Ableton’s Glue compressor is an amazing tool, but can be quite tricky. Since it is modeled after an analog SSL compressor which behaves somewhat counter intuitive there are some things you have to know about this plug-in in order to use it effectively.
In this video I am going over those the things and below you find a text version of this article:
Fact #1: Changing the Ratio changes the Threshold
You might have already noticed that the glue compressor behaves a bit weird when adjusting the ratio. When leaving the threshold constant, changing lowering the ratio will lead to more compression. This is super counter intuitive since you would expect less compression to happen when lowering the ratio from for example 10 to 4. The increase in compression amount happens because changing the ratio of the glue compressor also changes the threshold. You you’ve heard right! Even though you have a know to change the threshold level you can not rely on the number it shows you, since the level changes with every different ratio setting you chose. This is also the case on the actual analog SLL compressors and since the plug in is supposed to emulate one of those, it also behaves the same way. What this effectively means in that you can not just switch back and forth between different ratio settings, but have to also adjust the threshold when doing so.
Fact #2: The Knee gets sharper with higher ratios
To get a good visual representation of this, you should really check out the video, but I will try my best to also explain it just with words. The knee of a compressor is the DB area around the threshold. You can choose on some compressors, how large you want this area to be in DB like 6 db for example. What this means is that instead of starting to apply the complete ratio of compression when reaching the threshold, the compressor already starts compressing 3db before the threshold and slowly start getting closer to applying the whole ratio of compression. But ones the threshold is reached the compressor still doesn’t apply the complete ratio, but start getting closer and closer to that, until the level reaches 3 db above threshold at which point the complete ratio of compression will be applied.
In the case of the glue compressor the knee gets sharper the higher you set the ratio. In other words: the area before and after the threshold where the compressor kind of glides into applying the ratio will be smaller. so instead of 6 db, 3 db for example. and when setting a ratio of 10 even less. A soft knee can sound smoother then a hard knee since the compression doesn’t set in so abruptly. A higher ratio already means more compression, but the effect gets enhanced by a knee which also gets sharper.
Fact #3: You can use oversampling
If you right click on the Glue Compressor you actually get the option to enable over sampling. While this will cost you some more cpu, it can increase the audio quality since it causes less distortion. This is especially the case when compressing stuff containing lots of high frequency content, like hi-hats, cymbals, crashes and rides. It can lead to them sounding less harsh. I don’t want to go too deep into what exactly oversampling is at this point, but felt that mentioning this feature is worth it, since its kind of hidden, since you might now right click on the plug-in.