Not enough information for what type of space is system used for. Is it background or intrusive like abercrombie & fitch stores designed to force the parents of teenagers out of the store asap? What type of music? What's the TV for? What size? Do you play movies with sound or just silent? What's in the space, i.e. carpets, tables, clothes, etc., etc. etc.? A layout of the space would help. |
A retail space with ambient, background music is a much different environment than a dedicated listening space. I would go with companies that specialize in directional loudspeakers for those types of spaces, e.g., Meyer Sound, Holosonics, etc. |
I do a fair amount of work on the prosound side, in addition
to my home audio designs. My speakers are used every
weekend in live gigs all over the country.
The key to high quality sound in a big room, like your 24 x
90 foot room, is speakers that have well-controlled
radiation patterns and smooth off-axis frequency response.
Here's why: The direct sound from the speakers, or first-
arrival sound, only dominates at close range, typically
about 5-15 feet (depending on how directional the speakers
are). Beyond that distance, the reverberant energy in the
room dominates the perceived tonal balance. And the off-
axis response is what dominates the reverberant field. So
if you want good sound for everyone else in the room, you
need speakers that do a really good job with the reverberant
field, which means they need to do a good job off-axis.
High quality PA speakers are designed to do this. So are
some home audio speakers, and they tend to look like PA
speakers. The type of radiation pattern you want depends on
where the speakers will be located. For example, if they
will be on the long wall, you'll want a much wider radiation
pattern than you would need if they were on the short wall.
In fact you might even want to use four smaller PA-style
speakers (two on each side in a splayed array) to give
adequate coverage if they will be on the long wall.
As for bi-amplifying, unless you are skilled at setting up
active crossovers, or have access to someone who is, I
recommend going with speakers that have a good passive
crossover already built in. In a high quality application
the crossover provides equalization tailored to the specific
drivers, and that's the part that takes some expertise to
get right.
The same tradeoffs exist for this application as for any
other: Box size vs bass extension vs efficiency. If you
can get away with large boxes, you'll have deeper bass
and/or higher efficiency. How important are low end
extension and SPL in this application? Does "TV"
= "action movies at high volume"?
Duke
dealer/manufacturer |
"The key to high quality sound in a big room, like your 24 x
90 foot room, is speakers that have well-controlled
radiation patterns and smooth off-axis frequency response. "
No doubt. |
If it's really a single, integrated space, it's hard to believe that one pair of speakers is the best solution. Since SPL falls off at a square of distance - folks sitting 15 feet from the speakers are going to experience something quite different from those sitting 50 feet away.
You might consider running your stereo input from the preamp into that ATI four channel amp and coming out full range into two pairs of stereo speakers spaced at thirds along the 90' wall. I'd have to think that's a more workable solution for most applications. |
The inverse square law (SPL falls off with the square of
distance) applies only to the direct sound. In a room,
there are two primary components of the sound field: The
direct sound, and the reflected or reverberant sound.
Unlike the direct sound, the reverberant sound is just about
constant in SPL (approximates a "steady state") throughout
the room. Up close to the speakers, the direct sound is
louder. Then as we move back, the direct sound falls off in
SPL according to the inverse square law, but the reverberant
sound stays just as loud. At some distance they become
equal in loudness, and then at greater distances the
reverberant sound is louder. There is some continued
falloff in overall SPL all the way to the back of the room
as the direct sound's contribution gets weaker and weaker,
but that falloff is asymptotic rather than linear, with the
reverberant field setting the lower limit.
(I've made a few simplifying assumptions here, such as
ignoring room boundary effects, lumping early & late
reflections together, and glossing over the transition zone,
but the general principles described are valid.)
Duke |
Duke,
While I completely agree that reverberant sound will mitigate the delta in SPL (from near field to distant listening), I don't think that's the relevant question here. The real question is: Will it mitigate the delta enough to be the optimal solution for the OP's application?
In almost every large commercial space that I can think of: Nightclubs and bars, restaurants, gyms, hair salons, retail stores, etc. - the preferred solution is multiple speakers. Shy of a combination retail/performance space (or possibly a pro-sound store), I'd think that very few retail businesses operating in anything like the OP's 90' by 24' room that would be best served by a single set of stereo loudspeakers - even if the power response of the speaker is essentially perfect over a very wide window.
According to the OP, he is not selling audio equipment. I am curious, are you suggesting that you think a single pair of loudspeakers is likely to be his best solution? |
Imo multiple speakers done right might be a better solution, depending on what the OP is trying to accomplish. But done wrong, they would be a worse solution, from what little we know (a TV screen is sometimes involved).
If multiple speakers are used, then we should time-delay the outputs of the speakers that are farther away from the TV end of the room. Otherwise listeners will get clarity-degrading arrival time miscues - they'd hear the side speakers first and then the front speakers, and the ears would localize the sound from where it first arrives, which would be distracting if the sound is supposed to come from the TV screen. Even with such time delay, there may still be areas of good and poor intelligibility within the room.
Unamplified music, from quartets to symphony to choral groups, is "played" from one end of the room only and people seem to not mind. So too with most amplified bands, but the average amplified band is seldom the paragon of clarity.
Without knowing what the purpose of the room is, it's hard to say what the optimum system would be. It may well be multiple speakers, properly delayed.
Duke |
