Small install spkrs with narrow coverage

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Peter Kowalczyk

Freshman
Apr 12, 2013
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Truckee, CA
I wrote a post earlier today, and thought I'd submitted it, but I guess it didn't stick. So here goes again, in abbreviated form:

I'm trying to spec an installed system for a long-and-narrow room with lots of reflective surfaces (Cafe w/ exposed brick walls and lots of glass and stainless steel. Client is on a very tight budget; my leading candidates are the JBL Control 25 and the QSC AD-S52, both 5" woofer two-ways with a multi-axis mount. However, they're both spec'd at 90 x 90 coverage, and I'd like to find something narrower to keep energy off the walls to begin with. Any recommendations?

Bonus points for a series with a companion subwoofer. Thanks,

P
 
Re: Small install spkrs with narrow coverage

My understanding is that pattern control is achieved either by using a horn (which rules out small cabinets) or by a columnar arrangement of drivers. There are "steerable" systems such as the Iconyx which can focus sound fairly much as needed, but even though they are more low-profile than horn-loaded cabinets, they still have to have room to be properly mounted...and they're probably not going to fit into the "limited budget".

So I'll ask this:

What's the height and composition of the ceiling??? An overhead, distributed system might be the alternative.
 
Re: Small install spkrs with narrow coverage

Peter Kowalczyk said:
I wrote a post earlier today, and thought I'd submitted it, but I guess it didn't stick. So here goes again, in abbreviated form:

I'm trying to spec an installed system for a long-and-narrow room with lots of reflective surfaces (Cafe w/ exposed brick walls and lots of glass and stainless steel. Client is on a very tight budget; my leading candidates are the JBL Control 25 and the QSC AD-S52, both 5" woofer two-ways with a multi-axis mount. However, they're both spec'd at 90 x 90 coverage, and I'd like to find something narrower to keep energy off the walls to begin with. Any recommendations?

Bonus points for a series with a companion subwoofer. Thanks,

P
Click to expand...
Not going to happen. In order to have narrow coverage-it takes SIZE-simple as that.

And for a given size-a narrower pattern will lose control at a higher freq.

Or put another way-for a given cutoff freq-a narrower pattern will have to be larger.

Yes you may find something that has a "narrower spec" HOWEVER it will only be at the extreme high freq-NOT where you are looking for. You HAVE to look at the overall pattern control (something that is sadly lacking in todays world".

Sorry-but the physics still rule and there is no way around it-despite what the spec sheet says-------------------------
 
Re: Small install spkrs with narrow coverage

Thanks for reminding me that I can't escape physics, much as I'd like to. I suppose that even if the pattern only narrowed at the extreme HF, it would still help (e.g., a single driver, run full-range, that becomes beamy in the higher octaves). My restriction here has more to do with budget than with size - we could fit a larger horn-loaded speaker, but unlikely to afford them along with everything else needed.

Dick - the ceiling is about 12 - 15' tall, open rafters. The owner plans to play video events (sports games, movies), so I'd like to keep the acoustic focal point at the end of the room with the screen. Column arrays can have precise coverage in the vertical plane, but their horizontal pattern is dictated by the natural dispersion of the drivers and their crossover (if there is one). I suppose one could always mount the array horizontally though.... I'll look into 'em, but I'm guessing that solution will be too costly as well.

Cheers,

P.
 
Re: Small install spkrs with narrow coverage

This is a classic "no win". Come up with something to satisfy the sound requirements and it'll be "too expensive".

Set up a f****** boom box at the video end and take 10% for "sound design".
 
Re: Small install spkrs with narrow coverage

Dick Rees said:
This is a classic "no win". Come up with something to satisfy the sound requirements and it'll be "too expensive".

Set up a f****** boom box at the video end and take 10% for "sound design".
Click to expand...

Basically, yes. The GM of the cafe is a friend-of-a-friend, so the assumption that I do the job for peanuts is implicit. Plus, they waited until a week before opening to contact anyone about a sound system, and want it installed by friday... riiiight.
 
Peter Kowalczyk said:
Thanks for reminding me that I can't escape physics, much as I'd like to. I suppose that even if the pattern only narrowed at the extreme HF, it would still help (e.g., a single driver, run full-range, that becomes beamy in the higher octaves). My restriction here has more to do with budget than with size - we could fit a larger horn-loaded speaker, but unlikely to afford them along with everything else needed.

Dick - the ceiling is about 12 - 15' tall, open rafters. The owner plans to play video events (sports games, movies), so I'd like to keep the acoustic focal point at the end of the room with the screen. Column arrays can have precise coverage in the vertical plane, but their horizontal pattern is dictated by the natural dispersion of the drivers and their crossover (if there is one). I suppose one could always mount the array horizontally though.... I'll look into 'em, but I'm guessing that solution will be too costly as well.

Cheers,

P.
Click to expand...

So, what sort of budget are you working with? For a few hundred bucks it is a no win.


Sent from my iPad HD
 
Re: Small install spkrs with narrow coverage

Peter Kowalczyk said:
Thanks for reminding me that I can't escape physics, much as I'd like to. I suppose that even if the pattern only narrowed at the extreme HF, it would still help
P.
Click to expand...
Let's look at the math a tad. On the QSC it looks as if the horn is 4" square. So if we say a "narrower" coverage is 60°. Then that would give pattern control down to about 4200 Hz.

Consider that the basic response (I said BASIC as in telephone response) is to about 3Khz, then you have no control over the pattern up to above the basic vocal range. And if you say that the top of the "usable" response is maybe above 10K or so-then you only have just over an octave of pattern control-in freq that are mostly harmonics and are probably getting lost when they hit the walls anyway-because of diffraction.


Just some things to think about. Is it really worth worrying about? Yes we would all LOVE for the pattern of a loudspeaker to be what the specs might suggest-but rarely is that the case-at least to any usable freq.

Remember that sound has size-and it takes size to control it. The lower you go the bigger the size-simple as that. To go an octave lower requires twice the size.
 
Re: Small install spkrs with narrow coverage

Dick Rees said:
An overhead, distributed system might be the alternative.
Click to expand...

I gotta agree with Dick on this one. An overhead distributed continuous voltage (70V) speaker system would probably be your best option here given coverage and budget. Maybe arrange it into a few volume controlled zones to allow them to adjust the coverage as needed. If they can squeeze some more out of the budget, you could look at some of Soundtube's offerings, but I don't think it will be necessary for this application based on the information given.
 
Rob Spence said:
So, what sort of budget are you working with? For a few hundred bucks it is a no win.


Sent from my iPad HD
Click to expand...

Yes, what is budget? Anything below $2k, maybe $5k, let them know what a realistic budget is, and prepare to walk. If they aren't willing to invest even a realistic minimum, why should you waste your time?
 
Re: Small install spkrs with narrow coverage

Ivan Beaver said:
Let's look at the math a tad. On the QSC it looks as if the horn is 4" square. So if we say a "narrower" coverage is 60°. Then that would give pattern control down to about 4200 Hz.
Click to expand...

What is the math that gives you this figure? I am curious because I have always understood, as you point out, that it takes a large horn to achieve pattern control at lower frequencies. What's confusing is that my Fulcrum boxes have relatively small horns but seem to have good pattern control. I have never bothered to ask those guys how they do it.
 
Re: Small install spkrs with narrow coverage

Budget is $3-4k, all inclusive (amps, processing, cabling, and my own take). I think we can do SOMETHING better than a boombox for this price. Personally, I'd rather limit coverage to a portion of the room with better quality than cheap out to get all the zones covered. Level variance is part of the goal - keep the sound in the seating area and away from the counter where staff/customer interactions happen. The owner seems amenable to implementing the system in stages - primary zones first within the initial budget, adding on later.

Regarding the suggestion for ceiling speakers: As I mentioned, I'd like to keep the focal point at the front of the room with the screen. The only approach I could think of to do this with a distributed ceiling system would be to delay successive elements moving back into the room. While this might work for some folks in the back of the room, I'd think it would create an unholy mess of multiple arrivals for those sitting near the screen. Is there a way to do this elegantly?

So, research continues, with a focus on finding a larger box with a proper horn that might fit into the budget. Or perhaps I'm over-analyzing... Thanks again for everyone's suggestions.
 
Re: Small install spkrs with narrow coverage

Information is hard to come by on this. You've said the ceiling height is 12 or 15 feet. Is it 12 or 15? Is it all one height or does the height vary??? If so, how and where? The extra 3 feet would be nice to work with.

You have not given a width or any diagrams showing the positions of any bars, counters, beams or other salient interior features. More information would help.

Last suggestion, now that there's a "budget":

JBL CBT 70J-1 in the center at the screen end with some half-round diffusers on the walls to either side at the right distance...if you have a 12' ceiling. If you have a 15' ceiling, add the 70JE-1 to get the LF extension.

I also don't recall you giving a room length, but if the single hang won't keep your SPL up towards the rear, hang another single 70-1 down the room in the middle and delay it as needed.

Please don't come back with "it must be stereo"...
 
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Re: Small install spkrs with narrow coverage

Peter Kowalczyk said:
Budget is $3-4k, all inclusive (amps, processing, cabling, and my own take).
Level variance is part of the goal - keep the sound in the seating area and away from the counter where staff/customer interactions happen. The owner seems amenable to implementing the system in stages - primary zones first within the initial budget, adding on later.

Regarding the suggestion for ceiling speakers: As I mentioned, I'd like to keep the focal point at the front of the room with the screen. The only approach I could think of to do this with a distributed ceiling system would be to delay successive elements moving back into the room. While this might work for some folks in the back of the room, I'd think it would create an unholy mess of multiple arrivals for those sitting near the screen. Is there a way to do this elegantly?
Click to expand...
I agree that a successive delay distributed ceiling system would be an unholy mess, as well as increasing cost from both hardware and install time.

I have some speakers that would work well for you and could keep you within budget, PM sent with some details.

Art
 
Re: Small install spkrs with narrow coverage

Jason Raboin said:
What is the math that gives you this figure? I am curious because I have always understood, as you point out, that it takes a large horn to achieve pattern control at lower frequencies. What's confusing is that my Fulcrum boxes have relatively small horns but seem to have good pattern control. I have never bothered to ask those guys how they do it.
Click to expand...
Freq of pattern control loss=1,000,000/(angle of pattern x size of horn mouth in inches)
 
Jason Raboin said:
What is the math that gives you this figure? I am curious because I have always understood, as you point out, that it takes a large horn to achieve pattern control at lower frequencies. What's confusing is that my Fulcrum boxes have relatively small horns but seem to have good pattern control. I have never bothered to ask those guys how they do it.
Click to expand...

Fulcrum significantly overlaps the hf with the coax woofer to gain pattern control.

Sent from my SCH-I545
 
Re: Small install spkrs with narrow coverage

Art Welter said:
I agree that a successive delay distributed ceiling system would be an unholy mess, as well as increasing cost from both hardware and install time.


Art
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Agreed.

While the idea of delaying the ceiling speakers "seems" like a good idea (as long as you keep going in the same direction) it is NOT.

This is because the downfiring speakers are not pointed in the same direction that the delay would be (ie further away gets more delay). But when you move closer to the non delayed speaker-and still hear the delayed speaker-the delay time is wrong. There is no way to set it right.

But there are also other issues to be considered. Lets say you have a stage and a ceiling distributed system. Maybe the ceiling in the room was very low.

If you don't delay the furthest speakers from the stage-then if somebody hits a snare drum (for example) you would hear the amplified sound first then the acoustic sound. This is not good.

So sometimes a set of compromises has to be struck-and often it is not easy to figure out what may be best.

As with all things-there are advantages and disadvantages to every approach. And the designer has to look at various options and consider exactly how the system will be used to get the best "overall" performance.

And sometimes you simply can't win or get it right-so it is what it is. And often the reason for a bad overall sound experience is that people are trying to do "sound" in a room that was not designed for sound, so there is only so much you can do.

I have told people "build me a room that is designed for performance and I will give you a better result".
 
Re: Small install spkrs with narrow coverage

Jason Raboin said:
What is the math that gives you this figure? I am curious because I have always understood, as you point out, that it takes a large horn to achieve pattern control at lower frequencies. What's confusing is that my Fulcrum boxes have relatively small horns but seem to have good pattern control. I have never bothered to ask those guys how they do it.
Click to expand...

Jason,

The number Ivan calculates comes from an empirical equation cooked up by Don Keele in one of his seminal horn papers from the 1970s. Ignoring mouth diffraction effects, it is a good indicator of the size a flare needs to be for pattern control at a given horn size and included angle.
 
Re: Small install spkrs with narrow coverage

Phil Graham said:
Jason,

The number Ivan calculates comes from an empirical equation cooked up by Don Keele in one of his seminal horn papers from the 1970s. Ignoring mouth diffraction effects, it is a good indicator of the size a flare needs to be for pattern control at a given horn size and included angle.
Click to expand...
And it is a good "guideline" of mouth size.

To me the most important thing is to "play with the numbers" by substituting different horn sizes and patterns into the equation to get an idea of how they interact and what the effect is.

And of course the number is not exact-as there is a large "grey area" in which the pattern is changing. it does not all of a sudden "stop having pattern control"-but is a rough idea.
 
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