Odd change in centre speaker level after moving sub

[supervij]

So I moved my new sub to a new location -- instead of being between the front left speaker and the TV, it's now located between the TV and the front right speaker.

I also did a minor bit of furniture moving, but that's off to the side of the HT: I moved a small side table from between two captain's chairs and placed it up a bit, a little closer, actually, to the front left speaker. And those two captain's chairs are now sitting side by side.

And the strangest thing happened when I went to level-match my speakers: the centre channel is now quieter!

Before, the centre was 3.5 dB higher than the front left. Now it's only 1 dB higher. Can the sub move and the very minor furniture move really contribute to a huge change in centre level like that?!

cheers,
supervij

PS: Just to be more clear, I always bump my centre speaker by 2.5 dB; otherwise, I find it gets overwhelmed the mains.

 

[Weasel9992]

Can the sub move and the very minor furniture move really contribute to a huge change in centre level like that?!

Yes...easily. To put it succinctly, absolutely everything matters...a 3.5dB difference is nothing.

Frank

 

[tcarcio]

I agree that it isn't a huge difference but if it were me I would put everything back the way it was and retest. See if there really is a difference and then move one thing at a time and see if that one item causes the change.

 

[Weasel9992]

I agree that it isn't a huge difference but if it were me I would put everything back the way it was and retest. See if there really is a difference and then move one thing at a time and see if that one item causes the change.

What I meant was that it's really, really easy to wind up with a difference like that. It definitely matters, especially if it's somewhere really obvious (100Hz, 2.5Khz, 12Khz). I agree...move everything back and see if you can repeat the difference.

Frank

 

[just-some-guy]

are you using the mic for the receiver ? its probably that the old configuration was putting more of a reflection to the mic, than the new config. and to your ears.

 

[supervij]

Thanks for the comments and suggestions, guys! Oh, and it's only a 2.5 dB difference in centre channel levels from the old setup to the new.

I'll have to find some time to change things back and move them one at a time. I've not only a roommate, but construction going on in my building. I like things to be quiet when I check the levels.

I used the YPAO with calibration microphone for the inital setup, but then I went back with SPL meter in tow and used the receiver's test tones afterward to get levels more accurate.

One thing I just remembered: the previous time I did the levels, I didn't use the receiver's test tones, I used instead the test tones in the AIX Records Blu-ray calibration disc. I'll have to check sometime to see if I can get same levels using either test tones. My receiver's an old(ish) one, and its YPAO has gotten things wrong before; is it possible that the receiver's test tones might be off as well? Or is it more likely that the AIX BD might have its levels incorrectly?

cheers,
supervij

 

[jostenmeat]

To me, 2.5 is a lot, but that is not at all in disagreement with Frank's assessment; that it is very easy to achieve.

You might want to get a mic stand/boom. That way, the exact same mic position can be used for either set of tones. My guess is that's it not so much the accuracy of tones, but mic accuracy and/or consistent placement. If the tones are using different frequencies, I suppose it's possible that your mic is more accurate with a certain range.

 

[tcarcio]

Thanks for the comments and suggestions, guys! Oh, and it's only a 2.5 dB difference in centre channel levels from the old setup to the new.
One thing I just remembered: the previous time I did the levels, I didn't use the receiver's test tones, I used instead the test tones in the AIX Records Blu-ray calibration disc. I'll have to check sometime to see if I can get same levels using either test tones. My receiver's an old(ish) one, and its YPAO has gotten things wrong before; is it possible that the receiver's test tones might be off as well? Or is it more likely that the AIX BD might have its levels incorrectly?

cheers,
supervij

That could be why you measured a difference. Before you do anything I would play the tones from your reciever and set the level to reference. Then don't change anything and play the tones in the disc and see what you get.

 

[supervij]

Okay, I had a little time to myself last night, so I checked out some more leveling stuff. First I used the test tones in my receiver, and calibrated all speakers and sub at 70 dB (I'd do 75, except I prefer to use the middle of the display, and I'd do 80, except the last time I did 80 dB I had a headache for the next day). Here were my calibration preferences:

L: 70 dB
C: 72.5 dB (need it bumped up, otherwise it gets overwhelmed by the mains)
R: 70 dB
SR: 70 dB
SB: 74 dB (what can I say? just seems to work well in my space)
SL: 70 dB
Sub: 70 dB

I then kept those settings in my receiver, and then popped in the AIX Blu-ray to check its levels. Using the LPCM played through the multi-channel analog cables, I came up with:

L: 70 dB (reference)
C: 71 dB (1.5 dB lower than receiver's test tones)
R: 70.5 dB (0.5 higher)
SR: 69 dB (1 lower)
SB: 68 dB (6 lower)
SL: 69.5 dB (0.5 lower)
Sub: 73 dB (3 higher)

As you can see, there are some differences in the measured values, the surround back seeming the worst. I sat in the same spot when taking these measurements, nothing changed. There were also some changes when I switched to the Dolby Digital 5.1, played through the coax digital cable:

L: 70 dB (reference)
C: 70 dB
R: 70 dB
SR: 68 dB (2 dB lower)
SB: *not on disc*
SL: 68.5 dB (1.5 dB lower)
Sub: 69 dB (1 dB lower)

I feel like I should start a new thread asking about differences between the AIX test disc and the test tones in people's receivers. I don't know which is right and which isn't. Looking at the results, I feel like there should be something wrong with my measurement methodology, but I sat in the same spot, I held the SPL meter exactly in the same way, so I dunno why so many differences in measurements. Any ideas, guys?

cheers,
supervij