

"YOU NEED TO COME OVER HERE and LISTEN to this!"

When he did, he heard what she had been hearing. The system was creating a inordinant amount of really bad reflections (most indoor sports facilities are acoustic toilets).

The problem was obvious: the multiple-source one-box-does-all array was creating SO MANY reflections and phasing problems that, by the time the sounds rattled around the room, it was a mess! The reverberant field was SO LOUD that it was obvious that there was NO way to overcome it with a whole bunch MORE of the arrays, with each of which generating THEIR OWN set of nasty reflections.

"If it excites the room THIS BAD with only ONE array", Carolyn said, "just THINK of what a WHOLE ROOM FULL of them would do!"

Well, it seems like they bought it anyway, and have had problems ever since...

BUT, like my late friend, Dr. Paul Venklasen, used to say, "Phasing! Phasing! No one thinks about phasing when they design these things!"

"The more we know, the more we realize how RIGHT those old guys at Bell Labs knew what they were doing", Don said with a glint in his eye and a smile on his face as he spoke...

[LICORNE]

If you want to impress your girl friend on the Line Array your installing you should descibe it like this: ?We?re gonna hang a logarithmicspaced, articulated spiral array in a horizontally asymmetric configuration employing frequency tapering and divergence shading, which will include isophasic high-frequency and mid-frequency apertures, hyper-cardioid low-frequency transducer sections, is controlled by finite-impulse response filtering digital signal processing, and works well with a psychoacoustic infector.?

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[Roger/Ana]

I once had a so called sound tech tell me that one Apogee AE5 would sound much better than a Altec A5X
So I borrowed one from a friend of mine
The A5X having a 515 and a 288 on a 805 multicell running Biamped
Needless to say the A5X blew the over processed AE5 right out of the water!
In fact that AE5 sounded like garbage!
Maybe thats why Apogee is no longer around (they stole the design from Harry Mccune Sound anyway)