Why do subs sound bloated or slow?

I have $15,000 speakers in a 2 channel system and the subs make them sound much better. My RELs are in the corners, where REL recomends that they be.

If you have good speakers in a 2 channel system a sub is not necessary. Use it for tv.

Thanks for the responses so far. In the OP, I wasn't trying to suggest that all subs sound bloated or slow. I was trying to identify some reasons, WHEN subs do sound bloated or slow, WHY that is the case.

Undoubtably, some of those reasons involve the design of the subwoofer itself, as Shadorne indicated. But I have noticed that, even with a well designed sub, seamless integration into a 2 channel system is very challenging. In the OP, I was proposing a theory that explains why sub integration into 2 channel systems so often fails, namely that it tends to result in one of the following scenarios:

1. Good transient response but poor frequency response. Hence "bloated."
2. Good frequency response but poor transient response. Hence "slow."

The reason why the above scenarios are so common, I believe, is because the measures taken to optimize frequency response are often bad for transient response, while the measures taken to optimize transient response are often bad for frequency response.

Has anyone else had this experience during sub setup?

Bryon

Mine are the REL B 2 (pairs) and are far to be bloated and slow ..........

Some people just plain and simple do not like bass no mater what it sounds like . I think many of them chime in their dislike of subs .

One reason they sound slow is if you have them placed the same distance as your speakers. Placing the sub as close to the listening position is best. The bass notes take longer than the mids and highs to reach you if they are placed next to your speakers.My rel t2 $800 msrp is placed 2 feet from my chair .Which also makes changing the volume on it very easy when neccesary.Never place it in a corner as you might for home theater. I sugest to anyone to try this location. You will not be dissapointed .

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...

It is much cheaper to make a subwoofer that plays bloated and slow - so that is mostly what you find.

It is extremely expensive to make a subwoofer with low distortion, significant SPL output below 30 Hz and a good transient response (low group delay). It requires a very large sealed box with a very expensive high quality large woofer.

I owned a REL Strata III and found it a very fast and tight sub. I have also heard subs that did not sound as calibrated...so it really depends on a number of things.

Room placement and crossover frequency will also affect the sound.

Under many circumstances, optimizing frequency response and optimizing transient response is a zero sum game.

Here’s what I mean: Much of the time and effort that goes into subwoofer setup is spent optimizing frequency response. That is typically done in one of two non-mutually-exclusive ways: Sub placement or digital EQ. Either of these approaches can result in a much flatter frequency response, making the bass sound less bloated. But both of these approaches can result in a sub-optimal transient response, due to the time misalignment between the sub and the mains. That makes the bass sound slow. To elaborate…

If placement is used to optimize the sub’s frequency response, then the sub often winds up closer to or farther from the listener than the mains, thereby misaligning the sub relative to the mains. Alternatively, if digital EQ is used to optimize the sub’s frequency response, then a processing latency is introduced into the sub’s the signal path, but not into the main’s signal path, thereby misaligning the sub relative to the mains. Hence either approach to optimizing frequency response can disturb the system's transient response, making the bass sound slow (or “out of sync”). On the other hand…

If you set out to optimize transient response, you will usually place the subs on a plane very close to that of the mains. Now the bass no longer sounds slow. But, due to room modes, this kind of placement often results in a highly uneven frequency response. Now the bass sounds bloated again...and so on.

The result of all this is that, when trying to optimize both frequency response and transient response, you often have the experience of chasing your tail. That is what I mean when I say that, under many circumstances, optimizing frequency response and optimizing transient response is a zero sum game. I do believe that there are solutions to this problem, e.g., the use of software that independently controls the EQ and the delay of both the sub and the mains. But most audiophiles who use subs don’t seem to avail themselves of that kind of solution, which can result in their systems sounding bloated or slow.

Bryon

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