Why do subs sound bloated or slow?

Bryon, I think you're on the right track but those two parameters you mentioned don't have to me mutually exclusive.

You can get the crossover point right either by ear or by measurement. Setting the time alignment (minimizing phase error) is probably more difficult, especially since most subs only offer absolute polarity or polarity inverted 180 degrees... the odds that either setting will be right by chance are near zero.

If the subs are not located in the same horizontal plane as the main speakers (and close to them) as is usually the case when they are placed in corners or close to the front wall, then unless you have subs with fully variable phase controls of at least 0 to 180 degrees, you'll need to do extensive trial and error to get the phase relationship correct between the subs and the sats. And yes, that's pretty much as hard as it sounds. The upside is that many subs offer full variable phase controls some even provide this feature via remote control so you can adjust it from the listening seat.

Frank

Well, the sub in my Home Theater sounds great for both music and movies and it aligns with the main full-range speakers seamlessly... and it's cheap! It's just set up really well (no EQ either -- digital or otherwise). So it can definitely be done, although like I suggested earlier, it's not that easy and you need to know what you're doing...

Bifwynne, thanks for your insights... at last someone gets what I was saying.

I have one sub set up in a two-channel system with Magnepans and it works quite well and another in my Home Theater (previously mentioned).

They both integrate very well and add some punch and weight on the very bottom which is all they are meant to do.

It's great that sub manufacturers are finally finding ways to do the necessary adjustments automatically because most audiophiles simply don't understand how to make the appropriate adjustments. I think that's why so many people complain about bloating and poor transient response and so have negative opinions based on their own experience (and failure to get it right).

Duke, you make a great point. The room acoustics play a huge part in getting good bass and unfortunately the majority of rooms were not designed with any thought to good sound reproduction. Many rooms are just plain horrible for proper bass reproduction.

That said, mapping the room response and selecting a subwoofer with the best characteristics for that particular room will make more difference (in many cases) than simply throwing more money into a sub thinking that just by buying an expensive product your results should be much better (not always the case...).

I will also add that I've had better luck matching subs to mains that delve below 50Hz on their own, which could be a coincidence but it's been my experience.