Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[ronkupper]

Hi Guys,

Any tips for what to set the Receiver Volume while using audio calibration clips to determine Reference Volume?


System:
HTPC HDMI --> Receiver |--> Power Amp --> Front Speakers
                                     |--> Powered Subwoofer
                                     |--> Surround Speakers

[6233638]

You need an SPL meter and would adjust the receiver to whatever setting plays the test clips at reference level. (83dB)

[mojave]

Are you using Tools > Advanced Tools > Audio Calibration > Volume Calibration? Those are designed to be played at 83dB. If using other calibration clips you need to find out at what level they are encoded.

Are you going to use internal volume in JRiver or the receiver to control the volume? If using internal volume, then set the receiver to maximum. This isn't 0, but is +13 to +18 on most receivers. You can lower it some if you have hiss in the speakers, but all the way up is the maximum digital signal. Lower the internal volume until an SPL meter reads 83 dB. In Tools > Options > Audio > Volume > Internal Volume Reference Level, set the volume level that played back at 83 dB.

[ronkupper]

Yes I was referring to the built-in Volume Calibration tunes.

I am using internal volume as it is required by at least one feature I use (loudness I think).

About setting the receiver to max - it is the only volume limiter besides the software and set to max a small mistake (with a high likelihood to happen over time) could easily blow tweeters and cones...

Even with JRiver Volume Protection enabled, what about the rest of Windows?

Perhaps you could describe what would be lost in quality if not setting the receiver to its maximum non hissing level?


Thanks,
Ron

[6233638]

The Loudness feature requires that you have your setup calibrated to reference level (83dB) and are using Media Center as the only volume control.
 
If you are set to anything other than 83dB, it is not operating correctly.
It follows specific loudness curves which require Media Center to know what the actual playback level is out of your speakers.
 
I do think it would be useful if you could set a custom reference level though, if you wanted the maximum level possible to be 60dB rather than 83dB for example. (limited by the receiver rather than Media Center)
 
If you are running your system like this where Media Center's internal volume control is the only one being used, I would not pass system sounds to that audio device. I would set something else as the default and use Loopback through Media Center if necessary. (which gives you the volume protection feature)
 
If your device has an ASIO driver, you could even disable the WDM device in the Windows Sound Control Panel so there is no possibility of audio being sent to it accidentally. (disabling the WDM device should not disable the ASIO device)

[Hendrik]

I do think it would be useful if you could set a custom reference level though, if you wanted the maximum level possible to be 60dB rather than 83dB for example. (limited by the receiver rather than Media Center)

You can set the reference level for loudness in the options. If you limit your whole system to never reach 83dB even at MC volume 100%, it might get tricky to setup though. But then 83dB at 100% should not blow your speakers usually, unless they are way small.

[ronkupper]

@6233638  - It makes sense the software needs to know the actual SPL at the listening point to apply the algorithm based on human perception of sound. Also good tips on avoiding windows sounds, Thanks

@Hendrik - So you say as long as I pick a 'Receiver Volume + Internal Volume' combination that measures 83dB SPL together and then set that Internal Volume level as the reference level it is OK?
What about Matt's instructions about settings the receiver's volume to it's max?

[6233638]

You can set the reference level for loudness in the options. If you limit your whole system to never reach 83dB even at MC volume 100%, it might get tricky to setup though. But then 83dB at 100% should not blow your speakers usually, unless they are way small.

This "reference level" setting tells Media Center what volume level is required (e.g. 50%) to achieve 83dB.
You cannot change the target reference level from anything other than 83dB.

[mattkhan]

If using internal volume, then set the receiver to maximum. This isn't 0, but is +13 to +18 on most receivers.

Is this generally safe? I have only measured the voltage on my SW output and that shows signs of clipping at +9 and is almost certainly clipping at +12 (max is +18).

[Hendrik]

This "reference level" setting tells Media Center what volume level is required (e.g. 50%) to achieve 83dB.
You cannot change the target reference level from anything other than 83dB.

Reference is reference. Its fixed by definition and the algorithms work by knowing exactly which level it is. I don't see where the problem is really, loudness scales to your current volume level, relative to what you configured as reference level, so if you change the reference or your configured level results in the same audio.

@Hendrik - So you say as long as I pick a 'Receiver Volume + Internal Volume' combination that measures 83dB SPL together and then set that Internal Volume level as the reference level it is OK?
What about Matt's instructions about settings the receiver's volume to it's max?

Its mostly fine to do it that way if you absolutely need a way to limit the maximum volume on your receivers side to prevent damage.
Its better to avoid the receivers volume control if you can, but if you can't, and you have a SPL meter, all MC cares about is to know which internal volume represents 83 dB SPL, it doesn't really care what your receivers volume dial is set to - as long as you never change it, but control volume with MCs internal volume control.

[ronkupper]

Thanks, that clears the subject.

I'll now go look into what are the effects of limiting the receiver's volume on the sound quality.

Best regards,
Ron

[6233638]

Reference is reference. Its fixed by definition and the algorithms work by knowing exactly which level it is. I don't see where the problem is really, loudness scales to your current volume level, relative to what you configured as reference level, so if you change the reference or your configured level results in the same audio.

Loudness assumes that you are calibrated to 83dB with a -20dBFS signal.
Can you not imagine a setup where you want to prevent the possibility of 103dB being played out of your speakers, or where your speaker/amplifier combination is simply not capable of going that loud?
 
In a mixed setup where Media Center is not the only program playing through that audio device, you might want to limit the volume via the receiver rather than via Media Center - even if it's staying at a fixed level, you may not want it fixed at a level which could result in system sounds being played at 103dB.
 
It's not an issue which affects me (yet) so I'm not too concerned personally, but I can see why someone might want the option.

[Hendrik]

I suppose we could explore setting the reference level above 100% for this. Since it scales in dB you could in theory then use loudness on systems that can't ever reach 83dB.

[6233638]

I suppose we could explore setting the reference level above 100% for this. Since it scales in dB you could in theory then use loudness on systems that can't ever reach 83dB.

That's actually the solution I came up with when thinking about it earlier, as each percentage should be equal to half a dB.
 
But keep in mind, while the reference level is set to 83dB, this is with a -20dB tone - so your system might be capable of 83dB, but not 103dB. (the full dynamic range up to 0 dBFS)

[mojave]

The 83dB reference level calibration is based on SMPTE RP 200 as recommended by Bob Katz. However, reference level calibrations vary based on room size. ATSC 85 provides the following recommendations based on SMPTE RP 200. Probably most here have a room under 5000 cubic feet (~142 cubic meters).



I wish Loudness wasn't tied to Internal Volume Reference Level, but had its own setting. Music has no Reference Level. If I use Loudness for music I will typically lower my Reference Level by 10 dB or more to prevent excess boost in the bass and treble.

Is this generally safe? I have only measured the voltage on my SW output and that shows signs of clipping at +9 and is almost certainly clipping at +12 (max is +18).

What did you measure with to show clipping? What was your voltage at +9? I'd like to explore this further.

[mattkhan]

What did you measure with to show clipping? What was your voltage at +9? I'd like to explore this further.

a 60Hz sine wave and a multimeter on the pins of the xlr cable that heads for my amp, the approach is described in detail on HTS in this post - http://www.hometheatershack.com/forums/home-theater-receivers-processors-amps/35677-gain-structure-home-theater-getting-most-pro-audio-equipment-your-system.html#post317692

my results are on avs (http://www.avsforum.com/t/1528032/understanding-input-sensitivity-specs/0_100#post_24699593), another poster advised that given the way I'd measured at +3dB increments then not seeing sqrt(2) increase in measured voltage is indicative of clipping.

The HTS link describes a more detailed approach for determining the point at which you clip & I understand you can also use an oscilloscope.

[6233638]

The 83dB reference level calibration is based on SMPTE RP 200 as recommended by Bob Katz. However, reference level calibrations vary based on room size. ATSC 85 provides the following recommendations based on SMPTE RP 200. Probably most here have a room under 5000 cubic feet (~142 cubic meters).

Media Center uses 83dB so unless you can change that target, that's what you have to calibrate to.
 
However, since 1% = 0.5dB in Media Center you could calibrate to say 73dB at 80% volume which, assuming everything is behaving linearly, should be equal to 83dB at 100%.
 
The current issue is if you wanted a reference-level signal to play at 63dB, which means peaks of 83dB as the tones are -20dB, you would either need a setting of 120% in Media Center, or a way to specify your own target. (either because your setup can't go louder, or you want to limit the volume from the PC via the receiver)
 
Thinking about it some more, allowing values above 100% would probably be the best solution rather than allowing the reference level to be adjusted. It should save a lot of headaches.

I wish Loudness wan't tied to Internal Volume Reference Level, but had its own setting. Music has no Reference Level. If I use Loudness for music I will typically lower my Reference Level by 10 dB or more to prevent excess boost in the bass and treble.

I don't know how you could do it any other way. The loudness contours are specific to the playback volume. (phon on these charts = dB)
Not deviation from the reference, but absolute to the level coming out of your speakers.
It is assumed that mastering is done at 83dB, so reference level = flat.


 
Our sensitivity to low frequencies is diminished at lower volumes, and follows these equal-loudness contours.
These contours show how loud frequencies have to be so that they are perceived as being the same volume.
 
With an 80dB 1kHz signal, a 20Hz signal needs to be played back at about 120dB (+40dB) to be perceived as being the same volume.
When you reduce that to a 60dB 1kHz signal, 20Hz needs to be played back at 110dB. (+50dB)

If you assume that the content was mastered with 83dB as the reference level (let's use 80 for simplicity) then that when you reduce the playback volume to 60dB (-20dB) the bass has to be pushed up by 10dB to compensate.
This is not a "bass boost" it's what is required for the two tones to be perceived at the same volume.

If you reduce the volume even further to 40dB (-40dB) you need to boost the lower frequencies by 20dB for them to be perceived at the same volume.

I would assume (I haven't checked) that Media Center simplifies the loudness contours and boosts the lower frequencies by half of the reduction (-15dB volume = +7.5dB lfe) and does something similar for high frequencies.

[mojave]

Media Center uses 83dB so unless you can change that target, that's what you have to calibrate to.

Media Center use a -20 dBfs signal that you can use to calibrate to whatever dB level you desire. The standard recommended by Bob Katz in his book Mastering Audio: The Art and the Science is 83 dB. For playback, you can use other levels and these levels are based on rooms size. Just like the Equal-loudness contours changes the perceived level of frequencies based on volume, overall volume perception varies based on room size. If you read through all the mixing room calibration techniques that are used to master audio, you will find variations of 6 dB or more. Here are just a few links:

NEW UPDATED Room Calibration for Film and TV Post by Marty Humphrey at The Dub Stage
     
Standard Mixing Levels for Movie Theater, DVD, TV, Internet, Radio and Games

Mixing levels for Dolby Digital: DVD vs. theatrical

How To Make Better Recordings in the 21st Century - An Integrated Approach to Metering, Monitoring, and Leveling Practices.

Here is a summary:


I like my Internal Volume Reference Level consistent for all media. However, if I want to use Loudness and am watching a TV show, I would want to set Internal Volume Reference Level to 78 dB, for Blu-ray I use 83 dB, and for music I typically set it at 72 dB. In other words, I want Loudness to scale differently than my Reference Level since the mastering process uses different levels when determining what sounds "right" in the mastering studio.

Our sensitivity to low frequencies is diminished at lower volumes

If you look at the Equal-Loudness contours chart, you can see that at 1000 hz it takes a 40 dB volume change to perceive a change from 20 phon to 60 phon. At 20 Hz it only takes a 20 dB volume change to perceive a change from 20 phon to 60 phon. In other words, our hearing is more sensitive to volume change at lower frequencies. For this reason, when the Loudness setting doesn't match the same SPL used when mastering (regardless of the set Reference Level), the bass levels are much more easy to perceive as too loud compared to the rest of the music spectrum. This is why I have to lower my Reference Level for other media besides Blu-ray if using Loudness. The lower the Reference Level vs actual, the louder MC thinks I am playing and does less correction. The less correction actually sounds more "right."

Audyssey understands that different levels are needed and allows for 4 different calibration points when using Dynamic EQ;

What are the best Dynamic EQ settings for movies, music, and video games?
Movies are mixed in rooms calibrated for film reference. To achieve the same reference level in a home theater system each speaker level must be adjusted so that –30 dBFS band-limited (500 Hz – 2000 Hz) pink noise produces 75 dB sound pressure level at the listening position. A home theater system automatically calibrated by Audyssey MultEQ will play at reference level when the master volume control is set to the 0 dB position. At that level you can hear the mix at the same level the mixers heard it.

Audyssey Dynamic EQ is referenced to the standard film mix level. It makes adjustments to maintain the reference response and surround envelopment when the volume is turned down from 0 dB. However, film reference level is not always used in music or other non-film content. The Dynamic EQ Reference Level Offset provides three offsets from the film level reference (5 dB, 10 dB, and 15 dB) that can be selected when the mix level of the content is not within the standard.

0 dB (Film Ref): This is the default setting and should be used when listening to movies.

15 dB: Select this setting for pop/rock music or other program material that is mixed at very high listening levels and has a compressed dynamic range.

10 dB: Select this setting for jazz or other music that has a wider dynamic range. This setting should also be selected for TV content as that is usually mixed at 10 dB below film reference.

5 dB: Select this setting for content that has a very wide dynamic range like classical music.

[6233638]

Media Center use a -20 dBfs signal that you can use to calibrate to whatever dB level you desire. The standard recommended by Bob Katz in his book Mastering Audio: The Art and the Science is 83 dB. For playback, you can use other levels and these levels are based on rooms size. Just like the Equal-loudness contours changes the perceived level of frequencies based on volume, overall volume perception varies based on room size. If you read through all the mixing room calibration techniques that are used to master audio, you will find variations of 6 dB or more.

The short version is that, when features in Media Center are specifically tailored around 83dB, you should not be calibrating to anything else.
 
If your system cannot reach 83dB, or you want to use a lower reference level, it should be possible to "cheat" it by applying an offset to the reference level that you set. (every 2% = 1dB)

I like my Internal Volume Reference Level consistent for all media. However, if I want to use Loudness and am watching a TV show, I would want to set Internal Volume Reference Level to 78 dB, for Blu-ray I use 83 dB, and for music I typically set it at 72 dB. In other words, I want Loudness to scale differently than my Reference Level since the mastering process uses different levels when determining what sounds "right" in the mastering studio.

I thought that the average reference level was around 80dB these days, no matter what the media type is. I've never seen anything mention 72dB before.

Audyssey understands that different levels are needed and allows for 4 different calibration points when using Dynamic EQ

Their "dynamic EQ" setting seems to be there to account for dynamic range differences, as you would have to turn down the volume more with highly compressed tracks.
 
Volume Leveling in Media Center should take care of that, so that tracks are played on an even level whether they have a large or small dynamic range.

[mojave]

I rarely use Loudness and my system is capable of 120+ dB so I'm not sure why I'm continuing this conversation. 

The short version is that, when features in Media Center are specifically tailored around 83dB, you should not be calibrating to anything else.

There are no features in Media Center tailored to 83dB. Loudness is tailored to work with however it was mixed in the studio. Its up to the user to decide what level to use and it needs to be changed manually depending on content just like Audyssey explains.

I thought that the average reference level was around 80dB these days, no matter what the media type is. I've never seen anything mention 72dB before.

Audyssey Dynamic EQ offers an offset of -10 dB from Reference Level. I was at -11 dB because that is what sounded best with most of my music.

Their "dynamic EQ" setting seems to be there to account for dynamic range differences, as you would have to turn down the volume more with highly compressed tracks.

Audyssey's Dynamic EQ is based on the Equal-Loudness Contours and one reason why Loudness in JRiver was requested as a feature. You can read more in the Audyssey FAQ at AVS. 

[6233638]

There are no features in Media Center tailored to 83dB. Loudness is tailored to work with however it was mixed in the studio. Its up to the user to decide what level to use and it needs to be changed manually depending on content just like Audyssey explains.

No, loudness assumes that the reference is 83dB, and so playback at the reference level is untouched.
 
So if you have the reference level (83dB) configured for 100% volume, reducing volume by 20% (-10dB) to 73dB will use the relevant loudness curve - let's say +5dB LFE to keep it simple.
 
If you are calibrated so that your speakers are playing 93dB at "reference level" with the test tones instead of 83dB, reducing the output level to 73dB again means that you're at -40% now (-20dB) so LFE would be boosted by 10dB  rather than the 5dB it should be.
 
At 83dB ("10dB" below reference) it would be applying +5dB instead of zero.
At 93dB it should really be reducing LFE by 5dB, rather than not performing any correction because you're telling MC that playback is at "reference" volume. (which is 83dB in Media Center)
 
 
Now if you simply want to change the loudness behavior, you can cheat it by telling MC that your reference is something other than what it really is, but for it to operate as intended, your system should be calibrated to 83dB at whatever you specify the reference level to be in MC.
 
That doesn't mean your system is now limited to 83dB volume, just that you should be telling MC what the proper reference level is that makes your system output 83dB.

Audyssey Dynamic EQ offers an offset of -10 dB from Reference Level. I was at -11 dB because that is what sounded best with most of my music.
Audyssey's Dynamic EQ is based on the Equal-Loudness Contours and one reason why Loudness in JRiver was requested as a feature. You can read more in the Audyssey FAQ at AVS.

Again, it's quite clear from their text that they use the offset to compensate for dynamic range (loudness) variances in the source.
 
Volume Leveling in Media Center brings the loudness of all sources to the same reference (as best it can) so there should be no need for the offset.
 
For loud highly compressed rock/pop music, Audessy's offset is 15dB - pretty close to the -23 LUFS target for Volume Leveling, and about the same as the volume correction MC applies to this type of track.

[ronkupper]

What about the human factor?

In the Equal-Loudness studies volunteers were given headphones and were asked to determine when two tones of different freq. sound equally loud to them.

That seems pretty subjective to me...

In all occurrences of the studies (Fletcher-Munson, Churcher and King, Robinson and Dadson, ISO 226:2003) there were discrepancies.

The report comments on the surprisingly large differences, and the fact that the original Fletcher-Munson contours are in better agreement with recent results than the Robinson-Dadson, which appear to differ by as much as 10–15 dB especially in the low-frequency region, for reasons that are not explained.

(http://en.m.wikipedia.org/wiki/Equal-loudness_contour)

My point is that maybe there is also room for individual differences in loudness perception of different frequencies that could be taken into acount.

I mean we tune our systems for our own listening and it is within reason to assume we are not all averages of the ISO 226:2003 test subjects...

[6233638]

Well there's nothing preventing you from changing the reference level to alter the behavior of the loudness feature.
 
Ultimately, all we can do is use the data from studies like this.
That's how most audio and video standards are created.

[jkkwaz]

Just finished reading this thread and I'm still a bit confused as far as what the general consensus is for setting reference level. I have my htpc output through hdmi to a Denon x4000. I'd REALLY like to use the volume control on the receiver if that is at all possible. So can I set the receiver volume to 0, then set the test tones to 83 dB using internal volume, and then my receiver will be calibrated to reference with and I wouldn't need to touch the internal volume? I read about setting the receiver to +15 or +18, but I'm not sure I understand why...headroom maybe? Thanks for the help...

[Hendrik]

If you want to use the receivers volume control, the reference level and the loudness feature are meaningless, they only work with internal volume.

Many receivers have a builtin loudness feature under different names, though.

[jkkwaz]

This makes perfect sense. Thanks. And my receiver does have dynamic eq, which is similar to the loudness feature I believe. However, if I am not bitstreaming and am using the eq in the dsp, I'll need to set the preamp level to avoid having a net gain caused by boosting certain frequencies...so should I set that preamp level (in the eq portion of the dsp) and then my receiver at 0 and then set reference from there?

[LocutusEstBorg]

Only Dolby / DTS tracks are guaranteed to be reference level when decoded. I'm pretty sure any other sources of audio are not. This means iTunes purchased music or ripped CDs are not reference level, making the whole thing pointless even if your system is perfectly calibrated. You'll still get the benefit of equal loudness when you change the volume, but you have to offset the reference level on a per album basis, by ear, to personal taste.

This is clearly stated even in Audyssey's Dynamic EQ documentation.

[mwillems]

Only Dolby / DTS tracks are guaranteed to be reference level when decoded. I'm pretty sure any other sources of audio are not. This means iTunes purchased music or ripped CDs are not reference level, making the whole thing pointless even if your system is perfectly calibrated. You'll still get the benefit of equal loudness when you change the volume, but you have to offset the reference level on a per album basis, by ear, to personal taste.

This is clearly stated even in Audyssey's Dynamic EQ documentation.

You missed the part of the thread where JRiver can analyze audio and automatically attenuate the volume to "re-center" the audio so that it's all at the same reference level.  If you analyze all of your files and use volume leveling, this problem more or less goes away.

http://wiki.jriver.com/index.php/Volume_Leveling