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Old 28th February 2005, 06:35 PM   #1
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Default Mono or Stereo Subs?

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?
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Old 28th February 2005, 07:12 PM   #2
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Default Re: Mono or Stereo Subs?

Quote:
Originally posted by Matttcattt
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?

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.
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Old 28th February 2005, 07:21 PM   #3
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Default Re: Mono or Stereo Subs?

Quote:
Originally posted by Matttcattt
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?
Stereo. It is the only way to overcome the localization resulting from the high distortion inherent in the driver itself.
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Old 28th February 2005, 07:52 PM   #4
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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.
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Old 28th February 2005, 07:58 PM   #5
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Quote:
Originally posted by tiroth
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.
Are you saying that HT source is mixed so that bass is centred? That would be news to me. And 2 channel music? I really don't think so.
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Old 28th February 2005, 08:28 PM   #6
tiroth is offline tiroth  United States
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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.
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Old 28th February 2005, 08:37 PM   #7
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Quote:
Originally posted by tiroth
In your example, it is conceivable that nondirectional sub-bass could localize to some random corner, which is a lot worse in my opinion.
Yes, this is what I was thinking but did not expressly state. And the other thing I was thinking but did not state was that with stereo, the distortion would narrow the imaging but not totally collapse it to the centre.
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Old 28th February 2005, 09:28 PM   #8
tiroth is offline tiroth  United States
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Quote:
Originally posted by leadbelly
Yes, this is what I was thinking but did not expressly state.
I meant that as a potential criticism of stereo feed instead of mono to a pair of subs. Upon further thought, I can see why it could be considered desirable, but I still think mono would be better in this regard.
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Old 16th March 2005, 10:45 PM   #9
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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.
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Old 16th March 2005, 11:04 PM   #10
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Nonsense. Just do a search on THIS forum on key words like "distortion" and "localization" and see how many published studies give evidence to the contrary.
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