[zobsky]

Typically, if I were to mark my subwoofer pre-out as OFF, would that mean that the LFE information gets re-routed to my main front channels.

I ask because I'm pondering whether stereo powered subwoofers (each tapped off the speaker level feed to the main LR channels , rather than the mono LFE channel line level) would work better.

Thanks

[mjosef]

Yes... set your sub to "none" in your AVR speaker setup menu, and the LFE channel sounds will be rerouted to your main L+R speakers, which should be then set to 'Large'.

[Rashiki]

Typically, if I were to mark my subwoofer pre-out as OFF, would that mean that the LFE information gets re-routed to my main front channels.

I suppose it would depend on your surround sound preprocessor/receiver, but as far as I know that's the typical behavior.

I ask because I'm pondering whether stereo powered subwoofers (each tapped off the speaker level feed to the main LR channels , rather than the mono LFE channel line level) would work better.

Better in what sense? A pair of subwoofers might produce more output than a single subwoofer, but it wouldn't necessarily sound better. Subwoofers require precise placement to minimize room effects, so now you have twice as many subs to place. Also, by using the speaker-level inputs, you'll be adding another crossover into the mix which can also have an effect on sound.

Not that it isn't worth considering -- I've thought about doing exactly what you're suggesting, but haven't gotten around to trying it.

 -Rob

[Charles Calkins]

Yo!!!
 Two subs don't make no difference than one sub. Been there done that!!!

                   Cheers
                     Charlie

[Daryl]

Hi Zobsky,

If you set your sub-out to off and tap your subs off the signal heading to your L/R speakers then they too will recieve a full range signal which means more excursion and more distortion as well robbing you of headroom from your main L/R amplifier as your LFE signal is greater than you L/R signal when it is fully utilized.

You can connect both of your subs to the LFE output.

Ideally your satelites would be sealed with an Ftc about 90hz and your sub would have the option of no lowpass filtering and a flat frequency response to about 200hz.

This way a standard asymmetrical THX crossover built into recievers and pre/pros set to 80hz would give you a LR4 crossover at 80hz.

This will minimize excursion and  maximize sensitivity of your satelites which is needed.

Having more subwoofers gives you greater opportunity to nullify room modes.

One popular method is to use four subwoofers and locate them on the floor in the center of each wall in your room yeilding good results without spending time with acoustics software.

[ted_b]

Yo!!!
 Two subs don't make no difference than one sub. Been there done that!!!

                   Cheers
                     Charlie

I respectfully disagree...and I've been there too.  Seems too general of a statement to just let ride.....

Stereo subs would require a lot of work (making sure they don't mess with each other's phase and polarity, etc...kinda like working brightness and contrast..they affect each other, often detrimentally, if you don't pay attention), would require adjustable high pass filters for your front main speakers (don't run them full range with lfe signals going there too), and would require decent eq/measurement capabilities to really dial them in right (I use Velodyne SMS-1's), but the advantages are numerous.  To me one of the best benefits is the fact that you can place multiple subs in different spaces in the room, breaking up standing waves, etc.  Also, depending on your crossover frequency, some directionality may even be audible, and stereo subs help alleviate that issue.  You get better output, usually, since each sub needs to do less work.  I could go on.  There's lots of talk about dual subs at places like AVS forums, etc.  Folks like Craigsub are very helpful and full of information.

[zobsky]

Thanks for all the info.

Here's why I asked the initial question:

I'm building a set of line-arrays for HT/music purposes. I'm very tempted to try an open baffle design. The issue with this is that its harder to get the units to respond well down into mono-sub territory (I consider this point to be 70 - 80 Hz , for non directional bass). There are ways around this (for instance placing the subwoofer in between the L and R channels) but I wanted to think about the possibility of dual stereo subs (not dual mono).

I can easily do this with my outboard active crossover but was looking for a simpler alternative (trying not to get into multi-amping for this project).

Thanks

 

[ctviggen]

I personally have never liked single subs for music.  Unless you put the sub between the speakers (which I cannot do), it's easy for me to localize.  For home theater, a single sub isn't bad. 

[Bob in St. Louis]

Two subs don't make no difference than one sub.

  Hmm.....I have four times too many! 
<<<<<<<<<<<<<< See!

[gooberdude]

For HT you can probably get away with a mono sub.  If listening to music though, stereo is the only way.

[electricbear]

There seems to be a lot of debate on the subject of two subs vs one. There was a paper written by Todd Welti called " How many subwoofers are enough". This work is highly regarded in the audio community, see if you can find it somewhere, it's well worth reading. If I find a link to it I will comeback and post it for you.

[electricbear]

Ok I found a link to it .
www.harman.com/wp/pdf/multsubs.pdf

[dewar]

a related question i've been wondering about, If one is using 2 subs, one next to each of the main speakers, is there any benefit to running them stereo vs feeding them both the same mono signal? might depend on their crossover frequency i'm guessing?

cheers

B.

[JimJ]

If you've gone to that trouble already, might as well feed them their corresponding stereo signal...

[Daryl]

a related question i've been wondering about, If one is using 2 subs, one next to each of the main speakers, is there any benefit to running them stereo vs feeding them both the same mono signal? might depend on their crossover frequency i'm guessing?

You actually will benefit from the dual mono setup.

With dual mono subs you maximize their capability since both are assured of recieving the same signal both will reach their limits at the same time and you don't have the possibility of one sub exceeding it's limit while the other still has capacity left.

Due to the fact that your ears are only 7" apart you always hear the same thing in both ears at subwoofer frequencies.

Channel to channel differences at subwoofer frequencies occur in recordings simply because the recording might use microphones spaced 50' apart or some sort of pan-pot/fader control might be used in the recording process.

I use a home theater processor with all channels set to small and one subwoofer under the left speaker and one under the right speaker.

This way I can feed my signal to the processor as digital and crossover all channels to the subs in the digital domain before the signal is ever converted to analog.

[zobsky]

a related question i've been wondering about, If one is using 2 subs, one next to each of the main speakers, is there any benefit to running them stereo vs feeding them both the same mono signal? might depend on their crossover frequency i'm guessing?

You actually will benefit from the dual mono setup.

With dual mono subs you maximize their capability since both are assured of recieving the same signal both will reach their limits at the same time and you don't have the possibility of one sub exceeding it's limit while the other still has capacity left.

Due to the fact that your ears are only 7" apart you always hear the same thing in both ears at subwoofer frequencies.

Channel to channel differences at subwoofer frequencies occur in recordings simply because the recording might use microphones spaced 50' apart or some sort of pan-pot/fader control might be used in the recording process.

I use a home theater processor with all channels set to small and one subwoofer under the left speaker and one under the right speaker.

This way I can feed my signal to the processor as digital and crossover all channels to the subs in the digital domain before the signal is ever converted to analog.

Thanks,
I've decided that I'm going to go dual-mono

[dewar]

Good point Daryl, hadnt occurred to me.

JimJ, going stereo would require another plate amp unfortunately.

I'm guessing if there was a bass drum recoded in the left channel there might be some locatable frequencies in the low hundred hz's that might cause a miniscule shift of the image towards the centre if mono subs were crossed over at 80hz and with a low order slope? But it would not be noticeable like having a sub in the rear corner of the room.

cheers

B.

[hoosier21]

for 2 channel listening, 2 subs is the only way to go, been there and am doing that

[dewar]

I've got a subs either side of my mains, but before these two I had only one, centered between the mains. To be honest I cant tell much difference.

The Harmaon Kardon papers seem to deal only with the FR benefits of dual subs, i.e less pronounced excitation of room modes. But if one is EQ'ing for flat I dont see much theoretical benefit of having 2 subs (other than more output, if that is needed).

I'm presently running 3 subs which I find ideal: 2 dipole H-baffles either side the mains eq'd flat to 30hz, and a sealed 'critical q' sub in the rear corner eq'd flat from 30 down to 16hz (and with a house curve setting on the equalizer that lets me boost it a bit on movies). But I think I could happily live with only the sealed sub between my mains.

b.

[doug s.]

imo, if you are listening to music, two stereo subs is the way to go.  place then next to your mains.  you *can* tell the difference between stereo & mono, with a lot of music.  soundstaging will not be as good as if you run them mono.

two subs are easier to integrate into your room than a single sub - room nodes, etc, are evened out w/bass coming from two separate locations.  two subs are also better because you will be effectively reducing distortion for the same spl.

except for the room integration issues & the reduced distortion, i cannot comment about home theatre, as i do not own a tv...   

ymmv,

doug s.