What's WRONG with Subwoofers?

[Boomzilla]

OK, this'll probably be more of a rant than a question, but HERE's my answers to the title question in regards to MUSIC:

• Subwoofers don't go low enough - The average sub is designed for movie impact and has little if any response below 30 Hz. Many roll off significantly higher. For movie effects, it is only a small concession, but for music, those pieces that DO have content below the sub's roll-off suffer significantly.
• Subwoofers aren't clean enough - The average sub is designed to go loud, but without being particularly clean. Most subs don't publish distortion specs (for good reason). Those that do are one to ten orders of magnitude higher distortion than the speakers they supposedly supplement. The ability to play cleanly is of little importance for movies, but matters significantly on music. Subs that can play both loudly and cleanly usually require premium drivers & amps and cost more than their main speakers.
• Subwoofers aren't linear - This is my biggest peeve with subs. Most are designed as "one-note-boom-boxes." Again, for movie effects, who cares, but for music a linear response is necessary to accurately match the curve of the main speakers. Most subs just plain suuuuuuuck!
• Loss of stereo bass - Once crossed over to the monophonic " .1 " channel by the preamp or receiver, all bass notes below that frequency are reproduced by the single sub. For movies, who cares, but for music, there is often stereo bass information that just gets lost with a mono bass line. Even adding a second subwoofer doesn't restore this information, because both subs are still playing the (mono) output of the receiver.

OK - I've gotten my peeves out there. My preference is for a pair of full-range, floor-standing loudspeakers that don't require subs at all. Yes, this puts more of a load on the amplifier to both supply current and to control the woofers via a good damping factor, but that isn't an impossible task (unless you're driving with a gutless AV receiver). Your thoughts?

[Mr. RF62]

With a good Amplifier and a good subwoofer, you can achive the great sound that you are looking for the the $$$ a person prolly not has. A subwoofer with a high pass thru it can help with those low end passages, and unless you are listening to Beethoven(orchistral) or some organ music, I don't see why a person would need much lower then say 30Hz. But for the most part, I would agree that alot of subs just have a hump that play loud and people never get over, but THAT particular sub kicks @ss. [8-)] So just do it yourself. []

[Islander]

My preference is for a pair of full-range, floor-standing loudspeakers that don't require subs at all. Yes, this puts more of a load on the amplifier to both supply current and to control the woofers via a good damping factor, but that isn't an impossible task (unless you're driving with a gutless AV receiver). Your thoughts?

Yes, the ideal is a pair of speakers that are truly full-range. There are speakers out there like that. Wilson Alexandria Series 2s may be one example. Unfortunately, those guys cost around $150,000 a pair, so most of us compromise by getting subs to help our less-than-full-range speakers.

Is there really much music with content below 30Hz, other than some rare organ or synthesizer music? Anyway, I recall reading a thread here in the last day or two where someone mentioned his subs being flat to 15Hz or lower. It can all be done, if you're willing to spend the money.

As for the stereo bass effect, a bass instrument produces several frequencies along with every note. With a bass guitar, you hear the strings, the finger or pick on the string, maybe the resonance of the body, and even the response of the room, all at different frequencies. The higher part, the finger or pick on the string, is what will locate the instrument in space, with the lower parts of the sound being harder to localize, so your brain goes for what it can easily identify. Stereo subs might not make much difference above a certain point, perhaps 30-40Hz.

Organs and synthesizers might produce notes that are narrower in their frequency range, so you may have to spend a lot more to get the sound you like if that's your favourite kind of music.

[wim hoppenbrouwers]

Hallo. I noticed a big different in the lows with my new RF82. My old Infinity Qb went till 42 Hz , now it is 33 Hz (3dB).

Only the difference of 9 Hz you can hear very well.

We can hear now low sounds in the movies and music we never heard before.

One Q. what happens with the sound of 32 Hz? Do we hear them?

wim

[Islander]

One Q. what happens with the sound of 32 Hz? Do we hear them?

If you get a test CD or DVD you can hear for yourself. A loud 30Hz note will shake my whole room (but that may be a room resonance), but 25Hz is less noticeable. As for 20Hz, I can see by the SPL meter that the sound is there in the room, but I can't hear it at all.

Notes of 30Hz or lower are felt as much as heard, and as you go lower in pitch, you hear them even less.

Also, a difference of 9Hz would be inaudible at high frequencies, but when you get into the low range, 20-40Hz is a whole octave, so 9Hz in that region is almost half an octave, like 900Hz would be in the 2000-4000Hz octave.

[Boomzilla]

Is there really much music with content below 30Hz, other than some rare organ or synthesizer music?

Well actually, more than you might think. It isn't that there are that many fundamentals down there (unless you're listening to organ or synth), but when the frequency response begins dipping, it just loses the real. Keep in mind that the half-power level (-3dB down point) gives out at 30, the real frequency response dip begins an octave above (at 60 Hz). There's REAL music there, and it just doesn't sound like music if the bottom isn't there. Of course, most speakers and subs aint even close to 30 Hz as a 3dB down point. Most subs and speakers give up somewhere about 40 Hz. If that's the case then everything below 80 Hz is actually tipped down. Also, don't forget the Fletcher-Munson effect, which makes human hearing significantly less sensitive to bass frequencies anyway.

The higher part, the finger or pick on the string, is what will locate the instrument in space, with the lower parts of the sound being harder to localize, so your brain goes for what it can easily identify. Stereo subs might not make much difference above a certain point, perhaps 30-40Hz.

Yes, I'd agree that a mono bass line below 40 Hz should be inaudible. Most AV receivers, though, cut in the mono sub at considerably higher frequencies. Even if the user is trying to set the sub crossover down to 40 Hz, most main speakers are already struggling to produce 40 Hz. A smooth transition is unlikely unless the crossover is set at least an octave above the main speakers' 3dB down point.

[Boomzilla]

One Q. what happens with the sound of 32 Hz? Do we hear them?

wim

Actually, yeah - we can probably hear down to about 20-25 Hz with the ears. At or below that frequency, you "feel" the frequency in your chest & internal organs. At the live symphony, when the bass drum gets whacked, you not only hear the sound, you feel it (particularly if you're seated close to the stage). That's what I like to hear at home too. The low bass adds a significant amount of realism to the reproduction. Of course, with Klipsch Heritage speakers, none of them (not even the mighty K-Horn) produce actual fundamental notes below the mid 30s. Alas, a (good - even VERY good) subwoofer is needed in conjunction with the Klipsches to hear ANY real organ or synth fundamentals. Once you've heard a system that can do that, though, it's hard to do without.

Does this necessity alleviate my complaints about subwoofers - not at all. A cheap sub sounds exactly like just what it is - a cheap sub. There ARE subs that will go low, clean, and flat. They just aren't cheap! Thiel, Revel, M&K, Sunfire, and Velodyne all make some fine subs. This is NOT to say that every model from those companies is a good product - only that some of their products that I've owned were very good. Other companies may make good subs too - I just haven't heard them. The majority of "subwoofers" on the market aren't really subs at all - they're powered woofers that have no chance of reaching subsonic frequencies.

I hope this answered your question.

[JJkizak]

My RSW-12 works just fine down to 19hz and it is very loud, same as 30 hz. 40hz is a bit louder as the K-horn starts chimming in. My ears do fine on the low end but stop dead at 12khz. The SPL meteer shows all the way up to 20Khz with the Crites tweets.

JJK

[CECAA850]

All of your pet peeves about subwoofers can be conquered by building an IB. All but the stereo part, that's up to your processor.

[Coytee]

Your thoughts?

Sounds to me like you're a candidate for a Jubilee audition [A]

[DrWho]

Your thoughts?

Well since you asked.... []

Your first item "Subwoofers don't go low enough" is in direct
opposition with "Subwoofers aren't clean enough". If we assume that all
subwoofers need to cover at least 80Hz and then dig as deep as you want
to go, then digging deeper in the same sized enclosure will always
increase the distortion at the same price point. You could throw money
at the problem and go with an insane driver/amplifier, or you could
make the enclosure larger....I personally think the real problem with
subwoofers is that everyone tries to make them too small....and that is
directly impacted by the people buying the subwoofers and preferring
them to be smaller. Anyways, I'm getting off topic....the point is that
you can't have both at the same time without making other compromises.

For what it's worth, I also think way too much emphasis gets
placed on low frequency extension. I am definitely a bass freak and
want my bass deep, fat, loud, and clean, but that doesn't mean I need
10Hz extension, or really even 20Hz for that matter. Heck, I can't even
hear a 25Hz tone....I can feel it, but it doesn't sound like anything
other than air moving. I personally am not willing to give up more
distortion in the audible band for more inaudible air blowing.

I
agree with you about mono versus stereo bass though. However, I can
understand that if you want the same level of bass performance from a
mono system, then you will need to double the investment to acheive
stereo subwoofage. I wonder at what price point it makes more sense to
double the performance of your mono subwoofer, versus making the
transition to stereo with half the performance (assuming of course that
price/performance is a 1:1 ratio).

Btw, what do you mean by "Subwoofers
aren't linear"? I'll apologize in advance for being an engineer, but
are you talking about the linearity of the frequency response?
Distortion? Power Compression? all of the above?

[Boomzilla]

...Your first item "Subwoofers don't go low enough" is in direct opposition with "Subwoofers aren't clean enough"... digging deeper in the same sized enclosure will always increase the distortion...You could go with an insane driver/amplifier, or you could make the enclosure larger...the point is that you can't have both at the same time without making other compromises.

You're right if you're talking about plain cones in boxes. In fact, VERY few subwoofers rely on simple box/cone physics anymore. Some manufacturers, such as Velodyne, use accelerometers on their cones with sampling & feedback circuits to increase linearity. Others, such as Sunfire, use megawatt amplifiers to extend linearity. Most (good) sub manufacturers also include room equalization microphones and circuitry that extend the response of the sub in the specific acoustic environment in which the sub must work. These "tricks" do a good job of maximizing frequency response and minimizing distortion. Despite those tricks, you're completely right that bigger subwoofer enclosures are better subwoofer enclosures.

...I also think way too much emphasis gets placed on low frequency extension...I personally am not willing to give up more distortion in the audible band for more inaudible air blowing.

We can agree to disagree on low frequency extension, but I agree wholeheartedly that such extension shouldn't come with the pricetag of more distortion in the bass fequencies

...Btw, what do you mean by "Subwoofers aren't linear"? I'll apologize in advance for being an engineer, but are you talking about the linearity of the frequency response? Distortion? Power Compression? all of the above?

I just LOVE engineers (LOL). I was speaking specifically of the linearity of the frequency response. Thanks for asking!

[DrWho]

The problem with a servo subwoofer is that your driver needs to have
high frequency extension way beyond the intended passband in order for
the correction to actually reduce distortion. If you figure 100x, you'd
need a subwoofer that can do 8kHz (yikes). 10x is probably more
realistic (800Hz), but then the distortion reduction benefits aren't
going to be huge. I could try to calculate it out, but I'm too
lazy...it might come to around a 0.1%THD reduction or thereabouts. Btw,
I'm not knocking the Velodyne designs because they start off with
awesome drivers, but I think it's the awesome drivers that are mostly
responsible for how they sound.

As far as Sunfire, all I gotta
say is they always sound like fluttering fart boxes...even their top of
the line models [] I'm sure I would find that the Fathom F113 sounds
very similar too, but I haven't heard it yet. It's impressive what they
do in those little boxes, but I don't think the super high-fidelity
seekers would want to stop there. But then I don't suppose it's fair to
lump a house sized 10Hz bass horn into the same category? (even though
it might cost about the same).

I agree wholeheartedly that such
extension shouldn't come with the pricetag of more distortion in the
bass fequencies

And therein lies a classic engineering
problem....extension and distortion are tradeoffs. Increasing the
extension increases the distortion - it's just how the world works []
So then which becomes more important? Correlating performance criteria
to what we hear and prefer is what I like so much about audio compared
to other fields of engineering.

Sorry for all my rambling, but you did ask for my thoughts....well here they are as they came outta my head []

So what are you running in your system right now?

[Boomzilla]

...Sunfire, all I gotta say is they always sound like fluttering fart boxes...It's impressive what they do in those little boxes, but I don't think the super high-fidelity seekers would want to stop there...Increasing the extension increases the distortion - it's just how the world works...So what are you running in your system right now?

The key to using any Sunfire, so far as I've seen, is to cross them over at a VERY low frequency. If they're used in their true element (i.e. as SUB-woofers instead as of woofers), then they don't fart so much (or if they do, it isn't noticeable).

Increasing extension does increase distortion, but ONLY if all other factors are equal. The "house sized horn" you mentioned would have BOTH low frequency extension AND low distortion, for example. I must also politely disagree with you that the servo systems do not decrease distortion. Velodyne has some very good white papers on why this is so. I refer you to them on that topic.

Finally, you ax what I'm running - I ** had ** a pair of Heresy IIs crossed over at 90 Hz to a M&K MX-350-THX sub. With the sub set flat, the two 12" drivers (used to "correct" each other in the same enclosure) would produce true subsonics (all be it with higher distortion although significantly less than any other sub I've heard). It sounded good, but I finally decided that a pair of Cornwalls would be more to my preference. The sub is sold & I'm waiting to find some Cornwalls before letting the Heresies go. Yes, I'll be "subsonics free" with the Cornwalls, but I've decided that I can live with that. I'd prefer K-horns, but I've no corners. If I don't find any Cornwalls, I could consider some Revel Performa F-30s again or else I'll just go back to a %)(&*&% subwoofer.

[colterphoto1]

Your thoughts?

Sounds to me like you're a candidate for a Jubilee audition

The Jubilees dont go that low at all. On my bass test track Starship Trooper, the Moog Taurus bass pedals are almost non-existant with Jubilees.

[colterphoto1]

I think what Doc is trying to say is that 'It's all about compromise'- did I get that right Doc? LOL

[Islander]

As engineers sometimes say, TANSTAAFL (There Ain't No Such Thing As A Free Lunch).

Electrical engineers may sometimes say TANSTAANFS, meaning "There Ain't No Such Thing As A Noise Free System".

Found that in Wikipedia while reading the entry on Robert Heinlein. There was a smart dude!

[Don Richard]

Full-range speakers with response to 30 or 35 Hz, in conjunction with a "butt shaker" bolted to the listening seat gives a lot of LF impact without messing up the response and clarity of the mains.

[Mr. RF62]

Full-range speakers with response to 30 or 35 Hz, in conjunction with a "butt shaker" bolted to the listening seat gives a lot of LF impact without messing up the response and clarity of the mains.

Is a sub a sub if its inaudible??? (too Low frequency)

[Islander]

That would technically be a "real" sub, as opposed to the low-range speakers most people call subs.