Applying any EQ generally affects the sound (due to phase and whatever). With TrackPlug, if I use a HPF at 40hz, will it only affect the sound from 40 down, or will I get moderate distortion in other regions as well? Is the same true of the brickwall EQ? While there are no doubt subjective opinions, it seems that this should be objectively verifiable.

I know… just listen, but I’m more thinking in terms of the accumulated effects of applying HPF to many or tracks, and in some case, I might have someone else do my mix in a listening environment that is more revealing than my own.

Thanks in advance.

Applying the HPF at 40 Hz does slightly affect frequencies above 40 Hz, but at higher frequencies, the effect is pretty negligible. At 40 Hz, the response is -3dB, and above 40 Hz it approaches 0 dB. This curve is smooth - it has no ripples. Below 40 Hz the response drops off at 12 dB/octave, so at 20 Hz for example the response is -15 dB, at 10 Hz it is -27 dB, etc. The brickwall achieves a much faster rolloff, 60 dB/octave, and above the cutoff frequency it gets back to 0 dB very quickly. However one additional difference with the brickwall filter is that there is a slight ripple in the response since the brickwall uses an elliptical type filter.

When you say distortion, I assume you mean just a change in the frequency response, rather than a non-linear distortion which introduces new frequencies. The HPF filters in Trackplug are linear and can only affect the frequency response. They do not add any new frequencies via harmonic or intermodulation distortion.

Hope this helps,

Bill

Thanks for the info!