alignment and sound quality

[aurgathor]

I'm planning on building a sealed box with a Bravox EXS15D-4 ( Bravox EXS15D-4 Extreme Duty 15" DVC Subwoofer 4 Ohm Per Coi 269-534 ) and I wonder how much, if any audible difference will be between the Qtc of 0.58 and 0.71. I know that 0.71 will provide the flattest frequency response, but 0.58 should have a better transient response. (tighter bass, I guess)

TIA

 

[weltersys]

Don't you mean Qtc, the value of Qts when enclosed in a cabinet?
It is possible you might hear the Qtc difference outdoors, though the difference between .58 and .71 is not much.

On the high end, like a Qtc of 2,( +6 dB at resonance) the underdamped ringing may sound bad (or good to those fond of droning bass) but for Qtc values below 1, hard to hear much difference in a small room.

Much of what we think of as good transient response in a woofer is determined by how well the phase aligns with the top cabinets in the crossover region, and up there, the response of the subs, regardless of Qtc will be the same.

Art

 

[aurgathor]

Ooops, that was a typo. Yes, I meant Qtc. Corrected.

What do you mean about: " how well the phase aligns with the top cabinets in the crossover region." That's a head scratcher to me.

TIA

 

[OscarS]

he means the actual phase response of the summed system. If a woofer and a mid are crossed over into each other at 1000Hz, but the phase response varies greatly between the two drivers, it makes "pleasant sounding" integration difficult because of the crossover slope that is always present---both drivers will be playing the same frequencies near the X-over point, yet with different phase outputs can lead to partial cancellations and just flat out sound weird.

 

[aurgathor]

Thanks, I got it now.

 

[bentoronto]

he means the actual phase response of the summed system. If a woofer and a mid are crossed over into each other at 1000Hz, but the phase response varies greatly between the two drivers, it makes "pleasant sounding" integration difficult because of the crossover slope that is always present---both drivers will be playing the same frequencies near the X-over point, yet with different phase outputs can lead to partial cancellations and just flat out sound weird.

... and if you move your head three inches, or change the driver positioning an inch or two or change the test tone by a fraction of an octave, or can't actually measure the crossover components worth a damn....

There are all kinds of theoretical catastrophes not worth losing practical sleep over. Get the main design parameters right and don't sweat the trivial stuff. Good treble leads to tight-sounding bass.

Looks like quite a nice woofer. All the stuff south of 30 Hz is just show-biz and the bigger the boom the better down there.

B.