Why do subs sound bloated or slow?

You shouldn't really "hear" the sub. If you do, they are too LOUD!!!

There's an element of "When did you stop beating your wife?" to this discussion. It starts with the presumption of guilt (for subwoofers) and asks for proof of innocence.

I can (and have) set up subs that sound somewhat overdamped - producing a lean sounding tonal balance (to my ear) despite flat on-axis measurements at/around the listening position on my RTA unit. My Rythmik subs allow for adjustable Q and I have backed off the most highly damped setting for just this reason. I have also heard many extended/full range speakers that sound underdamped, bloated and "slow".

The question of properly damped bass isn't unique to subs. As to group delay issues attendent to placement, endless screwing around with varying placement of subs relative to mains leads me to believe that it's a non-issue, but that would have to be qualified for related variables, including:

Crossover frequency and slope. IF these issues are actually audible at higher frequencies (and, as a practical matter, I have my doubts) , a lower crossover frequency and steeper slope would largely determine how audible they are in a given system. It would also allow increasingly greater separation as the crossover point drops and/or the sub's high cut slope is steepened. IOW, generalizations would be misleading.

The relative damping of the subs and mains at/near the x-over point. IME, there is a pretty good chance that the (sealed) sub is more highly damped than the main speaker (if not matched with care) and the qualitative result of this mismatch is hard to predict. Incidentally, this one is -again- not unique to subs. Many a 3 way full range speaker can exhibit problems in the lower crossover region.

and

The sensitivity of a given listener, among others.

Bottom line, it will be VERY difficult to prove inocence (or guilt) using the math cited here, but much easier using your ears.

Just MHO, as usual.

Marty

"There's an element of "When did you stop beating your wife?" to this discussion. It starts with the presumption of guilt (for subwoofers) and asks for proof of innocence."

Yes, good point!

Subs are not more problematic in general than most other ingredients used to produce good sound.

They can be done well or not just as easily.

One more thought re: cbw's observation that his subs are sentitive to movements of 1 inch. That would be a little extreme IME, but his point is taken. Small movements of the source of deep bass can audibly affect the perceived sound, but once again I'd be inclined to attribute this to room interactions (rather than increased group delay) and note that it, too, is not unique to subwoofers.

Marty

I should note that I didn't mean to be dismissive of Bryon's initial observation which (I assume) is paraphrased as:

"If you're gonna fix the room induced FR problems by separating the source of bass from the rest of the spectrum and moving it closer to the wall (in the form of a sub), you're gonna induce time domain issues."

Assuming that this was the original point (and I apologize if I've mischaracterized it), the issue I have lies not in the general idea, but in the use of the terms "slow", "bloated", and "zero sum".

Even if you concede that gains in FR come at the expense of issue in the time domain (and those using even cheap HTRs needn't necessarily concede this as these units generally compensate electrically for the difference in physical distance), that does not mean that these issues:

A: will be perceived as slow and bloated for time domain problems

and/or

B: will audibly cancel each other out (zero sum).

Indeed, I personally find the former orders of magnitude more audibly troubling than the latter. And I also believe that any audible effects in the time domain can be largely mitigated through careful set-up. In sum, I'd say that, in a well set-up subwoofer system, the benefits in FR obliterate any costs in the time domain.

But, as noted, that is me, personally, and I understand that others may reach a different conclusion.

Marty