How do I know if I need a sub woofer?

It can be difficult. You don't know what you are missing if you can't hear it.

I had a nice pair of ADS L-810II speakers that I purchased new in the late 70's. They were a "full range" speaker and really nice example for that era, still in use by my little brother. With my present, way short of state of the art system, I am frequently shocked by low frequency information that I never knew existed.

I presently have a pair of KEF R3 Meta bookshelf speakers with dual HSU subs. Those subs are essentially flat to around 20hz. I hear (and feel) low frequency music that just was never there before, even on decent headphones,

A subwoofer's job isn't only shoringup bass. 

Room bass management of nodes and anti nodes because... Physics of sound vant be circumvented is why one needs a subwoofer or two.

Has nothing to do with playing low alone even though that is a key objective

Depends on what your listening objectives are.  Home theater- subs can come in handy.  Mostly 2-channel music, you would be better served by using speakers that can supply ample bass bandwidth.  

The sad reality is that unless you have full range speakers (usually very large $) AND sufficient current (not just watts) to drive them you need subs.  Sigh. 

You will know, if, you are not happy with the low frequencies your speakers put out.

First, you want at least two subs, and second there are very few systems that wouldn’t benefit significantly from subs.  Anyone who tells you differently hasn’t heard decent subs properly set up and dialed in.  Not only will your in-room bass improve but also imaging and an expanded 3D soundstage.  Once you listen with good subs you won’t wanna listen without them. 

I agree with soix.

Agree all systems benefit from an appropriate pair of subs...

you can't sleep at night!

There are all kinds of technical reasons, but the ultimate answer is, What do you hear, or miss?

Go to a live performance of chamber music and listen to an acoustic bass (instrument). Chamber, because there is more chance to hear the bass by itself. Acoustic, to get a direct feel for how an unadulterated bass instrument sounds and feels.

Then listen to similar music on your system. You will hear the bass differently. If the bass lacks depth, or floats strangely around the room, *and if you want to try to improve those shortcomings*, then you might try subs.

Cheers.

Thanks everyone. You have given me a lot to think about....I hope this doesn't keep me awake tonight.  Elliot what should I do if I have trouble sleeping...

The room will have a big influence on wether you need subs or not. 

Seems most add subwoofers for the following reasons:

• fill in bass for standmount speakers 
• adding more bass energy 
• Improving fidelity- seamlessly fills in bottom end and supports up to midrange 

Sound meter app + streamed white noise will inform you for certain. 

Subs? We don't need no stinkin' subs.

I think well integrated any sub is worthwhile, the problem is the "well integrated" part is often a beast to achieve.  

So, to quote the Bard, "what dreams may come must give us pause and make cowards of us all." 

Start by measuring, and considering your room first.  An untreated room may have far too much treble already.  The room may be giving you a lot of bass in the wrong areas.  Room treatment and careful EQ may be a better starting point.   Use the AM Rock room mode simulator to help en sure your speakers and listening position are in the right spots.

If considering a sub, where will you put it?? The room simulator will help you find  an optimal location. 

my point is, as audiophiles, if we need a sub, we subconsciously know it, and don't sleep well.

buy a stereo pair of front facing subs, no ports, and locate them adjacent to your mains, to you gain more lows and get the directionality contributing to imaging that the overtones give.

As long as you own good speakers that (1) comfortably reach down to the low 30Hz range, whether floorstanders or bookshelves, and (2) have reasonably wide horizontal and vertical dispersion, you don’t need a subwoofer. I’m talking strictly about music listening. The problem with subs for music is that they are very difficult to blend seamlessly with the main speakers, especially in terms of pace and texture.

Movie watching is a whole different story.

Just be careful reading measurements...lots of speakers rated -3db at low/mid 30's, are doing that measured at very low volume and very very close to the speakers...and are not even close to that at 10 feet away at full listening volume...that's why a pair of subs can make a huge difference in many ways..and while 1 sub is difficult to set up, 2 are much easier...

@jl35 +2

Mike

As long as you own good speakers that (1) comfortably reach down to the low 30Hz range, whether floorstanders or bookshelves, and (2) have reasonably wide horizontal and vertical dispersion, you don’t need a subwoofer. I’m talking strictly about music listening.

@lanx0003  That’s just simply not true.  Along with bass there’s considerable information below 30Hz that conveys sense of space, expands soundstage, and improves imaging.  I’ve heard this on several $100k+ systems (along with my own where my speakers go down to 28Hz @ -3dB) where the speakers went well below 30Hz and when the subs are turned off the soundstage just collapses along with a good level of overall enjoyment.  

…there’s considerable information below 30Hz…

+1 @soix - it’s obvious once you hear it 

Maybe you haven’t heard a truly good system that delivers excellent imaging and soundstage without the aid of subwoofers. At audio shows, high-end systems are usually not demonstrated with subs. Dealers want to highlight the unique, inherent sound characteristics of their speakers and electronics—not the contribution of a subwoofer. On the rare occasion when a subwoofer is present in a demo room, the first thing I (and many other audiophiles) ask is, *“Is the sub on?”* If the answer is yes, the immediate request is usually to turn it off.

Listen, I don’t wish to argue with you—especially on this subject. My personal conclusion, based on numerous trials with one or two subs from AR, SVS, and REL (brands known for musicality), is that none of these experiments have been satisfactory to my taste. Even when I carefully dialed in the position, crossover, phase, and volume, and set high/low-pass filters to leave headroom for amplification, EQ, and other fine adjustments, the results still fell short in terms of pace and texture. Larger woofers sitting in separate boxes, driven by separate amplifiers, are just extremely difficult to blend seamlessly compared to the integrated subwoofer designs you find in speakers from companies like GoldenEar.

And yes, I did miss out on those sub-30Hz information, but I would rather have a coherent, natural presentation of the music than be distracted by non-integrated bass floating around my listening space and ruining my appetite.

If you have a 2 speaker stereo setup I suggest getting a sub.  Probably 2 depending on the room.  Even with a soundbar setup a sub helps the sound in my experience.  

@elliottbnewcombjr....buy a stereo pair of front facing subs, no ports, and locate them adjacent to your mains, to you gain more lows and get the directionality contributing to imaging that the overtones give.

Your comment may work very well with -6dB sub-bass woofers as their dramatic mid 30hz roll off does not excite a rooms bass modes despite the main speakers often being located in a middle of the rooms extra low frequency draining null.

-3dB subwoofers require very precise standing wave bass mode room positioning to enjoy the subwoofers delicate extra low frequency potential which is present on many recordings.

Unfortunately there are no requirements to qualify using the word subwoofer. Fortunately manufacturers such as REL and Perlisten publish their low frequency limitations. Buyer beware.   

I have large speakers with 15" woofers that are spec'd to 30 hertz.  When I measure my in-room response I have strong output to 20 hertz, the lower limit of my analyzer.  I would still like to have subs but space and monetary concerns have kept me back.

A long time ago my speakers were Dahlquist 30i's which were considered full range but I felt the low end was too polite and I picked up a 15" Velodyne sub just to see what a sub would do in my system.  As expected, there was no increase in slam but the low end reached much lower, which I did like.  I picked up a second sub mostly because I could tell where the sub was when listening and I wanted to even out the output.

What I didn't expect was the change in soundstage on live recordings.  I attended a lot of large venue rock shows back then and with the subs I had a lot more of a feeling of the venue space.  I reasoned that in a large hall or stadium there was a whole lot of subliminal sound that I could now hear-- noise produced by the shuffling of thousands of feet, people talking and eating, and more stuff that was producing low frequency sound that I just hadn't been aware of in the recording until I added the subs.  It added a whole new dimension in my room, and made those live shows much more realistic.

The setup I have now plumbs the depths pretty well but not like those subs did, and I miss the environment they provided.  But to get what I think I would like would require large subs that reach real low with high output, and a pair of such would be physically imposing and lots of $ so I get by with what I have....

Bill

Room size and acoustics factor into bass levels which is why you need to measure to truly know what is missing or not. 

Maybe you haven’t heard a truly good system that delivers excellent imaging and soundstage without the aid of subwoofers.
 

@lanx0003  Well yes I’ve heard plenty of those systems, and it’s clear you’ve never heard good subs properly dialed in or you’d understand what I and several others here are saying, but clearly you do not.  Saying something ignorant like subs aren’t needed if your speakers go down to 30Hz just underscores you’ve no idea what you’re talking about here and what subs done right can actually do.  There’s a reason companies like Magico, Wilson, and others make subs costing into five figures, and it’s not just to pair with monitors.  Case in point, here’s a Stereophile review of the Wilson LōKē sub paired with the Alexia V that go down to 19Hz where the subs made a substantial improvement not only in the bass but in the overall soundstage.  Pretty much says it all and completely debunks your position. 

https://www.stereophile.com/content/wilson-loke-subwoofer

From the conclusion of the review…

I expected bass to be bigger, deeper, and more fleshed out with the LōKē. That it certainly was. What I did not expect was the ability of Wilson's smallest subwoofer to enhance every aspect of the listening experience—especially the sense of space. As the soundstage grew deeper, wider, and more coherent, as soundstage boundaries became more evident, as air between and around instruments and voices increased and the quality of music reproduction rose to mesmerizing levels, my appreciation for the transformative potential of the LōKē grew exponentially.

I am happy with the sound....enjoy listening to music...have an incredible fleshed out sound with delightful micro dynamics that make the music accessible. So why would I need a subwoofer? 

For all the reasons listed above.  It makes everything better when done right.  I bought two and it took my system to the next llevel, improving soundstage depth and width as well as imaging.  Of course it also filled in below where my stand mounts cut off.  I would not build another system without them.  

**Maybe you haven’t heard a truly good system that delivers excellent imaging and soundstage without the aid of subwoofers.

Well yes I’ve heard plenty of those systems...

Okay, you had. Then I am not concerned that you might be as ignorant as you were on the other subject like the cable impedance issue. So let me ask you if the soundstage is already ’excellent,’ why do you need an additional subwoofer to artificially expand it. What you experienced is likely the reverberation added by the subs, going beyond what the actual music content presents. Remember, my bullet #2 in the original statement already covers my requirement for soundstage.  Don’t just quote the bullet #1.

My system renders a soundstage wider than my speakers, which are set 11 ft apart, and deep enough that at times I feel like I could walk into it when such music content is in the recording. The height also resembles the actual performer’s presence. What more could one reasonably want from subs?

So let me ask you if the soundstage is already ’excellent,’ why do you need an additional subwoofer to artificially expand it. What you experienced is likely the reverberation added by the subs, going beyond what the actual music content presents.
 

@lanx0003  The sub is reproducing frequencies and information not previously presented by the speakers because they can’t.  That’s not artificial, it’s just uncovering more of the recorded information that’s already there.  If you think that’s artificial then you go ahead and believe that. 
 

What more could one reasonably want from subs?

Did you not read the review of the Wilson sub?  That’s what good subs properly set up can provide and perfectly coincides with what I’ve heard, and that’s in a system that likely makes yours look like a toy in comparison.  If you wanna just go on convincing yourself that your system is perfect and subs would provide no benefit and are artificially enhancing sound then live happily ever after in denial, but as I and many others here have heard for ourselves you’re not even aware of what you’re missing.  Ignorance is bliss.

@sounds_real_audio “l am happy with the sound”

No need for a sub. “(l)….Have an incredible fleshed out sound”

You said it yourself. “So why would l need a subwoofer?”

So in this case, there appears to be really no need to waste any more time offering further advice in this discussion.

Next question …. 

@soix  Ignorance is bliss.

Speak for yourself, Mr.  Stick with your crappy streamer and DAC, and keep convincing yourself that you managed to blend in subs seamlessly. Do you even own a $9,000 Wilson sub? I suggest you stop recommending outdated gears or things you’ve neither owned nor auditioned for a meaningful period of time.

@ronboco I was thinking the same thing with respect to room size.  My system is in a large room with concrete floors.  I have the floot space to locate a sub on the outside of each main (full range towers) .  It sounds great.

But, if my system were in a small room, I don't think I would want subs. My speakers would probably do fine without them.  I think subs would be difficult to integrate in a small room.  I'm just guessing.  

You just might be surprised at what you're missing, in any case won't know until you've tried. Most are agreed this more than about filling in missing freq. This as much about improved sound staging through the cues offered by those lower freq that are either missing in action altogether or rolled off in main speakers. I'm getting nearly flat freq response down to 33hz in my room at listening position, subs not doing a lot here, but the added low freq cues greatly improved sense of spaciousness, could never go back to no subs.

And yes, I agree it may be hard to provide a coherent presentation when adding subs, I tired for years and absolutely could not achieve the kind of coherence I was seeking. I was and am extremely sensitive to coherence to the point I had to quit three way speakers for two way and single drivers for nearly a decade. Going back to three ways via present Khorns, took me years of listening and mods to bring these up to my requirements. Adding a pair of REL's really completed the picture,  with careful setup I've been able to achieve wonderful coherence. 

By the way there is nothing 'artificial' in adding subs. Subs are simply reproducing freq info contained on recordings, attaining flatter freq response and hearing those cues which improve sound staging is simply exposing what's contained within any particular recording.

I listen to a lot of old jazz, a lot of it on records recorded and made 50 or 60 years ago.  Mono, early stereo as well as re-issues.  My main speakers go low enough I reasoned.  Besides, a lot of those records had to have the lows cut off so the crappy arms of the day wouldn’t jump right out of the record grooves.  I figured I didn’t need subs.  Paul McGowan kept harping about them, though, and my dealer agreed so finally I sprung for a pair of REL 212/SX.  Keep in mind now there is no information on most of the old records I like to listen to.  The RELs are set up so you would never know they were on...until you turn them off.  All of a sudden the room collapses.  It is like stepping from a big open space into a closet.  Of course I had to try listening to things with some real bass too.  And lo and behold the rafters do shake when the spiffy material is on the turntable.  But that is not the point at all.  It is all about opening up the space.  One other thing I have to comment on without wanting to pick a fight with anyone.  I was in the high end hifi business for almost a decade while I was in college and part time for a few years after graduation.  I have attended a lot of hifi shows.  Personally, I have never heard a good sounding anything at any show ever.  

And yes, I agree it may be hard to provide a coherent presentation when adding subs, I tired for years and absolutely could not achieve the kind of coherence I was seeking. I was and am extremely sensitive to coherence to the point I had to quit three way speakers for two way and single drivers for nearly a decade. Going back to three ways via present Khorns, took me years of listening and mods to bring these up to my requirements. Adding a pair of REL's really completed the picture,  with careful setup I've been able to achieve wonderful coherence. 

Congratulations! I admire your persistence. I’m guessing you added a pair of T/5s (33 Hz)? I tried to make a single T/5x work in both my larger living room and a moderately sized master bedroom. Yes, the experience was better than with SVS subs in terms of coherence, pace, and texture. The sense of spatial cues was impressive, and I even told a colleague I wouldn’t go back to the pre-subwoofer era.

Nevertheless, when the pace of the music picked up, the sub couldn’t quite keep up with the beat. My Buchardt S400 MkII, in a moderate space, delivered more articulate bass notes down to 35 Hz (-3 dB) effortlessly, even more so than with the subs. The Linton’s bass notes were even more nimble and agile. Of course, the definition of ‘coherence’ is subjective and varies from person to person. I enjoyed the augmented soundstage, but the trade-off in pace / texture held me back.

At this point, with an enhanced soundstage from upgrading my digital front end—including streamer, DAC, and cabling—I honestly don’t miss the subwoofers. I feel I’ve already achieved what they offered. The extra reverberation and lingering decay from subs no longer appeal to me; I now prefer a similar soundstage with pinpoint instrument separation and clearly defined imaging.

Well, to sub or not to sub—that’s the question with no definite answer. I can see why many people prefer having one(s), but I also understand others, myself included, who feel no real need for it.  The last thing you should do in this civilized community is castigate people for having legitimate differences of opinion.  You probably know who I am talking about.

The other question would be, should I get sub(s) or use that money to get better speakers...

Pair of REL T9x, a single sub has never worked for me.

Understood.  Empirical evidence has suggested dual works better than one in terms of better elimination of nulls caused by room mode but it does not resolve the pace issue.

buy this, enjoy it? DONE! Sleep well.

https://store.christianmcbride.com/products/christian-mcbride-edgar-meyer-but-who-s-gonna-play-the-melody?srsltid=AfmBOoplzVr4lJta9Vyk8pj2s6H5GbaJdzpJFFdCzAH_byXcoVAySgeo

Edgar usually plays Cello, but it’s two Upright Bass this time (and they both play a little piano).

This, similar is almost 50 years older

https://en.wikipedia.org/wiki/Double_Bass_(album)

My friend has a situation where he often wonders if he needs a sub, especially after listening here, but I usually conclude after listening at his place that he really has enough in his listening space. 

I brought this LP to his place, we thoroughly enjoyed it, I’m sure he slept better that night.

Sometimes, just because you can doesn’t mean you should, it’s a blessing to be happy with what you have.

i.e. Spikes below speakers. I didn’t think I gained, and in fact lost the ability for alternate toe-in, I gave my spikes to the same friend many years ago, he still uses them, I wish we could alter the toe-in for two listeners like I do when he or others listen here.

https://www.audiogon.com/systems/11516

some listeners are never going to like subwoofers...

Besides extending the bottom octave of your system, adding subs will also improve soundstage width and depth. 

There is some spatial information in those very low frequencies.

It is most noticeable in orchestral classical music, but all music will benefit in this aspect.  

The only way to find out is to try one and see if you like it! What speakers are you using?

to hear and FEEL pipe organs as they were meant to be heard and FELT, you need to be able to reproduce cleanly down to about 16 cycles per second. precious few stereo speakers can do that trick. a pair of subs is mandatory for all us pipe organ lovers.

The last few pictures in my virtual system demonstrate how multiple subwoofers not only extend the low end response but also reduce room modes and concomitant ringing. This is objective. There are subjective improvements in depth and soundstage as well. 

I listen at low volumes late at night---if I want a little more bass, I use the loudness on my integrated. I will say that I did have a REL sub and sold it since I didn't use most of the time. But now I miss it. 

How do I know if I need a sub woofer?

   Only you can answer that.  Do you feel like you're missing something?  Do you live in a space where you won't bother/intrude on neighbors?  I noticed a lot of responses on what equipment to buy, but that's not what you are asking.

Asked another way…. How do l know what l need?
 

In retail the worst thing is to have a buyer who doesn’t know what he/she wants.

If there is a dishonest seller, he will convince them of what they think they need.

If the retailer is honest, he may well have a head banging/nightmare experience.

The same thing can sadly apply in real life situations/relationships.