It was recommended to
me that I tune kick-drum samples to the key of my song, so I used a
tuner and an analyser on my stereo master and soloed the kick-drum
track. The tuner said that it was playing an Eb at 78Hz. As my song was
in Bb, I used a pitch-shifter to tune the kick drum down to Bb, but it
sounded really bad. What’s the right way to go about this in a digital
environment? I appreciate that I could just use my ears, but I’m
interested in it from a technical perspective.
The
traditional hardware sampler’s method of pitch-shifting audio — namely
just slowing down the playback rate of the sample — has the disadvantage
that it changes a sample’s tone, but this side-effect is usually less
disagreeable when processing drum samples than the
flamming/chorusing-style artifacts of most digital pitch-shifting
algorithms.
Via SOS web site
SOS contributor Mike Senior replies:
The discussion of drum tuning tends to receive most coverage with
regard to live kits and band recording, but the same kinds of issues
also apply for kits in hip-hop, R&B, and indeed any other style
based heavily on programmed drum samples. If any drum sample has a
prominent pitched element to its sound, there is the potential for that
pitch to conflict with the harmonies of the production as a whole, and
if there’s a clash, the pitch of the drum sound in question won’t tend
to blend as well with the mix. This isn’t necessarily a problem — and
in some cases it can help the drum sound poke out of the mix and remain
more up-front. However, if you do match the drum sample’s pitch to a
note that blends into the track, that causes the pitched element to be
masked by the other instruments in the track better, so its pitched
component becomes less noticeable. This means that you can often mix the
drum higher in the balance, thereby emphasising the noisier elements of
the sound and making the drum feel punchier. So, to some extent, drum
tuning is an artistic decision as much as a technical one. With
kick-drum samples specifically, however, there is the added issue that
many powerful-sounding electronic kick drums (most notably the Roland
TR808 kick) incorporate a very prominent, pitched, sub-bass tone, and
this will almost always make a mess of your song’s harmonies if it
doesn’t fit in with the key, so it’s usually safest to tune it to the
key note.
Pitch-shifting isn’t the way to do
this, though, because even the best pitch-shifters tend to compromise
the attack of percussive sounds. It’s much better to simply speed up or
slow down the sample’s audio as a traditional sampler might do. There’s
a way to do this with the audio editing tools in most sequencers as
well, but failing that you could import the sound into a dedicated
hardware or software sampler and adjust it from there. Yes, the tone of
the drum will change, but you won’t get the kinds of nasty, flammy
artifacts you’ll get from a pitch-shifter. I also wouldn’t trust a
tuner to reliably report the perceived pitch of a drum sound.
Pitch-detection algorithms are pretty good, but they won’t always agree
with what you’re actually hearing. Trust your ears.
The
simple answer to the question of how the lowest frequencies of the kick
combine with those of the bass is: they don’t! In almost all cases, one
of them gives way to the other to avoid exactly the kinds of problems
you’re anticipating. With 808-style kicks, you may even want to
high-pass filter the bass line to keep low-end sludginess at bay. In the
case where the bass has the sub frequencies, the kick can often be
surprisingly light sounding, but you usually won’t notice because it
never actually appears in the arrangement without the bass.
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