[Jazz B.]

I own a retail store which currently has cheap ceiling speakers. I have purchased 4 Mirage FX speakers with Omnipolar technology. I am hoping that these will help fill the store with much better, and even, sound.


The problem is, I don't know where to mount them. The store is 18ft wide x 55ft long with 17ft ceilings.


I plan to mount each speaker approximately 4-5 feet from each corner and aimed at the center of the store. Due to the design of the store, I can only lower them about a foot from the ceiling. I was told that I should mount these speakers upside down to take advantage of the omnipolar technology?


The wife works at the store full-time and I would like to make her day more enjoyable with decent sound rather than the annoying ceiling speakers that double in volume when you pass directly underneath them.


Any comments on my proposed installation?


Thanks!

 

[tadcu]

Hi Jazz B,


Mounting all speakers on the short walls 4-5 feet from the corners, (with the room being approximately 3 times as long as it is wide) will concentrate more sound at the ends of the room leaving a bit of a "hole" in the middle; the speakers would be approx 9' apart from each other on the room's short walls but 55' apart down the length of the room.


For more uniform sound distribution, mount 2 of the speakers near the corners BUT on opposite long walls and mount the other 2 staggered down the long walls, as follows: (consider the long walls as N and S...and the short walls as E and W)

1st speaker - mount on N wall at approx 7' from the NW corner

2nd speaker - mount on S wall at approx 21' from the SW corner

3rd speaker - mount on N wall at approx 34' from the NW corner

4th speaker - mount on S wall at approx 48' from the SW corner (i.e. 7' from the E wall)

(Simply: length of the room divided by speaker quantity and staggered across the room evenly from the end walls and down the room. With 4 speakers to utilize, the fact that the room is so narrow in relation to the length contributes to the speakers being much closer to each other.)


Yes, the omnipolar design should be mounted upside down. With that said, the Mirage FX model (I have Mirage OMD-5's and OMD-15's at home) appears to be a reasonable-quality speaker. But in a room the cubic volume (LxWxH) of yours and mounted at 16' AFF (above finished floor), there will be limited output volume and bass at listener level. Nonetheless, without knowing what model your ceiling speakers were and where they were located in the ceiling, I'd still guesstimate that the new sound will be lots better...and more evenly dispersed

Cheers.

 

[Wayne A. Pflughaupt]

I was going to recommend installing your speakers equidistance along one of the 55’ walls at ~9 ft. intervals, as that would get the best (read most even) coverage throughout the room given the narrow dimensions.


But then I noticed that you’re going to mount them 16 ft. up, so I don’t know. Wall-mounted speakers would sound best at ~8-9 ft high.


Your salvation might be the Omnipolar technology, so yes they should be inverted. (Actually, any speaker installed more than a foot or so above head level should be inverted.) However, the bracket the FX’s come with might preclude inverted mounting? I don’t think corner placement would work well unless you can get them tilted downward, and again I have my doubts that the stock bracket will permit this. As tadcu noted, a "hole" in the center of the room is a highly possible situation.


Four better-quality ceiling speakers, evenly spaced front-to-back I think would be a better option and give the best (again, most even) coverage. I can’t imagine why you’re getting a “beaming” effect with your current ceiling speakers. That shouldn’t be an issue with ceilings as high as that. Maybe you just don’t have enough of them installed to provide even coverage?


Other considerations: The speakers should be fed a mono signal. Stereo does not work in background commercial situations.


Also, if you were using ceiling speakers, they are typically 70-volt. If that’s the case, your Mirages won’t work with your current amplifier unless it has an 8- or 4-ohm output. And you’ll have to make sure you configure the speakers for the correct impedance load.


Regards,

Wayne A. Pflughaupt

 

[tadcu]

Jazz B.,


It's probably of minor concern at this point, and while respecting Wayne's valuable comments, standard commerical sound system design is that speakers should be half the distance from the end walls as they are from each other. In layman's terms: this is because speakers propagate their sound to the left and right sides (as well as top and bottom). So, placing the 1st speaker approx 7' from the end wall with it's sound progating 7' to each side means it "meets" the edge of the sound from the next speaker that's placed 14' away.....and so on.


And, as Wayne said, normal system design does indicate wall-mounted speakers should be located considerably lower than where you said you have to mount them.


With regard to stereo/mono: again standard commercial design indicates, as Wayne noted, that it should be mono. Yet, with your room proportions and a high mounting location, a stereo configuration could actually work out without a listener hearing only "half the music" (designer jargon meaning only one of the stereo channels). You would alternate the R and L channels as you progress down the room.


An appropriate stereo amplifier (i.e. one that is "happy" living with a 4 ohm load or even lower), could mitigate the usual requirement for a 70V commercial amp. I'm assuming, perhaps incorrectly, that you're on a budget.


In the commercial A/V integration world, we would not normally make the above suggestions with regard to consumer amps and stereo but in reality I've observed and heard dozens of sound systems with consumer amps (as long as they are robust models that can handle low impedances) and some with stereo layouts that work out well in rooms similar to yours. Where commercial 70V amplifiers (almost always mono) are really necessary is when/if you need an odd number of speakers or more than 4 speakers, when you need different types of speakers in different areas, when you need to control the volume separately in different areas and other design considerations.


Best regards to you both.

 

[Jazz B.]

Thank you very much for the detailed responses!


I am using an old Kenwood stereo amp that is rated at 100w x 2 or 50w x 4 at 8ohms. I have a Sansa Fuze Mp3 player connected to the amp using a headphone jack to L-R RCA adapter.


Since it is reccommended to use a mono signal, would a stereo to mono adapter work? Or am I better off converting all my MP3s to Mono? I have googled this option but I can't find the best way to combine both L and R channels into a mono signal.


Thanks,

Jazz

 

[Wayne A. Pflughaupt]

One way is to use the 10k version of this .


Regards,

Wayne A. Pflughaupt

 

[tadcu]

I'm with Wayne. The RDL-10k is the only passive off-the-shelf solution I found for converting stereo to mono in your application. I always specified it for new installations until we began modifying patch cords into y-connecters with the necessary resistor network. Our service techs always had them on their trucks.


I wouldn't convert MP3s to mono. Among other reasons, you might want to use your MP3 library elsewhere.


Circling back to my earlier comment: if you install the speakers down the length of the room as Wayne and I suggested (and mounted at 16 feet as you indicated), before you purchase the RDL you might listen to the system in stereo. If you hear an absence of one stereo channel as you walk down the room, it's a simple "fix" since the RDL goes right between the music player and Kenwood (no changes to speaker wiring).

 

[Speedskater]

An interesting thread on a similar question:

http://www.diyaudio.com/forums/pa-sy...ds-advice.html

 

[Gizmologist]

 http://www.soundsphere.com/


To convert an amp's 8ohm output for use with 70 transformer-equipped speakers, a large 100-400 watt, 70 volt matching transformer can be used if wired in reverse. The 8 ohm secondary goes to the amp and the 70v primary goes to the field line to the speakers.


Peavey makes a very robust transformer with all the data to configure the system

 

[Jazz B.]

I wanted to revive this thread just to say thanks to all the members who helped me out.


The speakers sound great mounted right side up. Although the soundstage sounds a little high (just above the head), it sounds MUCH MUCH better than the ceiling speakers. The wife finds herself turning up the music alot louder than normal because she enjoys the sound so much!


This is a great forum! Thanks alot!