While we’on on compression, have you ever wondered what the Lookahead menu is all about?
This value specifies how large of a buffer Compressor uses. A larger value means that the device has longer to analyze the incoming signal, which means that the attack can be more accurate. The nature of analog compressors is to reduce gain after the signal exceeds the threshold – there’s really nothing wrong with this from a sonic perspective, but a “perfect” compressor would be able to predict the future and reduce gain at the exact moment that the threshold is exceeded. By using a buffer, a digital compressor can do exactly that.
So, one way to understand Lookahead is as a modifier for the Attack setting. Try putting some heavy compression on a drum loop with fast Attack and Release settings and the Lookahead at 1ms (the default).
Listen closely. The transients should be pretty strong with an audible click on each drum hit. When you move the Lookahead up to 10ms, however you’ll find that the Compressor’s attack has gotten really fast and the transients of each hit have been softened signifigantly. The opposite is true when you go to 0ms.
Now, try messing with the Attack a bit. With Lookahead at 10ms, my experience is that the results are always smoother sounding. This is probably the desired setting for the most transparent compression. However, If you’re looking for an agressive smack where you can really hear the compression kicking in, the lower Lookahead settings may suit you better.