the THX reference is clear in that -20dBFS should produce 85 dBSPL. if you do the math then one speaker can be asked to produce 105 dBSPL @ 0dBFS.
http://www.acousticfrontiers.com/2013314thx-reference-level/
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Neumann 7.2.4 Hometheater Layout ?
- Thread starter vince32837
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the THX reference is clear in that -20dBFS should produce 85 dBSPL. if you do the math then one speaker can be asked to produce 105 dBSPL @ 0dBFS.
http://www.acousticfrontiers.com/2013314thx-reference-level/
No, please explain why somehow the fact that multiple speakers increase the SPL/distortion ratio doesn't "count".
i said that it counts and your calculations are correct, it's just that each speaker needs to be capable of 105 dB peaks, not combined output.
Not what your link says:
Reference level for all channels except low frequency effects is calibrated by adjusting the audio chain such that a pink noise signal recorded at -20dB relative to full scale (0dB) creates 85dB sound pressure level as measured with a C weighted SPL meter at the seating locations
If you look at the calculator they posted at the end it seems to be about individual output, not combined output.
I don't see why the THX reference should be adjusted to combined output as then every setup will sound differently (depending on number of speakers) and the experience wouldn't be consistent.
The calculator is probably wrong, as the text is quite explicit. And honestly, it wouldn't make sense otherwise, as the goal of reference levels is volume at listening point, to "fix" the equal loudness curves (and probably frequency masking effects) at one SPL point, in order for flatness (and masked detail amount) to mean the same for everybody.If you look at the calculator they posted at the end it seems to be about individual output, not combined output.
I don't see why the THX reference should be adjusted to combined output as then every setup will sound differently (depending on number of speakers) and the experience wouldn't be consistent.
I don't really think so, the center channel would be working at 60 dBSPL @ -20 dBFS if a person has a 7.x.4 setup (like OP), that's abysmally low.
If all these 7 channels output the same signal, it really makes sense (at least in LF).
that's never the case though, center channel is working 90% of the time, rear channels 10% of the time or less. not to mention the ceiling speakers.
Which is why, as a complete surround noob, I supposed that only those 3 front channels received the same signal.
you forgot the
"Volume levels are adjusted for each channel individually until they read 85dB"
"The low frequency effects channel is calibrated higher, so that a -20dB signal reaches 95dBC at the seating locations."
Pretty sure "channel" doesn't mean individual speaker, but distinct signal (i.e., front, rear, etc...). And the fact that my reasoning about volume at listening point being the only thing to make sense still stands.
But I did glance over the word.
The article later says "If the playback chain is calibrated to produce 85dB for a -20dB signal at the listening position then the speakers and amplifiers could be asked to produce 105dB for a 0dB signal", which makes it clear to me.
I looked up more sources and I found this in Dolby Atmos Installation guidlines: https://www.dolby.com/siteassets/te...atmos-installation-guidelines-121318_r3.1.pdf
"Each full-range speaker should be calibrated to produce the same C-weighted sound pressure level (SPL). The target SPL can range from 79 dB to 82 dB SPL(C) at the central listening position, depending on the room size, when driven with pink noise with an RMS level of ---20 decibels relative to full scale (dBFS).
Calibrate the subwoofer level to give the same level for redirected bass content from fullrange speakers as those speakers produce in their pass bands. The target SPL can range from 79 dB to 82 dB SPL(C) at the central listening position, depending on the room size".
There is still room for interpretation, but considering the target level is even lower I'm almost certain now they're talking about individual speakers.
5.1 is 5 speakers and a LFE. One chanel is a speaker
it seems like you didn't learn enough because this is not the conclusion the discussion has reached.
I don't know what limits you're talking about as the speakers he intends to use will reach a peak of 97 dBSPL (generous estimate) and this is far from the limits of our hearing.
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Following this thread. Home theater SPL estimation has always confused me. Some questions:
If I measure 85 dB SPL at 2m with -20 dbFS pink noise, what will the peak SPL be?
I measure again, but at 4m. What will be the SPL reading with same pink noise?
What room sizes and monitoring levels are used for home theater audio mixes?
If I measure 85 dB SPL at 2m with -20 dbFS pink noise, what will the peak SPL be?
I measure again, but at 4m. What will be the SPL reading with same pink noise?
What room sizes and monitoring levels are used for home theater audio mixes?
0dBFS which is 105 dBSPL.
the same level you measured at 2m but 6 dB lower, everytime the distance doubles you substract 6 dB.
Here is a nice article to read about that, and there is a video in the end of the article with the audio engineer and showcases the State of the art room and setup.
https://www.genelec.com/-/reference...r-morten-lindberg-s-stunning-immersive-studio
This layout is possible, but depends on priorities.
You need to understand all the use cases and real required SPL (including any headroom required for DRC correction if needed), then decide.
All active monitors have protection and barely will be damaged, but KH310 are still nearfields and I see no reason to use them if they will be constantly driven to distortion.
I think it's better to consult professional installation company.
You need to understand all the use cases and real required SPL (including any headroom required for DRC correction if needed), then decide.
All active monitors have protection and barely will be damaged, but KH310 are still nearfields and I see no reason to use them if they will be constantly driven to distortion.
I think it's better to consult professional installation company.
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