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previous: Terry This is an interesting point, about... -- 1/25/1999 8:41 AM View Thread

Re: speakercabs; Thiele?

1/25/1999 9:24 AM
Re: speakercabs; Thiele?
I would recommend you get the book "Loudspeaker Design Cookbook" by Vance Dickerson (sp?). I think this would be better for learning a little about various types of speaker enclosures, rather than just jumping into a black box calculation program. The basic equations (although iterative) are simple enough to solve with the help of graphs, and you'll develop a better feel & understanding of what's going on as you vary one or more parameters.  
Ported cabinets, with decent bass response, for drivers having relatively low Qts figures, usually require a box with a volume on the order of 2 to 3 cubic feet. The basic reason for ported enclosures is to recover some of the cone's back wave, in phase with the front wave, and to suppress or attenuate the impedance peak near the driver's resonant frequency. Closed cabinets tend to provide rather even damping for smoother overall response, but unless they are very large will restrict the cone's motion. This smaller box arrangement can be a good thing to control over-excursion of the driver's suspension, but deep bass response may be compromized.  
There are many different T-S alignments, all giving different bass rolloff responses using different box sizes. For a guitar, you don't need (or want) bass response down to 30 hz. Thus, you can use a box smaller than optimum for better high output cone control with a cutoff frequency well above the drivers natural resonant frequency (Fs). The driver will last longer (as long as it can take the heat) if it's motion is restricted.  
Get a couple books. You'll learn a lot for little investment.