[Bob Katz]

What do you think of linear phase equalizers? Do you ever use them? Any particular reasons for your preferences?

[Robert Bristow-Johnson]

Not a lotta attention to this one.  But, for me, an interesting topic.

[Bob Katz]

Oh yes. I’ve written a whole book chapter on the subject! 🙂

[Alexey Lukin]

I use linear-phase EQ when I need a “manual crossover”. I EQ one signal with a low-pass then I invert phase and mix with the original to get the high-pass band. Before RX started supporting frequency feathering of selections, I used this technique to apply “gentle” edits that change the amount of processing in frequency. For example, I could apply 12 dB of noise reduction below 1 kHz, 6 dB of noise reduction above 3 kHz, and some crossfade in between.

[Bob Katz]

Hi, Alexey! It’s great to see you here.

The applications I was primarily thinking of was use of (or potential use of) LP equalizers in music production: Recording, mixing, mastering. I’m curious to hear how other engineers may choose to use them or not to use them in music production.

Yes, Linear phase in more “scientific” applications is often used behind the scenes, such as in multiband dynamics processors.

So many people don’t realize the issues that can occur with minimum phase equalizers. For example, MS manipulation with minimum phase equalization can mess up the stereo imaging.

 

[Alexey Lukin]

Hi Bob! One more case where I would use a LP EQ is to attenuate noise that is well separated in frequency from the signal. If the vocal is above 100 Hz and mic stand thumps are below 50 Hz, I would use a LP highpass filter, so that phase of the vocals is not shifted.

[TiKkO Rome]

“The LP’s ability to preserve the depth of the mix is frequently an advantage when mastering, because altering a band’s level does not move instruments forward or backward in the soundstage”. 😉