19-Jul-2019, 11:06
In an earlier post you compared reproduction of a single tone at 40 Hz with reproduction of a single tone at 1000 Hz and observed that it takes much more power to reproduce the 40 Hz tone at a level that sounds as loud to us as the 1000 Hz tone and it does, but when both tones are present it takes virtually no more power to produce both tones at the same perceived loudness level as it takes to produce the 40 Hz tone at that perceived loudness level on it's own because what is causing the power requirement is not our perception of how loud each frequency in the signal is when there's more than one frequency present, it's the actual SPL of the bass frequencies that is the prime determinant of the power requirement. That's because the SPLs of the bass frequencies are much higher than that of the mid and high frequencies present in the music and the total SPL of the music is not much higher than that of the bass frequencies because of the way in which SPL levels which are measured in dB, a logarithmic scale add together.
If we have 2 tones, 40 hz and 1000 Hz, and they both have an SPL of 60 dB, the total level will be 63 dB. If we have a 40 Hz tone of 60 dB SPL and a 1000 Hz tone that we perceive as being equally loud, it will have an SPL of around 20 db and the total SPL will be around 60 dB. It's the low frequencies which dominate the total SPL, the mid range frequencies add very little to the total SPL when the bass frequencies are present at a level which we perceive as equally loud as the mid frequencies because our ears are more sensitive to the mid frequencies. Our ears are also less sensitive in the high frequencies so they will only sound as loud as the mids when they are at higher SPLs as the mids but there's no instrument producing a fundamental higher than 7 kHz or so and while they produce overtones, those overtones are lower in SPL than the fundamentals. Our ears have a very similar sensitivity at 7 kHz as they do at 1 kHz so it takes roughly the same amount of power to reproduce a 7 kHz tone at the same perceived level as a 1 kHz tone and since overtones in music are almost always lower in level than the fundamental the overtones, reproduction of high frequencies above 7 kHz contribute less to overall power requirements because they're being reproduced at much lower levels.
Because musicians balance the levels of their respective instruments so the overall sound of all notes being produced by the group has a balance where the bass is present at levels we perceive as being close to that of the mid tones, sometimes softer when the mids are what's important to the music and sometimes louder when the bass is important and sounding louder than the mids, the bass is always going to be generating higher SPLs than the mids and higher frequencies, the total SPL is going to largely track the SPL of the bass frequencies, and it's reproduction of the bass that's going to contribute to how much power you need to reproduce music. OK, there's more notes present in the mid range of music than there are in the bass where there's usually only a couple of notes present at once, but you need a lot of notes in the mids to raise the SPL of the mid range to that of the bass notes so the bass is always going to be the dominant factor in determining how much power you need if there is low bass present in the music.
That means that reproduction of an electronic track with "epic levels of infrasonic bass" is going to take a lot more power to reproduce at a given perceived level (ie how loud it sounds to us rather than what the actual SPL is) than a solo acoustic instrument such as a piano or a small classical ensemble playing a sonata where there's less bass present and what bass there is at frequencies much higher than infrasonic frequencies. Even reproducing the sonata at a level higher than the level at which most people would play it could easily require a magnitude less power than playing the electronic track with infrasonic bass at the same level. Let's say you're playing the electronic track at a total SPL of 90 dB, a 40 Hz tone of equal perceived loudness is going to be around 65 dB in level and the mids much much lower again. Pretty much all of the power you're using is going to the 20 Hz tone. Genuine infrasonic tones are lower than 20 Hz and require more power again if they're going to be loud enough for you to feel them rather than hear them because they may be below the lower limit of audibility.
The take away from all of this: the lower the bass notes present, the more the power you're using to reproduce the music at a given level is being devoted to reproducing the bass and the less power is being used to reproduce the mid range and higher. The less bass there is, there of the music will fall into the area where our ears are more sensitive, the louder it will sound to us than bass at the same SPL, and the softer we're likely to reproduce the recording because so we're likely to use less power to reproduce music with little bass content at a level we like than we are to reproduce music with a lot of bass, especially very low bass, at a level that's equally satisfying.
My 140 Pro sounds great with a pair of Focal Sopra 2s but I don't play Kraftwerk :-)
If we have 2 tones, 40 hz and 1000 Hz, and they both have an SPL of 60 dB, the total level will be 63 dB. If we have a 40 Hz tone of 60 dB SPL and a 1000 Hz tone that we perceive as being equally loud, it will have an SPL of around 20 db and the total SPL will be around 60 dB. It's the low frequencies which dominate the total SPL, the mid range frequencies add very little to the total SPL when the bass frequencies are present at a level which we perceive as equally loud as the mid frequencies because our ears are more sensitive to the mid frequencies. Our ears are also less sensitive in the high frequencies so they will only sound as loud as the mids when they are at higher SPLs as the mids but there's no instrument producing a fundamental higher than 7 kHz or so and while they produce overtones, those overtones are lower in SPL than the fundamentals. Our ears have a very similar sensitivity at 7 kHz as they do at 1 kHz so it takes roughly the same amount of power to reproduce a 7 kHz tone at the same perceived level as a 1 kHz tone and since overtones in music are almost always lower in level than the fundamental the overtones, reproduction of high frequencies above 7 kHz contribute less to overall power requirements because they're being reproduced at much lower levels.
Because musicians balance the levels of their respective instruments so the overall sound of all notes being produced by the group has a balance where the bass is present at levels we perceive as being close to that of the mid tones, sometimes softer when the mids are what's important to the music and sometimes louder when the bass is important and sounding louder than the mids, the bass is always going to be generating higher SPLs than the mids and higher frequencies, the total SPL is going to largely track the SPL of the bass frequencies, and it's reproduction of the bass that's going to contribute to how much power you need to reproduce music. OK, there's more notes present in the mid range of music than there are in the bass where there's usually only a couple of notes present at once, but you need a lot of notes in the mids to raise the SPL of the mid range to that of the bass notes so the bass is always going to be the dominant factor in determining how much power you need if there is low bass present in the music.
That means that reproduction of an electronic track with "epic levels of infrasonic bass" is going to take a lot more power to reproduce at a given perceived level (ie how loud it sounds to us rather than what the actual SPL is) than a solo acoustic instrument such as a piano or a small classical ensemble playing a sonata where there's less bass present and what bass there is at frequencies much higher than infrasonic frequencies. Even reproducing the sonata at a level higher than the level at which most people would play it could easily require a magnitude less power than playing the electronic track with infrasonic bass at the same level. Let's say you're playing the electronic track at a total SPL of 90 dB, a 40 Hz tone of equal perceived loudness is going to be around 65 dB in level and the mids much much lower again. Pretty much all of the power you're using is going to the 20 Hz tone. Genuine infrasonic tones are lower than 20 Hz and require more power again if they're going to be loud enough for you to feel them rather than hear them because they may be below the lower limit of audibility.
The take away from all of this: the lower the bass notes present, the more the power you're using to reproduce the music at a given level is being devoted to reproducing the bass and the less power is being used to reproduce the mid range and higher. The less bass there is, there of the music will fall into the area where our ears are more sensitive, the louder it will sound to us than bass at the same SPL, and the softer we're likely to reproduce the recording because so we're likely to use less power to reproduce music with little bass content at a level we like than we are to reproduce music with a lot of bass, especially very low bass, at a level that's equally satisfying.
My 140 Pro sounds great with a pair of Focal Sopra 2s but I don't play Kraftwerk :-)
Roon Nucleus+, Devilalet Expert 140 Pro CI, Focal Sopra 2, PS Audio P12, Keces P8 LPS, Uptone Audio EtherREGEN with optical fibre link to my router, Shunyata Alpha NR and Sigma NR power cables, Shunyata Sigma ethernet cables, Shunyata Alpha V2 speaker cables, Grand Prix Audio Monaco rack, RealTRAPS acoustic treatment.
Brisbane, Qld, Australia
