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post #1801 of 2445 Old 02-20-2014, 06:22 PM
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Originally Posted by Brian Fineberg View Post

What size are the cabinets you are now using? And what drivers? I'm very interested in your comparison to the xs30's also cost of the project. Thanks!!

LTD-M18 cabinets with UXL-18 drivers. XS30's are not even on the same planet....Jbrown has a build thread in the DIY section. Enter at your own risk or you might end up joining the dark side. smile.gif
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post #1802 of 2445 Old 02-20-2014, 06:26 PM
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Link? In a gluten for punishment

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post #1803 of 2445 Old 02-20-2014, 06:28 PM
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Originally Posted by Brian Fineberg View Post

Link? In a gluten for punishment
http://www.avsforum.com/t/1506201/ltd-m18-sub-build
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post #1804 of 2445 Old 02-20-2014, 06:31 PM
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Thank you smile.gif

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post #1805 of 2445 Old 02-20-2014, 06:35 PM
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Quote:
Originally Posted by basshead81 View Post

889 is not 5star...I calculated your score a couple posts up. smile.gif

Just for grins, I re-calculated using Neutro's estimated numbers (your results were assuming PB13s, and the PC13 is down approx 1.5dB @ 20Hz):
Quote:
Originally Posted by neutro View Post

PC13-Ultra: estimated as the PB13-Ultra - 1.5 dB
Sealed: / 83.1 90.0 96.1
16 Hz tune: / 87.8 103.6 107.7
20 Hz tune: / / 95.9 109.1

... and that gave



The 5.0 star rating that confuses me is circled above in red.

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post #1806 of 2445 Old 02-20-2014, 06:38 PM
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Quote:
Originally Posted by Vader424242 View Post

Just for grins, I re-calculated using Neutro's estimated numbers (your results were assuming PB13s, and the PC13 is down approx 1.5dB @ 20Hz):
... and that gave



The 5.0 star rating that confuses me is circled above in red.

Hmm according to the OP you have to have a score below 299 to get 5 star...a score of 889 is 4 star. Must be a glitch in the auto cal. Utility.
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post #1807 of 2445 Old 02-20-2014, 06:59 PM
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Quote:
Originally Posted by Brian Fineberg View Post

What size are the cabinets you are now using? And what drivers? I'm very interested in your comparison to the xs30's also cost of the project. Thanks!!

I bought my UXL-18's from the group buy so roughly $1600 for the four drivers, two inuke 6000DSP's $799, and few odds and ends from monoprice and parts-express $130 and about $300 worth of wood, nails, screws and glue. So basically for the price of a single Triax I've built a setup that would definitely be a set above a Triax. And I am certainly not putting down the Triax, just being realistic smile.gif

I did love my XS30's but got the DIY itch. Tom & Jim and all of their products are top notch stuff at their price points.
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post #1808 of 2445 Old 02-20-2014, 06:59 PM
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Quote:
Originally Posted by Pain Infliction View Post

To be honest, I have never understood why the bass is calibrated at 85db to 75 for the speakers.

Is that the way to interpret it? I don't think it means that the bass channel is +10dB hot (louder than the speakers).

Rather, I thought it meant the bass channel has extra +10dB headroom (for the sound designer to play with if he wanted to push it).

Would appreciate any clarification on this.
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Due to the way bass waves are perceived, bass needs to be jacked up 10dB and this is taken into account at the mixing board.

Reference level is:

Speakers are 85dB +20dB headroom.

Subwoofers are +95dB +20dB headroom.

Many confused reference level play to be +105dB for speakers and +115dB for subwoofers when in fact, that's not correct. Those figures have peak headroom added in.
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post #1810 of 2445 Old 02-20-2014, 07:08 PM
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Quote:
Originally Posted by BeeMan458 View Post

Agreeing with you, the only way I can see or understand things, DEQ ain't as good as Audyssey claims it is. If it were, neither you, I or the lamppost would find need to run their subs hot. Either which way, despite the unoriginality of my thoughts, I'm so glad this solution came to mind as even at -15dB, we still get excellent tactile feel where before, with the driver three feet from the back of the MLP, I was lucky if I felt the occasional thump in the back of the chair. Now we get everything, floor, feet, tactile feel in the back of the chair and in the seat cushion, subwoofer created breeze across the bare toes and the whole room, rumbles shakes, rattles and rolls, the way one would expect it to yet we're still down -10dB MVC.

Now that's what I'm talking about.

I don't think DEQ is meant to work the way you want it to work.

In your case you want reference level (0 dB) bass at -10dB MVC. But I don't think DEQ is trying to achieve that (hence you feel DEQ isn't as good as claimed). If your MVC is -10dB Audyssey DEQ still wants the bass to be balanced relative to -10dB MVC and it compensates accordingly.
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post #1811 of 2445 Old 02-20-2014, 07:12 PM
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Quote:
Originally Posted by BeeMan458 View Post

Due to the way bass waves are perceived, bass needs to be jacked up 10dB and this is taken into account at the mixing board.

Reference level is:

Speakers are 85dB +20dB headroom.

Subwoofers are +95dB +20dB headroom.

Many confused reference level play to be +105dB for speakers and +115dB for subwoofers when in fact, that's not correct. Those figures have peak headroom added in.

True, the bass would have been adjusted at the mixing board to the level the mixing engineer wanted. But would it be a +10dB increase across the board for bass? If they use the Fletcher Munson curves, I think it is a sliding scale increase.

As for reference level, I thought it was:

Speakers are 85dB +20dB headroom.
Subwoofers are 85dB +30dB headroom.

I might be mistaken, gotta re-read.

Edit: read a couple of articles:
http://www.hometheaterhifi.com/volume_7_2/feature-article-misunderstood-lfe-channel-april-2000.html
http://www.acousticfrontiers.com/home-theater-blog/2013/3/14/thx-reference-level

Yup appears that subwoofers are 95dB +20dB headroom.
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post #1812 of 2445 Old 02-20-2014, 08:34 PM
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OK, I ran a graph from the LP at my measuring location and not my lap. This was Linear PCM from Ps3.



Here is bitstream from Ps3.

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post #1813 of 2445 Old 02-20-2014, 09:02 PM
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Quote:
Originally Posted by jchong View Post

Is that the way to interpret it? I don't think it means that the bass channel is +10dB hot (louder than the speakers).

Rather, I thought it meant the bass channel has extra +10dB headroom (for the sound designer to play with if he wanted to push it).

Would appreciate any clarification on this.

The LFE channel was originally created to give an extra 10db of headroom. I believe that is why subs are calibrated to 85db (when using a -30dbfs tone).

No subwoofer I've heard has been able to produce the bass I've experienced in the Corps!

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post #1814 of 2445 Old 02-21-2014, 02:54 AM
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The LFE channel was created to put loud LFE's in to a separate channel that would not fit the dynamic range of the other channels. The .1 channel has enough headroom to allow the equal loudness contour of the loudness curve. The .1 channel is a discrete channel that may also contain redirected bass from the speakers set to small. In theory the point one channel may be ask to do a max of around 121 or 122 db at the subs peak. This channel should be thought of as a playback channel with LF content and redirected bass.

Reference level is the 85 + 20 db and the 85 +10 +20 db which peaks at 105 and 115 for the speakers and sub respectively.

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post #1815 of 2445 Old 02-21-2014, 04:11 AM
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Quote:
Originally Posted by jbrown15 View Post

I bought my UXL-18's from the group buy so roughly $1600 for the four drivers, two inuke 6000DSP's $799, and few odds and ends from monoprice and parts-express $130 and about $300 worth of wood, nails, screws and glue. So basically for the price of a single Triax I've built a setup that would definitely be a set above a Triax. And I am certainly not putting down the Triax, just being realistic smile.gif

I did love my XS30's but got the DIY itch. Tom & Jim and all of their products are top notch stuff at their price points.
Thanks!! Maybe when I build my dedicated ht I will tackle DIY smile.gif

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post #1816 of 2445 Old 02-21-2014, 08:09 AM
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Quote:
Originally Posted by derrickdj1 View Post

The LFE channel was created to put loud LFE's in to a separate channel that would not fit the dynamic range of the other channels. The .1 channel has enough headroom to allow the equal loudness contour of the loudness curve. The .1 channel is a discrete channel that may also contain redirected bass from the speakers set to small. In theory the point one channel may be ask to do a max of around 121 or 122 db at the subs peak. This channel should be thought of as a playback channel with LF content and redirected bass.

Reference level is the 85 + 20 db and the 85 +10 +20 db which peaks at 105 and 115 for the speakers and sub respectively.

Ahh thats it!! When the speakers are set to small the lfe channel can be called upon to deliver 121-122db peaks from redirected bass. I was trying to remember where I read about the LFE channel needing 121-122db of headroom during reference playback...your post brought it all back. Thx!!
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post #1817 of 2445 Old 02-21-2014, 09:11 AM
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Quote:
Originally Posted by basshead81 View Post

Ahh thats it!! When the speakers are set to small the lfe channel can be called upon to deliver 121-122db peaks from redirected bass. I was trying to remember where I read about the LFE channel needing 121-122db of headroom during reference playback...your post brought it all back. Thx!!

I thought reference level for peaks on the LFE was 115db... not continuous.

http://www.avsforum.com/t/1252556/what-is-reference-level

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post #1818 of 2445 Old 02-21-2014, 09:18 AM
 
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My understanding, the whole idea of the additional headroom is to reduce peak performance stress off the subwoofer amplifier. Another 6dB in output assures one of having minimal harmonic distortion at peak reference level play of 115dB. Adding a second sub goes along way in addressing this issue.
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post #1819 of 2445 Old 02-21-2014, 09:19 AM
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Originally Posted by ellisr63 View Post

I thought reference level for peaks on the LFE was 115db... not continuous.

Where did I say 115db continuous?

When your mains are set to small redirected bass signals are sent to the lfe channel. LFE+redirected bass can equal 121-122db peaks at reference. Basically the sub is hadling all the bass duty so it may be called upon to deliver more then 115db peaks at reference.

You can verify this by changing your speakers back amd fourth between large and small...you should notice the sub level drop when all speakers are set to large.
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post #1820 of 2445 Old 02-21-2014, 09:20 AM
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Quote:
Originally Posted by BeeMan458 View Post

My understanding, the whole idea of the additional headroom is to reduce peak performance stress off the subwoofer amplifier. Another 6dB in output assures one of having minimal harmonic distortion at peak reference level play of 115dB. Adding a second sub goes along way in addressing this issue.

It does but that is not what I am saying...read my post above. smile.gif
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post #1821 of 2445 Old 02-21-2014, 09:21 AM
 
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Quote:
Originally Posted by basshead81 View Post

When your mains are set to small redirected bass signals are sent to the lfe channel. LFE+redirected bass can equal 121-122db peaks at reference. Basically the sub is hadling all the bass duty so it may be called upon to deliver more then 115db peaks at reference.

In my opinion, only if overdriving the output and intentionally trying to exceed peak subwoofer output of 115dB and the speakers themselves, with peak headroom, are expected to top out at 105dB and no more. Above that and in my opinion, the viewer is exceeding what the producer and mixer laid down on the track.

In my opinion, just saying, if someone wants to exceed these published THX standards, they're welcome to but in doing so, they're clearly outside the limits set by THX and this point needs to be openly acknowledged.
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post #1822 of 2445 Old 02-21-2014, 09:27 AM
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Originally Posted by BeeMan458 View Post

In my opinion, only if overdriving the output and intentionally trying to exceed subwoofer output of 115dB and the speakers themselves, with peak headroom, are expected to top out at 105dB.

Negative...I will try once more.

When you set all speakers to small, the bass that is filtered out at crossover is redirected to the LFE channel. In order for the listener to recieve all of the source content, the sub must now play the LFE effects + the redirected bass from the other speakers. If you switch your speakers from small to large you will notice a difference in sound and output.
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post #1823 of 2445 Old 02-21-2014, 09:28 AM
 
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Quote:
Originally Posted by basshead81 View Post

It does but that is not what I am saying...read my post above. smile.gif

I did before I responded and again before starting to compose this post. Even with bass managed bass + LPF for LFE @ 120Hz, my understanding, it's still not to exceed 105dB peaks for speakers and 115dB peaks for subwoofer content.

...confused.gif

What am I misunderstanding>

...confused.gif

I'm not arguing, I don't understand. All our speakers are set to small. All crossovers are set to 80Hz. The LPF for the LFE channel is set to 120Hz and the LPF on both subs is set to 120Hz. Set up this way we have a boatload of headroom and the highest I've recorded on a handheld sound meter is 114.8dB. I know things can go louder, I'm not into louder but instead, I'm into flat reference capable play back and lately I broke with tradition and dialed in a well discussed house curve or what ever it's being called these days.

According to your "negative," it's obvious that I'm missing something or the whole ballpark so if you'd be so kind to flag me in, that would be cool.

...confused.gif

Are you saying there's +6dB worth of redirected bass from all the speakers to the LFE channel and that needs to be added in, above and beyond the demands of the LFE channel of +115dB peaks which then requires a subwoofer system, capable of additional filtered <80Hz content, jacking the need of the subwoofer system up to +121dB to +122dB? because of the added filtered content?

(i think i got it)

...confused.gif

-
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post #1824 of 2445 Old 02-21-2014, 09:45 AM
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A blu ray track was intended for the listener to get all effects from all speakers. When you set a speaker to small you compensating for its inability to reproduce the effects of that channel at reference playback below the crossover point. In order for those effects to not get filtered out, they are redirected to the LFE channel. When that occurs the LFE channel can be called upon to produce peaks higher then the standard 115db. This is why avr sub calibration will set your speakers large if they are deemed fit for the task. The 105/115db reference peak standard protocol is for all speakers set Large + LFE, not Small + LFE. When you set all speakers small you are asking the subs to pick up the extra load.
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post #1825 of 2445 Old 02-21-2014, 09:47 AM
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Quote:
Originally Posted by basshead81 View Post

Where did I say 115db continuous?

When your mains are set to small redirected bass signals are sent to the lfe channel. LFE+redirected bass can equal 121-122db peaks at reference. Basically the sub is hadling all the bass duty so it may be called upon to deliver more then 115db peaks at reference.

You can verify this by changing your speakers back amd fourth between large and small...you should notice the sub level drop when all speakers are set to large.
I don't see how LFE would ever exceed the 115 db reference level unless you raise your volume above reference level... As i am not aware of the LFE+ redirected bass making any difference in the 115db reference level. If I am wrong please correct me.

I just posted the Question to Audyssey on their website.

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post #1826 of 2445 Old 02-21-2014, 09:55 AM
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I see the redirected bass from the speakers having no more of a signal strength that won't exceed 105dB as would be the case if not redirected and the same with the LFE channel who's signal is spec'd to 115dB. I don't know nothing about nothing.

As to <80Hz crossed over to the LFE channel, I have no idea. What ever happens, at full on reference, expectedly, our subwoofer system has plenty of headroom and is up to the demands of the task.

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post #1828 of 2445 Old 02-21-2014, 10:38 AM
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Quote:
Originally Posted by BeeMan458 View Post


What am I misunderstanding>

...confused.gif


...confused.gif

-

Pretty much everything.

At least in this post you asked a question vs posting grossly inaccurate info as factual.

With the addition of 2 more channels in 7.1 lossless formats, there is a potential of 105dB peaks from each channel being redirected to the SW channel and added to the 115dB peaks of the .1 channel.

Although this is a theoretical possibility of actually occurring in a soundtrack, it is an extremely unlikely one because of the requirements for making it happen.

1) All channels in the 7.1 sound track would have to have all content in the subwoofer range.
2) All channels would have to have coherent content simultaneously.
3) The LFE content would have to be coherent with all 7 channels content.
4) all 7.1 channels would have to have the above required content encoded at 0dBFS (Zero Decibels from Full Scale)

IF that were ever to occur on a disc, here is how it would be tabulated:



Adding 7 coherent and equal levels adds +17dB. Adding that 17dB to 105dB peaks from each of the 7 channels = 122dB. Adding 122dB plus 115dB (a logarithmic formula) is calculated in the graphic above, summing to a 125.207dB peak.

Finally, that maximum level is at the Listening Position, not 2M Ground Plane (which is the equivalent to 1M Free Air). So, every doubling of distance from 1M to your Listening Position requires +6dB of output over your subs 2M GP or 1M FA output.

The requirement of your subwoofer system, in the never-gonna-happen theoretical 7.1 lossless format recorded sound scenario described above, is lessened by the phenomenon referred to as Room Gain. This phenomenon occurs in every room and has nothing whatsoever to do with the size of the room, how "sealed, as in air tight" the room is or what the rooms longest dimension is. Rather, it has to do with a) the sound transmission losses due to the construction method of the boundaries in your room subtracted from b) the gain realized by the reflections of the sound off of the boundaries in your room. Sound reflected off a boundary reflects back into the sound arriving later that hasn't yet reached the boundary. That interaction may be constructive (an increase in level), or destructive (a "dead spot" of no sound) and everything in between, depending on the wavelength and the distance from subwoofer to boundary. Sound pressure waves are spherical and the sphere increases in diameter as frequency decreases. So, as frequency decreases and wavelength increases there is less and less chance for the reflections to be destructive and more and more chance that the reflections will be constructive across multiple reflections off of multiple boundaries.

Since most every house built in the past 100 years in the US used 1 of 3 basic construction methods and your listening space may be predictably on one of 3 floors in the structure a simple formula can be applied to find the capability of your system.

As the metric for reproduction of recorded audio has been 20 Hz on the low end for decades, most electronics have been filtered below 20 Hz at arbitrary points for all of those decades to protect against DC offset (a bad thing). DC offset protection is easily accomplished by adding FR filtering capacitors on either the input or output ends of the analog signal. The more pieces in the signal "chain" (player, AVR, outboard EQ, amplifier), the more potential for an early rolloff in FR below 20 Hz because the roll offs are additive. The bottom line here is "If it ain't goin' in, it ain't comin' out". Obviously, if part of the spread of frequencies that make up this max SPL scenario is below the roll off of your system, you'll never be able to reach the max SPL because some of the energy is simply missing from the equation.

Finally, be aware of the limitations of a hand held SPL meter. If your in-room FR has a peak at 'x' Hz, the meter will register that peak and add everything below the peak. What does that mean? Let's say your FR at the LP is flat save for a +10dB peak at 40 Hz, induced by the room. If your SPL reading would have been 100dB, it now will read 112dB on the meter. Say you get your flat-to-2 Hz EQ in the chain and flatten the peak. Most SPL meters are 'C' weighted and roll off the low end dramatically. So, if you use a 'C' weighted meter and the content of the peak you're trying to capture has most of its energy below 30 Hz, your reading will be considerably lower than reality.

Out of time. Hope this helps.
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post #1829 of 2445 Old 02-21-2014, 10:38 AM
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This directly from Audyssey tech support... "Small/Large does not effect the LFE audio content, just bass management of satellites to subwoofer.
Simply, Large=No subwoofer available, do not use crossover and Small=Subwoofer in use, send satellite frequencies best handled by subwoofer to subwoofer.

More details on small vs large here: http://www.audyssey.com/blog/small-vs-large
A Q&A was also done on the topic here: https://audyssey.zendesk.com/entries/74454-Bass-Management-and-LFE-NOT-the-same-thing-

Best regards,
Audyssey Support"

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post #1830 of 2445 Old 02-21-2014, 10:47 AM
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Quote:
Originally Posted by bossobass View Post

Pretty much everything.

At least in this post you asked a question vs posting grossly inaccurate info as factual.

With the addition of 2 more channels in 7.1 lossless formats, there is a potential of 105dB peaks from each channel being redirected to the SW channel and added to the 115dB peaks of the .1 channel.

Although this is a theoretical possibility of actually occurring in a soundtrack, it is an extremely unlikely one because of the requirements for making it happen.

1) All channels in the 7.1 sound track would have to have all content in the subwoofer range.
2) All channels would have to have coherent content simultaneously.
3) The LFE content would have to be coherent with all 7 channels content.
4) all 7.1 channels would have to have the above required content encoded at 0dBFS (Zero Decibels from Full Scale)

IF that were ever to occur on a disc, here is how it would be tabulated:



Adding 7 coherent and equal levels adds +17dB. Adding that 17dB to 105dB peaks from each of the 7 channels = 122dB. Adding 122dB plus 115dB (a logarithmic formula) is calculated in the graphic above, summing to a 125.207dB peak.

Finally, that maximum level is at the Listening Position, not 2M Ground Plane (which is the equivalent to 1M Free Air). So, every doubling of distance from 1M to your Listening Position requires +6dB of output over your subs 2M GP or 1M FA output.

The requirement of your subwoofer system, in the never-gonna-happen theoretical 7.1 lossless format recorded sound scenario described above, is lessened by the phenomenon referred to as Room Gain. This phenomenon occurs in every room and has nothing whatsoever to do with the size of the room, how "sealed, as in air tight" the room is or what the rooms longest dimension is. Rather, it has to do with a) the sound transmission losses due to the construction method of the boundaries in your room subtracted from b) the gain realized by the reflections of the sound off of the boundaries in your room. Sound reflected off a boundary reflects back into the sound arriving later that hasn't yet reached the boundary. That interaction may be constructive (an increase in level), or destructive (a "dead spot" of no sound) and everything in between, depending on the wavelength and the distance from subwoofer to boundary. Sound pressure waves are spherical and the sphere increases in diameter as frequency decreases. So, as frequency decreases and wavelength increases there is less and less chance for the reflections to be destructive and more and more chance that the reflections will be constructive across multiple reflections off of multiple boundaries.

Since most every house built in the past 100 years in the US used 1 of 3 basic construction methods and your listening space may be predictably on one of 3 floors in the structure a simple formula can be applied to find the capability of your system.

As the metric for reproduction of recorded audio has been 20 Hz on the low end for decades, most electronics have been filtered below 20 Hz at arbitrary points for all of those decades to protect against DC offset (a bad thing). DC offset protection is easily accomplished by adding FR filtering capacitors on either the input or output ends of the analog signal. The more pieces in the signal "chain" (player, AVR, outboard EQ, amplifier), the more potential for an early rolloff in FR below 20 Hz because the roll offs are additive. The bottom line here is "If it ain't goin' in, it ain't comin' out". Obviously, if part of the spread of frequencies that make up this max SPL scenario is below the roll off of your system, you'll never be able to reach the max SPL because some of the energy is simply missing from the equation.

Finally, be aware of the limitations of a hand held SPL meter. If your in-room FR has a peak at 'x' Hz, the meter will register that peak and add everything below the peak. What does that mean? Let's say your FR at the LP is flat save for a +10dB peak at 40 Hz, induced by the room. If your SPL reading would have been 100dB, it now will read 112dB on the meter. Say you get your flat-to-2 Hz EQ in the chain and flatten the peak. Most SPL meters are 'C' weighted and roll off the low end dramatically. So, if you use a 'C' weighted meter and the content of the peak you're trying to capture has most of its energy below 30 Hz, your reading will be considerably lower than reality.

Out of time. Hope this helps.

If I understand you correctly... It is possible to exceed the 105/115 reference levels but that would not be at the MLP since when you run Audyssey it is setting the reference levels for the MLP, correct?

Denon 4520ci, (3) JBL 2360As/EV DHA-1s, (3) 1/4 Pie bass bins, MiniDSP 2x4s, (4) Klipsch HIPs, (2) Klipsch KP3002s, PS3, XBox 360, (3) Intel NUCs, Monoprice Redmere, Monster HTPS7000, 2 SUPER SPUD subs, Panasonic AE8000us SeymourAV 180 (195" diagonal) scope screen, Yamaha P7000s (for the subs), (2) Yamaha P2500s amps for the front (3) bass bins.
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