Exploring Logic’s Compressor plug-in

Plug-ins are funny things. Most DAWs come with a complete set of excellent effects, but often these get overlooked in favour of third party add-ons. And Logic Pro 9’s Compressor plug-in is a prime example.

I’m not going to disparage works from the likes of Universal Audio,Sonnox or Focusrite, as many of their plug-ins are truly exceptional pieces of software, promising accurate recreations of analogue equipment, complete with GUIs that offer agonisingly realistic recreations of front panel controls. But, in reaching for them, it does often mean that we overlook some gems that are right under our noses.

When Logic Pro 8 arrived, all the effects had received a significant overhaul. Unfortunately, few people really noticed as the editor window remained pretty much exactly as it was. It hadn’t metamorphosed into an 1176 or LA-2A recreation… or had it?

Although Compressor looked the same outwardly, Apple had put a lot of work into the algorithms. The current Compressor in Logic now lets you choose from six different circuit types, based on the way that different topologies of actual physical units affect the way a compressor affects the audio. The following choices are available:


    • Platinum. This is pretty much the same algorithm used in previous Logic versions.


    • VCA. Good examples of Voltage Controlled Amplifiers are DBX 160, prized for fast response times.


    • FET. The epitome of a FET based compressor is the Urei 1176. Not as fast as VCA, with similar characteristics to valve.


    • Opto. Optical compressors respond in a similar fashion to valves, with good response to transients. The most popular example is the Telectronix LA-2A.


    • ClassA_R. Forum juries are out on this one, but the Class A part suggests a valve model of one type or another.


  • ClassA_U. See above, but may well be based on a variable ‘Mu’ type device, similar to a Manley.


So, while there’s not a lot of technical literature to support the different circuitry types in Compressor, there’s definitely scope to use the different circuit types to start moulding the acoustic signature – for example, knowing that an SSL compressor is a VCA design gives you a good starting point for dialling in that particular sound.

But circuitry isn’t the only advance. The current Compressor in Logic Pro 9also has some hidden parameters, accessed by clicking the expansion arrow in the bottom left hand corner. This gives you access to Output Distortion with three types – Soft, Hard and Clip (plus the omnipresent ‘Off’). These are useful for generating the extra harmonics associated with valves all the way through to the limiter-smashing effects of units like the Empirical Labs Distressor. There’s also a full and flexible side chain filter complete with key frequencies and, last of all, one of the most interesting features – a Mix control, which allows you to compress all of the signal (as is usual) or only part of it, giving you an easily controllable way of blending a dry and compressed signal.

If you’re a long-term Logic user who hasn’t really explored the new features of the Compressor plug-in, I’d advise setting some time aside to explore the new sonic options before reaching for something else!

For more information on Logic Pro 9, give our audio team a call on 03332 409 306 or email audio@Jigsaw24.com. You can also share your tips on the circuitry and parameters in Logic’s compressor in the comments below, and we’ll be in touch.


Rob H
Rob H
Call us: 03332 409 306