Two Subs?

My listening room is 22L x 12W x 8H. I'm currently using a single REL Storm III. I'm toying with the idea of getting a second REL; but how can I determine if my room can actually accommodate two RELs without having to buy the second REL?

What would you be trying to achieve by getting a second sub? Your REL probably has enough output for your room size, for music. I used a Storm III in a 30x18x9 for music and it was ok. But I grew interested in acoustics and got myself a measuring mic and card, and realized how much the room was effecting the response. I now have two 12" Rythmik subs, each set up differently, and placed asymetrically, and it sounds so much better than with the single REL. My goal was to smooth the room response, and I did.

But bottom line, depends on what you are trying to solve. 1 sub is better than none, 2 is better, 3 would be even better. Note that when using multiple subs, each sub doesn't need to be as powerful/expensive as when you are using a single sub.

I hope this helps.
I assume that your system does not include Audyssey (or similar) room correction software. If that is true, a pair of optimally placed subs will (virtually) always provide smoother response and generally provide much smoother response than a single sub. Even if you don't need the additional clean output capability that adding a second sub will provide, you will almost certainly hear real benefits in bass articulation. As to room overload, just dial the subs'll still hear the benefit of the second sub.

Good luck.

I've always heard that 2 subs were better than one, but concerned about my smallish room. Guess if I buy used, I can always resell if I can't integrate the 2nd sub successfully.
Thanks for your thoughts!
What's the concern with the smallish room? It does not matter how many subs you place in the room -- 2, 4 or 10. You will match the levels to the main speakers. The benefit is, as Marty said, potential smoother response over a wider area and less distorted bass. But, if you're using the standard REL speaker level connections, you'll still have the same distortion from your main speakers regardless of how many subs you use.
Bob - What do you mean when you say "standard REL speaker level connections"?
I suppose he means the REL recommended approach of getting the signal to the sub from the speaker terminals, then the main speaker amp and the speakers themselves are still reproducing the whole bandwidth.

An alternative approach places a crossover between the pre and amp to filter the frequencies the sub is going to reproduce so that the main speakers only reproduce above the sub. Most speakers increase distortion at lower frequencies, so that's one benefit pursued by this approach. Same for the amp: you save headroom for the "higher" frequencies.

Of course the approach also has a downside: an additional circuit in the signal chain (the crossover itself), plus interconnects, etc. Another downside is the main speaker woofers are yet another source for low frequencies, helping to smooth the room response in line with what additional subs do. So a tradeoff, like we usually find not only in audio. Pick your poison, I guess! :-)
Got it! Thanks for the explanation. Hookup of current REL is via the speaker terminals. Dealer did the hookup upon delivery of my monoblocks. He says I'm precluded from wiring to my amps because they have a floating ground. So, a second REL will be wired to second speaker. Apparently, not optimum.
You may find this article interesting.
10-15-13: Rockyboy
Got it! Thanks for the explanation. Hookup of current REL is via the speaker terminals. Dealer did the hookup upon delivery of my monoblocks. He says I'm precluded from wiring to my amps because they have a floating ground. So, a second REL will be wired to second speaker. Apparently, not optimum.
This doesn't make sense to me. Whatever problems might result from connecting the sub to the output terminals of the amplifier, as a function of the internal grounding configurations of the sub and the amp, would also occur if the sub is connected to the speaker terminals.

Is/are the amplifier(s) the Essence Jasper mkII monoblocks referred to in your system description? And are they "fully balanced," as far as you know? In particular, do their negative/black output terminals have a signal on them, as opposed to being grounded?

-- Al
I don't think you need 2 subs unless your mains are extremely challenged...summing the left and right signals in the "high level" input of a REL and setting it at around 55 hz or so (or wherever your mains start to drop off) is all the bass you might need, but, of course, this is entirely room dependent. Multiple subs can get more standing waves and/or phase issues ramped up, and I prefer keeping my sub away from the gear. I am anti room correction device due to my inflated Professional Sound Mixer ego, and can (and do) adjust my REL level if it's out of balance. I think room correction gizmos are there for those who don't seem to be able to turn a sub up or down, insist on listening at extreme levels, the listening room is in an underground cavern full of medieval torture devices, bats, and dripping with moss, or simply feel so insecure about system set-up they require an electronic helping hand.
Two or more subs are mostly for balancing bass levels more smoothly across a room, not so much to get more or better bass at any one particular spot, though it may well help achieve properly balanced bass levels more easily there as well.

Duke from Audiokinesis is a proponent of using more bass modules for this purpose of helping to randomize bass modes throughout the room better. Of course, any pair of larger full range speakers do this to some extent, but best choice of placement for bass may not always be the best overall.

AK planetarium systems use 4 separate "bass modules" to help achieve this for example. This makes a lot of sense to me and the AK Planetariums are high on my list of potential high value speaker systems (especially for more problematic rooms acoustically otherwise) I want to hear someday.
As one who lacks PSM ego (tho I've got more than enough of the garden variety sort to offend most folks), I do use room correction. Attendant to that task, I've generated tons of readouts from my RTA that show FR at the listening position. Two subs generally produce notably better "looking" readouts at the listening position than one sub, prior to EQ. After EQ, two EQ'd subs probably produced better results than one EQ'd sub over a wide area - tho results at the listening position were awfully close. I say "probably" because the comparison is really dependent on how you define the "wider area".

I also emphasize "better looking" than "better sounding" only because the latter is subjective. However, to my ear, the results definitely correspond to the readouts - I much prefer the articulate bass sound of smoother FR at the listening position. IME, smoother response comes with multiple subs and/or room correction.

Just my own experience, FWIW.


PS - re: Bob's comment on the high level REL x-over scheme. There are advantages to inserting an active x-over that you forego when using REL's scheme. Believe what you will regarding the claimed benefits of REL's scheme, I'm pretty sure that Bob was expressing his own strong preference for actively crossing to the subs ahead of the power amp.
Yes, I'm a big fan of active crossovers. Every speaker I own utilizes them and I think they are especially relevant for integrating subs.

Though I agree with Lewinskih01's comments regarding the disadvantages in theory, I think they are outweighed by the advantages. An active crossover is another component in the signal path, but even inexpensive active crossovers have distortion specs as small fractions of one percent. Compared to the distortion produced by woofers easily reaching 20%, I'll take the active crossover. And, yes, the full range woofers are additional bass sources that can smooth the response, but they will not be clean bass sources. Spend some time studying the sub measurements and you'll see that even for specialized speakers bass is very hard to do well.

Ultimately, for me, the goal is to get clean smooth bass and I know of no better way to do that than with an active crossover.
Sub measurements schmeasurements! I get lots of clean bass, because if I didn't I would be unhappy. Unclean bass indeed! Not sure what "smoother" sound means, but whatever I'm getting from my little REL seems smooth...I think it's dialed into maybe 58hz or something so it's actual low end only to maybe 25 hz (I measured sue me!) before it gives up the ghost. I've measured my listening room using digital real time analyzers with various serious stupidly expensive pro cardioid mics, active and passive pro EQs both graphic and parametric notching types, and other stuff to play with my room system, and I prefer none of the above in the system as it seems cleaner without it. I simply turn the REL up or down...a teeny bit...ahhhhh...perfect!
Back when I had the REL Storm I was getting much better bass response than when I didn't have the sub connected. No question it sounded, and measured better with the sub on. But there was no way around certain room modes, despite trying several diferent locations within the room.

With the two Rythmik subs well placed and dialed in I get much better sound than with the REL, at least for my taste. It took many iterations of placement and dialing in all the variables in the sub's amps, but well worth it for me. Frequency response is much smoother as well, and I was able to significantly reduce the impact from those room modes that were affecting the response so much. To me, this configuration sounds much better than the one with one REL.

But I don't have experience with active crossovers, although I've been toying with the idea of actively tri-amping.
Bob, what crossover do you use? Conceptually, having one amp for mid/highs, one amp for the bass drivers, and then the two subs running in mono makes sense to me, but trying it at home would be expensive.
I've always found room modes to be an issue with a single sub, ie very noticeable by ear variations in bass levels at different room locations. Also I find that it is possible to address to my satisfaction as long as listening position stays the same. I am confident the more sophisticated and complex eq solutions have up side as well, but not critical for me personally. I would prefer to have two subs rather than one though to help smooth out things within the room better and would probably go down that route next time, though I could probably live without it quite fine just as well as I have managed to do in the past.

For the record, "smooth" is used in that sentence to mean "flat" FR - as in the peaks and valleys evident in the readout of a single sub have been "Smoothed" by the addition of a second sub or EQ. I hope I made it clear in my post that it's a personal preference, but I definitely find the bass more satisfying when the read outs are smoother. I've never enlisted the help necessary for a blind A/B test, so there's always that factor at play, but I'm pretty comfortable that EQ and/or multiple subs is more satisfying for me.

Id never say that my preference is/should be universally shared, but - if asked my opinion - that's the way I'd point someone. YMM certainly V.

Martykl...I understand. And I also understand that room correction "flattens" bass, resulting in flattened bass even if the music has large bass as in a giant bass drum (for example, one of those pops up here and there in a fave Scofield/Frissell album). There's the rub. I'm happy you're comfortable with your flattened bass, as I'm comfortable with my sometimes bumpy, and to me anyway, more realistic room sound. Bass level issues are a matter of degreee of course and I can't live with what I consider to be unnatural lumpiness in anything, including people (Hollywood plastic surgeons get no "support" from me). I insist my preference be universally shared by everyone at all times forever, and invite everyone to join in my Campaign Against Unnatural Lumpiness.
I live in LA. No "natural lumpiness" here. All smooth, all unnatural, all the time. Couldn't be happier.
One man's meat....
Lewinski, my first system with bass management was using M&K pro speakers, sub and their analog multichannel BMC. After reading Dr. Floyd Toole's papers, I gave up the analog system for a digital one with room mode correction. That system was all JBL LSR4300 pro speakers and sub. My current system uses a Marantz AV7005, K+H O300D (3-way tri-amped) monitors and a pair of Hsu ULS-15.

For people not wanting to go the digital route there seems to be serious lack of BMC devices for integrating subs. Blue Sky still makes their analog multichannel device (seems just like my M&K BMC), but I don't know of any others that support balanced cables. Oh, Bryston has their 10B-SUB, but it's pricey. Hsu has an unbalanced BMC.

There are many inexpensive pro audio crossovers on the market like from Rane and Ashly, but nothing like the discontinued NHT X2 filter.
room correction flattens bass? I guess you have less knowledge about roomcorrection. Wolfy prefers bumpy humpy low's from his slow subwoofer. Maybe there are people happy with less? When it makes you happy, who am I :)
During a show I used audyssey pro. I played Kodo drums. I did this demo with and without roomcorrection. All the people found the drums superior in weight and dynamics with Audyssey Pro than without the roomcorrection. Also the palpable image of the drums where in a different league than without. I see you use a downfiring subwoofer. What would you like to change about the sound you have now?
Did you compare downfiring subs with frontfiring subs?
As an audio engineer, I can safely say that room correction absolutely "flattens" bass, because that's what it's designed to do. And Bo, you have no idea what my system sounds like, as I have no idea how you "played" Kodo drums with room correction at a show. Isolation booth? Did the "room correction" somehow stop the acoustic bleed through? I grew up with Japanese drumming here and there in Hawaii, and if you could really play those things there's no "room correction" that could stop 'em in a live setting. But then I suppose in the alternative universe you occupy there is room correction blanketing any aural phenomena, REL woofers are slow, and your posts make sense.
Maybe the poor systems you use flattens, could be. Audyssey pro uses EQ and Volume. These parts give you a much better dynamics than without. Downfiring subwoofers never will give a precise integration with the fronts. The floor colours often the low freq. Can be nice, but it is not a very natural sound in low freq. Subwoofers which can be used to 140 hz will integrate a lot better with the speakers. From 80hz low freq. become palpable. When we compare downwfiring sub with a frontfiring sub you will hear the difference in integration. With Audyssey Pro and sealed frontfiring we get a stealth integration. Many subowners and also Rel owners said that they never heard this level in subwoofers before. It is all about speed and integration. It is that simple! should perhaps familiarize yourself with audio terms..."flatten" in this case simply means to straighten a frequency curve using EQ and volume parameters designed into room correction devices. This is based on device measurements that "see" low frequency peaks interpreted by the device as undesireable room reflection generated standing waves, or what the designers of the gadget have deemed to be unnatural bass frequency modes. I assume you used a recording of a disregard the last part of my previous post, unless you really did play the things. Also, I use a sealed REL Q150e front firing woofer, although downfiring woofers can and do integrate fine with mains for many listeners who's ears might differ from yours...140hz is a ridiculously high frequency point for subs, and it's weird you think that should work well...hmm...sort of goes to credibility there.
A year ago my sub was set till 80 hz. It was based on the time I almost only sold Rel subwoofers. You could not use them to higher freq till about 60-70hz. I got the information of Audyssey people. So I start testing with 100 and also 120 hz. And I was amazed that the overwhole sound became more palpable and also more musically. Later I compared 120 and 140 hz. With 140hz it became even beter. Without Audyssey pro I could not have used it this far so easy. If you would have asked me a few year ago to use subwoofers this high I would have thought you are crazy. It changed my thinking about subwoofers. When you do many tests in audio sometimes your perspective changes. With Audyssey pro I have so much more control with subwoofers. When I would not have it, it would be a different world. It made me love subwoofers for stereo. I never thought I would use it for stereo myself. I am very sceptive in many things in audio. But hearing is believing. Audyssey still have no option to use 2 subwoofers for each front channel. Then I would play with 2 subwoofers as well.
There's no Audyssey Pro dealer close to me to perform analysis of my room. Any other room correction systems (for non-rectangular rooms) available on the cheap?
Rel Q150 was the most sold Rel at our shop at the time it came out. I prefer frontfiring. But in old houses with old floors you can get a lot of ( coloured) fun with them. It depends what you like!!
I've never heard the DSpeaker Anti-mode duocore, but it gets good reviews and (I believe) shows room analysis as well as providing correction. Underwood HIFI sells it on-line, and - I believe- provides an an-home evaluation/return policy.

Good Luck

BTW, I believe the cost is just over $1k, so I'm not sure it's "on the cheap" for you.
Bo...I can only assume things about your taste in sound quality based on your posts. When you claim to use subs crossed over at 140hz and then you filter the hell out of them with room correction, I can get a good idea of what you're looking for. Likely a sound similar to a Joe Bonamasa concert. When you make ridiculous and condescending statements about "coloration" you also strain credibility...I use a REL high level input which replicates the power amp tone, and any musical tone cues that would reveal innacurate coloration are absent at the low frequency points the REL produces with distortion inaudible when driven at reasonable levels. If you had listened to the things you supposedly sold, even with the unsophisticated and clearly untrained ears attached to your thick head, you might understand something about basic acoustics, musical accuracy, and what professional musicians and sound engineers often hear.
Rocky, Based on everything I have read concerning the use of subs, 2 are better than one, and can be more easily positioned for better bass response even without room correction. This has been stated by other posters prior to 10/17.
Let us know what you decide.

You can do room measurements the old fashioned way with an SPL meter, a disc of test tones and a pad of graph paper. Many people use the Radio Shack analog SPL meter. I'm sure others can suggest more accurate meters. Ethan Winer provides bass test tones on his Real Traps web site.

I think this exercise is beneficial so you can see how bass looks (and sounds the way it sounds) in your room now. If you have some freedom to move your sub around, then you can see the impact of doing so. Then if you get another sub you'll be able to see its impact on in-room response.
I use the Dspeaker Dual Core 2.0 in my 2.2speaker system. I also use it as the Dac and preamp. If you use it this way I would advise getting a good 12v dc linear or battery power supply.
My 2 subs are Shelby+Kroll Woofer Monitors which are a 10" down firing design.
My room is 15.5'w x 21'l x 8.25'h man cave/office.
The Dual Core can measure the room from 20hz-20kz and you can also choose what frequency you want to measure. From there you can make the necessary adjustments for the bass you like, and keep them in 4 different profiles that are easily accessible with a push of a button on the remote.

From the measuring tool I saw that I had a huge valley or "hole" from 35-55hz and a serious peek around 70hz. By placing the subs in the corners, turning up their gain,and running a 200hz correction the hole began to close and brought down the 70hz peek. I continued increasing the gain, doing corrections, and measurements until I got the bass to -1.5db from flat to about 120hz!
No cutting with extension beyond belief!

I never knew how many deeeep notes that Victor Wooten was using in Flight Of The Cosmic Hippo (Bela Fleck and the Flectones), but I do now!
The bass and drums on Hotel California from The Eagles "Hell Freezes Over" is deep,clean, focused, and very extended.
All of my music even single acoustic guitar music by Tommy Emmanuel and Frank Vignola has body and depth that are intoxicating to listen to. Hearing INTO the guitar body is something I was never able to do before installing the Dual Core.
I could go on and on, but if you are using 2 subs the Dual Core 2.0 is a must to get the most out of them without having to move your subs all around the room.
Oh and there is an adjustable subsonic filter so you won't fry your drivers.

A kindred spirit: room correction, Tommy Emmanuel, and Frank Vignola. My Ryan Thorell archtop is one of my favorite guitars (tho it's not the Vignola model, it has a strong family resemblance). And I fully agree that when you clean up the lower registers via room correction, the personality of the guitar being played is much more recognizable.

Rodge - Thanks for the tip on Dspeaker. I've gone to their site and products look interesting; so I sent a few questions. I already have a nice preamp and don't really need a DAC; so, I'm wondering if I should just get the Anti-Mode 8033 instead of the Dual Core 2.0. Hope to get some answers next week.
I had the 8033s for the subs and graduated to the Dual Core from the distributors request. The 8033s was very good, but the D/C took the sound quality up many a notch. The D/C has USB and Optical SPDIF inputs and an Optical SPDIF output. Therefore it can be installed using it in Pure Digital. Use either the USB or Optical inputs and the Optical out to your dac. You can run the necessary room corrections and use the dac/preamp/amp combo of your choice. The room corrections are done in the digital domain and will continue down stream to your dac. The D/C is a very user friendly piece and can find it's way into most systems.
Heck for the cost of one, you might want to check out it's dac and pre against yours and decide to use it that way. That's what I did and I'm very happy.

As noted above the D/C will sound better with a quality 12v dc linear power supply or 12 dc battery power supply. I checked with Dspeaker and a 12v dc LiFePo4 battery fully charged is 15v dc and will work with the D/C.

Hope this helps.
A kindred spirit: room correction, Tommy Emmanuel, and Frank Vignola. My Ryan Thorell archtop is one of my favorite guitars (tho it's not the Vignola model, it has a strong family resemblance). And I fully agree that when you clean up the lower registers via room correction, the personality of the guitar being played is much more recognizable.

So true!
Brings a whole new experience to the table.
I never knew Rodrigo y Gabriela could sound so good and precise. Like sitting third row center and getting the live sound from the stage!

Wow! A Thorell Archtop!
Serious player, no doubt! :-)
Nice ...very nice!

Rodge - don't know if you want to weigh in; but thread in Tech Talk forum is discussing performance of Dspeaker
I read through the thread and I can't comment on the clipping issue the one guy is having. The only clipping issue I had was from my former dac that had a 5v output and clipped the analog input. There is a sensitivity filter that can be placed on High or Low for this issue, and it worked for me. I have read about the MiniDSP and doing measurements with REW, but found the Dual Core 2.0 to do a very good job and never felt the need to go that route. If budget is an issue the 8033sII is a great product and should be seriously considered. I have the 8033c on my HT sub(SVS 2039+) and like what it does there.

I had read numerous posts and some papers about sub placement and tried to implement those techniques. It was a lot of work and in the end the Dual Core did a better job. I'm very happy with the sound quality with the subs placed in the r&l front corners of my listening room. If I could I would place a sub in the front Left or Right corner and a sub in the opposite corner on the rear wall. Play around with measurements and calibrations until I was satisfied with the bass.
"If I could I would place a sub in the front Left or Right corner and a sub in the opposite corner on the rear wall."

That would very likely be a bad choice as both subs would be exciting the same room modes. One sub in one corner is good, but the second one should not be in the symmetrical corner. Moreover, about midway of a wall would be more advisable.

The best configuration in my room has been one sub in between the main speakers and the second sub in a corner, with the front or back corners showing almost the same results (albeit with different settings/adjustments).

BTW, just like there is no substitute for good speaker placement, the same goes for sub placement. Sure, room correction will make it better, but the least correction you need to apply, the better.

First the professional microphone which is used with Audyssey pro measures a lot more information compared to a standard Audyssey microphone. Second we measure at totally different places and hights compared to the Audyssey way of measuring. This gives a very big difference in how much dynamics and information you can measure. The roomcorrection of Audyssey is only 1/3 of the whole system. By using the parts Audyssey volume and EQ to the max the end results are a lot better. Without it I would have a loss in dynamics. And it would be more the same like other room acoustic systems. By using Audyssey pro with EQ and Audussey Volume the volume of the sub can be set so much lower than without. This gives you more control and more drive as well. We learned to use it differently to get the results we wanted. Using the sub till 140 hz makes the palpable integration so much better. People Always say and think; so you do not use the subwoofer? Ofcourse I use the subwoofer. When I put it have you see the eyes of the people move. Using it till 140 hz is only possible of the timing and fast respons of the subwoofer. Next step will be the very Soon outcomming pure silver Audioquest Wild Dog subwoofer cable.

Audyssey requires that the subs be calibrated at 75db, IIRC. If you're using a pair of reasonably high quality subs, that requires quite a low setting, right there. The volume dials on my Rythmiks are set at the very low end of their range. I can't imagine going much lower.
I can even turn the volume of the sub quite loud without any problem. Calibrated at 75 db, the volume using with my measurment is a lot lower than with the Audyssey way. I use a Purist Audio powercable with 004 Oyaide. When we use a cheaper powercable. The volume will be higher as well. You can influence the control to the sub in many different ways. I know already that the new pure siver Audioquest Wild Dog will give a positive influence on the control of the sub. The Sub-3 from AQ also uses some silver. This made a big improvement also on the freq. from 60-140hz. Control and a better timing give you more space to use the subwoofer to his max. My Olive 06HD with also a Purist Audio powercable and a new Audioquest Wild Blue Yonder xlr gives with 132 db much more weight and drive to my PLW-15. A source with more weight and speed gives you superior control to your sub as well.