What is wrong with a sub?

I often read that if you go with this...you'll need a sub.  Seems to me to get speakers where no subs are needed you pay 1.5 -> 2X the price of the "lessor" speakers with a sub.  I kinda like my sub.  Am I bush league (I may be, but I mean because of the sub)?
I like to get my subs from Subway. The oven-toasted ones are my favourites. 
Be true to yourself.  If you like somehing, who cares what others
post?  They don't have your ears, or access to your gear in your
listening space.

There are things you can do that influence what you hear...
speaker positioning, for example.  Jolida Foz SS-T Sound Expander,
too.  And the general characteristics of your room, like flooring, windows,
and furnishings.

If you like your sub... great.  The real question: do you like 
your speakers, and 90% of what you are hearing through them???  

Nope, not at all. Integrating a sub well is the only issue. Done well they are spectacular.
@sgordon1 thanks for the support. To answer the first part, I do not have the time, or the money to test every combo. In cases where I do have the money, I’d like to know what others think hoping to put it all together and do it right. I have a set of speakers that my amp does not drive well. So I ordered another amp. Fun, costly and somewhat irritating. Maybe a sub would be the trick - too late, I ordered the amp.

Had I known how much I prefer the feel of speakers and sub over headphones I would have saved money and time there too. I didn’t need to spend what I did on head phones. A sub helps with that in my limited space. It also seems my speaker sub pair might sound better than what I can do for a few K more.
David, very few speakers do deep bass well. Those that do have what amounts to a built in sub. So, many of us add dedicated subwoofers to our systems to get the bottom octaves. I love my subwoofers. There is no way I could get realistic bass without them. I would think at my age I am anything but a bush leaguer. Enjoy your bass and your system subwoofer and all.  
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@elizabeth Exactly!  Seems like most people with subs just want to hear the thump, thump, thump.   

Used correctly a sub should just extend the lower range of your mains linearly within a few dBs.    At least that's the "audiophile" answer.

But lots of people like subs so they can turn them up and thump away.   I have also been known to do that on occasion when my kids were watching a movie.
Maybe "guys are bass crazy" because bass makes music as physical as it is. A lot of music systems sound anemic to me, lacking the physicality of live music. Dames listen to music from the waist up ;-) .
I like subwoofers because they help me achieve more of the visceral experience that I get listening to live music. 

Most speakers can't do that on their own or they may not produce an even bass response.  Maybe if you have a perfect room.  I don't.  In my main system I have Legacy Audio 20/20 speakers that have  combined total of 6 12" drivers and they can come close to "pressurizing" the room, but the quality of bass is better when subwoofers are added into the system.  I have 4 very large and powerful subwoofers in my system, but they are not set up to "thump", they are there to add body to the music and smooth out the bass response throughout the room.  They are barely noticeable unless I play techno or something else with really deep bass, then they come alive.

In my smaller computer system I have Focal Electra 1008 BE stand mount speakers and a single small 12" sealed subwoofer.  The sub just fleshes out the bottom end, it's not there to thump or pressurize the room.  It's a fairly small room and it just complements the Focals by producing the lower frequencies that they can't.
Big-Greg hits the nail on the head. People say all the time “my speakers go down to xx hz, I don’t need a sub.” The truth is very few speakers, even larger floor standing speakers, are FLAT to 40 hz. Most have a bit of a midbass hump, which gives a bit of a peak in the 70-90hz range, which then allows a stated -6db point in the 30-40 hz range.

Even those speakers that can dig down into the 30hz range, have limited output and suffer from increase distortion in the bass frequencies. To be able to reproduce decent levels (i.e. 105 db) at 30hz and below in all but the smallest room, with reasonable distortion, takes at least 4 10” long throw drivers, two 12”, or 1 15” (all have approximately the same displacement). Go down to 8” drivers (assuming you can find decent sounding ones with an xmax of at least 15mm) you are up to 8 drivers. You can cheat it a bit with large vented enclosures, transmission lines, or folded horns, but do end up with tradeoffs in group delay.

Many will disagree about the above, but it is nearly always true.  Take the Revel Performa F228be, a wonderful, full range, $10,000 pair of floor standing speakers.  At 50hz, they are coming off their midbass peak to 0db.  At 30hz they are 5db down from flat, and 9 db down from their 80-100hz output.  Again, this is measured at lower volume levels, so no dynamic compression.  


$57,000 Wilsons, same thing:   https://www.stereophile.com/content/wilson-audio-specialties-alexia-series-2-loudspeaker-measurements

As Big-Greg says it isn’t about boom (which is 60-90 hz). It is the deep, almost inaudible bass, especially in live recordings, which give the sense of a real space. When dialed in properly, you hear no sub, just an increased dynamic range and music that has an amazing foundation.
My experience is that it is not uncommon that the optimal spot in a room for bass reproduction is different than the optimal spot for mid-range and treble.  Inclusion of one or two (depending on the room) subs, integrated properly with optimal placement, can deliver superior sound vs. a full range speaker.

I prefer stand mounts with subs vs. floor standing.  Personal preference and is reflected in the speakers I produce.  
The comments seem to be supporting what I thought.
Taking this to the $2,000-$25,000 speaker range for music that has lower bass in it, for the same about of cash...
Equivalent or better sound will likely come at a lower cost with speakers and a sub, than buying speakers alone.
Many speakers build low range drivers in them, and buying the better mid-range speaker paired with a sub is likely a better value.  

FWIW I enjoy tube amps and lower power near field.  So I would not be buying a high watt SS amp to pair with some Maggie's which I'm told are great.  I had to choose between more expensive larger speakers with low range or going with a smaller speaker and good sub.  I did the latter, but am buying more stuff and wondering if I should change my thinking for a larger room.  I plan to do the same.  Good larger speakers, a sub to fill out the lower spots.  Music is Bach/classical (I don't hear the sub) and some pop/Fleetwood Mac kinda stuff where I certainly do.

You also need to keep in mind that part of the benefit comes from relieving the mains of the low frequency duties. This requires a crossover, preferably active, to limit the impact on the sound. Also, don’t go too small on the main speakers. I am a believer in Richard Vandersteen’s theory that your main speakers should be reasonably linear to one octave below the crossover frequency (so 40hz with an 80hz crossover). In the real world, your main speakers should have at least a couple of 5.25" drivers each or a 6.5" or larger to get proper integration.

And yes, the optimal position for speakers for best bass is usually different than the optimal position for imaging.  
@mcreyn - that was a bit Greek to me.  
What I have now:
300B SET (CAD-300SEI) with Watkins Gen 4 speakers on each side of my desk 8" high stands, REL i7(? small one) sub under desk to my left. 
The sub hooks to the amp speaker posts.  I'm pretty satisfied.

New amp is A/B 60W/channel and Vandersteen 2ci (which the SET amp can't push well).  This will go in a larger room with cinder block walls.  My plan is to get a larger REL sub and again hook to the speaker terminals.  I was also thinking Klipsh Forte instead.  Some of the Martin Logan looked good, but were pricey and had subs built in.  That kinda got me thinking why not separates (subs).

I had considered the "new at the time" Forte IIIs but I already owned two RELs so I went with Heresy IIIs (about half the cost of Fortes). I like the fact that a sub or two (or four) allows you to tailor the bass to the room’s quirks, and multiple subs work together to tame some room issues. "Full range" speakers aren’t gonna allow you to pull the low bass driver out of the box and put it somewhere else with its own controls, although that’s exactly what happens with a good sub. My RELs sound great with the main speakers running full range to their 58hz or so bass drop-off point, and these speakers display a nicely accurate bass to their limits, so overall it’s very satisfying and musically right. I tweak the sub levels a little here and there but very rarely need any EQ beyond that.
Better ones are damn heavy.
Subwoofers are absolutely audiophile. I think at times they get a bad rap because people don’t take the time to set them up correctly and all you hear is bass that sucks the detail and music out of the lower octaves. A properly set up subwoofer should simply extend the bass down to the lowest frequencies and you shouldn’t “hear” it - it should just sound like your mains play deeper. It also adds a nice tactile feel to your music, which is present in the live recording session.

There are are many benefits of a sub and mains over just mains. First, few mains can get as deep as a subwoofer. Second, the optimal place for a sub doesn’t always correlate with the location of the mains. Third, you can relieve your mains of sub duty which can improve clarity and give that duty to your sub which is made for it.

PS: If you go with a sub, use DSP so you can adjust the curve to account for peaks and valleys in the sound due to room effects. Or better yet, use multiple subs. Two is great. Four is better yet. 😀
@mkgus, thanks for that.  My one REL i7 I rarely hear.  Sometimes I do mess with the volume on it and pump it up beyond the music levels, but normally just because I want to wake everyone up.  

Got me thinking if 2 and 4 are better, is there any reason they should all be the same?  Could you mix an i7 with i9 or other brand?  I would tend to shy away from mixing brands.  But when I think of "real" bands and or orchestra there are different low end sounds of different power coming from different locations.  Maybe they balance those, just the base drums are not always center.  

I don't know what DSP is relative to subs.  I assume this? 
I mix 2 RELs from the same UK made era, a down-firing 100 watt Q108MKII, and a front firing Q150e...the synergy and tonal similarity between these two is remarkable, and they sound great.
Subs fill in the 'bottom' that the majority of speakers can't 'reach', w/out distorting their 'upper' frequencies.  Case in point:
I happened to be @ a instrument b&m store where some musicians started goofing about with various 'toys'.  While the 'regular frequencies' (80hz+) were covered by the monitors Just Fine, the 'subs' (which had 'ribbons' @ their ports, wagging about...) were 'filling in' the bassline that the monitors 'faded' from.  So, I took that as an 'instructive moment' that Any speaker shouldn't be expected to cover Everything....esp. when it came to moving 'bass line air'....since bass is mostly 'air movement' @ a major (and physical) process.  The aforementioned 'ribbons' were wagging about, in and out of their ports.  It's just how much 'air' you can excite, pure physics....

You want 'concert sound'?  Subs.
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I'm too new and inexperienced to take a side.  But as I posted - I like tube amps.  I like how they sound.  As such at reasonable price range tube amps there are no ribbon speakers I can use.  The subs having their own amps move the air fine.  I also like the argument that the position of the subs may not be where the mids are.  
Good subs add an "atmospheric" thing to a hifi system that has to do with charging the room with frequencies that exist in real music played live, not necessarily chest thumping low notes although they can do that also of course. My my main speakers have a very accurate low frequency range that sounds excellent without subs, but dial in the subs and man...something is just there that ain't otherwise...orchestral music sounds like it's in a real acoustic space, pianos sound like hey, that sounds like a piano! Subs aren't and never have been "lacking respect" in the audio community so don't get hung up on low notes, simply enjoy something closer to what music is supposed to sound like.
first 2 subs are a lot better. I have 2 and have experimented running just one. No comparison  The Achilles Heel  is when come with a built in plate amp with volume control and cross over point. Most of these are crude and cheap

Emerald Physics make a interfacing product called The BOM (bass management) which works pretty well for ~ $300, but to get the best Marchand offers excellent outboard active XOs, but they are costly
David, I am hesitant to use different makes and models of subs when putting multiple in the same room. I’m not saying it can’t be done or that it can’t sound great but I believe you stand a better chance at integrating them when they’re all the same model. If you already have multiple subs and want to try it out, let me know what your results are. 

As for DSP, it stands for “digital signal processing.” Some subs have it built in. With my system I added a MiniDSP inline with the signal going to the sub amp. It lets you tweak the signal in virtually unlimited ways based on what programs you upload to the DSP. I use it to cut and boost problem frequencies which are caused by my room modes. You can also adjust the phase, time alignment, delay, add filters, high pass, low pass, etc. 
1+ wolf_garcia. mkgus as long as you keep it symmetrical you will be ok.
If you use two subs up front they should be identical. If you were to add two more subs they could be from a different manufacturer. The DSP is great but you have to know what you are doing and to do this you need to be able to measure the situation with a calibrated mic. You can not change the nodes in the room. You can only correct the frequency response at your listening position. If the listening position is in a nul point
you want to move it back and forth a little in the room to where the bass is if anything too loud. In a nul point it will cost you a lot of power to correct. This is easy to do. Get a test record or download with frequency tones. Play a 40-60 Hz tone and walk back in forth in the room right between and 90 degrees from the speaker axis. You will hear the bass come and go as you walk in just a few feet! Mark the spot you like and move the listening position to it. Now correcting the response will save you power and you won't need a 2000 watt amp.
I within last year discussed subwoofers for music with a Wilson and REL dealer, who said that even the Wilson ALEXX, a phenomeonal $110k loudspeaker rated to 20Hz, benefits from well-done subwoofers.  The benefit is subtle, but it's there, according to his crew as determined in A/B testing in their listening room.
There are many good subs on the market. Just get good controls for the subs and consider how many you really need and placement. I have speakers that go below 30 but I tried one good sub and then, over the years I moved slowly to four. There are reasons for this but you will learn them on the journey. IMO there is a better sound with four subs than most other setups. And I am not talking wall shaking; I am talking immersion and realistic sound.
I bought a smaller REL i7.  I was thinking maybe I should go bigger. 
Assuming the same total $pend...
Seems several think having several smaller might be better than one bigger.  I expect bigger can go lower Hz.  If this was for a home theater, maybe I'd get the earth quake / bombs better with a single bigger sub, but for music, which is what I want, that little i7 REL is low enough - I think, then I don't have the bigger ones.

Thoughts on more smaller vs one bigger?

The simplistic statement by, once again, our eric squires, says it all. Purchasing the " correct " ones, and the " set up ", is the key. Subs ( Wawa, makes excellent Hoagies, and this is what they are referred to ) are needed in almost every situation, ime, but getting them to " match and blend " with the main speakers, and the room, is the ticket. I tried running my Lascalas, with a crossover, but based on my listening, I prefer them to run full range, and allow them to taper, naturally, on their own, and bring my built pair of subs in, at that point, where it is the most seamless, to me. I do not hear the subs as a separate entity. Took a lot of time, and work. Test tones with spl measurements can be a wonderful tool, as well as selecting a recording or two, that you feel, is truly wonderful, at that " transitional " point, between the mains, and subs. There are subs, that only excel with home theater, and subs, that only excel with music. Of course, there are subs, that excel at both. Anyone who simply plops down a sub or two, might find it great, but believe me, adjusting, and readjusting, tweaking and some more tweaking, can truly get you phenomenal results. Enjoy ! MrD.
I feel that adding a good Sub to a system can take it where no amount of cable or tweak $$ can bring you. I have Scansonic MB6’s and adding a JLA Fathom 113 v2 took me to a whole other level....it is incredible (to me) to say the least!!! (Now I need to save for a the CR1 crossover and I think, (based on what I have read) I will be satisfied forever.....unless I hit the mega millions, then a pair of M Q7’s will be ordered!!!
Idk, I spend a fortune on a pair of full range speakers and that’s what I expect. I had the salon 2’s and couldn’t get smooth bass from them below 60 he as common in this room, I get the dolly and bring my bipolar sub out of the ht and within a half hour I had flat response to 20 hz... I found nothing musical about what I was hearing, too much mechanical excitement with that much power. Personally I like it speaker that can play reasonably flat to 40hz and roll off after that for music .
Using my brain, not my ears, seems that the lower freq are just fine located in different locations.  I would not buy a full range speaker until I had this figured out.  If the speaker is just more cone speakers of different size and the bottom one is big - why not have it located someplace else?
In live music the instruments are in different spots.  Bi-symmetrical (stereo) may be because we are bi-symmetrical with two ears.  However lows are both felt and heard.  I feel a sub which is why for me speakers sound better than headphones.  I'd rather move the sub around. 

Never had much success integrating a sub in a 2 channel system.
Always found it reduced upper frequencies transparency even when set up right.

Guess the benefit of being old and new (to audiofile stuff ) is I have not had that issue, which was the reason behind the OP.
Integration not always easy
Stand mounts with subs are regularly suggested to me as I obsess over my next pair. But apartment living seems like subs would be a no-no. I had been looking at stand mounts that hit around 40hz so I wouldn’t need a sub, but I’m discovering that even with my current (rolls off at 50hz) parts of the room load up and I feel like that’s where I’ll have issues.

im coming around to integrating a sub, but afraid my situation won’t be a workable one. I may just buy a refurbed or scratch and dent sub and try it and see how it goes.