Eq

[kidthatplaysguitar91]

This may be random/dumb question but what part of a sound is effected when you change some EQ settings. I know that sound waves vibrate a certain number of times per second to make a pitch. But what makes the EQ?
:cool:

[Motleyguy]

EQ stands for Equalization, which allows you to equalize the frequencies in an audio signal, by either boosting them or cutting them. There are a few different types of EQ's, but the overall concept is the same. You select a frequency in the signal, the type/quality of the EQ unit depends on just how selective you can be. Some allow full selective capabilities, others have just a single pre determined frequency, but most have a range of frequencies (lows, low - mids, hi mids, hi's). Once the frequency is selected you either boost it, or cut it, to make the signal sound better.

[Mispeled]

All sounds have a certain fundamental frequency, which is the main pitch that you hear when it is vibrating (e.g. for the A string on a guitar, it's 110 hz). However, there are also a lot of other higher frequency waves vibrating "within" the main pitch; they're called harmonics or overtones. For acoustic instruments they are generally fractions of the fundamental frequency, like in this picture:
http://en.wikipedia.org/wiki/Image:Overtone.jpg

So when you're EQing, you're controlling how much and which harmonics are in your sound.

[kidthatplaysguitar91]

EQ stands for Equalization, which allows you to equalize the frequencies in an audio signal, by either boosting them or cutting them. There are a few different types of EQ's, but the overall concept is the same. You select a frequency in the signal, the type/quality of the EQ unit depends on just how selective you can be. Some allow full selective capabilities, others have just a single pre determined frequency, but most have a range of frequencies (lows, low - mids, hi mids, hi's). Once the frequency is selected you either boost it, or cut it, to make the signal sound better.

I know what EQ is, i was asking what part of a sound wave makes EQ.

[kidthatplaysguitar91]

All sounds have a certain fundamental frequency, which is the main pitch that you hear when it is vibrating (e.g. for the A string on a guitar, it's 110 hz). However, there are also a lot of other higher frequency waves vibrating "within" the main pitch; they're called harmonics or overtones. For acoustic instruments they are generally fractions of the fundamental frequency, like in this picture:
http://en.wikipedia.org/wiki/Image:Overtone.jpg

So when you're EQing, you're controlling how much and which harmonics are in your sound.

So within the sound wave for the pitch, theres other things going on within that?

[Motleyguy]

I know what EQ is, i was asking what part of a sound wave makes EQ.

No part of the sound wave makes up EQ. EQ is something applied to sound waves to make them sound better. Every sound is made up of multiple frequencies. There is the fundamental frequency (or pitch), and then there are the harmonics and overtones. A frequency in it's purest sense is a Sine Wave (like in math or physics) and it repeats a certain amount of time per second (cycles per second or Hertz). For example, the fundamental frequency of a low E on a bass is 63 Hz, or 63 cycles per second. The overtones and harmonics ring at varying octaves, depending on the timbre of the instrument. For example, 63 would have an overtone around 120 Hz, 240 Hz etc. There would also be a lower tone ringing at 31 Hz, but generally you wouldn't hear that in a recording, and it is very low. I'm just using bass as an example of course. It isn't really a case of "other things going on within the soundwave" but rather, other waves being produced at the same time, but not at the same amplitude (volume) of the fundamental note.

So, by using EQ, you can cut out bad overtones/frequencies, or boost good frequencies to shape your sound. But no part of a sound wave makes up EQ. I hope that was easy enough to follow.

[kidthatplaysguitar91]

No part of the sound wave makes up EQ. EQ is something applied to sound waves to make them sound better. Every sound is made up of multiple frequencies. There is the fundamental frequency (or pitch), and then there are the harmonics and overtones. A frequency in it's purest sense is a Sine Wave (like in math or physics) and it repeats a certain amount of time per second (cycles per second or Hertz). For example, the fundamental frequency of a low E on a bass is 63 Hz, or 63 cycles per second. The overtones and harmonics ring at varying octaves, depending on the timbre of the instrument. For example, 63 would have an overtone around 120 Hz, 240 Hz etc. There would also be a lower tone ringing at 31 Hz, but generally you wouldn't hear that in a recording, and it is very low. I'm just using bass as an example of course. It isn't really a case of "other things going on within the soundwave" but rather, other waves being produced at the same time, but not at the same amplitude (volume) of the fundamental note.

So, by using EQ, you can cut out bad overtones/frequencies, or boost good frequencies to shape your sound. But no part of a sound wave makes up EQ. I hope that was easy enough to follow.

So its not the sound wave itself but overtones that happen when a sound is made.

[The Chemist]

No. It's the filtering of frequencies.

Think: Lows, Mids and Highs on your Amp is a basic EQ.

[Motleyguy]

So its not the sound wave itself but overtones that happen when a sound is made.

Wrong, it is both, the center or fundamental frequency, and the overtones. They occur simultaneously.

[Moseph]

I think what is being missed in this discussion is the idea that all sounds are representable as a combination of what are called "spectral components" (sometimes "frequency components", but I think "spectral" is more accurate and descriptive in this case). The sounds themselves have very distinct and characteristic spectral content at a given point in time.

In other words, according to principles in complex mathematics (probably the most prominent of which being the Fourier Transform), all signals, for a given moment in time, can be represented as a sum of sinusoidal components (ie, sine and/or cosine waves of a given frequency).

Equalization is then the use of filtering of various types to alter the amplitude of those frequencies in relation to one another (adjusting all frequencies in the same manner is a gain adjustment, which is quite a bit simpler). I believe this is where the confusion lies: Equalization is a process and not an inherent property of sound. It seems to me like you're asking about spectral content, and getting responses related to the process.

Equalizers themselves have different controls which cause the filters to behave in different ways. The typical controls for a peaking type filter (which is the standard midband filter in a parametric EQ) are:

Gain: how much gain do you wish to apply to the selected frequencies in order to increase or reduce the amplitude at those frequencies.

Center Frequency: This determines the "middle" frequency of the filter, which for most peaking filters will be the apex (ie, local max/min) of gain adjustment.

Bandwidth: This determines how many of the neighboring frequencies of the center frequency are affected by the filter. A wider bandwidth means the filter will effect a larger number of the frequencies on either side of the center frequency, often called a "wider" filter because of how it looks on a spectrograph readout. A lower bandwidth will make a "narrower" filter, which has the opposite effect.

Many times Bandwidth will be related as "Q", which is an engineering symbol that is associated as "Quality Factor." Q is inversely proportional to bandwidth, so a higher Q will cause a narrower filter and vice-versa. It has helped me to think of it this way: A filter with an infinitely high quality factor will only modify the exact center frequency, and leave the rest unaffected. A filter that has a quality factor of zero will affect all frequencies.

Hopefully that clears up some confusion...