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Phasing caused by EQ
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routingwithin
IsraTrance Junior Member
Started Topics :
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Posts :
204
Posted : Sep 23, 2014 12:47:27
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Hey guys hope all is well on your side.
Today I would like to clarify a bit about “Phasing caused by EQ”. For some of you this will be an obvious subject, but many still find it tricky to grasp.
“In addition to adjusting the relative amplitude of frequency bands, an audio equalizer may alter the relative phases of those frequencies. While the human ear is not as sensitive to the phase of audio frequencies (involving delays of less than 1/30 second), music professionals may favor certain equalizers because of how they affect the timbre of the musical content by way of audible phase artifacts.”
Phasing occurs if you boost or cut when using an EQ, however when cutting frequencies the phasing is less audible. The more EQ you apply to a sound, the more out of time delays ( phasing ) there will be present within the altered frequency bands, resulting in an unbalanced stereo effect.
By using Linear Phase EQ’s, phasing can be decreased, but they will still add phasing if EQ’d too much.
“Linear phase is a property of a filter, where the phase response of the filter is a linear function of frequency. The result is that all frequency components of the input signal are shifted in time (usually delayed) by the same constant amount, which is referred to as the phase delay. And consequently, there is no phase distortion due to the time delay of frequencies relative to one another. For discrete-time signals, perfect linear phase is easily achieved with a finite impulse response (FIR) filter. Approximations can be achieved with infinite impulse response (IIR) designs, which are more computationally efficient. “
Let’s create an example of this. Compose two Leads and boost each lead by 9db with medium wide Q, in an area which sounds nice. Then play them together and move your head horizontally between the speakers while looking forward. You would be able to hear the phase shifts occurring. That all over the place stereo effect that you hear while moving are the delays of the frequencies caused by phasing.
Phasing may be overlooked, but note- that it will start to irritate the listener or producer the more and more that we listen to it. It also causes the music to lose its solidness and replaces it with a mangled stereo effect.
Some solutions would be to stick with Linear phase EQ’s when eq’ing and also never cut or boost too much on an instrument. Staying around 3db cut/boosts should be a safe amount – also the obvious rule of thumb: Boost wide – Cut Narrow.
You can go more than 3db, but always keep in mind when pulling down that band that the more you change… The more noticeable phasing/time delays you are adding to the sound.
Cheers
  " We are together in this matter you and I, closer to death, yes, closer than i'd like. How do you feel? - There can be no division in our actions, or everything is lost. What affects you affects me. " |
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PoM
IsraTrance Full Member
Started Topics :
162
Posts :
8087
Posted : Sep 23, 2014 13:57
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are you sure about these stereo effect ? if both left and right channels are boosted by the same amount both channels should be identical.
also linear phase have some artifacts that may be worse or not depending the source and sound after.
phase shift in the eqs affect the tightness of the sound, it can make it sound less "focused" and more loose imo (and i think it s logical cause of the delays/phase shift happening )
i have the feeling linear phase (but if there was no pre ringing ) sound closer to some analog eq, than digital phase eq.. strange all this.. but i feel like it keep the sound more integrated when boosting and cutting |
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routingwithin
IsraTrance Junior Member
Started Topics :
46
Posts :
204
Posted : Sep 23, 2014 14:53
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with stereo effect i am not talking about it changing the actual stereo image. I mean like u said, less focused and more loose.
everything has its ups and downs... just saying that linear phase eq's causes less phase shifts compared to others.
Problem with talking about sound production is when people discuss a subject like EQ, they aren't always on the same page, due to the fact that the main subject divides into sub-subjects- each aspect being a solution for different types of situations.
" We are together in this matter you and I, closer to death, yes, closer than i'd like. How do you feel? - There can be no division in our actions, or everything is lost. What affects you affects me. " |
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