HPFs causing serious overshoot

Alécio Costa - Brazil

Well-Known Member
Joined
Mar 19, 2002
Hi friends. Until now one had given me a reasonable explanation about serious overshoot with digital equalizers.

I will explain the situation:
I am a budget mastering engineer down here in Brazil, although have done some nice tasks...

Generally I master with the following (very simple) chain:

Waves Q10 > TC Master X 5 Band Mode > Digi Power dither Level 3 > Waves PAZ..

or Put L1...

Whenever I apply one or two HPF´s at my Q10 and with audio files under 0db with NO gain changes at all at itQ10, I hear nasty digital distortion.

So, I have to lower the Gain input of this Q10 plugin module...

Other guys have also reported this and people try to convince me that most digital equalizers do that.

However, my 02R equalizers never show this.

I am not bashing at Waves anyway, just would like to have a more technical explanation for that.

If you want to talk about La Place transfer function , poles and zeroes, let us go. I will try to understand / study that either.

Thanks In advance!
Nice thursday!

Eng. Alécio Costa
Singer/Musician/producer/recording Engineer
studiodp@terra.com.br
br.geocities.com/studiodigitalp
:w:
 

Michael Fossenkemper

Distinguished past mastering moderator
Well-Known Member
Joined
Sep 12, 2002
Location
NYC New York
It has to do with the phase shift and x-over points on the eq. When you kick in the HPF, the phase shift that is created, raises the level slightly around the x-over point and now your eq is clipping. Same thing happens on even the most expensive eq's. For example, I have a weiss eq-1 lp/dyn. If I do the same thing on this eq, it will clipp, if I put the eq in linear phase mode so there isn't any phase shift, It doesn't clip because no boost is being added and there is no phase shift around the HPF. Same thing happens in analog eq's, they just don't clip as hard a plugin's.
 

Alécio Costa - Brazil

Well-Known Member
Joined
Mar 19, 2002
so do you think I will have to re-evaluate the phase at the very bottom end, let us say 0Dc to 40hz?

What shall we do so besides lowering the input level of that stage?

Thanks

BTW.. when are you coming to Brazil my friend?
:w:
 

Kev

Well-Known Member
Joined
Nov 13, 2001
Originally posted by Alécio Costa - Brazil:

What shall we do so besides lowering the input level of that stage?
If you want to keep using that EQ then you must lower the input level.
:c:
 
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