Mastering 101: Signal flow & metering

Signal flow and metering are essential components of mastering that help set up your master for success.

This post is the second article in our introductory guide to mastering. If you’ve missed an entry, click on any topic below to catch up:

  1. What is mastering?
  2. Signal flow & metering
  3. EQ
  4. Compression
  5. Limiting
  6. Preparation

Signal flow

Let’s just dive right into it — here’s a good starting point for a digital mastering path in your DAW:

Source → EQ → Compressor (2 dB gain reduction) → Clipper → Limiter (3 dB gain reduction)

  • Source: This is your stereo track that you’d like to master (alternately, it could be stems, but mastering with stems is a whole different ball game).
  • EQ: Your EQ can be placed here or later; you make the call. Some people place an EQ both before and after the compressor, as the compressor tends to color a signal (we’ll talk about this more in a future entry). Regardless, note that there’s generally no gain reduction happening here.
  • Compressor: Remember, mastering is about subtle touches – you should avoid anything that’s significantly more than 2 dB of compression at this stage. You want to feel the compression rather than hear it.
  • Clipper: Using a clipper is a process that distorts your mix. Yes, you read it right — distorts. The sad truth these days is that to reach commercial loudness, you need to distort your mix (we’ll revisit this later in the guide).
  • Limiter: Similar to the compressor, the limiter will sound unnatural if it brings more than 3 dB of gain reduction to your track (unless the mix has tons of headroom). Although some may choose to produce a “pumping” effect for creative purposes, it’s generally recommended to keep gain reduction to a minimum.

This signal flow may not make any sense to some of you, but it’ll soon become clearer as we go through this mastering guide.

The takeaway here is that to make something louder, you need to reduce the dynamic range. That said, the more dynamic range a mix has, the louder it may be on streaming (check out this article if you’re interested in learning more on this).

Metering

In mastering, we usually use VU meters that give us RMS (root mean square) readings of our master. In essence, VU meters give us a good indication of the average levels of our master. A good inexpensive meter to consider getting is PSP’s TripleMeter.

signal-flow-metering-psp-triplemeter-01

A few things to note about VU Meters:

 0 VU is relative: The digital value of 0 VU is defined using the meter calibration control. The reason for this is to allow scaling for different target levels.

signal-flow-metering-psp-triplemeter-02

2. Target levels: In the mastering world, there are general reference points in respect to target levels. For PSP TripleMeter, you can calibrate 0 VU by clicking PSP VU 3. This will surface the ‘back’ of the meter.

Below are rough target levels for some common genres:

  • Classical: 0 VU = -18 dBFS
  • Jazz: 0 VU = -9 dBFS
  • Pop: 0 VU = -8 dBFS
  • Aggressive pop / hip hop: = -7 dBFS

Because 0 VU is relative, it doesn’t necessarily mean you’re clipping even if you surpass it. If you’re only touching the 0 VU mark occasionally, you have a dynamic master. If you’re going over 0 VU and into the red occasionally, you have a louder but less dynamic master. And if you’re slamming the red, you have a compressed master with less dynamic range.

Creating a mastering template

Now that you know about signal flow and metering, it’s easy to create a reusable mastering template in your DAW. All you have to do is set up and save a master track with plugins in this order:

  1. EQ
  2. Compressor
  3. Clipper
  4. Limiter
  5. VU meter (with your target level set according to genre)

That’s it for this entry — next, let’s cover EQ basics.


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December 23, 2019

Reuben Raman Product Marketing Manager at Splice