Why do subs sound bloated or slow?

Spatial issues are not that important in the LF as we are talking only a few milliseconds with waveforms that are 50 milliseconds long at 20 Hz. A PEQ will delay only a few milliseconds also so no big deal.

Group delay can be a lot more than a few milliseconds and can be a problem as it can add delays that are equivalent to moving your sub 30 feet....

Transient response is important but spatial positioning of a sub is not the big deal you make it out to be - as long as sub and speakers are within a few feet of being the same distance to the listener then no big deal. Of course this argument only holds for very low frequencies and a mere 2 milliseconds can be important at 1 KHz

The answer is simple. Its because people stick there ultra powerful subs in a corner, which throws massive boom, and is often far away from the mains as well. I have been saying the same thing here, and nobody seams to get it. Put the sub under the center channel, between the mains.....put your electronics in the corner! If you do this all the problems are gone. In the older days subs stunk IMO, even the good ones cant compare to subs now. Back then corner placement was about added db gain(they still never blended right then either). These days, putting these huge, powerful subs in the corner is rediculous. The ONLY way I would try a corner placement is if you were running the sub under 40HZ. Otherwise it never sounds right to me.

Why dont you put your main speakers against a wall, or corner? -Bloated, muddy, heavy bass, right? So why do it to your sub? I ran my sub at 100HZ with my Magnepan 1.6's and in the center position you would NEVER have known it was coming from the mains. Phase/distance issues are GONE!

I dont like any subs sound placed out of center.

01-24-11: Shadorne
Spatial issues are not that important in the LF as we are talking only a few milliseconds with waveforms that are 50 milliseconds long at 20 Hz.

Shadorne - I agree that, at 20Hz, which is a wavelength of over 50 feet, and which corresponds to a time scale of around 50 ms, a few milliseconds of time misalignment is probably no big deal. But what about at 80Hz, which is a wavelength of about 14 feet, and which corresponds to a time scale of around 14 ms?

Let's say the delay introduced by EQ is something like 2-4 ms, and that the delay introduced by placing a sub in the corner, when the mains are out in the room, is something like 3-6 ms. In systems that combine corner placement with EQ, you might have a delay between 5-10 ms. All of these numbers are an appreciable fraction of 14, the number of milliseconds that corresponds to a wavelength of 14 feet and a frequency of 80Hz.

IMO, this math illustrates that the use of EQ and/or the use of corner sub placement could introduce delays that result in significant time misalignments. As to whether those time misalignments are audible, I can only say that, from my experiences with sub setups, differences of LESS THAN A FOOT are easily audible, even in circumstances where there is little or no difference in frequency response.

Transient response is important but spatial positioning of a sub is not the big deal you make it out to be - as long as sub and speakers are within a few feet of being the same distance to the listener then no big deal.

You may be right that I am exaggerating the importance of time alignment at low frequencies, though it is not my intent to exaggerate. My view about the importance of time alignment at low frequencies resulted from about 2 years of periodic experimentation with placement, EQ, and delay. But I suppose the view I'm advancing might be considered unconventional. Though, if it is unconventional, then why do several different manufacturers of full range speakers make an effort to time align their drivers, INCLUDING the woofers?

It seems to me that the importance (or lack thereof) of time alignment at low frequencies essentially depends on the human limits of temporal resolution at low frequencies. The limits of temporal resolution has been studied in depth, where estimates place it on the order of magnitude of MICROseconds, with some estimates placing it as low as 5 μs. But these studies tend to measure higher frequencies. I do not know the human limits of temporal resolution at lower frequencies. If they are anything even vaguely approaching those of higher frequencies, then it would lend credence to the idea that time alignment is audible at low frequencies, making time alignment an important consideration in subwoofer setup.

Bryon

"Many subs have group delays of up to or more than 1 cycle. Of course this is audible."

I don't remember the exact group delay figures used in the study I read, but they were consistent with what one would expect from a well-designed vented system. Using digital signal processing, group delay was isolated from frequency response (don't ask me how they did it). On test signals group delay was slightly audible, but on music it was statistically inaudible. The audible effects normally attributed to group delay were replicated by a frequency response curve mimicing the high group-delay system, even if the group delay is eliminated by DSP. So while large group delay correlates very well with perceived "slowness" in the bass region, it is not the actual cause.

I currently have my subs next to my mains, slightly forward. They are sensitive to movements of one inch. I can play a passage and it will sound right, but if I move the subs an inch forward or back, and it's out, and stays out if I move it farther. In previous setups, I've been able to introduce a delay to the mains relative to the subs (in Pure Music, for example), and I had the same results: the coherence of the sound was sensitive to delays that were a fraction of a millisecond.

So time alignment is crucial, and I don't think the subs will ever be truly integrated in a system until that is achieved. I think once it is tackled, EQ is available to deal with the frequency response of the room. That's my current approach, and I don't think I've sacrificed much, except that there are subwoofers sitting in not-inconspicuous locations in my living room.