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Old 6th January 2004, 02:36 PM   #1
BAM is offline BAM
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Default Two questions of speaker theory

I have a couple questions concerning loudspeaker theory. These might be a little advanced, and the first one is highly theoretical (though I might use the second one in a design if it will work).

1. If you have drivers that you want to equalize in order to extend the low-end response (by compensating for the driver's natural rolloff), and you want to use a bass-reflex box, would you simply lower the Fb so the point at which the air in the port is damping the woofer's motion is adjusted to compensate for increased excursion at these lower frequencies?

2. What do you get when you are tuning a big bass reflex box and you adjust the air volume of the box so that the necessary length of the port is equal to 1/4 of the wavelength of Fb?
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Old 6th January 2004, 02:47 PM   #2
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Yes.You can lower the Fb..the response looks overdamped.Then EQ that response
www.linearteam.dk winisd pro,get the update too.

What do you get when you are tuning a big bass reflex box and you adjust the air volume of the box so that the necessary length of the port is equal to 1/4 of the wavelength of Fb?

You get a Transmission line with a box acting like a filter(daline style)

And i dont think you want a miniature TLine
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Old 6th January 2004, 03:28 PM   #3
sreten is offline sreten  United Kingdom
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Quote:
1. If you have drivers that you want to equalize in order to extend the low-end response (by compensating for the driver's natural rolloff), and you want to use a bass-reflex box, would you simply lower the Fb so the point at which the air in the port is damping the woofer's motion is adjusted to compensate for increased excursion at these lower frequencies?

A sixth order bass reflex alignment requires an overdamped 4th
order reflex alignment. To do this you must drop the port frequency.
The 2nd order Q = 2 to 3 high pass filter is centred on the port
frequency, so maximum boost is at the point the port is maximally
loading the cone.

sreten.
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Old 6th January 2004, 03:35 PM   #4
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Or just play around
Ofcourse u DO need knowledge for using box programs! the program doesnt tell you when ur doing a bad thing,like EQIng 20db below resonance causing distortion....

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