Hi Navin ,
First I would never recommend targeting closed box Qtc above ~0.6 if the box is supposed to be placed near a wall/floor boundary.
IME, Lower end flat or slightly peaking speakers should always be away from walls if mid bass muddying sound is to be avoided.
IMO a T-TQWT isn’t more complex to build and is far more forgiving if deviating from a correct dimensioning and the box is self-bracing as using only 3 dividers (one divider + 2 bracings).
Your slim corner suggestion would IMO, be difficult to get right if not the 4 drivers are placed in separate compartments and placed at positions where the acoustically gain is similar and not counteracting.
If you put the drivers in a row at of bottom of a tall 9’ stuffed pipe you are asking for trouble, as there would be passband resonance losses.
See the submitted picture where this is simulated (pipe closed) compared to if the drivers are mounted close to each other in a less tall box near the floor corner.
Open up an aperiodic terminus would make it worse: the f-3dB will decrease and if the (aperiodic) port is at the ceiling corner the output will introduce more or less a dip centered at about 63 Hz based on a 9’ pipe and ceiling height.
A T-TQWT has only one terminating port hole that if done right can be placed very close to a PI/8 corner where any room boundary are at an even low distance allowing flat acoustic gain for the whole passband below 80 Hz with no introduced FR dips.
b
First I would never recommend targeting closed box Qtc above ~0.6 if the box is supposed to be placed near a wall/floor boundary.
IME, Lower end flat or slightly peaking speakers should always be away from walls if mid bass muddying sound is to be avoided.
IMO a T-TQWT isn’t more complex to build and is far more forgiving if deviating from a correct dimensioning and the box is self-bracing as using only 3 dividers (one divider + 2 bracings).
Your slim corner suggestion would IMO, be difficult to get right if not the 4 drivers are placed in separate compartments and placed at positions where the acoustically gain is similar and not counteracting.
If you put the drivers in a row at of bottom of a tall 9’ stuffed pipe you are asking for trouble, as there would be passband resonance losses.
See the submitted picture where this is simulated (pipe closed) compared to if the drivers are mounted close to each other in a less tall box near the floor corner.
Open up an aperiodic terminus would make it worse: the f-3dB will decrease and if the (aperiodic) port is at the ceiling corner the output will introduce more or less a dip centered at about 63 Hz based on a 9’ pipe and ceiling height.
A T-TQWT has only one terminating port hole that if done right can be placed very close to a PI/8 corner where any room boundary are at an even low distance allowing flat acoustic gain for the whole passband below 80 Hz with no introduced FR dips.
b
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I think your idea i nicer. Are you suggesting the use of multiple drivers or just one? The other idea your suggestion raised was a Tapped horn as disucssed in the collaborative tapped horn project in the link below.
http://www.diyaudio.com/forums/subwoofers/97674-collaborative-tapped-horn-project-350.html
Horizon,
have you see the Quarter Wave website. It can offer you many ideas.
Quarter Wavelength Loudspeaker Design Gallery
i see for long time thread is dead well. adding some interesting link for you guys YouTube - Rotary Subwoofer - Worlds Lowest Freq Subwoofer
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