Recording - March 2015 - 46

Paul J. Stamler

Welcome to Crosstalk! This month's collection of
wisdom was inspired by an interesting letter from
reader (and Readers' Tapes contributor) Steve
Bonaccorsi:
Hello Mike: I wonder if you could address the
issue of clipping in an upcoming magazine. I am
currently using a Pro Tools PC-based system. From
what I have read about digital recording, it seems
that the direction is to always avoid clipping at
all costs, yet I can't seem to avoid it completely.
I always do my best to make sure my inputs are
adjusted so that clipping does not occur. However,
as my tracks develop, I find that clipping sneaks
back in. For instance, I'll do multiple tracks of
vocals, each with no clipping. Then I'll attempt to
route them to a single auxiliary track, in order to
add equalization, etc., and... boom... clipping
occurs on the combined track. At that point, I
start lowering the fader on the aux track and, as
a result, the vocals begin to lose their strength in
the mix. I try to address it with a compressor, but
I begin to notice that the quality of the vocals
begins to get compromised. Frustrating.
Also, I routinely get clipping on certain components of drum tracks, e.g. snare drum cracks, kick
drums, etc. In many cases, I'll have multiple
tracks with no clipping and then when I go to the
master track... clipping. Again, as I lower the master fader... the whole track loses loudness compared to professional CDs.
Do you have any suggestions or tips? Is "occasional" clipping okay (e.g. snare drum hits) or
should it be 100% avoided? Is compression the
typical answer? If I looked at a professional mixing job, would I see no clipping? I'd appreciate any
insight you might be able to provide. I really enjoy
Recording and hope you can address this issue
sometime in the future. Is it just me? Thanks-
Steve Bonaccorsi
Several authors answered Steve; I found it fascinating to see where they agreed and where they differed,
and where each writer chose to look at the problem of
clipping, from the inputs to the mix bus. Some of these
answers are relevant to Steve's case directly, others are
more generally useful; if you've been having issues
with clipping and loudness, you're bound to find something worthwhile here.-MM
46

RECORDING March 2015

Hi, Steve. It sounds to me like you have two problems, not really related:
clipping on the Aux bus and weak vocals in the mix. The clipping on the
Aux bus happens because you're combining several tracks' worth of material onto a single bus, and the signal levels are adding up to more than the
bus can handle-so it clips. The solution is not to turn down the fader on
the Aux track; that simply lowers the level of an already-clipped signal. The
solution is to turn the levels down on the individual track faders (or Aux send
controls) until there's no more clipping on the Aux bus. Yes, I know that the
situation in digital mixing isn't exactly the same as it would be in an analog console, but in many DAWs it's similar enough that the above holds.
About the lack of impact from your vocals: There are two classic ways to
make vocals "pop out" of a dense mix. One is indeed compression, and I'd
venture to suggest that if the quality of the vocals is being compromised by compression, you should first try it on an unclipped vocal mix, as described above.
If that doesn't work, you should consider trying a different compressor plugin rather than the default ones that come with the version of PT you're using...
M-Powered 7, if your Readers' Tapes information is correct, which is quite
long in the tooth at this point. I've had good results with the Sonitus:fx
Compressor, which nowadays is only available from Cakewalk and not compatible with Pro Tools, but there are many other great examples that work with
PT, both in RTAS for old versions like yours and in AAX for the latest revs.
The other trick for making vocals pop out is this: first, make a submix of
everything except the vocals, taking care not to clip the bus you're mixing
to. Then use an EQ to pull down a midrange frequency (usually about 500
Hz), about 1 to 1.5 dB. (The Q should be low, for a fairly wide band rather
than a narrow notch.) Then put an EQ on the vocal tracks, set to the same
frequency and Q, but boost that frequency by 1-1.5 dB. It's a subtle move,
but it can make the vocals stand out wonderfully without huge tonal changes.
For your drum buses, once again the answer is not to lower the master
fader, because that comes after the clipped bus; the solution is to lower the
individual channel faders.
A typical professional mixing job won't have clipping anywhere in the
signal chain unless the guitar player was using a fuzzbox. Professionals
avoid clipping by proper gain staging, as described above. Material that
has been "squashed" by inappropriate mastering (Google "loudness wars")
may indeed have clipped signals, but it will also sound awful, and even if
a professional was paid to master it that way, he or she is probably embarrassed about it now... or should be.-PJS

Giles Reaves
Hi Steve: Let's start with one of your statements that I think is most important. You ask if the direction is to avoid clipping at all costs, and I say YES!
It's easy to avoid clipping (once you know how), so why not do it?
It sounds obvious, but to avoid clipping, you simply turn down your
level-it's all about leaving headroom so that when you add tracks together they won't clip. There are other issues too, and I'll address them by
answering your specific questions.
If "clipping is sneaking back in" to your buses, then in one way or another, you've not turned your tracks down enough, or you're recording too hot.
When recording audio, you should consider peaking at around -12 dBFS
on every single track you record. This gives you the necessary headroom to
mix all tracks together with less chance of clipping. For plug-in instruments,
use the same reference levels so that all tracks have similar peak energy.

Recording - March 2015

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