Understanding subwoofers

[SHB]

It seems that most audio fans and reviewers don’t really understand the advantages subwoofers bring to your listening experience other than more low bass.

• If you use stereo subs and set your crossover to around 200Hz, you can increase the dynamic range of your system by 6dB or more. If you’re using small two-way speakers, the increase will be in the more area. This is not an insubstantial improvement.

• Running a stereo setup with the subs covering the first decade of the audible range will decrease harmonic & intermodulation distortion by an order of magnitude and eliminate Doppler distortion altogether. This will improve the reproduction of all audio below 500Hz.

• You can stick your subs in the corners where they’ll perform best and place your mains where they sound best in your room.

• Subs are the only speakers where buying more will improve your system’s sound. The more subs you have, the more dynamic headroom you have and the less distortion you’ll have in your room. Two subs are better than one. Four subs are better than two.

• Regardless of their size, all loudspeakers’ area of poorest performance is the lowest octave they can render. That’s the region where distortions skyrocket and phase/temporal anomalies increase logarithmically.

Even with sealed subs, there’s no way of getting around it. What the sub can do is move that region to the area where our ears are least sensitive to group delay and THD.

Since very few instruments have fundamental notes below 30Hz, banishing the majority of nonlinearities in your speakers to an area that is very rarely used by music is just smart design.

• Whether you’re running stand-mount or floor-standing speakers, not having your mains being rattled by low bass will improve their sound. It’s a small consideration, but could still make an audible difference.

• Having a modular, upgradable system just makes more sense than using a monolithic box. You can build a truly great speaker system over time rather than trading in for ever larger speakers that don’t quite cut it.

• Sub/sat systems are truly the prime option today for not only the best audio reproduction, but also the best return on investment.

Even that hideous, idiotic, $788k, alleged greatest speaker ever (not) by those douche bags at Wilson Audio is essentially a sub/sat system. They were just stupid enough to bolt the mains to the subs.

 

[levimax]

Sub integration is not nearly as easy as many make it out to be and true full range speakers have some advatages so things are not as clear cut as many believe. Once you move the subs more than 1/4 wavelenth of the crossover point away from the mains you give up all the advantages of having a point source (time domain accuracy, larger sweet spot, stereo bass). At that point you hope you can find locations in the room for the subs that smooth the FR and are actually available. If that happen you will end up with smoother response, poor time domain behavior, mono bass, and a very small sweet spot. The other issue is that due to do the nature of LF and small rooms gating is not possible and FFT is much less accurate so it is very difficult to get accurate LF timing measurments for proper integration.

In my experience trading some FR smoothness for much easier integration, better time domain performance, bigger sweet spot, and stereo bass you get with full range / colocation is often worth it.

 

[Devnull]

This makes no sense. Subs in the corner of the room crossed at 200 Hz means you lose localization cues. Subs spread around the room should only be used below 80Hz or so, this way they can't be located. You are also assuming that the sub has clean frequency response to well above 200 Hz which a lot of don't because they weren't designed to run that high.

To integrate even 2 subs much less 4 subs properly you need to have a decent amount of patience and a bunch of DSP available. Now throw in crossing them up in the localization frequency range and you've opened another can of worms.

 

[DanielT]

• If you use stereo subs and set your crossover to around 200Hz, you can increase the dynamic range of your system by 6dB or more. If you’re using small two-way speakers, the increase will be in the more area. This is not an insubstantial improvement.

A question of definition. Two subwoofers in stereo + crossover 200 Hz. Should this be considered subwoofers or bass boxes?

If you place two two-way speakers on the two stereo subwoofers/bass boxes, in my eyes it becomes more or less two three-way speakers.

Since very few instruments have fundamental notes below 30Hz, banishing the majority of nonlinearities in your speakers to an area that is very rarely used by music is just smart design.

For my part, I'd rather have a good midbass punch with a fairly high SPL capability with relatively low distortion than dig down to 20 Hz. Or 30 Hz..maybe even, almost 40 Hz I can compromise in that case.
Both would be preferable but it costs a fair amount of money to get.

 

[levimax]

Both would be preferable but it costs a fair amount of money to get.

If you are willing to go DIY big enclosures and big pro drivers, low and clean and high SPL bass doesn't have to cost a lot of money. Big subs will also play clean at very high SPL at much higher frequncies than smaller subs. If you colocate with the mains at a higher than normal crossover ~ 200 Hz you will have punch and slam of your dreams and be able play low and clean and have enough headroom to use DSP (including wise DSP boost) to get FR more or less as smooth as distributed subs. I see size as the real cost more than dollars.

 

[robh36062]

They were just stupid enough to bolt the mains to the subs.

Agree to disagree. Nothing wrong with stacking subs under mains. You are putting your mains and listening position in the 3 best acoustically "correct" locations where room modes are minimized. It can work quite well. This is how you would place a full range speaker so no real difference.

Rob

 

[Oddball]

• Sub/sat systems are truly the prime option today for not only the best audio reproduction, but also the best return on investment.

I agree with the general principle. Also with the concept of separate modules. You can choose to co-locate mains and subs, or not - whatever works the best. But couple of points.

Building a high SPL system (say 110dB at 200hz @MLP) to handle peaks with acceptable distortion and otherwise acceptable response/dispersion will require careful choice of main speakers. Compromising to lower peak SPL will make things easier. Lots of people are saying that they are listening at 60-80dB, which is fine as personal preference. I would myself always build a system for full immersion and almost life-scale reproduction for the moments you really want to enjoy the content in that way.

Subs are in that respect easier. Buying 2 initially and then if needed expanding to 4 would provide better response and some more headroom aka lower distortion. The size of the subs/amps is really driven by room and goal to reach certain SPL at certain low frequency.

Bass management and integration of subs and mains is a bit of a pickle though. But also many ways to do it more or less right and enjoy the endgame. I would not cross anything at 200hz (if not co-located) as for a number of people (me included) that is way past the localization. That will also be sub dependent as some subs also start to raise in distortion above 100 or so hz.

Devil is in the detail, so even after choosing the right speakers for one's use, understanding bass management and integration is really important.

 

[Steven Holt]

I hope that people are reading between the lines in this excellent post (thank you SHB). There is not one mention of the BRAND of sub -- a sub from Dayton Audio (check them out, they make really good stuff) will work just as well as a sub from SVS or REL for MUSIC applications. I can't speak to HT, that's somewhat of another animal. And please, pay attention to Oddball's post above, especially the last line -- he's dead on.

 

[SHB]

Agree to disagree. Nothing wrong with stacking subs under mains. You are putting your mains and listening position in the 3 best acoustically "correct" locations where room modes are minimized. It can work quite well. This is how you would place a full range speaker so no real difference.

Rob

I actually use two stacked subs under LS50s for speaker stands. I wasn’t going to leave it that way unless it worked which, because of the odd geometry and the acoustic treatment in my room, it does.

My point about the Wilson’s is only that you have no option.

 

[SHB]

I hope that people are reading between the lines in this excellent post (thank you SHB). There is not one mention of the BRAND of sub -- a sub from Dayton Audio (check them out, they make really good stuff) will work just as well as a sub from SVS or REL for MUSIC applications. I can't speak to HT, that's somewhat of another animal. And please, pay attention to Oddball's post above, especially the last line -- he's dead on.

As a bassist, I’m quite enamored with the subs that Rythmik makes. I have four of their L12 servo subwoofers.

Playing my six string bass through my home theater sounds awe inspiring.

 

[suttondesign]

Truly deep, powerful bass without too many response irregularities down to 20hz is a game-changer and extremely pleasurable. I have only been able to achieve it in domestic rooms with multiple subs.

 

[sigbergaudio]

Many super-expensive high-end top-of-the-line systems are actually sub-satelite systems, I'm always baffled why it's not done more.

 

[SHB]

A question of definition. Two subwoofers in stereo + crossover 200 Hz. Should this be considered subwoofers or bass boxes?

If you place two two-way speakers on the two stereo subwoofers/bass boxes, in my eyes it becomes more or less two three-way speakers.


For my part, I'd rather have a good midbass punch with a fairly high SPL capability with relatively low distortion than dig down to 20 Hz. Or 30 Hz..maybe even, almost 40 Hz I can compromise in that case.
Both would be preferable but it costs a fair amount of money to get.

Item 1: Po-tay-to, Po-tah-to… who gives a crap. If you eliminate all of the distortion your mains will be producing trying to reproduce low bass, it sounds awesome regardless of semantics.

Item 2: As a bassist, mid-bass punch is a fallacy. Fundamentals above a Middle E (82Hz) on a bass have no punch. Thumb hammer on open E string… that has punch.

Nothing sucks more than a wimpy Low B note (30.5Hz) with its fundamental 10dB below its first harmonic (61Hz). It sounds weird.

Again, my point is about moving all of the major group delay and distortion artifacts to a region below the common music spectrum.

 

[DanielT]

Item 1: Po-tay-to, Po-tah-to… who gives a crap. If you eliminate all of the distortion your mains will be producing trying to reproduce low bass, it sounds awesome regardless of semantics.

Item 2: As a bassist, mid-bass punch is a fallacy. Fundamentals above a Middle E (82Hz) on a bass have no punch. Thumb hammer on open E string… that has punch.

Nothing sucks more than a wimpy Low B note (30.5Hz) with its fundamental 10dB below its first harmonic (61Hz). It sounds weird.

Again, my point is about moving all of the major group delay and distortion artifacts to a region below the common music spectrum.

Okay you have a point. If we talk about 200 Hz cutoff frequency it doesn't matter what you call it then; subs, bass boxes and so on.

What you say about As a bassist, mid-bass punch is a fallacy.. was interesting.

 

[robh36062]

I actually use two stacked subs under LS50s for speaker stands. I wasn’t going to leave it that way unless it worked which, because of the odd geometry and the acoustic treatment in my room, it does.

My point about the Wilson’s is only that you have no option.

Hello

OK with any full-range system you don't have a choice and the Wilson's do not have separate bass modules it's integrated into one enclosure. Now if you are saying that all full-range systems should be manufactured with accompanying subwoofers, limiting the main systems to HT category boxes that's a hard sell.

That said I do use subwoofers to help out 40-50Hz systems to both extend lower and take the heavy lifting off their woofers effectively bi-amping them at 80Hz. It helps

Rob

 

[Oddball]

Many super-expensive high-end top-of-the-line systems are actually sub-satelite systems, I'm always baffled why it's not done more.

My best bet is that people are anxious about sub integration and also making their large towers "obsolete". Both are not accurate assumptions. Sub integration is easier than one would think and large tower will still play clean and loud in above 100hz range. Change overall is difficult, so not all take it well.

 

[thcdru2k]

Subs clearly help with extension, headroom, and lowering distortion in the mains. The catch is integration. Once they are not co located or crossed higher, you can trade point source behavior for smoother response and more output. Whether that is a win depends on timing and phase alignment.
So it is less about sub vs no sub, and more about how well the system is integrated overall.

 

[Oddball]

Subs clearly help with extension, headroom, and lowering distortion in the mains. The catch is integration. Once they are not co located or crossed higher, you can trade point source behavior for smoother response and more output. Whether that is a win depends on timing and phase alignment.
So it is less about sub vs no sub, and more about how well the system is integrated overall.

Right - but with all we have at our disposal nowadays, if sub is not well integrated it would imply that the one integrating is is not up to the task, or in milder case just out of budget?

 

[Sokel]

Going up to 200Hz(!) with subs (which ones have clean output all the way through up there without gobs of distortion?) is effectively trying to built a 3-way.
Anything other than co-location is out of the picture there (even above 120Hz) unless one wants male voices to sound like coming from cave-like mouths.

And then is integration. One must have extensive abilities and gear to measure and integrate a 3-way as a whole (anechoically, on a turntable, away from boundaries, etc, the works )

Or are we confusing subs with stuff like W371A or the upcoming Ascilab bass stand which are build and measured for bespoken applications, etc?

 

[MKR]

Or you can have full range mains with cardioid down to 40Hz, monopole to 20Hz, side (of MLP) cardioid subs to 40Hz, dual monopole ULF to 15ish Hz directly behind MLP. Finish it off with center tower with cardioid to 40Hz … sounds real good to my ears

More than one way to skin the proverbial cat (sorry cat lovers)