the gate/expander in use

written by susiwong

A basic gate has a single parameter, the threshold – when the level is above the threshold the signal passes unchanged, when the level drops below the threshold the signal gets switched off, simple as that. Attack time ideally should be as fast as possible without causing clicks or distortion, so it’s preset to a sensible compromise with most gates, a few good gates even offer you a choice of two settings. Knee, hold and release determine shape and speed of the fade out, release is responsible for the overall decay time, knee changes the behaviour around the threshold level, helping you avoid the dreaded “motorboating” effect where the gate switches on and off rapidly. Think BSS or Drawmer gate vs Alesis compressor …

Hold simply specifies the “reaction time” from the moment the signal passes the threshold till the begin of the gain reduction – critical to preserve as much meat as possible from drums or keeping guitar decay intact. This is mostly what separates the good from the bad and the ugly. Last is the “range” or “floor” parameter, it sets a certain minimal volume to which the signal gets attenuated when dropping below the threshold, instead of being muted completely. Very helpful when you need to reduce the background noise between a singer’s phrases for example, much less obtrusive than muting the track completely. Set the floor so the background noise gets masked well enough by the music, often 3dB or 6dB are enough. This technique is also known as downward expansion, paired with a longer release and soft knee it’s often used for distorted guitars (with slow decay), too.

Some good gates offer sidechain filters allowing you to “zero in” on the important part of a complex signal, take a tom mic of a multi-miced drumset for example, where a lot of similar signals (bleed) are fighting for control. Difficult even with sidechain, impossible without. Worth noting that these filters do NOT influence your audio signal, only the signal used for detection, hence the name sidechain. And finally an external sidechain allows you to even borrow a signal from another channel to trigger your gate – the creative options are huge.Unfortunately not all hosts have this implemented in a user-friendly way. One popular example is tightening up the bass by triggering its gate from the kick.

A few things that work for me personally, ymmv:

  • Vocals, sax etc.
    • As described above, expansion is the way to go, all you want to achieve is gently fading out the ambient noise without drawing extra attention to it.
    • You’ll reach a level where the noise is getting masked by the rest of the music.
    • Slow release, floor as high as possible, 3 or 6dB should be fine. Soft knee.
    • Of course there’s always the time-consuming method of manually editing out the noise, I like to do that on lead vocals, but quite often on background vocals or quick demos a gate is perfectly adequate.
    • All that said, there definitely are singers where muting the complete track might be a better solution. 😉
  • Drums
    • Start with a gate, fast attack, use hold and release to shape the decay (the “boom” noise”) to taste.
    • When you start to “get there” you can try to experiment with the floor parameter for fine tuning.
    • Watch out, a big part of the sound might actually be on other channels (“bleed”), so solo your main track from time to time to get a feel for that.
    • If you need the gate to react e.g. to a single tom only, ignoring the prominent bleed from the neighbour drums, the sidechain is your friend. Use the HP/LP filters to single out a small frequency band unique to the tom in question, with a bit of experience and luck you often can isolate a tom pretty well. Granted, nobody said it would be easy …
    • Btw, the famous ’80s “gated drums” effect, pioneered by Phil Collins and others, doesn’t gate the drums themselves. Instead you have insane amounts of (plate) reverb on a send, often compressed, and you gate the reverb tail with a hard gate in time with the rhythm of the music. This gated reverb sound blends with the original sound to form an artificial, bigger than life new drum sound.
  • Electric guitars
    • A mix of the above techniques, really.
    • Put the gate as early in your chain as possible, noise that isn’t there anymore can’t be amplified by the extreme compression of your OD/distortion devices …
    • Those OD/distortion thingies, especially in the digital domain, typically produce much less noise of their own than most people think, but they blow up every tiny bit of noise fed into them to monstrous proportions. Metal distortion is not funny … 😉
    • The problem is the decay of the notes. As long as you have kind of an “on-off” signal like in palm-muted heavy rhythm guitars you can deal with a lot of noise easily using a hard gate with fast timings.
    • Subtly decaying notes from a bluesy guitar and you might well be SOL …
    • Your best chance is to get as clean a signal as possible to start out with, PUs, shielding, cables, DI, tubes and biasing, switching off unneeded electrical devices, and finally your playing position (“turn to Mecca” – move around until you find a position minimizing EMI/RFI noise and STAY THERE !) – all make a big difference.
    • Then see what you can do with soft expansion as described above, or try manual editing.
    • Some folks swear by dedicated NR devices for guitar (Hush, Decimator, Denoiser etc) which combine an expander with a dynamic LP filter – very effective but somewhat tricky to handle and not available in software afaik.

All in all gating can be a big step towards a clean mix and I couldn’t live without it, but you have to know where to stop. I’ll take a noisy but natural signal over a chopped off, “over-gated” one every time. And as for all the creative applications of gating – experiment and write a cool article here … 😉

Comments

  1. Before someone writes something different here: The best Gate ever heard is the Gate in Wave Arts Trackplug. Actually the best was Kjaerhus Golden Audio Gate, bur Kjaerhus dont exist anymore.

    Now i am interested in, which one you think is better.

    • Both are/were fine gates.
      The real question however is not what we were using in the past …
      Now is the perfect time to start a discussion about gating techniques, won’t you share what made these gates special to you, Bob, to get the ball rolling ?

      • In fact, a precisely used good Gate can do wonders in different ways. It can fade out all room signals, almost as the drums would have been recorded dry. It can do general fade in and fade out jobs on the clips, also in very musical manner. It can shorten too long Hall decays better than the Hall-Algos themself. And if the gate is realy realy good (thats why i named Trackplug) it even can stop the hihats sounding like the drummer would have done it, and make a Jazz drum out of a Heavy Metal one.😉
        Unfortunaltely it cannot improve my English skills, but i hope you understand, what i mean. However, IMO you can forget to achieve all this with most of all Freeware plugins out there. I suggest a gate is always just as good as the compressor it could be.
        How was that ball, susi ?😉

        • Great balls (of fire) – this is the type of creative applications I meant.
          Also the mentioned backing vocal tricks,keep them coming, everybody !
          Nothing wrong with your English at all, btw, perfectly fine.
          Not all of us are native speakers (including myself) – hey, the info counts, not some geeky grammar rules.

  2. I’ve used Drawmer and BSS. I keep going back to Aphex 622. Check it out.

  3. Recently I recorded a band where 3 of the members would sing the same rhythms. I sidechained the lead vocals to the other 2 and set an expander on each. Ensuring that the lead vocal has the first and last sound on each phrase is a great way to keep it up front without having to distance the others with eq or reverb.

  4. when doubling vocals a gate can help pretty much to manage the uneven vocal releases. a soft knee can do wonders here …

  5. Good and straight to the poit susiwong, Not much i can add except…

    Yeah i am a swearer of certain devices for certain jobs. As a typical high-gain and down-tuned axe slinger there are two i would not even consider playing without:

    1. Boss NS-2 Noise Supressor. This works just about as spot-on as i could ever wish for. It has a built-in loop which is where boost/overdrive and most ‘effect’ pedals go and it isolates them and keeps the signal from chattering. However put a high-gain distortion pedal inside that loop and it chomps down doing overtime on the signal, So the outright high-gain distortion boxes must be placed after the NS-2 like one would chain any pedal.

    2. Surprisingly Line 6’s ToneCore-Series ‘Uber Metal’ Distortion pedal has a gate built-in. Not only does this pedal sound very good for most distortion sounds i have ever needed but the built-in gate is superb and tailored just right for the pedal (no user controls as such with just a three-way mini switch for off/I/II) II being the strictist most setting. Unfortunately it only works in conjuction with the distortion and AFAIK Line 6 have done or are discontinuing the ToneCore-Series.

    3. DBX 166XL Compressor/Gate – Needs no introduction and if i did not have the afforementioned then i would be using this one with my guitar setup. Its also a good workhorse for use on drums and like the mentioned Drawmer 2xx (forget the number of the top of head) excels in a live setting as it does the home studio plus it has compression if needed🙂

    Nekro/Dean > High-Gainer, No Earner ;P

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