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In Reply to: RE: High efficiency + sealed cabinet? posted by hitsware on March 25, 2014 at 17:21:47
Q I take to mean resonance, but what this has to do with driver performance in a sealed enclosure I don't understand. I'd love to be enlightened. It does seem to me that some designs from the era when watts were not free used drivers such as what I am enquiring about, please correct me if I am wrong. Many thanks!
Follow Ups:
Q means many things, but where sensitivity is concerned the primary Q considered is Qes. Drivers that work well in sealed enclosures tend to have high Qes, but high Qes also translates to low sensitivity. Very low Qes will usually give high sensitivity, but at the cost of low frequency response, especially in a sealed alignment.
Thanks, so would you say that a high efficiency sealed enclosure is a sort of mutually exclusive terminology?
> Thanks, so would you say that a high efficiency sealed enclosure is a sort of mutually exclusive terminology?
Pretty much, certainly as far as low frequencies are concerned. You can use a very low Qes driver, like a JBL E130 (0.21), to realize 101dB sensitivity from a sealed box, but the f3 will be around 150Hz.
A 2 cu ft 2nd order sealed box with an F3 of 30hz can only be 0.18% efficient (84.55dB).
A 2 cu ft 4th order vented box with an F3 of 30hz can only be 0.36% efficient (87.56dB).
A 2 cu ft 6th order vented box with an F3 of 30hz can only be 0.90% efficient (91.54dB).
fantastic paper."Marketing Considerations
The biggest problem with the sixth-order vented system (V6TH) is the rather anemic looking 200 mm (8 in) driver in the 2 ft3 box (the marketing department won't like it).
But now lets look at that 380 mm (15 in) driver in the closed-box system (Wow, we can really sell that one !). Well, maybe we can put a 300 mm (12 in) or 380 mm (15 in)
passive radiator with that 200 mm (8 in) driver in the vented sixth-order system and come up with a sellable package (this system is quite close to the Electro-Voice Inc. system
described by Newman in (6.,7). "
Karlson Evangelist
Edits: 03/25/14 03/25/14 03/25/14
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