Two Subs Vs. One

Trying to augment the sound from a pair of Totem Hawks in a large room (rest of system is an Olive Musica server, Eastern Electric Minimax Pre, Classe CAP-150 Amp). I am doing some in-home auditions of affordable single subs (mostly REL) and really like what they do for the sound. So far, I am leaning toward two smaller subs, one behind each speaker (ie. REL Q108E's - I like the sound better in that position and it looks better - wife factor) versus one larger one in the corner (ie. REL R-205). Can't find two demo units of the same sub to audition the two-sub option and was wondering if anyone had experience with this comparison.
I prefer two subs. But with subs, wave effects in the room are always a concern.

With one sub, I had to be careful with room nodes and resonances. Proper location of the sub would avoid nodes and resonances, at least the major ones. Also, I discovered when I had just one sub that the two inputs from the two channels were treated differently, with one of the two channels significantly deemphasized somewhat arbitrarily so as to avoid cancellations because the bass waves could have exceeded the distance between microphone positions. The good news is that the best placement for the sub was different from the best placement for the monitor speaker, and having them separate allowed me to find the best placement for each. If they were all part of one speaker box, placement could only be optimized for one.

With two subs, the potential cancellation effects have to be dealt with through room placement. At least, I can dedicate each of the subs to each channel and not worry about the built in deemphasis.
I have two Vandersteen 2Wq subs with a pair of Duntech Princess speakers with the subs positioned behind the main speakers. They are 10 inches from the side wall and 21 inches out from the back wall and the sound is great. If I disconnect one of the subs, the impact and fullness of the sound collapses to some degree. CDs have base in both channels whereas vinyl usually sums the bass from 30-40hz down.I would definitely go with two.
I use one sub but crossover very low, 45hz and run my speakers full range. The sub merely augments the RM 40's so the volume is very low. My speakers, VMPS RM 40's, have good powerful bass into the low 30's. I mean honest bass, not the bass that most manufacturers advertise. I don't know about your Totem's so you'd have to make your own calculation.

In my case one good sub is the wiser choice. Two subs do have advantages, especially if you have to cross over higher. Also they can help balance room problems but as the poster above mentions, can also increase problems. With four large bass traps and digital equalization I don't have that problem.

If you can crossover below 60hz I'd go for one better sub. A low, below 80hz, crossover makes it easy to integrate and has less potential problems. If down the road you want two you hopefully can afford the second sub.

In either case I'd get a sub. There's alot more bass than most people realize until they hear it for themselves. I'm surprised how much comes out of my sub being crossed over at 45hz with a 24db slope. It's help to my large mains has been a very good investment.
Assuming budget limitations, would it be better to go with one big sub (e.g., Rel B3) or two smaller subs (R205 or B1)?
I've never understood the two sub approach for the following reasons.

Finding a good location for a single bass source can be trying; finding two good locations for two subs seems nearly impossible in practice.

Assuming that bass can not be localized, having a "left" and a "right" channel sub doesn't make sense. Note that Vandersteen subs, due to their gentle first order crossovers, will be localized and thus, a left and right is a requirement. You are forced to deal with the multiple bass source problem described above.

Another problem with two smaller subs versus one larger one is the distortion produced by the smaller woofers. I believe the physics is that the larger the box/driver the better the bass. It's for this reason, as well as multiple bass sources, that you don't want to run the main speakers full range.

The only reason I would ever consider two subs is to increase SPL beyond what could be cleanly produced by a single sub and in that case I would stack the subs.

This article might be of interest:
Warnerwh...I too have a spectrum analyser, and in general I can't agree with you about how much signal lies below 45 Hz. What kind of music are you playing? Some recordings do go right down to 20 Hz, but in my music library these are the exceptions. Also, if you are playing vinyl, rumble and warp will keep your SW busy, but do you really want to listen to rumble and warp?
Remember, bass below 80hz is really non-directional. Why not try 1 sub and if you don't get enough "slam" then add a second. You may be amazed that in normal listening that you probably won't be able to tell if 1 sub is connected or two.
Elevick..."Remember, bass below 80hz is really non-directional". This is widely stated, but, to my ears, is not true.
As far as smoothing out the bass response 2 subs can be better than 1, but only if you take great care in setting them up. In order to do this properly you really need some sort of tool that will give you visual feedback on how the bass is behaving such as a computer program like ETF, or a stand-alone unit like a velodyne sms-1.
..."Remember, bass below 80hz is really non-directional". This is widely stated, but, to my ears, is not true.

Eldartford, would you explain why you believe that is so?

Bob_reynolds...I am not quite sure what your question is, but...

It is widely stated that a very LF sound source can't be located by a listener. Without getting into whether the statement is true or not, my contention is that it is widely stated. I believe this because it is often said in Audiogon postings which I have read (and other reviews). When something is said often enough people accept it as true.

I believe that a LF sound source can be located simply because I can do it, and I don't think that my ears are anything special. The ability to localize the sound is most obvious when it comes from behind the listener in a multichannel system. Left to right localization is also easy unless, as is often the case (particularly with LPs) the LF signal has been blended to mono. A mono LF sound will create a phantom image between two subwoofers, just like higher frequency sound. Also, if multiple subwoofers are operating out of phase, through either electrical connections or placement, the sound will have a "diffuse and directionless" quality...exactly what happens at higher frequency.
Thanks for all the advice - really appreciate it - it's always interesting to hear several logical yet contradictory and often mutually exclusive opinions on audio topics - part of the fun really.

I decided to start my sub experience with a single unit and do it in the least expensive way while still going for a quality unit. I bought a HSU research sub on-line. Easy to hide (wife factor), great reviews from mags and audiophiles, reportedly more oompf than the small RELs, 30-day refund option and if I find I want to try a second unit it is easy and cheap to do.

My room is huge, it's a bit of a sonic mess, I am very limited in placement options and a big powerful sub will not fly in the family/listening room - so spending huge cash on a top notch sub likely makes little sense. I will settle for a noticeable improvement in sound for awhile, play around with the HSU and maybe a second one at some point and see where that takes me.
You might to look at the following article which talks about how to maximize the use of subwoofers (both number and placement)
I agree with Eldartford when at very close range and at higher SPL levels.

I find I become aware of the general direction of a sub when I am within about four feet of it in 25 foot room (very close range and the lower the cut off the closer I need to be to know where it is). This tends to work only at higher SPL levels so maybe floor vibrations are providing higher frequency harmonic clues or it is the small amount of energy from the driver above the cut off....who knows.

I do agree that a sub position behind the listener does not seem to work as well...perhaps because this ends up being quite close to the listener. My preferred option is placement at a similar distance to the listener as the main speakers and for practical puproses to one side of the room or the other (rather than between the two speakers). Sub to ceiling, sub to side wall, sub to rear and front walls all being different lengths (this seems to be a good rule of thumb).

Two subs does complicate things as cancellations will also affect the sound field...probably a harder setup.
Eldartford, I was asking under what circumstances you can localize bass frequencies. You provided that. Thanks.

Yes it is widely stated and accepted that frequencies below roughly 80Hz can not be localized. I can't site the references for this, but I'm sure Tomlison Holman had a good reason for picking that value for the THX standard.

I was wondering if in your case it was a matter of level differences that you were hearing. I know that was the case for me before I calibrated the levels with the M&K test tones. And I agree with Shadorne that I can still localize the sub when it is rumbling the corner for sustained periods during DVD movies.

Thanks again,
Tim916 hits the nail on the head IMO.

I have posted my experience in this thread:
In defense of my statement, find us an engineer please. You may be "feeling" the bass when it is really loud or close. But, hearing it is another story. I'm not a bass heavy person. If you came to my house, you would be hard pressed to find my 15" velodyne, let alone tell if it's on or off unless listening to a track that has lots of deep bass. And yes, when watching a movie, I can localize the bass because it shakes the heck out of my room!

I was always taught a simple sub set-up technique for people without the money or access to test equipment. Place the sub anywhere. Get on your hands and knees and crawl around the room while playing some strong bass pieces. Where the bass sounds strongest or best is where you should move the sub to for optimum room response. Far from perfect but if you can't decide on the final location this may help.
Where the bass sounds strongest or best is where you should move the sub to
And that's usually going to be in a corner. Other factors in the whole one vs. two subs question are (1) where the crossover is set, (2) if your mains are runing full-range or are high passed, and (2) the distance from the sub(s) to the mains. These factors affect a listener's ability to localize the bass.
If your room is large, go fo two subs - I have tried one and two subs and found a lot of differences, particulary on how two subs clean the midrange better than on trying to cope with both channel information.

I might be a different animal, but the radiation pattern is localizable from my listening position (my room is not huge as you mentioned is yours) thou.

Good Luck

The bass cabinet itself radiates energy and harmonics above its determined crossover point. This is one reason you can audibly determine the location of your sub and one big reason it effects the blend into the mains as well as the tone quality and staging aspects of the mains. Two sub set up properly sound better than one, again because they will blend better and increase the stage size and focus. Tom
Theaudiotweak...That's a good point about the caninet vibrating at higher frequency. However, it doesn't apply in my case because my custom subwoofer systems are embedded in a wall (and built like a brick SH).