Why use more than one subwoofer?

[Grandpaw]

In the past I have read about people having two or three subs and have always wondered why they find that necessary. With my system I use a Infinity SWS 212 sub-woofer. My receiver is set flat on the sub output and the actual sub is set to around three on the volume. When playing movies using these setting this sub will shake the whole house. My house is brick and about 2600 SF and I just don't understand why anyone would need multiple subs unless the unit you are using just can't do the job. So back to my original question.... Why do you think more than one sub is necessary (assuming the first one is a decent sub)? I have always wondered and just had to ask. Thanks, Jeff

[PAT.P]

It a matter of choice for me .I find using two sub works better for me in a 26x16 room.I had one and when listening to movies or music, my ears were concentrating only at the sub.With 2 sub it all blends in into the room and I enjoy more.One sub is rear projected and the other is front projected ,it works for me .:ihih:

[kexodusc]

There's plenty of reasons for and against using multiple subs.

Your room's natural acoustics will cause a very uneven response from your sub - it's unavoidable, rooms just do that. You can treat the room to minimize the effects. You can also add another sub, which reduces the variance. It's not uncommon to see a response +/- 12 dB or worse in an untreated room. Adding more subs can balance out the cumulative interaction between the subs and the room's nodes and modes.

There's also more output, swept volume, less distortion, etc, that comes with adding a second unit, and if your crossover is high enough and not sharp enough, it could balance out some localization inssues. So some minor sound quality improvements.

I have a woofer and amp I keep meaning to put together to turn my system into a dualy - haven't gotten around to it yet. I would always recommend you do the first sub was well as you can before adding a second. I think in many systems, one better sub is better than two slightly inferior subs. YMMV.

[Geoffcin]

In the past I have read about people having two or three subs and have always wondered why they find that necessary. With my system I use a Infinity SWS 212 sub-woofer. My receiver is set flat on the sub output and the actual sub is set to around three on the volume. When playing movies using these setting this sub will shake the whole house. My house is brick and about 2600 SF and I just don't understand why anyone would need multiple subs unless the unit you are using just can't do the job. So back to my original question.... Why do you think more than one sub is necessary (assuming the first one is a decent sub)? I have always wondered and just had to ask. Thanks, Jeff

And I've had good results.

It's not about how loud you can make it, but how GOOD you can make it sound.

[Sir Terrence the Terrible]

There's plenty of reasons for and against using multiple subs.

Your room's natural acoustics will cause a very uneven response from your sub - it's unavoidable, rooms just do that. You can treat the room to minimize the effects. You can also add another sub, which reduces the variance. It's not uncommon to see a response +/- 12 dB or worse in an untreated room. Adding more subs can balance out the cumulative interaction between the subs and the room's nodes and modes.

There's also more output, swept volume, less distortion, etc, that comes with adding a second unit, and if your crossover is high enough and not sharp enough, it could balance out some localization inssues. So some minor sound quality improvements.

I have a woofer and amp I keep meaning to put together to turn my system into a dualy - haven't gotten around to it yet. I would always recommend you do the first sub was well as you can before adding a second. I think in many systems, one better sub is better than two slightly inferior subs. YMMV.

Just to add to Kex's post. Having dual subs also reduces cone excursion by splitting the bass output between to subs. This lowers distortion and allows detail in the bass to be clearly heard. It also doubles the radiating area of the bass of that particular channel which would give the ability of the channel to play much louder.

[Grandpaw]

Thanks to all so far for the replies to my post, they are very much appreciated.

With the fact that I am not driving my sub hard and it has two twelve inch speakers I feel like I am moving a good bit of air without driving it high enough to cause distortion. If you are familiar with this sub how does it compare to the newer ones.

I am not in to keeping up with all the new equipment available out there but this is what I have and it serves me very well. I only have a few friends with newer stereos that I can compare mine against but I still prefer mine to theirs.

I would be interested in knowing how this setup would compare to newer systems if you have possibly heard any of the speakers I have.

Due to the fact my equipment is a little older than some of you have it may be something that you are not familiar with. They are oldies but goodies.

This is what I use

Infinity SWS212 sub has two twelve inch speakers with a 300 watt amp
I only use the sub for movies. My main speakers give me enough bass for music by themselves.

Front speakers are Infinity Kappa 7.1 series II floor standing speakers.

Rears are Infinity Kappa 6.1 series II floor standing speakers

IL36C center channel

Onkyo TX-DS777 receiver

[Sir Terrence the Terrible]

Thanks to all so far for the replies to my post, they are very much appreciated.

With the fact that I am not driving my sub hard and it has two twelve inch speakers I feel like I am moving a good bit of air without driving it high enough to cause distortion. If you are familiar with this sub how does it compare to the newer ones.

I am not in to keeping up with all the new equipment available out there but this is what I have and it serves me very well. I only have a few friends with newer stereos that I can compare mine against but I still prefer mine to theirs.

I would be interested in knowing how this setup would compare to newer systems if you have possibly heard any of the speakers I have.

Due to the fact my equipment is a little older than some of you have it may be something that you are not familiar with. They are oldies but goodies.

This is what I use

Infinity SWS212 sub has two twelve inch speakers with a 300 watt amp
I only use the sub for movies. My main speakers give me enough bass for music by themselves.

Front speakers are Infinity Kappa 7.1 series II floor standing speakers.

Rears are Infinity Kappa 6.1 series II floor standing speakers

IL36C center channel

Onkyo TX-DS777 receiver

Your receiver is s brute that much is for sure. I am familar with all of your equipment. Very good classic stuff, and good stuff is timeless. I would say your sub compares favorably to most subs out there. 2 12" drivers can move alot of air. I cannot see that you would need another unless your room was a very large open design.

[Grandpaw]

Sir Terrence, thanks for taking the time to reply. I wasn't sure if anyone would be familiar with what I have. When you do a search for Kappa speakers there is a lot of car speakers that come up but not much on the home units. The reviews on my speakers that I found were very positive. The one thing that I have noticed is the soundstage both in width and depth is great as long as they can be placed about three feet from the walls. When these speakers are placed at this distance they just seem to disapear all together.

I don't know if all speakers need space around them but it does make me wonder when I see speakers set on shelves in entertainment centers if the sound would be greatly improved by moving them to stands and giving them a little room to operate, Jeff

[robotec]

How does one connect more than 1 sub to a standard AV Receiver? My receiver has only 1 LFE output port.

[kexodusc]

Hey Robotec,

Just use a Y-splitter at the end of the subwoofer cable or at the receiver out and run to two subs...you can probably run up to 4 off the voltage most a/v receivers send through the subwoofer cable.

[jocko_nc]

Robotec:

I have duals subs that I use primarily for music. I do cross over a little high, my monitors are more "mid-bass" than low frequency woofers. The subs are somewhat directional. That said, I went for the most musical driver I could find, the Dayton Reference. I have them connected in stereo, using the AV receiver pre-outs from L and R, the full signal. From the subwoofer I go on to the main power amp for L and R. Crossover is on the sub amps. It works good, as loud as someone could want (I hope) and very, very musical. You do have to be mindful of ground loop noise from the electrical outlets.

Most other subs I have heard sound boomy and artifical. Maybe that is how they are set up, but mine sound like really deep, detailed speakers. I guess they are technically satellites.

I avoid the LFE output, concerned that is may not be the same as the low end of the full signal. ?????????.

jocko