I'm using Reaper for production at the moment and I'm using ReaEQ for the EQ mixing. There's an option on there called Show phase. Having looked on the Cockos Wiki it describes this as : "Shows or hides the phase of the output signal (relative to the input signal)". When selected some sort of red line appears throughout it. Would someone be able to explain to me a little bit more about what this represents? Thanks
Quick EQ Question
- Thread starter Steve1234
- Start date
DestroyTheColossus
Member
- Mar 18, 2008
- 280
- 0
- 16
The process by which regular EQ's work will change the phase of the input signal around the EQ changes you make. This isnt too big of a deal for most instruments, but when you are EQing two things that should be in phase with eachother it can be. This is why they have linear phase EQ's, which do not change the phase while EQing, but they are much more processor intensive which is why they arent used as often. Something like EQing parallel compression signals, or individual mics on the same guitar signal would benefit from linear phase EQ. The reaper EQ is not a linear phase EQ, so it will change the phase of different frequencies based on how you EQ. So the line that shows up when you hit that button is showing you how the phase is changing based on your processing. The phase change will be more drastic the more drastic your EQ is.
BassTard
Member
Think of phase as a very, very short latency on the affected frequencies. Since each frequency is a sine, this can be described as a phase shift.
Here's a little picture out of Wikimedia:
The black curve represents the original signal, a phase shift equals a slight displacement of the sine.
Actually only sines can be shifted by any amount of degrees. Complex signals (such as audio) can only be flipped upside down (shifted 180°). But an EQ shifts single frequencies (it's delaying them) of the material (and this can be displayed by ReaEQ).
Note that every physical device that changes the frequency response will also shift the phases. It's not only EQs, every speaker out there is a phase shifter as well. So phases are in fact an everyday part of recording. (Eg. the immense importance of cabinets.)
Here's a little picture out of Wikimedia:
The black curve represents the original signal, a phase shift equals a slight displacement of the sine.
Actually only sines can be shifted by any amount of degrees. Complex signals (such as audio) can only be flipped upside down (shifted 180°). But an EQ shifts single frequencies (it's delaying them) of the material (and this can be displayed by ReaEQ).
Note that every physical device that changes the frequency response will also shift the phases. It's not only EQs, every speaker out there is a phase shifter as well. So phases are in fact an everyday part of recording. (Eg. the immense importance of cabinets.)
John_C
formerly Skeksis268
^^ good
a minor correction: phase can be used to describe relative displacement of more complex waves, it's not just restricted to sinusoidals.
Also, flipping polarity is the same as a 180 degree shift only for waves symmetrical about the direction of motion, amongst other criteria. Crucially, it's NOT the same for almost all musical signals that aren't coming straight out of a synth.
a minor correction: phase can be used to describe relative displacement of more complex waves, it's not just restricted to sinusoidals.
Also, flipping polarity is the same as a 180 degree shift only for waves symmetrical about the direction of motion, amongst other criteria. Crucially, it's NOT the same for almost all musical signals that aren't coming straight out of a synth.
