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September 22, 2007 - 10:29pm
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in-celing speaker connection
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Total Number of speakers?
5
5? Are you just messing with us? Using an odd number of speakers in a stereo system? Eight speakers with four per side connected in a series/parallel combination to a receiver or integrated amplifier would work well.
no, I am not messing with any one. They are all mono speakers. Placed one per every 10 feet or so. This is a one big hall way and we placed 5 speakers on that hall way.
thanks
Just a background music system ?
Will you be extending that number of speakers at a later date or will you remain with the 5?
Normally for backgound music systems using many numbers of speakers with strange configurations, it tends to be the domain of 100V line High impedance systems rather than Hi-fi.
Pity you got the speakers first -- we have no idea of their specs.
But with just 5 speaks -- An ideal would be to choose 4 Ohm versions at about 2/3rds rated output of the intended amplifier - run in the array shown in diagram.
Look for a speakers efficiency rating in SPL(Sound Pressure Level) find something that is efficient at/or above 90db/W at 1 Meter.
Clever array design - obvious when it is illustrated so well, but I wouldn't have thought of it on my own. Well done.
Hehe - thanks Elk
Just one small anomalous issue in that phased array. Wonder
If anyone will spot it
Well, for one, it doesn't matter since the speakers have been purchased and installed with the wiring already in place.
Since this is a partially existing system I would suggest you contact a shop in your area that does such installations. They can advise you on the proper amplifier to drive these speakers. Bogen and Davis should both make models that will suit your needs at very low prices. You haven't stated whether this group of speakers will require volume controls on any of the speakers. That would change the system requirements and the recommendation for amplifiers.
If you just must do this the improper way, buy a receiver/integrated amplifier with a mono switch. Make a two speaker series connection on one speaker output to give you a 16 Ohm nominal load. The other speaker output gets a three speaker series/parallel connection to give a nominal 8 Ohm load. Use the balance control to make up any differences in level between left and right outputs and, if this is intended for background music only, you should have no real problems other than explaining to your business partners why this all looks like such a kludged together fire hazard.
If you require volume controls for individual speakers, you should buy impedance matching type controls placed either in a central switch box or at the individual speaker locations. This would solve any series/parallel connection problems you might have. As I described above, you would run one set of (two) speakers off one channel's output and the other (three) off the opposite side's output. The impedance matching devices will take care of the rest. Therefore, you would need a central switch box with provisions for at least three speaker sets. Autoformers are best for this application. They cost more but give better protection in a central switch location than a lower priced switch box which merely places a large, unsophisticated load resistor in series with the output. If you buy impedance matching volume controls for each location, you'll end up with autoformer types. Either way, at background levels, this should be fine.
The issue I see is that - assuming the speakers are identical - the speaker in series will receive a great deal more current than the other four. This may or may not be a problem, depending on desired listening level in various locations.
Spot on Erik -- the one on its own at the end of the chain will be receiving between 3 to 6 dB more than the others.