[solidwalnut]

Sub-ranges of the Audio Spectrum

In order to make tonal (equalization) adjustments to the sound, it's important to recognize the different parts of the Audio Spectrum.


In the frequency range of 10k-20k Hz (very high) there is not much energy or musical content and we perceive this as a soft hissing sound. If your sound seems to be lacking in brightness or clarity do not increase the level of this frequency range, as the only result will be to add lots of unwanted noise (or in the case of extreme power, it could destroy your tweeters or high frequency elements of your speakers).


The range of 5 kHz to 10 kHz (high) is where we perceive the brightness of a sound. There is very little musical content (fundamentals) but it does include most of the harmonics and also the sibilance of a voice (the ssssss sound) and cymbal sounds. These frequencies add clarity and presence to the overall sound. Better to boost in the 6.8 kHz range than in the 10 kHz range. An interesting note is that tape hiss is normally in the 8k range.


When a sound seems to hurt or sounds hard to our ears it's more than likely that we have too much in the 2.5 kHz to 5 kHz frequency range, the upper mid band. This is the range where our ears are the most sensitive, especially around 3 kHz to 3.8 kHz. Here we can find the screechy part of vocals, snare drum crack and bass drum attack sounds. Reducing the level in this range can also reduce overall clarity.


The mid band itself can be broken down further into 2 more ranges, the first 800 Hz to 2.5 kHz. Too much of this range can again result in a hard sound. The second range is 315 Hz to 800 Hz and has lots of upper resonance (drone), especially around the 315 Hz to 500 Hz range.


Too much of the lower mid band, 160 Hz to 315 Hz, results in a very muddy/woody sound with lots of lower resonance, and too little and a loss of warmth. This range contains the fundamentals for the snare drum, toms, bass guitar, tenor vocals, etc.


The sub bass, lower bass and the bass bands are where most of our audio energy is found. This overall range, 160Hz to 40Hz, unchecked can be responsible for most of our level problems, lots of meter level, yet does not sound very loud, usually caused by on stage low frequency resonance. The interaction between bass guitar, guitar, lower keyboard notes, low toms and bass drum are the reasons for this. This is the range we feel more than hear, especially below 40 Hz.


The frequencies below 40 Hz are not useful unless you have lots and lots of power amps and a sub bass speaker system, these frequencies will quickly suck up most of your power. Ahhh...so this is how they're getting all that thump. All those extra car batteries.


If the sound system seems to be over driving yet not very loud, your problem could lie in the sub bass and lower bass range. If you want to feel a bit more kick in your sound, boost around 80 to 100 Hz and remove everything below 40 Hz.