Response Shapes of Various Values of Qts and Qtc

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diyAudio Moderator Emeritus
Joined 2001
This chart gives you the response, whether in free air or in a closed box, of various of Q.

Free air = Qts
Closed Box = Qtc

For example, if the Qtc or Qts of your speaker is .5, you can see that it will be 6 dB down from the midpoint. Other values are given, so you can judge the response shape of most any speaker and box combo you are likely to encounter.

This is taken from an article in the Journal of The Audio Engineering Society by Richard Small.

The article is Closed Box Loudspeaker Systems Part 1: Analysis.

It is in the December 1972 issue. Also in the Loudspeaker Anthology Collection, Part 1 of the Journal of the Audio Engineering Society.

I took Richard Small's graph and caption and added some additional labelling, which is in color. Mr. Small is known for the Thiele-Small parameters, as well as many other pioneering contributions to loudspeaker design.
 

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For playing around with such types of curves for a special chassis
i like to play around with Basscad from K. Föllner.
You can enter values with the Thieles of your speaker and see it on
the fly.

The crossover simulation is neat also, cause you can switch around
on the fly also.

His site is "Selfmadehifi", unfortunately the software is only german,
but who cares with all this numbers!?

http://www-user.tu-cottbus.de/~foellnk/hifisite.htm

Wombat
 
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