6 ms·

FYI, EQs will distort audio. Especially if the adjustments are large. Your average EQ will introduce phase shifts to the various frequencies that make up a sou

FYI, EQs will distort audio. Especially if the adjustments are large. Your average EQ will introduce phase shifts to the various frequencies that make up a sound. Linear-phase EQs don't phase shift but they also introduce pre-ringing and post-ringing effects.

bitbang 5y ago
Depends largely on how it's implemented. There is a big difference between the quality of a well implemented convolution engine and a crappy biquad filter.
- l33tbro 5y ago
  Where would something like Fabfilter fall in the scale? I imagine there's some pretty complex stuff going on under the hood.
  - serverholic 5y ago
    Fabfilter isn't really doing anything magical. Its default mode is a pretty normal EQ with phase shifting. Linear-phase mode is like any other linear-phase mode with the same drawbacks.
    - l33tbro 5y ago
      Probably the UI that made me think it was a Wonka creation. It's really not sonically much different to a stock EQ.
- nitrogen 5y ago
  Note that not all biquad filters are crappy.
ishitatsuyuki 5y ago
Analog distortion of signals also affects the phase. A digital filter might or might not compensate for it, but it's not always bad. Also, human ears tend to be more sensitive to amplitude than to the phase. Especially if the same filter is applied on both channels, which leaves the phase difference unchanged.
- serverholic 5y ago
  It's more than just human ear sensitivity. Phase shifting changes the relationship between frequencies in a sound. For example, phase shifting can change the amplitude of a sound. Analog hardware is especially sensitive to changes in amplitude so you might be introducing distortion just by shifting phase.
h2odragon 5y ago
At headphone sizes, does your DAC have a good enough clock to even speak about phasing?
praash 5y ago
Phase shifts make no practical difference when you're equalizing headphones. You really shouldn't need to use notch filters there. EQ phase is relevant if the dry signal has a chance to mix with the EQ output. Changes in phase is not "distortion". When you end up making large boosts (especially to make sub bass audible), that's when your headphone drivers might start to distort sound. This is fixed with less volume, obviously.
- serverholic 5y ago
  An EQ that cuts frequencies can actually increase the amplitude of the waveform due to phase shifts. It's not just boosting. What I'm talking about is more relevant on analog gear which is more sensitive to volume.
willis936 5y ago
The primary measurement is called group delay, which is the derivative of phase with respect to frequency (since a linear phase is just a uniform delay). Fortunately we have studies from the 70s publicly available that establish a group delay audibility threshold. FIRs add vanishingly small amounts of distortion. Their real drawback is in the added delay. For asynchronous music playback this is nothing to worry about, but for video or anything interactive (communications or gaming) it's going to be a real tough pill to swallow.

bitbang 5y ago

Depends largely on how it's implemented. There is a big difference between the quality of a well implemented convolution engine and a crappy biquad filter.

l33tbro 5y ago
Where would something like Fabfilter fall in the scale? I imagine there's some pretty complex stuff going on under the hood.
- serverholic 5y ago
  Fabfilter isn't really doing anything magical. Its default mode is a pretty normal EQ with phase shifting. Linear-phase mode is like any other linear-phase mode with the same drawbacks.
  - l33tbro 5y ago
    Probably the UI that made me think it was a Wonka creation. It's really not sonically much different to a stock EQ.
nitrogen 5y ago
Note that not all biquad filters are crappy.

ishitatsuyuki 5y ago

Analog distortion of signals also affects the phase. A digital filter might or might not compensate for it, but it's not always bad. Also, human ears tend to be more sensitive to amplitude than to the phase. Especially if the same filter is applied on both channels, which leaves the phase difference unchanged.

serverholic 5y ago
It's more than just human ear sensitivity. Phase shifting changes the relationship between frequencies in a sound. For example, phase shifting can change the amplitude of a sound. Analog hardware is especially sensitive to changes in amplitude so you might be introducing distortion just by shifting phase.

h2odragon 5y ago

At headphone sizes, does your DAC have a good enough clock to even speak about phasing?

praash 5y ago

Phase shifts make no practical difference when you're equalizing headphones. You really shouldn't need to use notch filters there. EQ phase is relevant if the dry signal has a chance to mix with the EQ output. Changes in phase is not "distortion". When you end up making large boosts (especially to make sub bass audible), that's when your headphone drivers might start to distort sound. This is fixed with less volume, obviously.

serverholic 5y ago
An EQ that cuts frequencies can actually increase the amplitude of the waveform due to phase shifts. It's not just boosting. What I'm talking about is more relevant on analog gear which is more sensitive to volume.

willis936 5y ago

The primary measurement is called group delay, which is the derivative of phase with respect to frequency (since a linear phase is just a uniform delay). Fortunately we have studies from the 70s publicly available that establish a group delay audibility threshold. FIRs add vanishingly small amounts of distortion. Their real drawback is in the added delay. For asynchronous music playback this is nothing to worry about, but for video or anything interactive (communications or gaming) it's going to be a real tough pill to swallow.