3 subwoofers - can it be done and is it crazy??

If I buy a new sub I want to try use both the old and the new subs. But on my receiver ther eis only one LFE output and I don't know how to connect two subs. The more important thing is: will the old sub do more bad than good?

There is no such thing as overkill. I would use the 10 as a midbass driver from say 50-80 Hz and the HSUs from 15-50Hz.

No such thing as crazy in this hobby, someone on the boards has 4 SVS Ultra PB13s. Go for a third, why not? Im going for a 3rd myself. I currently run dual PB12 Plus 2s and will either add one more or the PB13U, controlled by the SMS-1 of course.

Yes, Virginia, you are crazy. Welcome to the club.

4x PB13s isn't much around here.. Come back when you have real subwoofage.





No such thing as over kill, just use 'Y' splitters.

I wouldn't call 80 - 50hz a midrange freq. It sounds like the suggestion was to send some bass to the 10 inch subwoofer and the lower bass to the other subs.Not so simple to do. If you don't have a very capable preamp which lets you customize multiple high and low pass crossover points, you would need an external crossover. The receiver's sub output (from 80 hz and down for example) would be split with a y connector. But how do you make sure that the MA doesn't get anything below 50 hz? And how do you make sure that the other subs don't get anything above 50hz? Need some inline high and low pass crossovers.

But maybe if the other subs have a selectable high pass crossover, you can feed them 80 - 20 hz, but use their internal crossover to eliminate everything above 50 hz. Then pass everything above 50 hz to the MA sub.

Even if your other subs have a selectable high pass crossover, I wouldn't do it. Sounds complicated. Plus you have to factor in the interaction of different crossover slopes.

Yes, it is very difficult to implement properly with 'stock' equipment.

Connecting multiple subs of disparate capabilities is problematic. As an example, let's consider 2 hypothetical subs. One subwoofer has a low-end capability of 18Hz. The other sub has a low-end capability of 30Hz. To calibrate both of these subs properly requires calibrating each one individually, first, then level-matching them properly by lowering the level of each one an equal and appropriate amount to compensate for their additive effect. Once this is done, both subs will end up calibrated properly, more or less, over the range of frequencies that they share (30Hz+). But the range of the more capable sub from 18Hz to 30Hz will now be calibrated at too low a level. You definitely don't want your low-end capability to be calibrated at too low a level. But if you 'turn up' the more capable subwoofer to compensate for the low-end being calibrated too low, you will now end up being calibrated too 'hot' over the range that the 2 subwoofers share (30Hz+).

That said, you should do what you want to do. If you're happy with the results, that's all that matters.

I agree but I like the last sentence. Most forget to do that.

There actually wouldn't be a range that the subs' share, except for the range near the crossover point where they are all rolling off. What was being proposed was a 3 way system. 20k - 80 hz for the main speakers. 80hz - 50hz for the MA sub. 50 hz - 20 hz for the other subs. But I think that the range they share around the crossover point would be a problem.

I actually did this once, using an Audio Control Richter Scale III as the external crossover to split up the bass freq ranges being handled by each subwoofer. So I'm not saying it can't work. I just know that if it was so easy to do, the Velodyne Signature 1812 probably wouldn't be the only sub that I would have heard of to try it. There may be other manufacturers, but it obviously isn't commonplace.

I presently use 3 subs in my bedroom. 2 Fathoms F113s and 1 Krell Resolution 15. But I'm aware of the problems I have to deal with. And I don't use the Krell as an LFE subwoofer, so much as a speaker to flesh out the lower octaves for my center speaker ONLY. Even then, I know what I'm doing is wrong.

But I guess that goes back to the recent post. If you enjoy it, go for it. I just propose enjoying with full knowledge and awareness of what fidelity is technically being sacrificed in that enjoyment.

There's no right or wrong....but the more subs you put in, the more opportunities for problems that arise. I have 5 subs in my 2000 cuft sealed room...1 Epik Conquest, 1 PB13, 1 DD-15 and 2 PC-Ultras(TV-12) - and I have absolutely no doubt I am at the point of diminishing returns.

I do split the Conquest and PC-Ultras (12 hz tune) as LFE and the DD-15 and PB13 (10 hz tune) as low frequency crossover from the other 7 full-range channels.

I use an SMS-1 and Behringer DEQ 2496 for EQ (and of course the DD-15 has it built-in). Calibration is extremely time consuming...adjusting each unit individually, then in combination as LFE and subwoofer (low-freq crossover), then balancing crossed low freq with mains, then balancing them all together to find the best balance, location and EQ for individual and combined signal outputs.

I am quite happy with my end result but it required many days of painstaking planning and work....and if I were to start over from scratch with my total investment I would probably simplify my arrangement....but then it wouldn't be the hobby/challenge that it is!!!

Days of work. With both a SMS-1 and a Behringer and the DD-15's internal SMS-1. And you would simplify if doing it again. That's all I was saying.

I think it was Tom Nousaine who did a study of using multiple subs, and found that 4 subs came out to be the ideal. Either in all 4 corners, or in all 4 mid-walls. I know the editor of Secret's website uses 4 Velodyne HGS18s in their room.

3 is a nice round number! I have 2 Ultras myself controlled by an SMS and am saving up for a third! As was said above, kinda small for some of these circles, but hey, what the hell, it makes me smile!

I have one spot and one spot only to place my sub, a Mirage S12. It sounds great, especially with music. While movie soundtracks also sound great, I think I can do even better.
The one spot I can place the sub also limits the physical size I can use (socket for a central vacuum system and the electrical outlet need to be easily accessible. I can go higher, but not wider or deeper). My S12 fits perfectly.
What about stacking the subs? What problems might I encounter?

Stacking is good -- it just won't smooth out the frequency response in your room the way "one on each side" can. But you do get the maximum possible gain increase - 6 dB - by co-locating two subs.

So -- is your current one-sub placement noticeably boomy at certain frequencies - or - harder to spot - noticeably silent at certain frequencies?
Two stacked subs (or one larger sub) at that location will excite the room resonances in the same way, but more strongly.

So you might consider some bass traps or outboard EQ at some point, since you only have the option of one sub placement -- but only if you need to.

Personally I would sell your one Mirage and get a sub capable of more low frequency output -- as big as you can fit in your space and as much as you can afford (up the the PC13Ultra, anyway ) If you do have a noticeable frequency resonance, a sub with a built in PEQ would help tame it.

Thanks ggunnell . Actually I have no complaints about sound quality; the Mirage is terrific with music and movies. Movies are good, but more ooooopmph would be better.
I have a Mirage S10 in a second system upstairs, just thought I'd get opinions before I buggylug it down and jerk around with the wiring to try it.
It's tough gettin' old.......

Thanks again.

I am in the same 3 sub situation. I have (2) Klipsch sub 10s at the front with my MMG's and the Mirage OM200 on the surround channel with the MMGW. How should I set the crossover on these and how should the crossover be set on my Outlaw 990?

Not knowing your specific equipment my comments will be general, but when you run a sub off a specific speaker channel you have to set that channel as "Large" in your prepro, otherwise bass to that channel will be redirected to your subwoofer output and/or and other channels you have set to Large.

You can use the crossover built into the channel-specific sub to roll off it's output over a certain frequency, but how do you roll off the output to that specific channel's speakers below that same frequency? Usually the only way (without buying an external crossover) is to use the high level (speaker wire) connections on the sub -- assuming it has them. The built-in crossover for these connections is usually non-adjustable, often in the 100 to 120 Hz range.

You might get better bass by connecting all three subs to the subwoofer output on your 990, setting all your speakers to "Small", bass output to "Sub Only" and use a global xo of 80 to 100 Hz to start with. If you keep the one sub in the rear of the room you will have to independently delay the signal to it -- if this sub does not have a continously variable phase control to do this, you may be better off placing the third sub up front.

With 3 subs, two of them being the same model, the best way to go is to have the two identical subs located in the room symetrically, say mid-point of side walls, or whatever locations work best and given the full sub output.

The third sub could be put in a corner, or at the front mid-point, or back of room, and setup as a LFE only sub. This is how I've got mine setup. I generally use all 3 for movies and only use the identical pair for music.

Why it will give 6 db increase? According to my knowledge, doubling power will give ~ 3 db increase. To get 6db increase, you need to increase power by 4 times. Am I missing something?

Thanks,

The world where two PB-13 Ultra's is small is the world where many people live that aren't thinking clearly.

For a system, turning up the volume 3db requires twice the power. Say from 40~80wpc.
Stacking subs is a totally different thing, thus resulting in a gain of 6db.

I was describing the situation that would exist if one did NOT utilize, as you described, "................a very capable preamp which lets you customize multiple high and low pass crossover points, you would need an external crossover. The receiver's sub output (from 80 hz and down for example) would be split with a y connector. But how do you make sure that the MA doesn't get anything below 50 hz? And how do you make sure that the other subs don't get anything above 50hz? Need some inline high and low pass crossovers. ............." and instead simply tried to set up 2 (or 3) subs of disparate capabiltities to cover different ranges with no special accommodations for doing so. This is actually the more common way that a casual and less knowledgable user would attempt this. In which case the subs in question would essentially "share" the range of frequencies covered by the less capable sub.

I am in the process of hooking up 3 subs as we speak.
HSU MBM-12 for the 50-80hz range
HSU VTF3 MKII 55hz an below
HSU VTF3 HO with Turbo 55hz and below

It's a lot more work than you think, and I am about ready to pull my hair out 2 days into this project, and I think I've got the placement down. Now I need to recalibrate each of them. Then take some measurments. Then I have an EQ coming in on Wed, so that will start a whole new phase of this project

I'm strugling, but getting it done.....slowly

Nick

For the best result on hooking up your HSU subs, consult with Dr. Hsu. He designed them and he is the best expert for them. I have a 3.3 Turbo & MBM-12 in a 6000 cubic foot room and they do the job nicely.

Bill

Can't find an explanatory link right off, but it is 6dB -- if you've got a couple subs and a meter you can try it yourself.

The 'trick' is the co-location. Simply adding a second identical sub some distance away will give you the expected 3dB gain, although many residential rooms are small enough you'll see 4 dB gain with a "one on each side" placement.

But when the drivers are close together, 'sharing the same air', you get a 6 dB gain -- it's a wave phenomena. If someone has a good link to the math, or the relationship between dB gain and fractional wavelength separation between the drivers, please post!

There is a simple explanation for the 6db increase. First, you are doubling the power. That accounts for the +3db. Second, you are doubling the sound radiating surfaces when you double the woofers...+3db. Total, 6db.

Hi i agree with most of the above, but would stick to two or three decent subs.

One by the left speaker, one by the right and one centre between the two mains.
I use this configuration and find the sound great for movies and music.
Using bfd and separate peq-2200 and cx-3400 s,
sure sound treatmeat it would be even better again.

A sub at the rear is what Tom Holman recommends in his 10.2 so give it a try see what you think ?
And no you are n't crazy.

The debate around one massive sub as appose to two or three will go on till the end of time.....
But we have two ears one for left and one for right so think this is the best option as it just sounds so much better.
After all, our set ups are based on a stereo signal so why change just because dvds are recorded with a mono sub channel.

One day soon.. it will be stereo sub .2 (10.2) im sure IMO.
Cinemas and concerts etc. would n't dream of using one massive sub,
although two massive subs would be nice !


Go for it you 'll love it !!!

The facts are that two or more subs will give a better overall output, through out the entire room. Although each room has its own sonic problems, starting with subs in each front corner, or at the mid-point of the side walls is always a good start. And then just fine tune the locations, if needed.

There are already ways to get stereo subs. Some receivers and pre/pros have stereo sub outs. The other way is to connect a pair of identical subs, via speaker wire, to the L/R speaker outs of the receiver.
Then use a third sub for the LFE only.
Or use the rca line inputs on the two subs and set that to LFE only, plus the speaker inputs. In this case, the left sub and right sub are still stereo, plus they are both getting the .1 mono channel.