While -16.9 might keep you safe, a better option might be -20 dBFS.  Gives some 
headroom in case you need it.  Also, many consumer playback devices may not 
handle full scale output.
> On Sep 23, 2013, at 11:00 AM, sursound-requ...@music.vt.edu wrote:
> 
> Send Sursound mailing list submissions to
>    sursound@music.vt.edu
> 
> To subscribe or unsubscribe via the World Wide Web, visit
>    https://mail.music.vt.edu/mailman/listinfo/sursound
> or, via email, send a message with subject or body 'help' to
>    sursound-requ...@music.vt.edu
> 
> You can reach the person managing the list at
>    sursound-ow...@music.vt.edu
> 
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Sursound digest..."
> 
> 
> When replying, please remember to edit your Subject line to that of the 
> original message you are replying to, so it is more specific than "Re: 
> Contents of Sirsound-list digest..." so that it matches the post you are 
> replying to.
> 
> Also, please EDIT the quoted post so that it is not the entire digest, but 
> just the post you are replying to.
> 
> 
> Today's Topics:
> 
>   1. Re: Volume question WRT 7.1 sound recorded at listening
>      position. (dw)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Sun, 22 Sep 2013 19:53:35 +0100
> From: dw <d...@dwareing.plus.com>
> To: Surround Sound discussion group <sursound@music.vt.edu>
> Subject: Re: [Sursound] Volume question WRT 7.1 sound recorded at
>    listening position.
> Message-ID: <523f3caf.4040...@dwareing.plus.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
>> On 22/09/2013 12:51, Andy Furniss wrote:
>> Hi
>> 
>> I do not have a 7.1 sound system so can't actually test this, also as 
>> may become apparent I don't know much about sound :-)
>> 
>> I would be grateful if someone could correct/confirm the following.
>> 
>> If I were to mix down a digital 7ch to mono I have to reduce by 1/7 
>> amplitude to prevent clipping, so one channel will be -16.9dBfs.
> This assumes that all 7 channels are driven with the same maximum level, 
> in phase, and that this would get past the mastering stage,,
> I'm sure they bear in mind the possibility of stereo, or mono mixdown.
>> 
>> If I play the track over one speaker the volume difference between one 
>> and all channels will be 16.9dB.
>> 
>> If I were to measure the volume at listening position (assuming 
>> anechoic and equal speaker distance) with a real 7 speaker setup then 
>> the volume difference, because the speakers are not close, would add 
>> up using power not amplitude so the difference heard/measured between 
>> 1 and 7 at full power would only be 8.45dB, so there is quite a large 
>> dynamic range discrepency?
> 
> You would add powers if the 7 channels had random relative phase (which 
> is less likely with "anechoic and equal speaker distance"
> 
>> 
>> The real reason for this question is more to do with simulation than 
>> real life, so perhaps that will make a difference - if the speakers 
>> are infinitely far producing planewaves and a soundfield is at 
>> listening position would that change anything for what levels the 
>> virtual omni would "hear".
>> 
>> TIA
>> 
>> Andy.
>> 
>> 
>> _______________________________________________
>> Sursound mailing list
>> Sursound@music.vt.edu
>> https://mail.music.vt.edu/mailman/listinfo/sursound
> 
> 
> 
> ------------------------------
> 
> Subject: Digest Footer
> 
> _______________________________________________
> Sursound mailing list
> Sursound@music.vt.edu
> https://mail.music.vt.edu/mailman/listinfo/sursound
> 
> 
> ------------------------------
> 
> End of Sursound Digest, Vol 62, Issue 15
> ****************************************
> 
_______________________________________________
Sursound mailing list
Sursound@music.vt.edu
https://mail.music.vt.edu/mailman/listinfo/sursound

Reply via email to