A variation of flanking sub

[goldyrathore]

To smooth out bass Wayne recommends stereo flanking subs to smooth out the 80hz-200hz region and distributed subs for region below 80hz.

Below is a variation of the flanking subs using a bandpass sub where the subs have two sound sources due to placement of the ports which are diagonally placed. Flanking subs are placed closer to the floor and the bottom port just does the same. The top port is above the speaker height and thus quite far from the bottom port. This is intended to smooth out 200hz AND below to 50hz (first mode). The top port is a few feet apart from the bottom one and so the sub is more like distributed sub rather than a co-located one.

To further smooth out the initial few modes, the 50hz-80hz region may also be decorrelated by some form of cyclic change of phase from +-90 degrees.

Will it work to produce a smooth bass.

Note: Two drives are used for less vibration and to have more displacement area since below 50hz the driver is acting like a sealed one, its not related to the idea.

Thanks,
Goldy

 

[weltersys]

The top port is above the speaker height and thus quite far from the bottom port. This is intended to smooth out 200hz AND below to 50hz (first mode). The top port is a few feet apart from the bottom one and so the sub is more like distributed sub rather than a co-located one.

Will it work to produce a smooth bass.

Goldy,

Your diagram could represent "A", a slot loaded ported cabinet, both the slot and ports producing sound, or the slot area could be sealed, "B" all output emanating from the ports.

In either case, most of the low frequency output will be from the ports, assuming an Fb around 50 Hz, any distance the ports are apart less than about 5.65 feet is within 1/4 wavelength, virtually the same location. At two feet apart, the ports are co-located for most of their output.

In the case of "A", output up to 200 Hz will make the output location easily identifiable, instruments and vocals will wander in location between the main speakers and the "sub" location depending on output level of each and the notes (frequencies) being played. In the case of "B" it is unlikely that much more than an octave (50-100 Hz) will be produced smoothly.

So the short answer is no, it won't work to produce a smooth bass.

Art

 

[goldyrathore]

most of the low frequency output will be from the ports, assuming an Fb around 50 Hz, any distance the ports are apart less than about 5.65 feet is within 1/4 wavelength, virtually the same location. At two feet apart, the ports are co-located for most of their output.

So the short answer is no, it won't work to produce a smooth bass.
Art

Hi Art,

Its a normal 4th order sub as far as the ports are concerned (there are no slots), actually there are 2 subs placed opposite for separate physical locations. While the direct output of the ports indeed places them within 1/4wl at low frequencies, however they do interact with the room at different places. Isnt it true that bass response changes even if the source (or listener) is moved by even a few feet in which case this should work. A distance of ~4 feet can be achieved this way between ports.

Thanks,
Goldy