[iyonix-support] Re: Audio hardware questions
- From: Roger Darlington <rogerarm@xxxxxxxxxx>
- To: iyonix-support@xxxxxxxxxxxxx
- Date: Tue, 22 Feb 2011 20:59:20 GMT
On 13 Jan 2011, Alan Adams wrote:
> In message <88a2e69451.Iyonix@xxxxxxxxxxxxxxxxxxx>
> Ron <iyonix@xxxxxxxxxxx> wrote:
>> Jim Lesurf may be the person to ask or have discussion about audio
>> recording/playback, but maybe someone here can make things clearer.
>> Recording a wave file with !AudioIn from a few different places,
>> I have found the resulting wave to be a little quiet, and checking
>> them with Jim's Wave diagnostics they show to be typically at aprox
>> -6 or -7 decibels.
>> I believe the target is 0 decibels, and the volume difference of
>> 7 decibels is a fair chunk of volume when I adjust my surround
>> amp. It happens to display decibels as a volume setting while
>> playing.
> I wonder whether it is due to the discrepancy in what is regarded as
> "line" level?
> For professional equipment it is 0dBm, which is approx 770mV RMS.
> Most domestic equipment uses 100mV RMS. This means plugging the output
> of domestic equipment into the input of professional equipment
> produces low sound levels.
> If that were the case, then the 100mV signal would be about -9dBm. A
> little extra gain somewhere and -6 to -7 could awell be the result.
Eh???
Beg pardon...
A factor of 10x in voltage is 20dB.
A factor of 7.7x is 17.72dB, not 9dB...
dB(V)= 20x Log(10) [Vo/Vi.]
> <snip>
--
Cheers
Roger
Atomic Software http://atomicsoftware.org.uk/
Isotope Info http://rogerarm.freeuk.com/rogerarm/
Wild Flowers http://wildflowerfinder.org.uk/
Bury Walkers http://burystrollers.org.uk/
Oh no! I've only just managed to get it all in of kilter.
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