# Subwoofer Placement and Stereo vs Mono?



## Robertsmania (Jan 20, 2013)

My room has a lot of irregularity in its shape and I am experimenting with placement options for my subs.

I’m happy with the mains, they image very well and the frequency response graphs confirm that their output is very similar.

The initial/naïve placement I tried for the subs behind the mains put them in very different positions with respect to walls and produced drastically uneven output levels. Even when I adjusted them to be ‘equal’ on the SPL their frequency response was very different. Things sounded lopsided.

There are a couple other placement options I have for the subs that are more symmetrical – one is along the wall to the sides of my listening position and the other is in the corners of the room behind my listening position. My hunch is that placing them symmetrically will help them perform similarly and produce more consistent response.

I know the right thing to do is to experiment, try them in various positions and see what sounds best – but I do have a question about whether people think it makes sense to continue to pursue stereo subs or mix the inputs and make them dual mono?

If it turns out that I can’t get them to perform similarly even in symmetrical room placement, would it be reasonable to abandon the idea of having them be stereo? Each sub has two inputs and so far I’ve had them wired as stereo with L on one and R on the other. But it occurs to me that I could just as easily wire them to have both L&R going into each – so signal from each channel would come out of both subs. When a bass signal is mixed as mono and intended to come from both subs, it still would – and a stereo bass signal that was supposed to come from one channel would now come from both subs and I’m thinking it would sound the same as the same signal from the other channel?

Or would phase issues with the mains complicate things and keep it sounding lopsided?


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## tesseract (Aug 9, 2010)

Glad you could join us, Robertsmania! Nice system you have, I'm a big Vandersteen fan.

Running the subs mono won't be an issue. Two questions. Have you tried placing one sub up front and one behind the listening position? Are you using Audyssey?


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## rab-byte (Feb 1, 2011)

You can try the subwoofer crawl that's usually the best method if locating your sub.


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## Robertsmania (Jan 20, 2013)

Thanks for the replies! Last night I did the sub crawl, and confirmed that the positions along the walls to the sides provided the flattest response with good volume. Today I moved stuff around and did a rough pass at leveling them and so far I'm really happy!

I did experiment with the dual mono wiring, but went back to true stereo and will evaluate it like that for the next few days and then probably try it the other way just to see. But the good news is that the side placement has them sound very similar so I'm not as motivated to go the mono route as when I had them in the old location.

As far as Audyssey goes - yes my preamp has MultiEQ XT, as well as Dynamic Volume and Dynamic EQ. I'll probably post a separate thread with questions about that stuff but so far what I've found I like best is to level my subs first with just the direct input/passthrough. Run the Audyssey setup, check/fix the channel volumes (it always seems to set my right main a couple DB too low). Then I go back and re-level the subs. I find that the Audyssey drops the low end more than I like and adjusting it slightly after the setup sounds better to me.

I think that sounds better to me than using the Dynamic EQ - which does boost the low end but ends up sounding a little too boomy. So far my best results come from using the MultiEQ XT on its own with the other two features turned off.


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## primetimeguy (Jun 3, 2006)

Robertsmania said:


> Thanks for the replies! Last night I did the sub crawl, and confirmed that the positions along the walls to the sides provided the flattest response with good volume. Today I moved stuff around and did a rough pass at leveling them and so far I'm really happy!
> 
> I did experiment with the dual mono wiring, but went back to true stereo and will evaluate it like that for the next few days and then probably try it the other way just to see. But the good news is that the side placement has them sound very similar so I'm not as motivated to go the mono route as when I had them in the old location.
> 
> ...


Keep in mind that re-adjusting speaker levels using the receiver test tones is not accurate since the tones bypass Audyssey and therefore you are not measuring the EQ effects. If you are using tones from a disc then you are fine.


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## Robertsmania (Jan 20, 2013)

I'm using pink noise from my PC as the sound source, so it is still going through the processing - but that is a good point about the preamp's test signals.

So far I have to say that the new positions for the subs is working out really well. I've been doing more reading and realize that the way they are now happens to also be gain matched when they used to be completely uneven in the other location.

When I set them up in their current location it was shocking how much lower I needed to set them to get the same SPL levels but looking at the frequency response it was clear I was getting a much better curve. And its clear now that not driving the subs as hard helps a lot with their clarity and headroom.

Just moving them around the room has given me a pretty big step up in overall performance - for free!


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