Calibrate multiple side surrounds - AVS Forum
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post #1 of 13 Old 02-01-2013, 06:28 PM - Thread Starter
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I've been reading about using multiple side surrounds (a pair for each row) and I'm wondering what is required to calibrate a system that uses them. I have some ideas about what's required, but I haven't found anything that spells it out clearly.

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post #2 of 13 Old 02-02-2013, 01:14 PM
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Bump?
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post #3 of 13 Old 02-02-2013, 02:07 PM - Thread Starter
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smile.gif

HF, it occurred to me that we have a whole forum with guys that probably know the answer to our questions. Why not ask, right? biggrin.gif

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post #4 of 13 Old 02-02-2013, 10:16 PM
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And gals . Are you attempting to split the rear signal to separate amps ? Please say you're not thinking of using the back surround as the surrounds for the second row .

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post #5 of 13 Old 02-03-2013, 05:11 AM
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Just like in the commercial cinema - normal LCR, then an array for side surrounds - presumably one set of loudspeakers for each row of seats - then one pair of loudspeakers for the rear surrounds.

The question is what processing, exactly, is needed to separate the side surround signals prior to amplification into each of the loudspeakers in the side arrays?
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post #6 of 13 Old 02-03-2013, 07:04 AM - Thread Starter
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+1. What Fred said.

For the sake of argument, let's assume our AVR has one channel for surround left and one channel for surround right. Obviously we are looking at dedicated amps to drive 2+ surround lefts and 2+ surround rights, but what processing is required? I understand there is more than just time delay required. What DSP will provide that level processing?

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post #7 of 13 Old 02-03-2013, 07:33 AM
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My 2008 Denon 4308CI could do this, it has assignable amps and shows surround A and surround B, which both get fed from the side surround signal. I never used it, my assumption is during setup audyssey would ping each and set levels in accord. Was not popular, they dropped it from future models.


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post #8 of 13 Old 02-03-2013, 08:07 AM - Thread Starter
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I haven't looked at a lot of AVRs, but the ones I've seen recently with assignable inputs seem to be limited to assigning the rears to front wides, heights, or bi amped stereo. It would certainly be nice to have an AVR that did this natively.

I guess to get he conversation going a bit, I'll throw what little I "think" I know out there. To calibrate multiple surrounds properly, I believe you need to adjust the time delay as well as decorrelate the signals. This simulates signals arriving from multiple directions and multiple reflection paths.

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post #9 of 13 Old 02-03-2013, 01:15 PM
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I'm surprised to hear of an AVR that does this, but the product manual agrees with Mike. Of course it gives no details about what processing it applies.

The description and documentation is pretty thin in the owners manual, but it's there. See the sample image from the GUI description on pg 23 (notice it's labelled 7.1B and shows 9 speakers), and the rules for manual speaker setup on pg 28. http://usa.denon.com/DocumentMaster/US/AVR-4308CI-OM-E_305A.pdf The weird thing is that the product description says it has 7 amp channels. http://usa.denon.com/us/Product/Pages/ProductDetail.aspx?PCatId=AVSolutions(DenonNA)&CatId=AVReceivers(DenonNA)&Pid=AVR4308CI(DenonNA)

Of course while that's interesting and relevant from a practical perspective, what J_P_A is looking for is more of a nitty-gritty description of what should be done to properly process and decorrelate the signals.
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post #10 of 13 Old 02-03-2013, 06:52 PM
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Member nightlord from Sweden has a line array for his side surrounds.
Check out his build thread in the construction forum.


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post #11 of 13 Old 02-03-2013, 10:15 PM
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You need to delay and decorrelate the second row of side speakers, otherwise you'll get comb filtering. No AvR is going to do that, you need a standalone dsp.

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post #12 of 13 Old 02-04-2013, 04:52 AM - Thread Starter
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I assume the delay is to time align the signal with the first row? How much decorrelation? I hope that's not a bad question, but the correlation ratio can range from -1 to 1. I suspect something between 0 and 1 is what we're looking for, but I don't know how much. Do you always want 0 correlation?

Also, what would be a minimum DSP to do the job? I don't want to buy a Ferrari if a Ford will do smile.gif

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post #13 of 13 Old 02-04-2013, 10:47 AM
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Looks like there is the same thread going in two places. I will answer in the other one: http://www.avsforum.com/t/1455111/when-are-multiple-side-surrounds-necessary

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