What is Lookahead ?

Posted: Tue Apr 08, 2008 3:53 am

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

Posted: Tue Apr 08, 2008 6:09 am

Is it something function like Attack?

Posted: Tue Apr 08, 2008 8:07 am

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.

Posted: Tue Apr 08, 2008 8:17 am

Robak wrote:

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

Posted: Tue Apr 08, 2008 8:35 am

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.

Posted: Tue Apr 08, 2008 8:50 am

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.)

Posted: Tue Apr 08, 2008 8:54 am

Robak wrote:

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.
Wink

Posted: Wed Apr 09, 2008 12:22 am

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

Posted: Wed Apr 09, 2008 6:18 am

RemyRAD wrote:

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? Confused

15dB peaks beyond RMS...please Rolling Eyes

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.

Posted: Wed Apr 09, 2008 8:34 pm

Jeremy said:

Quote:

dynamics don't have any place in modern music...

+10

Posted: Wed Apr 09, 2008 9:10 pm

Hey buddies,

Thanks for the info.

Posted: Wed Apr 09, 2008 9:23 pm

Not that I had anything to do with it, but...

Thumbs Up

Posted: Thu Apr 10, 2008 11:37 am

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.

Posted: Thu Apr 10, 2008 10:13 pm

He was referring to RMS levels. Not peaks.

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