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#1
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Number of drivers, power, and db output
Lets say we have a subwoofer driven off a 500W amp and it can output
120db at a specific distance. Lets now assume that we have the same sub driven off a 250W amp and it now produces 117db at the same distance. (120db – 3db for half the power). Finally lets add another identical sub driven off another identical 250W amp and it also produces 117db. What will produce more output, the single 120db sub driven off the 500W amp or the two 117db subs driven off the two 250W amps? |
#2
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Computer Prog wrote:
Lets say we have a subwoofer driven off a 500W amp and it can output 120db at a specific distance. Lets now assume that we have the same sub driven off a 250W amp and it now produces 117db at the same distance. (120db – 3db for half the power). Finally lets add another identical sub driven off another identical 250W amp and it also produces 117db. What will produce more output, the single 120db sub driven off the 500W amp or the two 117db subs driven off the two 250W amps? In theory the output will be the same, in practice you may be able to get better loading with the pair, in particular if you are using horn loaded boxes then the increase in effective mouth area can be a big win. Also voice coil heating may be less of an issue with the pair of 250W units. I would be careful of comb filtering issues if I was using a pair of subs which were less then 10 feet apart but were too far apart to couple. Regards, Dan. |
#3
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"Computer Prog" wrote in message
om Lets say we have a subwoofer driven off a 500W amp and it can output 120db at a specific distance. Lets now assume that we have the same sub driven off a 250W amp and it now produces 117db at the same distance. (120db - 3db for half the power). Finally lets add another identical sub driven off another identical 250W amp and it also produces 117db. What will produce more output, the single 120db sub driven off the 500W amp or the two 117db subs driven off the two 250W amps? Presuming that the subs are linear, the amount of energy transferred into the environment is the same due to conservation of energy. However, two identical subs will not have the same radiation pattern as either sub. Two subs radiate their energy over a slightly smaller region, because the larger effective diaphragm will be more directional. If the measurement position is some distance from the subs, the SPL at the measurement mic will be higher for the two identical subs, presuming conventional side-by-side mounting and otherwise normal use. |
#4
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#5
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Yes, I was thinking somewhere along the line, doubling up on woofers
actually gives you +6 dB, instead of +3 dB. I haven't used it in a while, so I'm pretty rusty. |
#6
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"dangling entity" wrote in message om... Yes, I was thinking somewhere along the line, doubling up on woofers actually gives you +6 dB, instead of +3 dB. I haven't used it in a while, so I'm pretty rusty. It's true that two woofers at 50% drive power produce more output than one at 100% drive; this is because of 'mutual coupling'. For this to work, the drivers must be in a cabinet configuration that benefits from mutual coupling. I can attest from personal speaker building experience that it gives more bang for the buck to have two drivers instead of one, AND you improve reliability by lightening the burden on either driver. -- Take care, Mark & Mary Ann Weiss VIDEO PRODUCTION . FILM SCANNING . DVD MASTERING . AUDIO RESTORATION Hear my Kurzweil Creations at: http://www.dv-clips.com/theater.htm Business sites at: www.dv-clips.com www.mwcomms.com www.adventuresinanimemusic.com - |
#7
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"Mark & Mary Ann Weiss" wrote in message link.net...
It's true that two woofers at 50% drive power produce more output than one at 100% drive; this is because of 'mutual coupling'. For this to work, the drivers must be in a cabinet configuration that benefits from mutual coupling. There is no magic involved. Any competent dual-driver design minimizes the coupling between the drivers. For instance, this is achieved simply by putting two identical drivers in a single box and feeding them with equal amplitude and phase. |
#8
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On Wed, 20 Oct 2004 16:30:17 -0400, "Arny Krueger"
wrote: "Computer Prog" wrote in message . com Lets say we have a subwoofer driven off a 500W amp and it can output 120db at a specific distance. Lets now assume that we have the same sub driven off a 250W amp and it now produces 117db at the same distance. (120db - 3db for half the power). Finally lets add another identical sub driven off another identical 250W amp and it also produces 117db. What will produce more output, the single 120db sub driven off the 500W amp or the two 117db subs driven off the two 250W amps? I think we have been here before. . . Presuming that the subs are linear, the amount of energy transferred into the environment is the same due to conservation of energy. Well yes, 500 watts of power in, 500 watts of heat out. The room warms up just the same. However, two identical subs will not have the same radiation pattern as either sub. Two subs radiate their energy over a slightly smaller region, because the larger effective diaphragm will be more directional. If the measurement position is some distance from the subs, the SPL at the measurement mic will be higher for the two identical subs, presuming conventional side-by-side mounting and otherwise normal use. |
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