I'm considering the design of subwoofer for the mini home theatre in my bedroom area. I want the lowest bass possible in a 2-3cu ft max enclosure. The obvious choice here is the ACI SV10, as it has a huge xmax and doesn't need a lot of enclosure volume to play deep. In a ported enclosure of 2 cu ft with an Fb of 21Hz it plays impressively deep with an F3 of about 23Hz.
_BUT_ group delay reaches around 25ms at 20Hz in that alignment. Will this result in noticably 'loose' bass?
[Edited by Ignite on 10-29-2001 at 05:29 PM]
_BUT_ group delay reaches around 25ms at 20Hz in that alignment. Will this result in noticably 'loose' bass?
[Edited by Ignite on 10-29-2001 at 05:29 PM]
I believe that the Shiva drivers can be used in enclosures almost as small as 1 cu foot. Also have a look at Dayton's Titanic series of drivers. They have good output in relatively small sealed enclosures.
There considerable disagreement regarding how audible bass GD is. It seems pretty safe that say that 25ms won't be audible at 20Hz.
I think it is noticeable. 25ms delay means it sounds as if the speakers should be 340*0.025=8.5m moved to the back. 25ms is 180 degress for 20Hz, which is surely audible. It also depends on the top frequency of the sub.
I too face this problem .... given the wild phase changes and group delays of a ported enclosure, would it be possible to make some kind of parametric EQ that could cancel most of this out?
Perhaps, but probably not.
The only way to eliminate group delay is to change the timing of output at certain frequencies... something I have never heard of being done aside from per-driver timing.
I've opted for the design I was talking about to have a sealed enclosure and equalize for deeper bass.
The only way to eliminate group delay is to change the timing of output at certain frequencies... something I have never heard of being done aside from per-driver timing.
I've opted for the design I was talking about to have a sealed enclosure and equalize for deeper bass.
For those desiring more info on the GD topic here are a couple of references
Blauert, J. and Laws, P "Group Delay Distortions in Electroacoustical Systems"
Journal of the Acoustical Society of America
Volume 63, Number 5, pp. 1478-1483 (May 1978)
"The Differential Time-Delay Distortion and Differential Phase-Shift Distortion as Measures of Phase Linearity" by Marshall Leach,
JAES, Vol. 37, No.9, September 1989
Blauert, J. and Laws, P "Group Delay Distortions in Electroacoustical Systems"
Journal of the Acoustical Society of America
Volume 63, Number 5, pp. 1478-1483 (May 1978)
"The Differential Time-Delay Distortion and Differential Phase-Shift Distortion as Measures of Phase Linearity" by Marshall Leach,
JAES, Vol. 37, No.9, September 1989
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