bigshot
Headphoneus Supremus
The application of dynamics is a creative decision and should be up to the performers and engineers.
I think these measurements are best used to compare different masters of the same piece, rather than as absolute measures (especially given that they can disagree on the assessment of certain tracks). Here's the graph I got of DR rating versus log10(crest) for what part of my collection I've ripped (haven't made the log-scale ticks work yet, sorry):
https://drive.google.com/file/d/0BwmVtb5IwniEV2JkQXloLVd5ZnM/view?usp=sharing
This particular song has a DR5 rating, and a crest factor of 6.9 I think (-9.4 dBFS RMS, -1.0 dBFS peak). If a perfect sine wave is the 0 point for the DR number, then the crest factor for this song divided by the crest factor for a sine wave (1.414) actually gets really close to the DR rating (4.8). These calculations are also a lot easier for me to understand than the math done in the DR specs.
I know this is the SS section, but what would you say is an accurate measure of dynamic range?
Originally Posted by miceblue /img/forum/go_quote.gif
Setup #1 to me seems the most accurate because the HRTF from setup #2 can be variable depending on the ear's shape, material, size, etc. What would be the advantage of setup #2 and why is it that places like Innerfidelity and Golden Ears use a measurement setup similar to this instead of setup #1 where we know that if a headphone measures flat, it will follow the HRTF curve just like how flat-measuring speakers would be applied to our ears?
I only recently got thinking about a track's dynamic range measurement because I'm interested in calculating how much power an amplifier would need to provide from the track's RMS value to the track's peak, which happen to relate to the crest factor.
Furthermore, I'm interested in calculating how much power an amplifier would need to provide to get a quiet track A to sound as loud as loud track B. These calculations might be useful for determining what kind of power your amp would need in a practical situation.
yeah I wouldn't take DR as a an actual measurement of dynamic. the aim is more to give a general idea and help avoid overly compressed releases of one album thank to the website. it's useful, but it's not the best thing there is to measure actual dynamic. not that actual dynamic is in itself a perfect tool to say if a song is dynamic, it could just have a few very long quiet passages before going back to brickwalling and the absolute dynamic would look great.
I guess I've been been using the decibel units by mistake instead of the power all this time. When calculating power levels from dBFS values, what units would power be in this case? And how do I express the crest factor in terms of a decibel?
10 * log10(1.414) = 1.5 dB, but the actual value is twice that. Why is that so? I usually see 10 * log10(P1/P0), but sometimes I also see 20 * log10(P1/P0); when is 20 * used instead of 10 *?
Wow, that's quite an interesting mapping you have! I wonder what r value you would get if you drew a linear line through that data.
How long did it take you to go through all of your music?
Wow, that's quite an interesting mapping you have! I wonder what r value you would get if you drew a linear line through that data.
How long did it take you to go through all of your music?
I only recently got thinking about a track's dynamic range measurement because I'm interested in calculating how much power an amplifier would need to provide from the track's RMS value to the track's peak, which happen to relate to the crest factor.
Furthermore, I'm interested in calculating how much power an amplifier would need to provide to get a quiet track A to sound as loud as loud track B. These calculations might be useful for determining what kind of power your amp would need in a practical situation.
e.g. I'm listening to a loud track with an average loudness of around -18.7 dBFS (0 dBFS peaks) and I switch to a track in my playlist that's fairly quiet at -32.65 average dBFS (-9.6 dBFS average peaks, which is a 23.05 dB difference). How much more power would my amp need to get the quiet track to sound as loud as the louder one?
For volume differences:
-18.7 dBFS - -32.65 dBFS= 13.96 dB difference in volume (RMS)
10^(13.96/10) = 24.89
Actually, you would need to subtract 3.01 from the dB value, rather than divide it by sqrt(2), so it is 6.9 - 3.01 = 3.89 dB. However, the overall RMS level of this track seems to be in fact -6.9 dBFS referenced to a full scale sine wave, and the peak is obviously 0 dBFS as it is clipped, so the adjustment is not needed.
Measuring the frequency response of headphones as if they were loudspeakers does not give an accurate frequency response, because the effect of actually wearing them is different from just the HRTF in free air. For example, without a seal, headphones are not capable of an extended bass response. That is only one of the issues, but it already shows that setup #1 is not accurate, and the acoustic properties of the head and ears need to be simulated somehow, i.e. using a HATS like Inner Fidelity.
For matching the loudness of tracks, it is best to use ReplayGain, as it was designed specifically for this purpose. The relative increase in power needed to play the quiet track as loud as the loud one without clipping can then be calculated from the ratio of the peak levels after ReplayGain has been applied (as the loudness-matched quiet track will now have the higher peak level). Of course, the amplifier also needs to have enough gain if the peaks are well under 0 dBFS.
Why are you saying that the volume would be 13.96dB different? If you want them to sound as loud as each other, the volume difference is 0, since they're the same volume. You'll need more power for the higher peaks, and you'll need more gain to get the same output level from a lower input level, but the power required for the RMS volume won't change.
But what if I listen to a loud track and then I switch to a quiet track? The difference in volume is obviously there so the volume in terms of SPL per se isn't the same. I'm trying to calculate how much more power output an amp would need to provide to get that quieter track to sound as loud as the louder track in terms of SPL. Gain has nothing to do with it I think since I can use a 1.0x gain amp for both cases and for the quieter track I would simply just need to turn the volume knob, and hence power output no? That's always been the case for me with the Objective 2 at least. I have never found the need to use 2.5x gain or higher.
The volume knob adjusts gain - power is determined by the signal amplitude and the load being driven.
Pardon me while pick this nit.
Typically, gain is fixed. The volume knob just attenuates the incoming signal, and the amplifier's fixed gain is applied to that.
Ok, proceed.
se
Depends on how you define gain, really. I'm defining it as Vout/Vin, and not really caring what happens in the intermediate steps. You're correct about how it is frequently implemented though.