Two Subs...Gain Matching vs Level Matching - Page 10 - AVS Forum | Home Theater Discussions And Reviews
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post #271 of 276 Old Yesterday, 06:50 AM
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Originally Posted by trp3383 View Post
Hmmm now im confused. I guess I'll just try it both ways and see of there's any difference.

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post #272 of 276 Old Yesterday, 09:27 AM
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Hello, sorry if this has been mentioned before, when gain matching the (identical 3) 18" subs in the center of the room with mic an inch or so from center of cone what's the target dB level to shoot for? If I remember from trying this method before I was trying to get about 90 dB from each sub in the center of the room, please correct me if (probably) wrong. TIA
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post #273 of 276 Old Yesterday, 11:30 AM
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Reference is 85 dB, but the point is to get the subs at the same level relative to each other, not some absolute value. Then let the AVR (or whatever) set the levels as it normally does. The catch is that you need to loop back and check the AVR's levels to make sure you haven't max'd out the trim range, top or bottom. If you have, or are very near, then you should adjust the gain control on both subs equally (change them the same amount) to bring everything back into line. What I have done is to run the AVR's cal, tweak one sub so it is pretty close to the middle (say +/-3 dB), then do the gain cal by tweaking the "other" sub's gain control to get the subs gain matched. At that point put the subs where they should be, run the AVR's cal, and see where you end up. If one sub is too high or two low, adjust both subs' knobs equally to get the trims in range.

The times I have seen this procedure fail is when a person puts one sub say at the front wall and the other right by (or behind) the MLP, or (worst I have seen) one at the front wall, one at the back, and one at the side in a large room, so there is a dramatic difference in level at the MLP. That may make it hard to find a place where one or the other is not at the trim limits.

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post #274 of 276 Old Yesterday, 12:14 PM
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The thing is when audyssey set the levels, my mains, center, and rears are all around +/- 1db measure from my imm-6 with calibration file in audio tools using c weight slow from mlp. But the subs running together are around 65-67 db. How come audyssey is setting the subs so low?
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post #275 of 276 Old Yesterday, 03:53 PM
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Could be lots of reasons, including room nulls/dips and phase cancellation among subs, but also remember C weighting rolls off below 30 Hz so leaves out a lot of subwoofer frequencies. If Audyssey is setting them low there may be a peak it is measuring and trying to compensate.
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post #276 of 276 Old Today, 06:46 PM
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@Don T hanks for the info, that's makes sense with adjusting the gain on just the one sub, the two upfront will be equidistant to MLP and the third will be somewhat NF. If I can't the subs upfront dialed in and gained matched after the quick cal I should be OK, thanks again.

Jeffrey
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