Top Ten Pre-Mastering Pitfalls #2: Distortion (or IT’S TOO LOUD part ii)

 In Advice, Mixing


In the first of these posts I talked about how excessive levels combined with dynamic processing at various points in the production can give rise to a lack of energy and punch in a mix, making it sound flat and artificial. This time I’m warning against another consequence of excessively high levels: clipping distortion.

Clipping is what happens when your DAW (workstation), or a plug-in within it (or any piece of audio equipment for that matter) cannot pass or replicate the signal you are trying to create because it goes beyond the limits of the system. The signal wants to rise, but it hits the ceiling and just flat-lines there.

Back in the day when we recorded analogue onto tape, everyone seemed to have at least a rough idea how to use a VU meter to guide them towards a sensible operating level, with a reasonable amount of headroom. These days, it would appear that the nature of digital metering makes it harder to figure out how hot a recorded signal should be, and many amateur engineers will tend towards over rather than under-modulating the signal, whether it  be at the pre-amp stage, the A-D conversion stage, or internally within their DAW when bouncing down tracks.

The key thing here is; there’s just no need for it. As Mastering Engineer John Scrip says in his excellent blog on the subject:

“You’re in the age of 24-bit digital recording.

Relax and enjoy the headroom”

Now, you may think that distortion is only going to be an issue at mastering if it is particularly noticeable in your mix. You could be wrong. Your flat mix may not sound too distorted to you, but you’ve brought your recordings to a (hopefully) skilled and well equipped practitioner of the dark and mysterious art of mastering (not some numpty who’s just going to turn it up and make it more distorted). What happens next? We have no idea what fascinating techniques he or she might wish to employ to bring your tracks to life and give them the edge they previously lacked, or to help provide that ideal perspective and clarity to each and every instrument…  It would be a shame would it not, if the game-changing processing technique your Mastering Engineer has up his sleeve cannot be used because it reveals the distortion in your mix.

So – keep it clean guys…

Beginner’s Tip: There are new products coming on the market all the time designed to help you optimise your levels, but if you don’t have decent metering or are not sure how to use it, here’s a rule of thumb: If in doubt, turn it down. Where it was once essential to keep levels up in order to avoid noise in your recording, it is now far more likely that you’ll do damage by having your level too high than too low. It does not mean that you’re getting it wrong if your meters aren’t in the red all the time!

Still to come: file-names, media and The Mix Bomb (gulp!). In the next post: clipping of a different sort.

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Showing 2 comments
  • Matias

    PSP has a free VST, which is solely a VU meter. By default, it reacts as -14dBFS = 0VU (+4dBu), but it’s tweakable to allow the user some freedom. I prefer -18dBFS as my 0VU reference.

    • Nick Watson

      Thanks Matias – that’s a good call! I actually use VU meters a lot in mastering.

      The default calibration on the VST you mention is technically correct (0VU=-14dBFS), but your 4dB offset is just right for working on a mix without having to worry about clipping or limiting – you’ve got 14dB of microdynamics (that’s about as much DR as any open-sounding uncompressed mix is ever likely to need) plus a 4dB safety-zone (headroom in other words).

      The -18dBFS=0VU calibration is also used by the BBC and other European broadcasters, so you’re in good company.

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