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Recording Mythology, Pt. 7 / Compression and Gating

“What does this thing with all of the knobs and lights do?”

Boy, that question usually opens up a big can of worm that no one really wants to hear about. Usually I’d just rather kill someone who touches my compressor settings and dump the body out back.

Compression can be a real pain in the ying-yang to understand and it can be even harder to configure. Every compressor is going to be accompanied by a lengthy manual and it goes without saying that it will not only have to be read, the information must be digested.

At my home studio, I have four separate compression units with two channels each. Each unit is signal specific. This means that I basically find the setting that I like for a particular application and then hardly ever touch the knobs again. By the time you get the settings tweaked on your first unit, you’ll understand why I’d rather buy a new unit than change the parameters on one which I’ve already dialed in. The reason for this is that I run one piece of equipment, a microphone, for example, into one channel. This mic is positioned in front of a particular guitar amplifier, and I never intend to use this mic for anything else. Once the compressor gain is set, I don’t need to touch the unit again: as long as the mic preamp is set at an optimal level, the compressor will do it’s job.

The compressor, as I described earlier, cuts peaks and boosts the quieter passages, keeping the recorded signal, or the amplitude, at a more or less consistent level, yet it leaves all other parts of the signal unaffected. In other words, it works only when it has to. This is a very cool item that every serious recording studio incorporates and I strongly suggest that you get one and spend a lot of time learning how to use it.

Most compressors also include a gate. This is a feature that always gets used in my recordings. The reason it is referred to as a gate is because it works just like one. It opens the “ears” of the microphone when a signal is present and “closes” them as soon as the signal reaches a preset point of decay. Irrespective of how quiet a system is, there is always a certain amount of line noise. This refers to the natural noise that is inherent in electricity and electrical circuits. It is usually a very fine sssssssh. At first glance, this doesn’t sound so bad, but after eight or ten tracks worth, it adds up. The gate will shut at the point which you will select, so you’ll have to have the headphones on. If you play a single note on your guitar, let’s say the low E, and allow it to ring, the note decay will reach a point to where your signal is equal to that of the noise. And just before you get to this point is where you will want your gate to close.

Back in the early days of recording, it was important to keep the signal level as high as possible in order to mask the noise. When four track recording was the standard, noise didn’t present such a big deal, but as multi-tracking became the norm and track bouncing became popular, it was a different matter. (Track bouncing is what producers did in order to record more tracks than was physically capable on a given device. They would record four tracks, sum them into a stereo mix and then bounce, or transfer, these tracks onto another identical machine in order to record even more tracks. On a tape machine, tape hiss was another major obstacle, and with each bounce, more hiss was added.) If you have one of the newer versions of The Jimi Hendrix Experience Are You Experienced, which was transferred direct from the master tapes, and if you own some decent monitors, you can easily hear what Eddie Kramer was having to work with. This recording was ground-breaking stuff back then and cannot faulted for the shortcomings of the equipment.

These days there are a countless number of tracks and virtual tracks to choose from but the problem of noise is ever-present. If we want our recording to sound as professional as possible, we must keep our noise floor down to an acceptable level. The gate will fill the bill and regardless how many tracks you venture to stack up, our signal will be capable of remaining above the audible noise floor, or the gate will insure that quiet will represent silence. The primary concern her is that we do not want to cut off the tail of our signal. If the gate closes too rapidly, this is precisely what will occur. This is why musicians stay up all night: Tweaking their equipment. Sometimes the cutoff point is impossible to determine, depending on the signal. Let’s say we’re close-miking and recording an electric guitar through a 100W amplifier and the amp is turned up to twelve. Well, that would not be the wise thing to do, but some guitarists insist that they simply must record this way. (These guys are nothing but headaches.) Anyhow, let’s say that the amp alone is making about +20dB of noise in driver blow alone. (Blow is the noise that a speaker makes as a result of the amplifier circuit and is most commonly encountered in tube amps. You are actually hearing electrons smashing into the plate of the tubes.. but I won’t go into all of that or I’ll never get back on the subject at hand.) The way to tame the racket is simplified by use of the compressor and the gate. We’ll only have to crank the attack down on the compressor and close the gate…and the guitarist will cry about how one dimensional his guitar sounds. But that is an example in the extreme. Usually you will be able to use good judgement in ascertaining when to close the gate without clipping the tail. Usually.

There is another little remedy to the premature gate-cutting-off-the-signal-tail syndrome when we are dealing with extremely noisy signals, however, and I’ll cover that in my next epistle.

Now, go play with your metronome.

Johnny is a songwriter/composer who refers to his studio as his laboratory.

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About Johnny Nowhere

Johnny Nowhere is a songwriter/composer and owner of Hell Paving Company, music publisher. Johnny doesn't really exist outside of the music industry and Facebook. He is simply a figment of my imagination.

One response »

  1. You could certainly see your skills in the paintings you write. The world hopes for more passionate writers like you who aren’t afraid to say how they believe. All the time go after your heart.

    Reply

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