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Author Topic: Audio calibration tools  (Read 5957 times)

dean70

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Audio calibration tools
« on: January 27, 2013, 07:51:36 pm »

I have noticed that the 7.1 channel levels are different than the 5.1 calibration and the side/rear surrounds are the wrong channels. I can set the side surrounds correctly in 5.1 test, but 7.1 test shows different level & side surrounds are mapped to rear surround tracks.

edit: this is using the Play option (not Create Files).
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Matt

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Re: Audio calibration tools
« Reply #1 on: January 27, 2013, 08:03:03 pm »

Make sure you have DSP Studio > Output Format set to mix to the proper number of channels for your configuration.
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Matt Ashland, JRiver Media Center

mojave

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Re: Audio calibration tools
« Reply #2 on: January 27, 2013, 09:17:02 pm »

In a 5.1 system, the side surrounds are on channels 5 & 6. In a 7.1 system, the side surrounds are supposed to be on channels 7 & 8. If you are playing both 5.1 or 7.1 you should just leave your speakers set to 7.1. Selecting "5.1 (inside a 7.1 container)" will also map 5.1 side surrounds to channels 7 & 8.
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dean70

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Re: Audio calibration tools
« Reply #3 on: January 27, 2013, 09:33:19 pm »

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dean70

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Re: Audio calibration tools
« Reply #4 on: January 28, 2013, 12:44:32 am »

I swapped the side surround/rear surround connectors and now each channel goes to the correct speaker. Dam soundcard.
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dean70

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Re: Audio calibration tools
« Reply #5 on: January 28, 2013, 03:39:13 pm »

I have a question with the Subwoofer track - the level is so low it doesnt register on the meter. Is there anything special you need to do to set the level?

The actual subwoofer level is quite prominent in movies, but cannot get a good calibration level.
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dean70

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Re: Audio calibration tools
« Reply #6 on: January 29, 2013, 03:49:11 pm »

How do you use it to calibrate the Subwoofer level?
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Trumpetguy

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Re: Audio calibration tools
« Reply #7 on: January 30, 2013, 07:49:31 am »

side surrounds are the same for both 5.1 and 7.1

http://www.dolby.com/us/en/consumer/setup/connection-guide/home-theater-speaker-guide/index.html

Actually, no. The channel numbering is as follows, and correctly implemented in MC:
5.1: 0FL 1FR 2C 3SW 4SL 5SR
7.1: 0FL 1FR 2C 3SW 4RL 5RR 6SL 7SR

Reference:
http://en.wikipedia.org/wiki/Surround_sound#Standard_speaker_channels
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dean70

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Re: Audio calibration tools
« Reply #8 on: January 30, 2013, 03:52:25 pm »

Actually, no. The channel numbering is as follows, and correctly implemented in MC:
5.1: 0FL 1FR 2C 3SW 4SL 5SR
7.1: 0FL 1FR 2C 3SW 4RL 5RR 6SL 7SR

Reference:
http://en.wikipedia.org/wiki/Surround_sound#Standard_speaker_channels

It was actually the sound card (or the driver) that is completely messed up with the surround channel mappings - I have literally swapped every single surround channel (sub/center, surround side/rear) to get the correct mapping. I originally had it all setup & caibrated through a receiver and I am in the process of re-visiting all the settings with the sound card.

How can you set the sub level with the Sub test track - it appears to be way lower than -20db?



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Matt

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Re: Audio calibration tools
« Reply #9 on: January 30, 2013, 03:56:07 pm »

How can you set the sub level with the Sub test track - it appears to be way lower than -20db?

The decibel meter should read the same on the subwoofer as the other channels.

We target the standard +10dB calibration, but the calibration clips account for this.
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Matt Ashland, JRiver Media Center

dean70

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Re: Audio calibration tools
« Reply #10 on: January 31, 2013, 04:00:50 pm »

Tried again with the sub and noticed in the Real Time analyser it is the same db level as the other channels, but my RS SPL meter (thats Radio Shack btw  :P) reads low at this freq range. What SPL meter do you recommend?
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mwillems

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Re: Audio calibration tools
« Reply #11 on: January 31, 2013, 05:28:42 pm »

Tried again with the sub and noticed in the Real Time analyser it is the same db level as the other channels, but my RS SPL meter (thats Radio Shack btw  :P) reads low at this freq range. What SPL meter do you recommend?

Does your SPL meter give you octaves (RTA) or just a flat number?  I had your exact problem for a while, and it's really hard to get a sub calibrated correctly with just an SPL meter.  

Pink Noise is filtered to have the same amount of sound energy in each octave so if you're using a single number output SPL meter on a speaker that's only putting out sound over a narrower octave range you're going to get a much lower "total" SPL number.

For example, My sub only plays up to about 50 Hz, which is an octave and a quarter of audible sound.  My SPL meter shows it being much, much lower SPL than my mains even when it's calibrated correctly, because it's only playing 1.25 octaves, while my mains are playing almost 9 octaves, which means they're about 7 times as loud with pink noise playing (almost 8 dB).  

Edit: If you have an RTA device that will show you levels per octave (or 1/3 octave) you can get a more accurate comparative level that way.  Just try to get your sub so that (when playing JRiver's test clip) each octave measures at about the same dB level as each octave of your mains did with their clip (if that makes sense).  I can provide a picture of my RTA when it's calibrated if that would help.

Just saw you have a flat RTA reading; you're calibrated correctly and there's nothing wrong with your SPL meter.

Sorry for the poor reading comprehension :-)

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