[RandomDave]

Hi,
i've been wondering, how does output power of a DAC change with the increase of volume from a digital source?
Let's say my dac has rated max output 1.5Vrms. All of my songs are running replaygained to 0dB with clipping prevention. Now if i take a song, remove the replaygain information (which is lets say -8dB gain), the song is going to be louder (by 8dB). How do i know when my DAC actually outputs 1.5Vrms and when it outputs less (or more) if the digital volume can be increased by many dB over 0dB ?
Thanks a lot
Dave

 

[MindsMirror]

I think it's easiest to explain with an example.

I created a sine wave with an amplitude of 1, the maximum amplitude sine wave you can output from your DAC before clipping. If you played this back with no replaygain it would be 1.5V RMS, and it would be much louder than any of your music. When I scan it with replaygain in foobar, it says peak of 1.0 and track gain of -18dB. So after enabling replaygain and playing it back, it would be 18dB below 1.5V RMS, which is ~1/8th of 1.5, or 0.1875V RMS.

If I replaygain scan my copy of The Cranberries "Zombie", I get a peak of 0.994 (practically 1, so it can't really go any louder without clipping) and track gain of -5.67dB. So, without replaygain, it should sound around 12.33dB quieter than the sine wave. The RMS of actual music is not constant like a sine wave, but on average it should be around 12.33dB less. With replaygain enabled it just lowers everything, the peaks and the RMS, by 5.67dB. So basically, replaygain is trying to get all your music to have similar RMS or loudness to a -18dB sine wave.

Another example is Dire Straits "Brothers in Arms" which has peak 0.565 and track gain +5.66dB. So it's already quieter than the -18dB sine wave, it needs another 5.66dB to be similar RMS. However if you add 5.66dB to the peak of 0.565, you would end up with a peak of 1.08 which means there'd be clipping.

 

[RandomDave]

I think it's easiest to explain with an example.

I created a sine wave with an amplitude of 1, the maximum amplitude sine wave you can output from your DAC before clipping. If you played this back with no replaygain it would be 1.5V RMS, and it would be much louder than any of your music. When I scan it with replaygain in foobar, it says peak of 1.0 and track gain of -18dB. So after enabling replaygain and playing it back, it would be 18dB below 1.5V RMS, which is ~1/8th of 1.5, or 0.1875V RMS.

If I replaygain scan my copy of The Cranberries "Zombie", I get a peak of 0.994 (practically 1, so it can't really go any louder without clipping) and track gain of -5.67dB. So, without replaygain, it should sound around 12.33dB quieter than the sine wave. The RMS of actual music is not constant like a sine wave, but on average it should be around 12.33dB less. With replaygain enabled it just lowers everything, the peaks and the RMS, by 5.67dB. So basically, replaygain is trying to get all your music to have similar RMS or loudness to a -18dB sine wave.

Another example is Dire Straits "Brothers in Arms" which has peak 0.565 and track gain +5.66dB. So it's already quieter than the -18dB sine wave, it needs another 5.66dB to be similar RMS. However if you add 5.66dB to the peak of 0.565, you would end up with a peak of 1.08 which means there'd be clipping.

Now i get it, this helped me a lot. Thank you very much!