What is Lookahead ?

ray1018

Well-Known Member
Joined
Apr 25, 2005
I'm a Logic Pro user.
I saw the Lookahead setting at the bottom of Multiband Compressor (Multipressor) ~ from 0ms to 20ms and default is 5ms.

May i know how it work?
Thanks
 

Robak

Member
Joined
Mar 10, 2006
I'm not using Logic and haven't used that compressor but the term "lookahead" usualy means that signal is delayed so it can be analysed by compressor. The longer the delay time is the more precise the analysis. For example, thanks to this function compressor "knows" when transients will occur in the signal.
 

ray1018

Well-Known Member
Joined
Apr 25, 2005
Robak said:
I'm not using Logic and haven't used that compressor but the term "lookahead" usualy means that signal is delayed so it can be analysed by compressor. The longer the delay time is the more precise the analysis. For example, thanks to this function compressor "knows" when transients will occur in the signal.

Hey Robak,
Thanks for the info.
So, 'the longer the delay time is the more precise the analysis' means,gonna set the lookahead as much as it provide? for example, 0ms-20ms...i s'ld set it to 20ms?

Sorry for my fool question.
but need your hands.
Thanks
 

Robak

Member
Joined
Mar 10, 2006
As I said I don't know that particular compressor so I cannot help you much. I guess it's not as simple as just using maximum delay. Use your ears and included manual :wink:. BTW multiband compressors used by unskilled hands can do a lot of damage to your overall sound.
 

Cucco

Well-Known Member
Joined
Mar 8, 2004
Yes - look ahead is as Robak describes it. In general, the longer the look ahead the better, however, beyond maybe 5-10 ms should make no improvement.

Also - I agree with Robak in that using a Multi-Band compressor for mastering is usually a very bad thing. It's usually a very good sign of the worth of the ME when I see whether or not they use a MBC on a regular basis (or list it high on their equipment list).

I don't know of much that can't be accomplished with an EQ and Compression/limiting that would ever need to be accomplished with a MBC with some VERY rare exceptions (multi-band downward expansion for low-level noises, etc.)
 

ray1018

Well-Known Member
Joined
Apr 25, 2005
Robak said:
As I said I don't know that particular compressor so I cannot help you much. I guess it's not as simple as just using maximum delay. Use your ears and included manual :wink:. BTW multiband compressors used by unskilled hands can do a lot of damage to your overall sound.

OK man.will check it out.Thanks anyway.
;)
 

RemyRAD

Well-Known Member
Joined
Sep 26, 2005
For what it's worth..... I don't like look ahead limiters. They are important for proper peak control since it knows the peak is coming. But that really crushes the life out of your sound. Much more important in a broadcast application, or when cutting into lacquer. If anything, I turn off the look ahead feature in most of my software compressor/limiters. I want it to miss the incoming peak before it clamps down on my sound. This helps preserves transients.

In the days of VU meters, you never saw any peaks. But you knew your peaks were approximately 15 DB higher than your observed levels. But now everything has peak indicating meters taking a lot of the guesswork out of the transient transits travels.

You need both peak & RMS compressors/limiters, with and without look ahead.

I hope this peaked your interest?
Ms. Remy Ann David
 

Cucco

Well-Known Member
Joined
Mar 8, 2004
RemyRAD said:
In the days of VU meters, you never saw any peaks. But you knew your peaks were approximately 15 DB higher than your observed levels. But now everything has peak indicating meters taking a lot of the guesswork out of the transient transits travels.

You mean you didn't know the tricks for getting your VUs to read faster? WD-40 into the casing? Mounting the rack unit sideways to allow gravity to help the needles move faster? A helium-rich atmosphere in the studio to allow for lower air-pressure...

Besides, don't you know Remy, dynamics don't have any place in modern music? :-?
15dB peaks beyond RMS...please :roll:
Your music is only supposed to have 7-9 dB of dynamic range or it can't compete on the current market.

Don't worry - I know a couple recording schools in Maryland that will happily teach you these things. :wink:

When are you up for a beer in the near future? My treat.
 

Codemonkey

Well-Known Member
Joined
Dec 11, 2007
Heh...7-9dB in modern music?

Clubland 11 --> "Amazed" by Dancing DJs (and about 4 contributing artists) --> Volume display --> the lowest it got was -2dB.
 
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