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Linear Phase EQ

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Linear Phase EQ

Postby Dodger » Wed Feb 17, 2010 10:49 pm

Hi just started using logic and have noticed that the channel EQ and Linear phase EQ look exactly the same and really am just wondering....

what is a liner phase eq?

and how dose it differ from the normal EQ?

thanks Jack
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Re: Linear Phase EQ

Postby Hugh Robjohns » Thu Feb 18, 2010 11:56 am

A linear phase filter has constant group delay, which means that all frequency components of the signal suffer an equal delay time as they pass through the filter.

'Normal' equalisers aren't linear phase and have a group delay which varies with frequency. So some frequncies come out the far end slightly earlier or later than other frequecies. This results, inevitably in phase distortion -- but it is a distortion that we are used to and associate with recorded sound, and it is what makes different equaliser designs sound different.

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Re: Linear Phase EQ

Postby Dodger » Fri Feb 19, 2010 9:38 pm

thanks

so what are the applications of it ?

i heard it mentioned once in a music tech lesson we didn't go into much because he said we didn't need to know it and we need to get back to learning about wherever we were doing because we had gone off on one (there are only 3 of us in the class its easy)

any back on subject he said it was very processor heavy and can cause a lot of latency on channels applied on. if the channel you put it on is going to have a lot of latency on it then surely that defeats the object of having the linear EQ in the first place?

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Re: Linear Phase EQ

Postby Dodger » Fri Feb 19, 2010 10:21 pm

Also why am i on this little sort of rant ha ha

what is the difference between the adaptive limiter and the normal limiter?

i was recommended to use one for mastering? but i dont no why?

Thanks sorry if these questions are stupid..
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Re: Linear Phase EQ

Postby Mixedup » Tue Mar 02, 2010 7:58 am

Dodger wrote:so what are the applications of it ?

Think surgical/clinical for linear phase EQ. For non-linear phase think character. Linear phase EQs do tend to take more processing power. This SOS article might help. Also keep your eyes peeled for forthcoming Mix Rescue articles that address this issue in a practical context.
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Re: Linear Phase EQ

Postby Martin Walker » Tue Mar 02, 2010 1:33 pm

You may also find this review I wrote of Nugen Audio's SEQ Linear Phase plug-ins of help, since towards the end I describe how various linear phase designs sound in practice:

www.soundonsound.com/sos/jan08/articles ... lugins.htm

To my ears, Waves' LinEQ has an uncanny knack of being able to alter spectral balance without adding any character of its own; if you dial in more bass, for instance, you get more bass, but the sound somehow doesn't seem to be any 'warmer'. This absolute neutrality is ideal for some mastering applications, but not universally enjoyed.


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Re: Linear Phase EQ

Postby Shambolic Charm » Wed Mar 03, 2010 9:45 am

while were on the subject, are there any linear phase eq's that have a low latency?
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Re: Linear Phase EQ

Postby Martin Walker » Wed Mar 03, 2010 2:12 pm

Linear phase and low latency don't tend to go hand in hand I'm afraid :frown:


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Re: Linear Phase EQ

Postby MarcusH » Wed Mar 03, 2010 10:10 pm

Can't find it now, but I saw a video on the internet showing magnified, the changes to the waveform that Logic's normal Channel EQ makes. Using a kick drum track, the guy showed that Logic's EQ definitely created 'ghosting' - a second hit was clearly visible. More importantly, to my ears Channel EQ sounds dull and lacks clarity.

I do use Logic's Linear Phase EQ however, and there's a good trick to using it. Logic lets you switch between Channel EQ and Linear Phase EQ and the good bit is it keeps your settings. That means you can use Channel EQ when you need low latency - e.g. for tracking, and Linear Phase when you need good sound - e.g. for mixing.

In terms of practical use, I use my third party EQ plugins to improve the sound, and I use Linear Phase EQ for precise jobs, like filtering-out rumble or taking the ring out of a drum sound.
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