Here’s a little test showing the induced phase distortions on a Triangle wave by using a HPF (High Pass Filter AKA Low Cut) below the fundamental.
Filters used are:
Cubase Pro 8 PRE Low Cut (36db/oct slope)
Cubase Pro 8 Channel EQ High Pass II (24db/oct slope @ Q:5.0)
Fabfilter Pro Q2 insert Low Cut (36db/oct slope) Zero Latency
Fabfilter Pro Q2 insert Low Cut (36db/oct slope) Linear Phase
The Triangle Wave from the test generator with no filter applied
The Cubase LOW CUT (LC) filter at 343Hz and 36db/oct slope in the PRE induces phase distortion.
The Cubase Pro 8 Channel EQ High Pass II (24db/oct slope @ Q:5.0) filter at 343Hz induces phase distortion.
The Fabfilter Pro Q2 insert Low Cut (36db/oct slope) Zero Latency filter at 343Hz induces phase distortion.
And the benefit of a Linear Phase EQ…
The Fabfilter Pro Q2 insert Low Cut (36db/oct slope) Linear Phase filter at 343Hz DOES NOT induce phase distortion.
And yes I am aware in this test it is a Triangle (not a saw)
Thanks for this. Love when anybody’s willing to do the science!
PS: Did you notice that the 12 and 24db/octave roll-offs on the Pre cut filters are identical?
Hadn’t til you mentioned it!
The 12db/oct LC (the stock setting without right clicking and changing slope for the Cubase noobs) also caused severe distortions!
It distorted the Triangle to a Sine!
Here’s the 24db/oct setting and effect in PRE section LC
If anyone replicates these tests to learn more about how the filters and effects are changing your sound you also want to note the dbFS changes before and after applying the filters or effects.
The stock Cubase Test Generator effect is great for that as it will output a set -12db waveform reference.
In my tests I noticed the various filters and slopes can vary the resulting output by about -3db
Fabfilter’s Pro Q2 insert set to Linear Phase mode had the least distortion and reduction of only -0.2db
The PRE section doesn’t affect anything if you use it on the same Track as the Test Generator as the PRE is BEFORE the INSERTS. To test PRE section direct the output of your track to a Group Track and use the PRE on the Group.
