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#371611 - 03/30/12 10:36 AM LFE test tones.
Murph Offline
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Registered: 10/05/06
Posts: 6955
Loc: PEI, Canada
I was playing with speaker levels last night for no good reason and then re-ran the db calibration in my Denon to adjust them back to proper levels. I noticed that when the sub test tone was playing, the sound level constantly seemed to fluctuate. It wasn't in a sin wave type pattern either, it seem to randomly sound louder/quieter every second or two.

I wondered if maybe this was just my hearing or the fact that maybe I wasn't keeping still enough or ?? So I brought out my db meter and had it measuring while I listened. I know the average db meter is not very accurate at LFE frequencies but the changes on the digital reading by +/- up to 2 db did seem to match the fluctuations that my ear was hearing.

Is this a normal effect for subwoofer test tones? I don't recall hearing it before but maybe I just never noticed. Am I just paying more attention or is something a bit wonky?

I have a calibration DVD I can try tones from as well to see if I hear the same thing but I thought I'd ask the experts before I get too far into it.
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#371612 - 03/30/12 10:38 AM Re: LFE test tones. [Re: Murph]
CatBrat Offline
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Registered: 08/05/09
Posts: 6015
Loc: Milky Way Galaxy
That could be a case of comb filtering. I've noticed this when playing around with sounds with the M22 on wall speakers. Walking across the room would cause the sound to get louder and softer, very rapidly. Probably just an anomaly with any on-wall speakers.

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#371619 - 03/30/12 12:51 PM Re: LFE test tones. [Re: Murph]
michael_d Offline
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Registered: 07/23/04
Posts: 4195
Loc: Up yonder
I've always wondered why the spl wanders all over the place as well. Even with the meter set to a slow response, the db just bounces up and down, although the test tone does not seam to get louder - by ear.

I've also discovered that the Denon 4311 sets LFE about 10 db lower than the rest of the speakers. The 3808 always got the sub pretty close. I'm totally clueless why the 4311 is setting it so damn low.
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#371645 - 03/30/12 08:33 PM Re: LFE test tones. [Re: Murph]
fredk Offline
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Registered: 12/06/07
Posts: 7786
Loc: Canada
I noticed the same thing when I set up my sub. I just figured it had something to do with that other dimension that sucks socks out of your washer.
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#371646 - 03/30/12 08:39 PM Re: LFE test tones. [Re: fredk]
St_PatGuy Offline
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Registered: 03/07/05
Posts: 7463
Loc: Glendale, Arizona
Originally Posted By: fredk
I noticed the same thing when I set up my sub. I just figured it had something to do with that other dimension that sucks socks out of your washer.


With all those low frequencies that dimension has sucked up it needs some kind of damping.
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#371651 - 03/30/12 09:32 PM Re: LFE test tones. [Re: St_PatGuy]
fredk Offline
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Registered: 12/06/07
Posts: 7786
Loc: Canada
Originally Posted By: St_PatGuy
Originally Posted By: fredk
I noticed the same thing when I set up my sub. I just figured it had something to do with that other dimension that sucks socks out of your washer.


With all those low frequencies that dimension has sucked up it needs some kind of damping.

grin Thanks. I knew I was on the right track. I just couldn't quite put it all together.
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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!

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#371661 - 03/30/12 10:47 PM Re: LFE test tones. [Re: michael_d]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10634
Mike, if you mean that all your settings before you calibrated were the same with the 4311 as with the 3808, it would seem to indicate that the sub test tone in the 4311 is at a higher level. If so, the calibration is still correct when the 4311 sets it at -10dB, but lowering the sub level control before calibration would give an end result closer to 0dB.
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#371688 - 03/31/12 12:51 PM Re: LFE test tones. [Re: Murph]
michael_d Offline
connoisseur

Registered: 07/23/04
Posts: 4195
Loc: Up yonder
Uh....I don't quite understand what you wrote there John.

My standard MO is to run the Audyssey auto set up first. I let it do it's thing, then I go into the manual set up and change the crossover (as generally, the mains are set to large), then I verify SPL with my Radio Shack digital meter. The 3808 would get the channel levels very close, including the LFE channel. The 4311 however, consistently sets the LFE channel about 10 db too low. I'm not sure why it is doing this.
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#371749 - 03/31/12 09:53 PM Re: LFE test tones. [Re: michael_d]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10634
Mike, I suppose that's why I began the previous reply with "if you mean". I interpreted what you were saying to be the fairly common observation that after the calibration(with the sub correctly set to equal level with the speakers)the receiver had set the sub trim much lower than the speakers(e.g., speakers at +2dB, sub at -8dB). This is no big deal and running the calibration again with the level control on the back of the sub set lower brings the sub balance point closer to 0.

I see that what you really mean is that the sub level, as measured with an SPL meter, is actually 10dB too low after the calibration. This of course can be easily corrected manually, but no explanation for the difference immediately comes to mind. The Denon manuals do have a 10dB sub attenuation setting that can be applied for certain material, but this isn't the default, and doesn't accidentally get set during an auto-calibration. Generally, as you noted with your 3808, the auto calibration would be at least as accurate as a manual calibration with an SPL meter.
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#371780 - 04/01/12 01:36 PM Re: LFE test tones. [Re: Murph]
michael_d Offline
connoisseur

Registered: 07/23/04
Posts: 4195
Loc: Up yonder
Ya, this is just weird. All the Audyssey and DD volume nannies are turned off too, so I have no idea why it's reading LFE as high as it is. It does have a pretty neat feature for running two subs. At the beginning of the calibration, it makes you adjust the sub gain if it thinks it is too high. It sends a test tone to each sub, and you just dial it down while the display tells you what the DB is. This is quite helpful for balancing the two subs. Very cool feature....
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