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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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In Reply to: How Is Efficiency Determined In Multiple Drivers? posted by thetubeguy1954 on April 4, 2007 at 12:33:06:
Sensitivity uses 2.83V measured into 8 Ohms irrespective of the system's impedance. Another way to say that is we'll use a solidstate amp, drive it with a fixed Voltage, and we'll see how loud the system is. Is that your frame of reference?If 'yes', here are two rules of thumb. First, each time one doubles the number of drivers and wires the new driver(s) in parallel with the 1st one(s), output increases 6dB. Half of the 6 comes from doubling the cone area and half comes from doubling the power delivered by the amp (because the impedance is halved so twice the current flows).
Secondly, each time one doubles the number of identical drivers and wires them in series, the output remains constant. That happens because in spite of the 3dB increase due to doubling cone area, the amp power is halved. Three dB plus -3dB equals zero.
Now you can count the doubling of drivers and whether you're paralleling or seriesing the new drivers and determine the aggregate output.
Also a consideration, when you get to enough drivers and IF you've configured them as a linesource, is that LSs lose only 3dB of loudness when doubling distance instead of a point source's 6dB loss per distance doubling. I'll let you struggle with that one, but surely you get some additional increase in output.
But let's get to your 93dB-sensitive driver. Adding one in parallel with the 1st increases system sensitivity to 99dB. (Paralleling these might or might not be OK for your amp; you didn't share the driver's impedance with us.) Doubling the driver count to 4, assuming the 2nd pair is wired in parallel same as the 1st pair is, and wiring this pair in series with the 1st pair, will produce the same 99dB output, but now the system impedance is back to that of a single driver. So if we started with an 8-Ohm driver, we have a 4-driver, 8-ohm system with 99dB sensitivity. Now if you wire another quad the same as the 1st quad and add it in parallel with the 1st quad, you'll have a 105dB-sensitive system with half the impedance of a single driver.
I have NO idea how this multiplication of drivers changes the bass response.
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Follow Ups
- There's a difference between speaker Sensitivity and Efficiency. - jeffreybehr 11:10:38 04/05/07 (0)
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