Will a subwoofer add depth and clarity to my system, or just bass?

More Audiokinesis gold:

The ear simply does not have the time-domain resolution to hear a slight timing mis-match in the subwoofer region. The ear is UNABLE to even detect the presence of bass energy from less than one full wavelength, compared to which small timing errors are insignificant. What the ear IS very good at, is detecting SPL differences in the bass region. This is implied by the bunching up of equal-loudness curves south of 100 Hz. So the ear can indeed hear something going on as you fine-tune the phase control, but what it’s hearing is the effect on the frequency response.

If the main speakers are a bit muddy in the upper bass, you can have the subs overlap them a bit and then use the phase control to dial in some cancellation, thus improving the clarity.

I’ve had many customers claim to hear an improvement in clarity from the addition of subs without highpass filtering the mains, and I’ve heard it too, but cannot explain it, apart from the occasional situation described in the preceding paragraph. Of course there is also the improvement in clarity that can come from highpass-filtering the main speakers to reduce cone excursion, in which case the transparency of the highpass filter can be a factor.

Regarding adding a sense of depth or sense of envelopment/immersion, if you have two subs, you can place one at either side of the listening position and dial in 90 degrees of phase difference. This will tend to synthesize hall ambience. Credit to David Griesinger for this idea. The 90 degree phase difference ("phase quadrature") will also tend to improve the modal smoothing.

Sometimes adding a subwoofer to a tonally well-balanced system tips the spectral balance to the dark side. When that happens, we can bring balance to the force. We can add a rear-firing tweeter to just nudge the spectral balance back to normal, without messing up the imaging by adding another source of first-arrival sound.

Duke

More pure gold. I’ve copied the whole post just to pose a pop quiz and see if anyone can answer: what one single letter best differentiates Duke’s highly informative post from all the rest?

Hint: to understand the answer is to understand the problem.

Today’s post is brought to you by the letter "S".

The letter "S" has the Super Power of being able to turn singular into plural. But not always! Due to a design flaw it can only do this when used at the end of a word. Luddite Forces in the Audioverse exploit this weakness. In a typical mind-trick they say, "This is the subwoofer you are looking for." See what they did there? The original quote was, "These are not the DroidS you’re looking for." They dropped the "S"! Pulling you back, always back, to the singular.

It’s a trap!

Don’t go over to the Dark Side. Unleash the power of the letter "S". Use four subs.

You can lead a horse to water....

And I totally believe that you are quite capable of hearing when you had the correct phase setting. I just think you are most likely hearing the frequency response improvement that arises from your phase optimization

- audiokinesis

Hey Duke that is an interesting point you raised there. Reading between the lines you seem to be implying two distinct aspects- timing and frequency response. The way I've been thinking of phase is it sort of emulates location. Like, if the wavelength is 10 feet and you move the speaker 5 feet its the same as 180 degrees in phase. Yet I know that's really simplistic, its not just the one 10 ft wave that was shifted they all are. So is that why the setup (if I even understand that fully!) is first to get the four subs located one by one for flat response, and then fine tune with phase? To minimize messing up timing in the process of trying to get flat response?