How do you know if you need to add a sub (without auditioning one, I mean)?

How do you know? Very simple. Count your speakers. If you count less than 4 subs, you need to add subs. At least until you reach 4.

Yes it really is that simple.

(Add "a" sub. Good one. Like I would go for that. Just one sub. Chuckle. Snort.)

There is low frequency info in a lot of recordings that you are missing if your system cannot go down to 20 Hz. So the answer is you need a sub. I prefer a forward facing sub between the speakers, a stereo pair is better, and stereo towers are best. 

Though most speakers will go down to 50hz, the addition of a subwoofer adds thae very low bass notes that a speaker is unable to reproduce.

Do you 'need' it, probably not. But, if you are looking to get every bit of sound you can, then a sub is what you want.
When dialed in properly, as subwoofer offers that 'je ne sais quoi'.

My pick for a sub would be a Vandersteen. It utilizes a crossover that relieves the amp from reproducing the power demanding bass notes, and integrates quite seemlessly.
B

Not only do subs add very low notes that the vast majority of ’full range’ speakers aren’t capable of reproducing, but there is a lot of ambient information in low frequencies. Especially in classical music, recorded in a concert hall.

Even if the music itself does not have any very low frequency info, the concert hall does.

If you want to hear a concert hall become bigger and the boundaries better defined, add subs.

You don't need a sub.  If you're satisfied with your system's sound without one, then you've already answered your question.  Now, adding a sub(s) can have a very positive effect on your system, but I would classify that as a want, not a need.  For some people a subwoofer is essential, for others not so much.

OP here. Thanks for the responses so far. Is there a consensus as to how much one needs to spend to get a decent sub that really makes a difference? I’m not saying I want to spend the bare minimum, I’m just interested in a basic parameter.

I’m sorry, first poster. Add an S to the word sub.

"...Is there a consensus as to how much one needs to spend to get a decent sub that really makes a difference?..."

You never want to buy a cheap sub but good affordable subs like HSU Research work really well. 

You need at minimum to add a stereo pair to just about any system 

I'm in the russ69 camp ALL the way. I like columns.

Second they don't have to be powerful subs. They just need to be well made, if your doing low riders (under 24"tall) a pair of 10" HE reference drivers go a LOG ways too.

I'll give you a "Sonic NUGGET" that is hard to beat. It's my go to driver for 17 hz to 300 hz. 90+ % efficient.

https://www.parts-express.com/Dayton-Audio-RSS265HO-44-10-Reference-HO-DVC-Subwoofer-295-463

600-800 watt drivers, they are VERY low distortion 2 is plenty ONE  per enclosure. They work well every way I've tried them. Sealed, ported, multi, and passive radiators.. Just a GREAT driver..

You should hear 4 in a column 72" tall tuned with  a pair of 12" HE PRs.
I did TWO... 8 CF enclosures. Smooth as silk..

It pressures a room so easy and evenly. I use a 2496 active OX full blown Active DSP with on the fly correction from a laptop.. 300.00 dollars
NOT expensive.. an amp 3-500 for 12K.

What kind of budget is OK? There are 1800-2500.00 DBA kits.. James Romney (sp) and a Guy that is on AG.. nice enough fellow. Answer any questions.. 

If you don't try at least one sub, you will never know what you're missing. I think at least 2 subs are needed for a decent stereo, but TRY a good one that goes down to 20Hz., you'll be impressed for sure.

Hey M6, Bruce here... the reason why you have your ATC’s (your welcome by the way!).

Sooo, interesting responses. Conflicting comments here, yet all true.

You’re lucky in that everyone who answered is knowledgeable and provided excellent advice already. 
To start, you’re satisfied so theres no need to add a sub!  Just enjoy your system 😁

BUTT (yes, its a big butt)...

there is more to be had good Sir!  Add at least a pair of awesome subs (think SVS SB 2000 pro or higher or REL T7x or higher, or equivalent used.. at least 2 identical subs, 4 is better, 6 better, get the idea?)

Anywho, three elements to music.  Treble, mids and bass.  No single element is more important than the other no matter your perceived preference or musical tastes.  Bass  (its not base by the way) provides the foundation of the music and will clean up the mids and highs while expanding the soundstage, if it doesn’t drive you crazy in the pursuit therof.

Hey, Bruce. I am eternally grateful. I won’t forget you.
I was researching subs and decided that if I gathered enough extra bucks, I’d start with a used SVS PB3000 and take it from there. We have a large, cathedral ceilinged, complex room or I’d aim at something smaller. So I appreciate your right on the mark advice. You haven’t been wrong yet.
marc

I meant sb3000

How do you know?


You spend $50-100 on a microphone and spend an hour learning to use REW. Anything else is just guessing. Best part is it will help you to optimize what you have and if you get subs, it will help with that too. Anyone tuning by ear I guarantee has uneven bass. They will swear up and down they don't. They do.  Look at hilde45 post.

If you're not sure about subs, why don't you try a new SB3000? That way you can return it if you don't like the improvement. If you do like it, then you can look for a second used SB3000. What do you think?

A pair of SVS sb3000s is a great choice.  I love my sb4000 and have experience with the 3000 series and I don't think you would be disappointed. You also may want to look into a pair of HSU uls-15s if the larger box size doesn't put you off. 

Fiesta: great idea.
Guy: big sub=divorce.

Please read the first response again. Notice specifically mentioned is the number of subs. Not mentioned at all is how big or powerful. That's because when it comes to subs how many matters much more than how big. So, you need four. Any size. Take your budget, buy four subs with it. That simple.

Almost any speaker can be improved with the addition of a good sub or subs (my opinion).

Subs, well integrated, can be glorious, reduce coloration and increase the sense of scale (physical image width/depth) as well as dynamic range. The problem is always, always always getting it well integrated.

I've been here long enough to stop trying to help individuals do this and recommend if you want to go this route  you rely on automatic room correction and experts with the room treatment.

I wrote about this here:


https://speakermakersjourney.blogspot.com/2020/04/how-to-not-buy-subwoofer.html

Erik: Thank you so much. It was very helpful.

 By specs, they don't go low.


My W18E001's dual Thor cabinet go down to 40hz
Just added a  2.2uf  Mundorf SESGO cap to the 10 uf Mundorf Supreme Gold/silver and man, massive bass. 
Caps make a dif.
I would never add a  sub, as my other tech geek mentioned, a sub is  for HT, not  high fidelity.
Change out the caps in the  bass to Mundorf SESGO, and hear what happens. 
They are not cheap, but well worth it. 
I don't believe in the 20-40 hz range , = there is not much there to make any dif. 
Just get the 40-60hz range working at max, and thats all you need.
Now if you really want to go extra bass, replace your 8 inch woofer witha  Seas Excel Graphene W22 at $1k pair. 
= Beats out any sub for hifi. 

Subs, well integrated, can be glorious,

~~~~~~~~~
Read above, 
Just bashed your sub idea.

Almost any speaker can be improved with the addition of a good sub or subs (my opinion).

HT usage, 
For hifi, a  sub will pollute the  soundstage. 

To start, you’re satisfied so theres no need to add a sub!

~~~~~~~~~~~~~~~~~
Adding a  sub in the OP system, will only make a  unhappy camper, out some $$$$.
Subs are for HT ONLY, 
Subs should havea  label
~~NOT FOR HIFI USE~~~

With all the speakers I auditioned before buying, I tried both with and without a sub. With some speakers -- big towers like the Focal 948 and Martin Logan ML 60 Xti, the single large driver REL sub I had didn't do all that much, not even for imaging, etc. If I had had a sub which could really reach down there -- 14 hz or 20 hz, then what @simonmoon said about atmospherics would probably have become evident.

That said, every other speaker I listened to was improved by a single sub. Bass notes appeared, image and soundstage enlarged and got more definite, and (most surprising) the tonal richness of mids and upper frequencies were altered in a good way. I'm now on my way to stereo subs before, one day, going with a swarm.

As for price, I think there are good options out there and some have been listed already. I think you could likely get set up pretty nicely for under $2k for two.

hilde45,


Did you run your mains full range or with a cut-off?  Are you running room correction?   If so, the mains may have been driven less hard with the subs reducing distortion.

Which subs have high pass filter outputs that go to the speakers, to relieve them of reproducing very low frequencies?  I could see how that would reduce distortion.  An extra active crossover is too much cost and complexity for me.

Thanks for the responses so far. Is there a consensus as to how much one needs to spend to get a decent sub that really makes a difference? I’m not saying I want to spend the bare minimum, I’m just interested in a basic parameter.

There are plenty of great subs. In smaller systems I've really enjoyed the SubX from Goldenear.

But one thing you'll run into right away in most rooms is standing waves which will make the use of one sub hard to do and likely causing the sub to be inconveniently placed. These are bass notes whose wavelength is significant- under about 80 Hz they are over 14 feet long. Such a wave can bounce off of the wall behind you; at certain frequencies when it comes back to the listening chair will cause a loss of bass energy as it can be out of phase with the incoming waveform.


I know Erik gave advice about using room treatment and room correction for this problem. In a nutshell, it will make little difference if bass is being cancelled by standing waves!. When bass is being cancelled, room correction will ask the amp to make more power at that frequency, and of course that power will be cancelled- you'll have the same problem and the amp will run out of gas. Room treatment won't fix it either, unless you're able to have the bass traps actively move about the room as the bass notes change :)


But there is an elegant solution, and one of the best ones isn't all that pricey. I'm referring to the use of a Distributed Bass Array (and the best example of this is the Swarm from Audiokinesis.com). A DBA uses four subs placed asymmetrically in the room. Because the wavelengths are so long, bass below 80Hz is omnidirectional- you can't tell where its coming from. Its the harmonics of the bass notes from your main speakers that allow you to place the source in front of you. So in a DBA, with the bass coming from a variety of directions, the standing waves are broken up, causing the bass to be evenly distributed around the room.


The Audiokinesis Swarms are designed to be placed directly against the wall so as to take advantage of the room boundary effect, which is +3dB per octave going down from 100Hz or so. In this way the Swarm subs can be fairly compact as they are designed to roll off at 3dB/octave over the same range. The result is flat response to 20Hz. They need a subwoofer amp but Duke at Audiokinesis can guide you on that- its not expensive.

As long as the subs are not making any output above 80Hz they will not attract attention to themselves. So they should be crossed over lower, maybe at 50Hz or so. In most rooms this is insanely easy to set up.


After this is done then Erik's suggestion of room treatment and the like is useful but not before!

Sound meter (you can use an app on a smartphone) and white noise as a source ( available to stream via internet).

If you do not see response down to 20 hz, you are missing the lower octaves that you should be able to hear and a proper sub would be the remedy.

Use the same app and white noise to adjust the sub to proper level and crossover frequency if you get to that point.

Wow, what ton of helpful responses.

Need? Why?  
I do not comprehend.  
I have subs because I enjoy hearing freqs (if present) that are below the capability of my mains.
Maybe you NEED a haircut. There are actual reasons for that.

Depends on what kind of music you listen to and how loud you play it. If you are listening to bass driven music like blues and rock a sub is almost essential, other genres, not so much. The biggest issue with subs is integrating them. Integration is a 2-way process in that you need to integrate them to the room as well as your system. There are tools out there that make the process much easier but most 2 ch. systems are not designed to allow their incorporation.

Multiple subs definitely makes the integration task much easier. I have never heard an actual Audiokinesis "Swarm" bass system, but what I have read about it I believe it is probably the best bang for the buck sub system available and probably one of the easier systems to integrate since I believe the Dayton amp that comes with the system has both low and high pass filter capabilities, which in my opinion is essential for proper integration. Other good value subs I'm familiar with are SVS and Rythmik and HSU is probably worth looking at also. For a little more money the "e" series subs from JL Audio would be worth a look since they also have low and high filter capabilities.

In response to the question below, I run my mains full range and use no room correction.

As for "needing" a sub, well, I am fine with the word "need." Because it's not just about the notes down below. My room was as dialed in as it could possibly be, and I still had some peaks and dips well above the sub range *until* a sub was added, crossed over most effectively around 100 hz. Somehow, that addition changed peaks and nulls in the SPL all the way up to 300 hz. Whatever additional bass I was hearing, it was the effect on other problematic aspects of my room response which solidified for me the use of subs.

So what does anyone think of the idea of using a Loki as a very inexpensive experiment to see if more bass even suits me. I know it won’t be the lower register bass and there are plenty of other differences between this and a sub. Nonetheless, I still wonder what someone more expert than I thinks about this idea.
Along those same lines, if someone has a loki with speakers like mine or similar speakers, what sort of Settings did you end up with? Do you adjust them enough to justify having the Loki? Where is the best bang for the buck in terms of the band adjustment?
As usual, I have a suspicion that a lot of these questions are naïve, born of ignorance, or perhaps just unanswerable. It does no harm to ask, though.

A Loki does a nice job of boosting bass and also taming treble or bringing midrange more forward. It won't be money wasted even if you go on to get subs, and they sell pretty quickly, used, if you want to put it back out there. Low risk, medium reward experiment. It's a good idea.

You don't NEED a sub, but you may want one. Suggest that you buy a Hsu VTF 15H Mk 2 in plain black for under $1,000 (costs another $150 fro wood veneer finish) and see how you like it. Strongly advise that you add a second one when you can afford it.

The ATC SCM40s have low frequency extension as good as any three-way speaker of their size and better quality bass than than nearly all at that price point. I know that model. The specifications ATC provides is a bit misleading because their speakers are tested or the specs published differently than others.

I too would recommend an audiokinesis system if you want to go down that route. I have heard it. It is very good, affordable and lends itself to setup success rather than frustration. Otherwise a sub would be way down on my list of rabbit holes.

So what does anyone think of the idea of using a Loki as a very inexpensive experiment to see if more bass even suits me. I know it won’t be the lower register bass and there are plenty of other differences between this and a sub.

Think you just answered your own question. Why even bother? You’ll be missing many of the benefits of adding a sub(s) so really what’s the point, especially when you can try actual subs in your system absolutely risk free? I frankly don’t understand the hesitation.

To the OP, mild curiosity has now reached the point where you NEED four subs and people just don't understand why you're hesitating.  


If you want more bass, then EQs can do the job.  If you want deeper bass, then a subwoofer is your tool.  Keep in mind that there really isn't much musical content below 40Hz on most recordings.  On most popular recordings over the last 60 years, bass was in the 50 to 160Hz region.  The lowest note on a 4 string bass guitar is 41Hz, but it's fine if your loudspeaker doesn't go that low because the low E note has a large amount of overtones that fill for the fundamental.  Reading into many of the comments above I suspect people are setting the level on their subwoofer(s) so high that they can hear the subwoofer.  It's can be impressive, but it's not very accurate.

It is simple, 99.9% of systems improve with subs. 

61: great information. Thanks so much.

I had the same question.

I took my 20 yo home theater sub (B&W ASW1000 which is just fine for move explosions and helicopters) and hooked it up to my dedicated 2 channel system, just to see what it sounded like with my B&W 805D3s, not expecting much. I dialed the crossover down to maybe 50Hz, set the volume to just under where it was obvious, and immediately heard the difference. Even that old tubby/slow HT sub added a depth and warmth that wasn't there before. Whole experiment took maybe 30 minutes.

After proving the value to myself, I got 2 REL S510s and took the time to place them and dial them in. Night and Day. Shocking, really.

If you don't have an old sub laying around, borrow one from a friend or you can probably find a used one on craigslist for super cheap. It doesn't have to be very good or modern to do your own experiment.

Or you can do like I did. With the do it yourself.

Buy at least a pair of 18" woofers. You will need that size of different reasons see below.

To get a better chance to be able to get definition, fastness and so on.

Go for a open baffle (OB) "enclosure" (one reason you have to go big on the woofer with inefficient enclosure). But we are after the best SQ not efficiency.. 😉

Buy a Ikea cabinet that comes with a door. Take out some on two of the sides of the door so it will fit inside of the cabinet. 
That is your front baffle, on the door make a hole for your driver.
https://www.ikea.com/se/sv/p/knoxhult-vaeggskap-med-doerr-vit-10326791/

Get creative and brace the cabinets insides with maybe something like 4 by 4 that will act as the distance inside were you fasten the front baffle (the door). The object is to make a H-frame OB.

Then you use REW, mic and DSP. 
For finding crossover point (slopes), phase (delays), level match, PEQ, custom curve and if you are a vinyl guy a rumble filter you will probably need that. 😉

Custom curve is the other reason you need to go to big drivers. To be able play louder as the frequency decreases so you compensate for your ears lower sensitivity when frequency drops. That will make your ears to experience that the frequency response is flat to 20 Hz (and beyond). (That is one example of that our hearing is not like a measurements microphone when our hearing is NOT linear).

The "down side" is that nobody else can say i have heard those and it sounds .. or the second hand market the subs are worthless when nobody knows what they get..

But do we care what others think and do we want to flip them or play music?..

Now when done put on the dark side of the moon you can thank me later, your are welcome.

You will hear new stuff on that record that you did not hear before and you thought you had fully experienced that record and knew how it sounds.. It is now a totally new experience.

You will hear a second pair of a heart beats that is lower in frequency and level. Than the "normal" heart beats are at..

So new "music" information that the artists intensional put into their tracks for you to experience. So until now in other words you have not experienced dark side of the moon fully as pink floyd intended you to do..

And that were released 1973. So the questions are.. ..how much music information have you missed out on since then.. and why you dont have a reproduction system that supports all the frequencies that your ears can hear? 🤔

When you think about it like that then the decision-making is simple..

There are very few systems that do not benefit from subwoofers and bass management. However, adding cheap subs without a dedicated 2 way crossover is frequently worse than having no subs. To add subs correctly you either need a room control system with bass management or a calibrated mic measurement system like Dayton's Omnimic along with EQ capability. Trying to do it by ear is very difficult if not impossible. 
Doing the DIY thing is a good way to get higher quality subs at a better price and there are some very capable plate amps available. I personally prefer passive subs with outboard amps and crossovers. I would never go less than two 12" subs or four 10" subs. Contrary to lay instinct, larger drivers are not "slower" than small drivers and they have significantly less distortion. Get the largest ones you have room for. 

So what does anyone think of the idea of using a Loki as a very inexpensive experiment to see if more bass even suits me.

If you have a standing wave in the room, EQ and room correction won't do anything to fix it!

Forget the Loki and at least try a pair of subs...subs do so much more than only deep bass for a system...then decide exactly what configuration works best for you...

How do you know if you need to add a sub (without auditioning one, I mean)?

short answer is you don't