Well...I sense some opposition.from my response already...but unless your living room is MSGarden...the addition of using two subs will be counter productive simply because the bass wave generated by one supb will be more than adequate...the benefits of two subs are in my experience being pushed by dealers
This has been gone over many times, check the archives. One is good, two is better. I went from one REL to 2; REL recommends two. How on earth Phase could declare "the bass wave from one sub will be more than adequate" is beyond me. As if all subs had the same bass wave and all rooms and tastes were the same. One may well do but 2 will be better in most rooms.
Bass wave is simply frequency generated...and your listening position will be within a wave...which can be 20-30ft or more in dimension...point being...if one is already surrounded by a bass wave...the addition of another sub is not going to add or improve bass...unless you have an extremely large space...or a space with some odd configurations...the benefit of two subs could be applied to one superior one...just my .02...
Take out the doubt and experience it !!! There are far to many variables to know if one or two subs are better in your room just try it both ways and let us know your outcome. Good Luck
Two subs provide a lot more flexibility. It may be easier to place two small subs (two 9" cubes in my 2-channel system) than one larger one. Two can help break up room nodes that cause standing waves. Improperly done two subs could be out of phase and cancel out the lowest notes, but properly done they will reinforce each other. For a good, coherent stereo image, the sub(s) should be in a consistent geometrical relationship with the listener and the main speakers. With a single sub you are often limited to a narrow range of ideal listening positions. Two subs make it easier to maintain a consistent geometry throughout the room.
A second sub also adds at least another 3 dB dynamic range.
I have two subs in both my 2-channel analog living room system and the 7.2 channel HT rig down in the family room. In each case there was a noticeable improvement in the clarity, imaging, and dynamic range when I added the second sub.
Two subs are better. No question about it. I've tried it both ways.
Just bought 2 M&K 150 watt 8'' subs. 2 will spread throught the room better. And, at 190.00 each, the deal was good. Sometimes I use just 1 for AB comparison, but I'm glad I got 2 small subs instead of 1 big sub, at lease for 2 channel.
If you cross over to the subs very high (>100hz to 150hz), there are 3 very clear POTENTIAL benefits to a pair of subs vs. a single sub. However, the key word is "potential" and the ability to realize that potential will depend upon - among a few other things - what device you use to effect the crossover.
1) At a sufficiently high x-over points (per above) you can maintain stereo integrity.
At some point - people seem to debate exactly what point - the crossover frequency is low enough that bass becomes monophonic and this benefit does not persist, per Phasecorrect.
2) Careful placement of a pair of subs will provide MUCH!!!! smoother FR in most rooms. Not even close. This is IMHO the biggest benefit of a pair of subs BY FAR. IME, a subwoofer almost always interacts with the room to create peaks and dips that will exceed +/- 10db at the listening position. A pair of carefully placed subs can reduce that to +/- 3 or 4 db. This is an immediately audible difference.
If your x-over is effected with a PrePro that has Audyssey, ARC or similar digital room correction ("DRC"), or stand-alone correction/x-over like the Velodyne SMS-1, you can get to the same place by EQing a single sub.
3) You will always get more clean output potential from a pair of subs than from a single sub (assuming that the subs in question are the same model).
A single high output sub may cost less than a pair of lower output subs.
#2 is the key. If you are using DRC, a second subwoofer is a nice luxury. If you are not, a second subwoofer will almost always provide VASTLY smoother bass response.
All IME. However, ME is now up to 5 years of continuously tweaking subs in my system, so I feel pretty good about this advice. I really doubt that YMMV.
I went from dual NHT subs with an NHT X2 sub crossover to a single REL Storm III using speaker level connections. In my room, the Storm III was a nice improvement. But it must be said that I am lucky enough to not have any nasty room modes and I am crossing over quite low at 40Hz. And damn do the REL subs integrate well with speakers.
I just added one sub to my analog system. I can't locate it or specifically hear it. However, if I turn it off, I notice it and the missing LF. I have a fair sized room 17d x 35w w/14ftcathedral ceilings, a 8ft wall behind and another 17 x 35 kitchen/dining room on the other side. The sub is set about half way. It's a NSM 15EXP with a10in driver. Plenty of bass for me. Mated with C & C Abby's.
I just switched from one Martin Logan Abyss to a pair of Emotiva X-REF10 subs. I never really made a huge effort to dial in the Abyss; that said, I'm not done with the options for doing so on the X-REF10.
I started with a single X-REF10 to get some idea of the room modes and best guess for crossover frequency and phase settings. After that, I installed the 2nd sub. Both are symmetrically located on either side of the centerline of the front wall, maybe 1/3 the way in from each sidewall. (My room is 22' x 13' x 9', and my system is on one short wall.) The difference with 2 subs, while not huge, was definitely noticeable. HOWEVER, I use small monitors (Von Schweikert VR-1) and I have the subs crossed over at a high frequency (125 Hz). So, it's not surprising I can tell the difference between a single mono sub and a pair in stereo.
As others said, depending on your mains and your crossover method, it may not make a big difference to go with a pair of subs.
I've had 2 Rel Storm III's in my system for several years now. They are paired with Audio Physic Virgo II's. I can't live without the bottem end extension and inhanced upper bass/lower mid-range that running 2 in stereo provide.I run the Rel's (high level) directly off my Virgo binding posts. I plan to go with a full range speaker someday, Revel Salon or Wilson Shasha, once I have heard them in my room A/B-ed with my current system. I have tried in the past but it is hard to beat this setup.
I owned a single REL Storm III, then added another and hooked up as true stereo. I like this setup. And I have owned several other REL subs - they are all awesome, but I definitely prefer the "ST" series over many of the newer models... I LIKE DOWNFIRE!!!
According to Jim Smith in "Get Better Sound", stereo requires two subs for proper imaging; one sub is fine for home theater.
Agree with Loydc comments. I used a single REL for few years & then upgraded to two RELs. The improvements were very evident. Imaging improved the most. Although they say deep bass is non-directional this is something you will immediately disagree with once you hear 2 subs.
Crossing over at 40hz the bass wave is so large it is impossible to distinguish its location...however one has to have true full range output to do this...and a speaker either images well.or it doesn't...regardless of a sub
Two subs in almost ANY room will sound better.
what do you connect the subs to? to the L/R speaker? or to preamp?
I actually have a Rel Storm III working together with my B&W 804S, in a 3700 cu ft room. I like it with the Rel a lot better than without, BUT I'm looking at getting rid of the Storm and bringing in 2 subs + Anti-Mode 8033. Rel sounds nice but not very articulated, and I'm crossing it over with the ABC network at about 45 Hz. I'm inclined for sealed enclosures now, and also considering servo-driven subs (Rythmik).
FWIW, in Sound Reproduction Floyd Toole recommends two subs playing the same summed up signal from L & R, placed at 25% of room width at each side of the front wall. So if the wall is 16 feet wide, one sub at 4 ft from one side wall, and the other at 4 ft from the other. By doing this the first 3 width room modes are kept in check. Then I further plan to improve things with DSP by the 8033.
Also FWIW, when I grew dissatisfied with the Storm I was thinking a larger, huge amp-driven sub to replace it. Some folks made me rethink this.
Anyway, my two cents.
Just wondering for those rel owners with 2 subs, when you hook up via high-level inputs only, doesn't that mean that both subs are outputting the identical sound? In order to achieve true stereo do the subs also have to receive low-level inputs from a variable output low-level amp connection with left and right?