Do you have any pointers on making a great sub-bass
synth sound to underpin bass lines? It seems to be one of those things
that’s hard to get wrong but, at the same time, difficult to get bang on
the money. Should I use sine, square or triangle waves? How steep a
filter should I use, and at what frequency should I set it? I’ve used
sub-bass synths with varying degrees of success, so I’d be interested in
any handy hints.
Via SOS web site
SOS
contributor Mike Senior replies:
Sub-bass synth parts can operate in
very different ways, so it’s difficult to generalise. The simplest
application is where you double your tune’s bass line at the octave
below using a simple sine-wave synth patch. In this case, there’s
nothing much to do other than set the synth’s level and have a listen
to it in solo, just to check that the synth’s envelope settings aren’t
so fast that they create unwanted clicks. Because a sine wave is
effectively only a single frequency, and that frequency doesn’t overlap
the main bass part’s range in this scenario, there’s no need to filter
the sub-bass synth at all.
Things get more
complicated if you’re using a sub-bass synth to try to beef up the
existing fundamental frequency of your bass part, because the sub-bass
synth, therefore, overlaps the main bass part’s frequency range. The
problem is that if the peaks and troughs of the ‘sub’ synth’s waveform
don’t track those of the existing bassline’s own fundamental frequency
component, the combination can actually end up sounding less bassy than
before! And because the relationship between these two sets of waveform
peaks will usually change from note to note, you may end up with a very
uneven low end that’s all but impossible to balance with the rest of
your mix. If the existing bass sound’s fundamental frequency is weak
enough, by comparison, with the added sine wave, this effect may not be
significant enough to be a problem, but if you do get into difficulties
you need to try to get rid of the original sound’s fundamental
frequency, in order to clear the field for the sub-bass synth at the low
end. A steep high-pass filter on the main bass part is one solution,
but at times you may need to use the more surgical approach of notching
out individual fundamental frequencies with narrow-peaking EQ cuts. A
high-resolution spectrum analyser may help, or you could, alternatively,
plug the bassline note names into the note-to-frequency calculator at www.muzique.com/schem/freq.htm, in order to find approximate notch frequencies. Again, though, filtering the sub-bass synth won’t help at all in this case.
In
some cases it makes sense to eliminate, very precisely, the fundamental
frequencies of your main bass part, to avoid troublesome conflicts with
an added sub-bass synth part. If you find yourself in this position, a
note-to-frequency calculator, such as this one at www.muzique.com, can save a lot of time by identifying the EQ frequencies you need.
The point at which filtering becomes an issue
is when you’re wanting to round out the overall low-end tone of the bass
sound, rather than just adding a sub-octave or emphasising the
existing fundamental. A sine-wave sub-synth won’t help you here,
because you want a waveform that has some harmonics in addition to its
fundamental frequency. I like using a triangle wave instead of a
sawtooth or square most of the time, because it seems to be better at
blending with (rather than overwhelming) the sound it’s layered with.
The triangle wave doesn’t have such dense harmonic spacing as a
sawtooth, and is duller-sounding and less characterful than a square
wave.
Whatever waveform you use, though, you
still need to take exactly the same precautions with the sub-synth’s
fundamental frequency as you do when using a sine wave. I’d also steer
clear of detuned multi-oscillator patches, because the ‘beating’ between
the two detuned layers may cause the sub-synth’s fundamental frequency
to fluctuate unacceptably in level. Stick with mono patches too, because
low-end stereo width can reduce the power and consistency of the bass
sound in mono, and will also interfere with vinyl pressing if you’re
planning to take that route. These restrictions mean that you only
really need a very simple instrument to generate sub-synth parts. For
the ‘Mix Rescues’ I do in Cockos Reaper, even that sequencer’s
no-frills little ReaSynth instrument is over-specified, and I’ve used
that as a sub-bass synth on numerous occasions.
The
decision as to whether to filter the sub-synth is purely a question of
what kind of low-end tonal enhancement you’re looking for. With a
triangle wave, in particular, you might not feel any need to filter it
at all, although I do personally find myself employing some kind of
low-pass filter to restrict its input to the lower octaves in most
cases. The slope of the filter is typically quite critical, though, so
if you can find yourself something with a variable roll-off slope, that
does give you a useful amount of extra control. However, I wouldn’t
use a resonant filter in this kind of application unless that filter is
set to track the synth oscillator’s pitch, otherwise the filter’s
resonant peak ends up boosting different harmonics as the note pitches
change, and this makes the sub-bass synth less likely to blend
consistently with the main bass part.
One final
point to make is that sub-bass synth parts usually need to be
controlled quite tightly in terms of dynamic range, or else they can
really eat into your track’s overall headroom. It’s also usually
sensible to avoid having a sub-heavy kick sound when there’s a
prominent sub-bass synth underpinning the bass line, for similar
reasons. There’s only so much space down there, so if you want massive,
subby bass, you either have to sacrifice some of the kick’s weight or
turn down the overall level of your track to accommodate the
low-frequency build-up.
No comments:
Post a Comment