Why do you need compression
Of all the processes used in the production of modern music, signal compression is perhaps the most difficult to perceive. This is primarily due to the fact that often the result of processing the sound by the compressor is barely audible – especially for beginners. Another difficulty lies in the number of variable compressor parameters: they are not as few as it might seem, and besides, changing each of them does not always lead to obvious results. The fact that these parameters are interconnected only significantly complicates the situation. And finally, an ordinary sound engineer can simply bewilder the amazing variety of types and models of compressors – he will have to rack his brains about choosing the right device before proceeding with his direct duties. Here is the trivial example for you: suppose you need to compress the record to hell. Which is better to choose? A compressor based on VCA (Voltage Control Amplifier), or based on an optoelectrical element? Transistor or tube (or maybe a hybrid of both)? Analogue or digital? A hardware compressor, or limited to a program that performs its functions? And so on and so forth. With so many options available, it is not surprising that compressors and compression are still a mystery to many users. However, if you decide to achieve some success in recording and mixing, mastering the skills of working with signal compression is simply necessary for you. Moreover, all the main directions of popular modern music – with the exception of classical and some jazz movements – are directly related to compression. There is one simple rule – if you do not know how to use the compressor correctly, you are unlikely to be able to achieve the best sound. This article will lead you through a labyrinth of all kinds of nuances that arise when working with a compressor, and also shed light on the features of its practical application. We start with the basics of signal compression, then give a few examples about how to use compressors. Also, we will talk about what features of the compressor you need to pay attention to and why it is important. In conclusion, I will introduce you to different types and designs of compressors, talk about some models and bring to your attention different opinions about which instruments which models of instruments are best suited for.
Why is this needed?
Compression falls under the category of dynamic processes. The term dynamic in a musical environment (and not only) means a change in volume level. Thus, the dynamic range of a signal is the difference between its quietest and loudest levels. The purpose of a dynamic processor, simply put, is to reduce or increase the dynamic range of the signal, which, in fact, leads to a limitation of the volume level within this range. Types of dynamic processors include devices such as an expander, a limiter, a gate, and, finally, a compressor. A compressor is a type of dynamic processor that, as it were, “compresses” the dynamic range of the signal and, due to this, reduces the difference in volume level between its barely distinguishable and “peak” parts. The process of lowering the volume level is called gain reduction. With sufficient experience, using this process you can achieve an order of magnitude more dense sound. For this reason, compression is the best means for characteristics whose level varies quite widely.
By narrowing the dynamic range, the compressor raises the overall signal level, avoiding distortion in its loudest parts. At the same time, with the help of compression, you can pull up the most quiet, almost inaudible sounds, such as the creaking of strings and the sound of a snare drum spring – the compressor will make them louder, cleaner and much more noticeable.
Of course, sometimes it’s completely undesirable for such unintended nuances, like breathing and other squeaks, to clog your recording, therefore, before you compress the signal, you should once again make sure that this process is necessary. In the end, the result of compression should sound better than the original.
You always have the opportunity to add compression during the mixing process, after the recording is made. But sometimes it is much more appropriate to use the compressor directly during recording, and this has its advantages. Firstly, a compressed signal can more clearly demonstrate your mistakes, which is especially important when playing an instrument with a wide dynamic range. Secondly, if you curb the “jumping” level already during recording, this will save you from similar problems during mixing, save time, effort, not to mention the apparatus, and allow you to completely concentrate on getting a high-quality “mix”.