can subwoofers make things worse?

No, a sub will not make it worse… will likely enhance a good deal, two would be best.

REL… the default choice for most. High quality and great method and controls to feather it in with your speakers so not to create a mid bass hump. 

I used a pair of REL T/Zero MKlll with Magnepan LRS+ in small room and sounded great...a poorly set up and integrated sub can certainly make things worse...

Actually, a subwoofer can make things worse if it is incorrectly positioned in the room and/or bass traps are needed and not used, the wrong crossover frequency used, or the volume not correctly set.  For most setups this means a certainly amount of experimentation is required. However, once these issues are addressed, a sub can be a big plus in a system. 

However, even when the setup is done correctly, there can be a few situations where a sub will still makes things worse. That's where the recording itself has bass or sub-bass problems. I forget the exact recording, but I can think of one I heard a few years ago where the orchestra was apparently on a poorly constructed wood stand or floor and the sub did nothing but reveal a lot of very annoying thump-thump from foot stomping. 

I tried 5 different subwoofers, 4 of them made an absolute mess, also in a small room. It's very hard to get it right, if you have limited space and options. I am still better off when I turn off my sub.

The quality of sound with or without a subwoofer is a matter of both execution and personal preference.  Even in very rooms, with unlimited budget and no placement limitations, some people prefer not having subwoofers.  I usually prefer not having a subwoofer because I do not prioritize having ultra deep bass and prefer "fast" and clear sounding bass that is well integrated with the rest of the sound  i also don't want the temptation to fiddle with the bass balance for different recordings.  A local dealer who makes custom speaker systems refuses to utilize subwoofers.  Even in some systems he makes with twin 18" woofers per channel, the bass response is flat to just 35 hz or so because other aspects than ultra deep bass are being prioritized.

I own the SVS Micro. That is your best bet.

Of course anything can make your sound worse if you don't know what you're doing

 But the SVS has a good Bluetooth app that lets you dial it in at your listening position

I have two REL T/5x subs I just purchased. I also have a small listening space (12x9 or something close to that). They were easy to integrate and they make everything sound so much better. Soundstage, imaging, musicality, all better, not to mention the increased bass response that, I think, is outstanding. They are fast and tight which is the sound I was looking for. Integration is easy even though there is no app to help.  They connect at speaker level with Neutrik Speakon connectors which, I think, makes integration easy and matches the input to both speaker and sub.  I would highly recommend getting two. I love the RELs but others like the SVS and the KEF. The T/5x doesn’t go as low as the other two but I get very good in room response from them. Two of the RELs are about the price of the KEF as well.

A sub shouldn’t detract if it’s setup well, and isn’t total junk. Depending on how you configurate it and the type of filters used, some subs offer a high pass filter to keep the lows out of your main speakers that theoretically could detract a bit, but it's easy enough to avoid by skipping the option of using that HP filter.

A lot of subs I’ve heard simply have the low pass crossover frequency set too high, and even more simply turn the gain up too loud relative to the mains, which can muddy upper bass/lower mids (including some vocals) and contribute to boominess. I don’t run my mains through most HP filters of a sub, and typically run them full range. Then set the sub at it’s lowest low pass crossover frequency (~40-50hz), and turn it up the gain just enough so I can barely hear it on bass heavy passages. IMO and in my setup, it’s better to use the sub to augment the bass I already have, and not feature the sub. Different playback volume levels might require some minor adjustment of the sub’s gain up or down, but it’s a matter of preference.

Room placement of the sub is also a significant factor....you’re gonna have to just experiment and see what works best in your room and to your tastes. Running two subs to help reduce room nodes is typically preferred over 1, makes placement less critical, but obviously doubles the locations you need to find.

Haven’t played with enough new subs to really recommend any of the good ones. My Dayton SUB1200 was fine for the price, but my old Definitive Technology PF1500 sounds better to me.

Good luck!

I have two Rel T/7i subs to supplement my Sf Olympica III’s and hear the same benefits as @jastralfu describes, albeit in a slightly larger room (16’w, 22’l, 10’h) -- the soundstage, imaging and presence (the apparent size of each instrument and player) was nicely enhanced and made more musical with the addition of the two Rel’s. The addition of the second Rel definately improved those sonic elements over my previous SLF850 sub (a 10") by itself and combined with the first T/7i. I set the crossovers at about 60db and the volume a little below 3 out of ten or 9 o’clock on a standard dial. This seems to work just fine for me, the subs do not call attention to themselves, the music seems to come from the Sf’s only.

It's not the quality of a sub that will really degrade the sound, it's the position, extension and whether or not you can clip excess peaks.

I recently added two Rel T9x, Klipschorns, 13'W x30'Lx9'h room. didn't really add much bass. but expansion in sound staging far surpassed my expectations. I've spent much more on electronics in the past and never experienced this level of expansion, should have done this years ago!

T series Rel's don't reach lowest freq in bass, but I've never experienced this kind  of coherence, integration with other subs, and those with dsp. With other subs constantly fine tuning sub settings with different recordings and volume levels such that it drove me nuts, gave up on subs for years.

I suspect two smaller T series would be seamless integration with your setup, as others have mentioned a single sub more difficult.  Smaller T series won't overload your room with deep bass and should provide very nice expansion of sound stage.

Doubt a sub or two will make things worse, but you have to take the time to find out where they sound best.  I currently am only using one and it’s six feet behind the listening position and only does sounds below 45hz.  You will have to figure where it rolls in and how fast the slope is. Mine is set at 12dbs, I believe and how much volume you want from it etc.

All the best.

I have two SVS micro subs, one sitting beside each of my powered monitors. It sounds well integrated and tight. The room (open floor plan) is 16’ x 24’ with openings all around. 
 

I’m probably a minority here, but I don’t want to see my stereo, at all. If I could buy an invisible stereo I would. So, not that the micros miss anything, but they are as big as I want in the room, and it’s a close call with them. 
 

The phone app is very useful, fyi, and two subs seem much easier to integrate compared to a single sub. SVS has a pretty good shipping and return policy if you are tempted to give it a whirl.  Check out the website. 
 

Hope this helps, best of luck with it!

Yes it sure can if the sub is not time aligned/in phase. I strongly recommend highpassing the speakers (cutting the bass of the mains) through an active crossover as the timing can be corrected. 
 

those small subs don’t play loud and deep. They tend to cut the low bass when pushed hard with digital perfection circuits. Erin’s Audo corner has measurements of a bunch of them on YouTube and probably his website too. Worth watching before you buy. If you have the physical room a good 12” is the way to go was they can always be turned down. 

It's all about what you want.

I believe the REL and the SVS offer easy to return trial periods. One is a sub-bass speaker and the other is a subwoofer. Get both of them at the same time and do your own side by side comparison. It's said they both offer useful phone setup support.

With its dramatic frequency roll off the REL is easily more forgiving of placement at the cost of articulately deeper frequency heft and air. ....Set it and forget it.

If the SVS is properly positioned within your room the flexibility of the remote controlled application adjustments will provide smoother speaker integration, EQ presets and volume control all from your listening position. ....Fun.

All the best with your search.    

The SVS SB1000 Pro would be a better choice than the 3000 Micro and isn’t all that much bigger, goes lower, and is $300 cheaper.  Just another option to consider.

Music or movies (or both)?

Big room or small room?

Neighbors?

The first two factors will depend on what you want and how competently you can work / trial your way through implementation.

The third factor, sub(s) will never make things better! 😉

In my case two Rel Carbon Specials slightly defocused midrange vocals. I tried everything - repositioning 1000X or more, and following all guidelines with respect to volume and crossover settings. Every time I thought I had nailed the setup, I realized the subs weren’t actually engaged at all! I really tried everything I was advised to try and did nothing but experiment with them every day for a month after break in. I was able to return them, luckily.

Of course, this is just my unique experience. I think most people love them, especially at this level. The deep palpable bass was excellent and well integrated. But they also didn’t produce the dynamic and energetic higher frequency bass I was seeking for my very large room with high ceilings, leaving my B&W 802’s a bit underpowered for my space. But the most annoying thing was that smearing effect on the image at center stage. Moved to Audiovector R6 Arrete’s and these gave me all I was looking for with their dual downward firing active drivers - and I have zero desire to add subs now. Bass is now deep, defined, punchy and dynamic with my Diablo 300. Really has the palpable “growl” back in bass solos that I was missing. I don’t have that same bass you “feel” with the Rel’s, but I really don’t miss it at all, and I don’t think I was every really going for that really low end anyways.  
 

Just my experience of course, which as I mentioned I think is unusual!

It’s not just subs reproducing otherwise unheard bass that exists in recordings (and all around us generally), it’s the effect of adding realism and sort of "charging" the room with a more genuine ambience. Even recordings without many really low notes like string quartets (lowest note on a cello 64.5 hz) benefit from a full range system. Unplayed piano strings resonate and give soul to an acoustic piano. Lifelike...you should want that.

Whether or not you agree with all of it, this article brings up many points for bassic consideration.

I use a REL 7i in a small space. Once properly tuned, it fits in perfectly. 

SVS Micro. I have a pair of them mated to a set of LS50's and it's a perfect match.

Subwoofers? We don't need no stinkin' subwoofers.

I have two 12" subs designed specifically for music by Rythmik and GR Research. In a very resolving system with full range speakers (mine play down to 26Hz before gently rolling off) you will find that some recordings sound much better with the subs and some sound worse. It's because of how different each recording emits bass. Most of my 60's and 70's rock recordings are deficient in bass and love added sub woofer with the crossovers turned fairly high. But the occasional excellent production/mastering/mixing/quality media recording suffer from the added bass. If a person were willing to dial in the sub for each recording it could work great but I find it best just to turn them off for really good recordings. Otherwise they just blur detail. All of this assumes the subs are setup correctly.

Bottom line, I think your stand mounts with limited low end would love a sub but a full range speaker with highly resolving system can be hit and miss. Still worth having though. Oh, and I would recommend considering Rhythmic with the custom audio grade driver by GR Research. They use servo technology unique from other servo units and sell direct so the bang for buck is serious.

Short answer: "Yes". If you reside in a multi-family dwelling, a subwoofer can make the relationship with your adjacent neighbors worse.

+1 @wolf_garcia Explains what I mentioned as sound stage expansion.

Rel T series don't move air and shake room, roll off bass in lowest registers. As others have mentioned neighbors can be a very real concern, I was the one calling police on a very careless neighbor! So, not wanting to bother my neighbors was a major concern when purchasing  these subs, I stood outside my house and not really much more boom than my Klipschorns without subs. Subs with lower reach and capable of much greater output will have much greater chance of bothering neighbors. My Genesis sub moves air and shakes room, makes it unusable in my situation.

Sub placement will be key in a small room.  Try to locate the sub(s) anywhere but in-between the main speakers.  

I've been around subwoofers since M&K first introduced them in mid-70s. I've used them with lots of speakers, large and small including Magnepans and KEF LS-50s, both notoriously difficult to get 'right' with subs. Two major success criteria:

1) the HP and LP filter should must be used, and set as low as possible. Typically no higher than 60Hz for music, and 80 Hz for Home Theater. The HP keeps the low bass out of the mains, improving their dynamics and power handling, by reducing their low bass load. OThis means no speaker-level connection - your preamp needs a Sub Out with bass management, or the sub itself needs line level inputs and HP line level outputs back to your power amp. The latter usually limits placement options, however. 

2) Placement and level settings will take some effort. However, same wall as your main speakers, roughly 25-40% of the way across the wall is a good starting point.

Listen to both male and female vocals first to make sure the sub isn't adding mud or chestiness, then to material with true bass, (Beyond The Missouri Sky, Pat Metheny & Charlie Haden) then sub-bass (I Believe When I Fall In Love, Stevie Wonder). Most people have never heard the pitch, tone, and texture of Charlie Haden's bass done properly or the sub-bass synth line that underpins that Stevie Wonder cut. A good sub, well placed will reveal what's actually on those cuts. 

Either the T/5 (or T/7) or the Micro 3000 are excellent choices for your system. The KC62 I would recommend if you had LS-50s.

Small rooms are always the source of the a lot of issues, as the bass wavelengths are longer than the room itself.  So is also our visually driven tendency to want to put a sub in a symmetrical location- half way between our mains for example.

So subs will excite some kind of room mode no matter what.    The issue is what do we do to mitigate that.  There are many solutions from bass traps to EQ.  My experience is that using more subs turned down low is better than one big one.  For example I would rather go into a small room with 4 cheap subs placed at different distances along the four walls of the room than one sub in corner.  

I think Duke had the right idea with his swarm product.  Also bass arrays work well, in small rooms or large, Bag End did a lot of work on that.  

So we have more trouble with clients buying one sub that we do with clients buying two.  Almost no problems with people buying 3 or 4.  With ATMOS this is a big issue, as much of the basic ATMOS info says subs in front but that doesn't really work in practice. 

I can only let you know what happened with our purchase of a set of year-old Quad ESL 57s many eons ago. They were sold to us with a Dalquist EQ-1W sub-woofer with a passive crossover at about 80 Mhz. What happened was the mid-range leaked through the sub-woofer, muddying up that glorious renown mid-range of the Quads. We did not try an active crossover or bi amp the system, which would maybe have made an improvement. My suggestion: just don't.

Kef Kc62 Is good I use that little guy in my kitchen system.

Rel is not good until S models or Carbon special

SVS is for home theater

i use JL Fathom F212’s in my big system. 
look at the JL E Sub

Remember using one Sub can make it worse easier!

it’s easier to integrate a pair of subs properly and balance out the room better

Thank you all for the replies. 

To answer some questions asked of me. It would be used for both, but primarily music - to add the bottom octave my speakers don't reach (48hz - 23khz). 

 The speakers are 2 feet from walls, and 6 feet apart and i sit 5 feet from them, dead center. The speakers "disappear" and fill the whole space in front of me. 

I live in a rented studio apt with no one underneath me. No issue with adjacent neighbors - only the guy who lives above me. He's been pretty cool so far. I wouldn't play the sub loud - just subtle addition of that low bass. 

I barely have room for a tiny single sub. A pair is not possible. 

Ive read recommendations for all 3, but the SVS micro may be the best combination of size, cost, and being able to set it from my listening position. 

Of course - last night i listened to James Taylor and Billy Joel and didnt feel like i needed a sub. Sounded great to me. But the common thought is, as soon as i add a sub ill hear what i was missing. I was told Best Buy Magnolia has SVS and KEF subwoofers. I can try to see them there.

In a heart beat 

The tools you need are DSP EQ and measurements.  Additionally, high pass filters and plugging ports in the main speakers, along with bass traps can also highly improve the integration and benefits of a sub, but the EQ and measurements alone are the minimum required to ensure any sub can go in without turning the room into a horrible sounding mess.

I picked up on this linkj reading  Audiogon.   His argument is that subwoofers are inherently out of phase alignment with the speakers.     Its worth checking out.

https://soundoctor.com/whitepapers/subs.htm

His argument is that subwoofers are inherently out of phase alignment with the speakers.

That’s why subs have phase adjustment.  Duh.

They certainly can make things worse! They can also make it much better if it’s dialed in correctly and time aligned with the mains. Also the type of bass. If you have a tight fast sub with a lazy bass speaker it will probably not blend well and vice versa. 

I have been using, and building subwoofers since 1978. Subwoofers, the way they are commonly set up, virtually always make things worse. 

To make subwoofers improve the overall performance of a system you have to use at least two 12" inch subwoofers. Projecting bass beyond 1 meter down to 18 Hz requires a lot of driver. Defeating room effects to some extent requires multiple subwoofers.  A two way crossover is mandatory. 1/2 the benefit of using subwoofers is unloading the bass from the main speakers which increases headroom and lowers distortion. Subwoofers have to be matched to the main speakers in phase and time. You can be in phase and out of time or in time and out of phase. Achieving this requires measurement and digital bass management. This is not just "room control" which is really speaker control. It is crossover choices, time and phase alignment and room control which is just amplitude adjustment. You also usually get EQ capability which allows you to dial up the volume in a controlled fashion.

@soix 

The phase adjustment on subwoofers is very close to totally worthless. 

Trying to adjust subwoofers by ear is extremely difficult it not totally impossible. Measurement is a must and unless you are extremely lucky the only way to dial in a subwoofer array so that it disappears is with digital signal processing, otherwise you have a home theater system with which fidelity takes a back seat to vibratory excitement. 

@epz 

I would forget the sub for now and spend the money elsewhere. It does not matter where your adjoining neighbor is, any effective subwoofer system will drive him nuts. I am lucky to be alive. How I ever made it to 30 is a mystery. 

Who remembers drive in movie theaters? You hung the speaker on your side window rolled it up and asked the age old question, "you're on the pill, right?" 

@sierratrails 

Yours is a classic story. The problem was the available analog crossovers were way to slow and there was really no way to phase and time align the subs. Digital electronics and digital signal processing were still decades away. I had electrostatic speakers and spent the better part of two decades trying to make subwoofers disappear. They always managed to creep into the midrange in stark contrast to the ESLs. I cross now at 100 Hz 48 dB/oct. The ESLs sing and the subs stay out of the midrange. Because the crossover is digital there are no ill effects. (other than being digital which seems to bother some people)

The phase adjustment on subwoofers is very close to totally worthless. Trying to adjust subwoofers by ear is extremely difficult it not totally impossible. Measurement is a must and unless you are extremely lucky the only way to dial in a subwoofer array so that it disappears is with digital signal processing, otherwise you have a home theater system with which fidelity takes a back seat to vibratory excitement. 

@mijostyn This is not my experience at all.  If you take the time to use the “crawl method” to find the best placements for subs (critical) and then take a little time to appropriately dial in the crossover, volume, and phase you can get subs to totally disappear in a system and provide all the sub magic.  I don’t think it’s luck, I think it’s having some knowledge and the willingness to do the work to dial it in.  That’s my experience anyway.  Agree at least two subs are necessary and placed in a staggered arrangement to deal with room modes.

I've already accepted that I have to budget for 2 subwoofers of high articulation. But beyond 2 subs, seems the improvements is not worth the additional cost.  

How much improvement can one expect for each additional sub added?

The cheap power supply in the sub may contaminate your grid.

@soix 

You can make things better with the crawl method but you can not dial the subs in perfectly. The computer takes all of several minutes to make the measurement and generate filters that match the subs to the mains perfectly. No need to crawl around. Another benefit is you can put the subs where they function best, in corners and against walls and dial them in perfectly. If you have a sub against the front wall, but keep your mains 5 feet in front you have a delay of almost 5 milliseconds. The effect is to call attention to the subwoofers and they do not disappear.  This and the shallow slopes of the crossovers forces people to use very low crossover points negating many of the benefits of using subwoofers. In most situations the best results could be achieved with crossover points between 80 and 120 Hz. You have to use a very steep slope to keep the sub out of the midrange which is poison. This can best be done digitally. The high crossover point allows you to EQ the bass just by adjusting the volume of the subs. Boosting bass below 100 Hz by around 6 dB gives a more realistic sound and the visceral effect of music come through clearly at less than ear shattering levels.

@kennyc 

The only limit is the room available. As you raise driver surface area you lower distortion. This can be done with larger drivers to a point or multiple drivers. I use eight 12" drivers in four enclosures spread out across the front wall forming a linear array. My main speakers are also line sources. In short, the minimum is 2 subs. The maximum is what you have room for. I do not think there is a point of diminishing returns. 

atmasphere

The way room correction works is its an active EQ device that compares the incoming signal to what it hears happening in the room. This might be done with a test signal.

So at that point if there is a dip, the room correction simply boosts the signal at the frequency of the dip. The problem is that if the dip is caused by cancellation, you can put any amount of power into that cancellation and it will be cancelled. So the dip remains.

That is why you have to break up the standing waves before room correction can really work.

If your listening chair is located in a null, room correction isn’t the solution for better bass. Relocating the sub is. Multiple subs provide an even bass response distributed around the room.

_ _ _ _

A 50 hz bass wave is 22 feet long. A 30 hz bass wave is 37 feet long. These waves are bouncing off the walls, ceiling & floor. Integration of subs with main speakers in a small room can be difficult. But it’s well worth the effort if done right. There’s a lot LF in music. Why not hear what the composers intended?

Rel and Kef are great. I currently own older pair rel subwoofers in my 2.2 audio system.

I would drop SVS. Not good at all unless you want a one dimensional boom.

pair is needed. I ran a single subwoofer for awhile and when I went to two it was very different and much fuller sound. Synthesizer bass effects became much more dramatic when panning between the two speakers as a lot of modern music does for effect. Drums sounded fuller and became more dimensional in the soundstage. 

I would drop SVS. Not good at all unless you want a one dimensional boom.

That’s just a ridiculous statement and not true at all.

@soix

have you ever compared subwoofers? Apparently not.
I have and stand by what I said per experience and am not some fan boy.

here is one review where the reviewer is kind to SVS and all its like brethren substandard like JB Audio, etc… Buy SVS if you want one dimensional boom that impresses the simple folks

Sudnh

I love it...." the simple folks "  yes indeed