Mixing subs/rear sub. standing waves? (1 Viewer)

[Robert Silge]

I posted a thread on this in the HT hardware, but no luck, or no one knows. So I thought I'd go into more detail here, and see if that doesn't entice a response.
I have a DIY sonosub. I am thinking of buying the Sony SA-WM40 as well. I am wondering about the effects of using both at once. Since I'm sure they won't have the exact same response to a signal, will this muddy my sound, and create interference?
My other thought is to hook the Sony (assuming it's not as capable a sub as mine, which I hope it's not) in at line level as a rear sub. Does this make a noticeable improvement? I could also put it at the back of the room on the same channel as my main sub, and hope sheer distance would overcome any interference issues (it's about a 25' room I think).
Since I'm going to do some sub surgery on my sono, I want the Sony as a backup in case I both something, but I'd also like to use it in tandem if possible.
Thanks guys,
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-Rob

 

[Greg Monfort]

It would be best to place it next to the sonosub if wired to the same channel.
WRT how it sounds, don't have a clue. I assume it will sound worse than the sonosub alone, though it will increase efficiency of the sub system 3dB in whatever BW they share assuming they have the same sensitivity rating.
If mounted at the other end of the room, there will be phase shift issues, but depending on where the listening position is, you may not notice them due to our poor hearing in the LF BW. I would probably hear it, but I seem to be more sensitive than most WRT phase. You'll just have to try it and see. If it's obvious, it will sound like you're sitting between front-to-back stereo subs, royally screwing up L-R imaging in the XO bandwidth.
If used to make the surrounds and/or rears fullrange, then there will be some phase shift mixed in to give the illusion of spaciousness or a point in space, so integration is determined by the system during setup. This would be my suggested application for it.
GM
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Loud is beautiful, if it's clean

 

[Robert Silge]

Would it fix any of these problems to switch the phase of one sub?
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-Rob

 

[Doug_H]

I upgraded to a new Velodyne a couple of months ago. I wasn't planning on using the old POS sub I had but I got bored and hooked them up together. I was expecting total crap sound but was very surprised that they complimented each other.
I placed them on opposite sides of the room R/L and the bass filled the front soundstage. It became seamless and as an added bonus they fill in each others gaps and weaknesses. I wouldn't swear this will work for everyone but you should hook them up and give it a go.
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The Mischievous Rogue Strikes Again!

 

[Greg Monfort]

>Would it fix any of these problems to switch the phase of one sub?
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At some frequencies, but make it worse for others. You would just have to try it.
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>I placed them on opposite sides of the room R/L and the bass filled the front soundstage. It became seamless and as an added bonus they fill in each others gaps and weaknesses. I wouldn't swear this will work for everyone but you should hook them up and give it a go.
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I prefer 'stereo' subs too, and you can use EQ to balance them to some extent if they are two different designs hooked to separate channels, but hooked to a common channel can cause problems in the BW where the front wall is >one WL wide. If this distance is < the XO's -12dB point, then you're home free, so for an 80Hz/4th order, the distance needs to be