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Oversampling
Gazillion Industries ·
A setting buried in the corner of your distortion plugin, usually off by
default, that costs CPU and latency and fixes a problem most people cannot name. It is worth
knowing what it actually does before you turn it on everywhere.
Oversampling runs a process at a higher internal sample rate than your session, then converts
back. It exists because distortion creates harmonics above the original frequencies, and any
harmonic generated above half the sample rate cannot be represented: it folds back down into the
audible range as content that has no musical relationship to what you played. Running the
process at two, four or eight times the rate gives those harmonics somewhere to go, and they get
filtered off before the audio returns to your session.
The short version
- Problem
- harmonics above half the sample rate fold back as harsh hash
- Fix
- process at a higher rate, then filter and come back down
- Where it matters
- distortion, saturation, clipping, limiting
- Where it does not
- EQ, delay, reverb, volume, panning
- Costs
- CPU, sometimes latency, occasionally a softer top end
- Rule
- on for anything nonlinear, especially on bright material
What aliasing sounds like
This is the whole reason the feature exists. Harmonics are orderly: at two, three and four
times the input frequency, they stay musically related to the note. Aliased content is not. It
appears at frequencies determined by arithmetic rather than by music, it moves in the opposite
direction when you play a higher note, and it sits in the mix as a metallic, gritty edge that
gets worse the brighter the source.
On a bass line you may never hear it, because the harmonics stay low enough to be legal. On a
bright hi-hat, a cymbal or a full mix, a hard clipper without oversampling will generate a great
deal of it. What aliasing is covers the
mechanism in detail.
When to turn it on
- Any distortion, saturation, clipper or limiter: yes, if the material is bright.
- On a mix bus or master: yes, because everything bright in the record is passing
through.
- On a bass or a kick alone: usually unnecessary; the harmonics are low enough to
survive.
- While writing: leave it off to save CPU, then turn it on before you bounce, if the plugin
offers a separate render setting.
- Four times is a sensible default. Sixteen times is rarely worth the CPU it costs.
BEEFY is our
saturation and loudness effect. Its page lists three knobs and two output switches, and it does
not claim an oversampling control, so treat it the way you would any nonlinear process: if the
source is very bright, feed it less.
Where it costs you
CPU first, and the cost scales: four times oversampling is roughly four times the work for
that plugin. Latency second, because the filters used to convert up and down introduce delay,
which your DAW compensates for but which adds up across a session and makes live monitoring
harder.
There is also a quieter cost. The filters are not free acoustically: some implementations
soften the very top end slightly, and a few people prefer the sound of a particular plugin
without oversampling for exactly that reason. That is a legitimate taste, not an error, as long
as you know that what you are enjoying includes a little aliasing.
Questions people ask
Should oversampling be on or off?
On for anything that distorts, particularly on bright material and on the mix bus. Off is fine
for EQ, delay and reverb, which do not create new harmonics, and off is a reasonable working
setting while you are still arranging.
What is the purpose of oversampling?
To give harmonics generated by a nonlinear process somewhere to exist above the audible range,
so they can be filtered away instead of folding back down into the mix as aliasing.
Does oversampling improve sound quality?
It removes a specific artifact. If that artifact was not audible in your material, you will
hear no improvement and will have spent the CPU for nothing.
How much oversampling do I need?
Two or four times covers almost everything. Higher settings produce diminishing returns and
substantial CPU cost, and they will not rescue a process that is being driven far too hard in the
first place.
What BEEFY does
BEEFY is a saturation and loudness effect for making sounds thicker, punchier and more up
front. It adds body, squeezes some space out of the peaks, and brings out harmonics that help a
sound feel bigger. BEEF brings weight, density and attitude;
COOK changes the color and bite from a rounder feel toward a brighter, more
cooked edge; JUICE sets the level going in, which is the control that matters
most here: feeding a very bright source more gently is the oldest way of managing what a
nonlinear process does with it.
A setting in the corner that costs CPU and buys you the absence of something. Worth it more
often than not.
Keep reading
BEEFY — saturation and loudness plugin for Mac and Windows. There is
a 28-second demo with three without/with comparisons on the page.
Hear it — $19