Matttcattt said:
Neither. I would run only one sub and feed it a mono signal.
You can experience some severe peaks and dips at various bass frequencies when using multiple subs. These peaks and dips are caused by room reflections.
If you must use two subs, locate them side-by-side and feed them a mono signal. Make sure that they are in phase.
These reasons do not make sense to me.
1. multiple subs offer at least the possibility to average room nulls and hence are more flexible and more likely to end up with a flatter response than a single sub. In an average non-symmetrical room, it is probably a challenge to create a response with two subs that is less flat than one sub. Common sense + measuring should give even better results.
2. If you place two subs on either side of the mains, feeding them a mono signal, any localizable distortion will pull the image to the center, which is exactly as it should be. I don't see a benefit to stereo vs. mono in this regard.
1. multiple subs offer at least the possibility to average room nulls and hence are more flexible and more likely to end up with a flatter response than a single sub. In an average non-symmetrical room, it is probably a challenge to create a response with two subs that is less flat than one sub. Common sense + measuring should give even better results.
2. If you place two subs on either side of the mains, feeding them a mono signal, any localizable distortion will pull the image to the center, which is exactly as it should be. I don't see a benefit to stereo vs. mono in this regard.
I guess, if I had to incorrectly localize bass somewhere, my first preference would be to the center of the stereo image. For multichannel, it would be better to have at least 4 subs and the virtual localization should be to the center of the room. (i.e. none in practice, one hopes)
In your example, it is conceivable that nondirectional sub-bass could localize to some random corner, which is a lot worse in my opinion. YMMV of course, I don't mean to imply this is the One True Path.
In your example, it is conceivable that nondirectional sub-bass could localize to some random corner, which is a lot worse in my opinion. YMMV of course, I don't mean to imply this is the One True Path.
If you had a pair of subs, would it be better to sum the two channels and run them in mono, or run them in stereo?
If you cross the subs over at 80 Hz or lower there is no such thing as stereo according to the research that has been done by Tom Holman and others. The ear can't localize sounds at frequencies below 80 Hz which is why the chose this frequency as part of the THX parameters.
Multiple subs are a good idea and there is no reason not to use more than one and some good reasons why you should. Tom Nousaine who writes for many audio publications has a subwoofer system which IIRC uses 24 drivers and goes down to 8 Hz.
Sean Olive has written a paper on the use of muliple subs which you can probably find easily enough.
When you have multiple drivers covering the same frequency range you have less excursion and therefore less distortion, at least if they are in the same box, I assume the same would be true if they are in multiple boxes.
Try posing this question at rec.audio.tech and you will probably get some get more definitive answers, but I'm sure there is no reason to not use multiple subs and no reason to run them in stereo if crossed over at 80 Hz or lower.
If you cross the subs over at 80 Hz or lower there is no such thing as stereo according to the research that has been done by Tom Holman and others. The ear can't localize sounds at frequencies below 80 Hz which is why the chose this frequency as part of the THX parameters.
Multiple subs are a good idea and there is no reason not to use more than one and some good reasons why you should. Tom Nousaine who writes for many audio publications has a subwoofer system which IIRC uses 24 drivers and goes down to 8 Hz.
Sean Olive has written a paper on the use of muliple subs which you can probably find easily enough.
When you have multiple drivers covering the same frequency range you have less excursion and therefore less distortion, at least if they are in the same box, I assume the same would be true if they are in multiple boxes.
Try posing this question at rec.audio.tech and you will probably get some get more definitive answers, but I'm sure there is no reason to not use multiple subs and no reason to run them in stereo if crossed over at 80 Hz or lower.
The best treatment of this subject I have seen is here:
http://www.harman.com/wp/pdf/Loudspeakers&RoomsPt3.pdf
http://www.harman.com/wp/pdf/Loudspeakers&RoomsPt3.pdf
My experience thus far. . .
I had a paid of mid-fi vented subs running mono placed 110% for WAF only. In that situation (one worse than anyone would desire) I had big-time room interactions and had a bad boom at 65 Hz (rat shak meter, nothing formal) and one at 30-ish Hz. It basically made HT 'theater-like' but music and TV terrible.
I tried stereo (line level, using the built-in crossover set to 80Hz) and it seemed both better and worse, depending. I wish I could explain, but I couldn't figure it out myself.
I finally disconnected one sub, switched back to mono and found it OK at best. I donated one of the $500 subs to a friend without one and ran the other for a while, still in the WAF position. I moved it to a few positions and saw a totally different sound (much better) but never measured it and eventually disconnected it, since I built a pair of mains that were pseudo-flat to 40Hz or so.
The current set-up is better overall to my ears, but does have less slam. At some point in the future, I hope to try a manifold set-up, using 4-8 subs running mono at center position, but it is a low priority on my list, as I have found decent mains good to 40 are better than my previous mid-fi set-up with subs and I would prefer to upgrade mains.
If I had to say, I would bet that with room treatments and measurements, a multi-sub system would be the best. However, with my level of software and experience (and patience. . . ), try and listen only yielded best results with one consumer level sub.
I will try multiple subs again in the future for sure, though.
Sandy.
I had a paid of mid-fi vented subs running mono placed 110% for WAF only. In that situation (one worse than anyone would desire) I had big-time room interactions and had a bad boom at 65 Hz (rat shak meter, nothing formal) and one at 30-ish Hz. It basically made HT 'theater-like' but music and TV terrible.
I tried stereo (line level, using the built-in crossover set to 80Hz) and it seemed both better and worse, depending. I wish I could explain, but I couldn't figure it out myself.
I finally disconnected one sub, switched back to mono and found it OK at best. I donated one of the $500 subs to a friend without one and ran the other for a while, still in the WAF position. I moved it to a few positions and saw a totally different sound (much better) but never measured it and eventually disconnected it, since I built a pair of mains that were pseudo-flat to 40Hz or so.
The current set-up is better overall to my ears, but does have less slam. At some point in the future, I hope to try a manifold set-up, using 4-8 subs running mono at center position, but it is a low priority on my list, as I have found decent mains good to 40 are better than my previous mid-fi set-up with subs and I would prefer to upgrade mains.
If I had to say, I would bet that with room treatments and measurements, a multi-sub system would be the best. However, with my level of software and experience (and patience. . . ), try and listen only yielded best results with one consumer level sub.
I will try multiple subs again in the future for sure, though.
Sandy.
Lynn Olson, Ariel speaker designer, wrote this regarding stereo woofers.
"Stereo woofers are the way to go, but not for the reasons
described in the hi-fi magazines. It is true that localization is very
difficult to perceive when the wavelengths are longer than 10 feet.
However, there is an effect known as "Spatial Impression," which conveys
the impression of size, or space, and it is quite important at very low
frequencies. A mono subwoofer, in other words, won't distort the image,
but it won't sound as spacious as stereo subwoofers! In addition, it has
been discovered in psychoacoustic research that a 2-speaker stereo image
grows narrower as the frequency is decreased ... which means that it's a
good idea to place the stereo woofers well outside the normal
stereo-pair, so the image retains its width and "air" over the full
musical spectrum."
"Stereo woofers are the way to go, but not for the reasons
described in the hi-fi magazines. It is true that localization is very
difficult to perceive when the wavelengths are longer than 10 feet.
However, there is an effect known as "Spatial Impression," which conveys
the impression of size, or space, and it is quite important at very low
frequencies. A mono subwoofer, in other words, won't distort the image,
but it won't sound as spacious as stereo subwoofers! In addition, it has
been discovered in psychoacoustic research that a 2-speaker stereo image
grows narrower as the frequency is decreased ... which means that it's a
good idea to place the stereo woofers well outside the normal
stereo-pair, so the image retains its width and "air" over the full
musical spectrum."
leadbelly said:
Motion pictures are mixed in that most of the low frequency information is panned to the LFE channel.. and usually the sub(s) in mixing stages is/are placed at the center of the screen. And screens are front and center of viewing position.
I personally know of no 2 channel mixes where all of the low end is expressly panned either left or right more than about 11 or 1 o' clock. Unless its classic stereo recordings where older mixing consoles only had pan switches instead of pots, but even then the bass guitar/drum section never dip below about 100-80hz or so.
To get back OT. In order for subs to be stereo, they need to be spaced accordingly. And the possible negative room interactions with spaced subs may outweigh the benefits. For solely 2 channel reproduction, there will be some room/system tuning that needs to be done.
IMO I prefer mono subs for the fact I use mine for HT as well as 2 channel, LFE is mono.
planet10 said:
A bloody silly use for flash i must say (but now thanx to OS X sitting as a pdf on my hard drive)
dave
Well EXCUSE me.....
Here's the link for the whole archive in multiple formats in .pdf as well:
http://www.audiosignal.co.uk/Gerzon archive.html
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