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This
is the second installment of a series
of articles detailing how to program
tight, effective analog bass lines
and some of the best synths for
achieving good bass sounds. |
One
of the well known "secrets"
of getting a good bass tone is to use
a synth that is optimized for creating
bass sounds. Even the greenest of novices
is often aware of the many famous "bass
synths" such as the Moog Minimoog,
the Juno 60, the Korg Mono/Poly or the
Oberheim SEM-based synthesizers. However,
good bass tones are not just restricted
to these synths alone. In this installment
we are going to examine some of the
factors that influence a synthesizer's
design that makes it a candidate for
a "good bass synth."
Not
all synths are created equally when
it comes to producing quality bass sounds.
But what are the factors that contribute
to a synth being a good bass machine?
Let's examine some of the common features
that often lend itself to creating quality
bass sounds.
A
crucial area of determining the effectiveness
of a synth for bass tones is the envelope
speed, which should be very fast.
Quick, tight envelopes lend themselves
well to punchy, "attacky"
sounding bass lines; synths with average
or slower envelopes are unable to adequetely
create these sounds and will be very
limiting. In general, the speed of a
particular synth's envelopes are open
to speculation and a great deal of subjectivity.
The best way to test a synthesizer's
envelope speed is to play it yourself
and experiment with different attack
and decay settings for both the amplifier
and filter. In general, on a synth with
fast envelopes you should be able to
set a modest (perhaps 15-20% of the
knob's travel) amount of attack and
not lose any punchiness, but instead
gain a zipping, ripping rise in amplitude
or filter movement.
SCI
Prophet 5
Along with the Minimoog, the Prophet
5 has some of the fastest envelopes
on any analog synth ever made.
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As
a general rule of thumb, most hardware
envelopes, such as found on any synth
made in the 1970's and early 80's, will
be pretty quick. Likewise, software
based envelopes such as found on the
Oberheim Xpander or Matrix 12, or the
Sequential Prophet 600, tend to be noticeably
sluggish. Most modern virtual analog
synths have pretty fast envelopes now,
due to the increase of available computing
power for the software and the keyboard
scanning. (Due to this phenomena, many
late 80's and early 90's synths have
a sluggish feel to them because of overworking
the CPU for both sound generation and
keyboard scanning. The Roland D-50 is
a famous example of a synth whose envelopes
feel slow due to the time it takes the
microprocessor to read and scan the
keyboard to trigger a note.)
Two
synths that you should definately check
out for hearing fast envelopes are the
Moog Minimoog and the Sequential Circuits
Prophet 5—both of which have incredibly
fast envelopes, probably somewhere in
the vicinity of 1 millisecond or less.
On the other hand, listen to a Roland
JX-8p or Sequential Circuits Prophet
600 to hear the effects of slower, sluggish
envelopes. After hearing for yourself
the differences between these synthesizers,
you can better evaluate envelope speeds
on other synths that you encounter.
Once again, measuring envelope speed
is often very subjective and requires
you to experiment and listen.
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Korg
Mono/Poly
The Mono/Poly's fearsome quadruple
oscillator power and bass compensated
SSM filter can create stunning
bass tones in the right hands.
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Besides
envelopes, the filter is probably
the next most important factor for determining
if a synth has a good bass tone. Generally
speaking, you want to have a 4 pole/24
db low pass filter for most bass sounds.
Normally, the 2 pole/12 db low pass
filter does not contain enough filtering
to produce strong bass sounds, although
the Oberheim SEM and OB series is a
clear exception to this general rule.
For the most part, you want a 4 pole
low pass filter in your synth, which
is, thankfully, the most common type
of filter found on analog synthesizers.
Another
critical factor of filters is how the
signal is fed into the filter itself
through the analog mixer. For some synths,
such as the Minimoog, a subtle amount
of clipping is introduced at higher
mixer setting which produces a warm,
distorted sound that the Mini is famous
for. Other synths, like the OSC OSCar,
are also capable of overdriving the
filter with a strong audio signal. In
general, unless you resort to some type
of modification, most analog synths
do NOT overdrive the filter at all,
which is a shame.
There
are a number of other features that
can help you assess a synthesizer's
filter for good bass sound creating
possibilities such as the presence of
variable keyboard tracking, the ability
to disengage the filter from tracking
the keyboard at all, precise control
of filter movement by the filter envelope
(or envelope if the synth has only a
single envelope), and odd features that
allow you to modulate the filter by
its own output. Modulating a filter
by its own output creates excellent
biting, edgey tones such as found on
the Pro-One or Prophet 5.
Studio
Electronics SE-1
Easily one of the most powerful
bass creating rackmounts, this
monosynth has all the capabilities
of a Rivera Music hot-rodded Minimoog...
plus more!
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Although
both the filter and envelopes are perhaps
the most important areas to consider
when evaluating a synth for its bass
creating capabilities, the oscillators
too play a large role. Typically, you
want to find a synth that has at least
two oscillators with good mixing capabilities
that allow you to turn one or more of
the oscillators off; this allows you
to have access to a greater number of
tones and the ability to mix different
waveshapes together. Another good feature
to have is the ability to set different
pulse widths for each oscillator—strangely
enough, this is a seldom seen feature.
At the very least, look for a synth
that allows pulse width modulation by
either the LFO or envelopes. Synths
that feature triangle and sine waves
are also good for producing bass tones,
and offer a wider tonal pallete than
the typical sawtooth and pulse/square
wave options. Triangle waves are especially
good to use as a "sub-oscillator"
an octave or two underneath the fundemental
pitch (the Korg Mono/Poly excels at
capers such as this).
Another
important factor is the "gutsiness"
of the oscillators themselves—which
can be, once again, highly subjective.
However, if you compare a number of
analog synths this characteristic will
soon become apparent. Look for strong,
harmonically rich oscillators that have
presence without becoming overly strident
in tone. Some good examples of particularly
strong sounding oscillators include
the Oberheim OBXa, the indomitable Minimoog,
the Korg Polysix and the Roland Jupiter
8. As virtually all analog synths subscribe
to the subtractive synthesis model (starting
with a harmonically rich waveform and
then subtracting from it by use of a
filter) having gutsy filters insures
that your tone will remain strong and
punchy after it has been processed by
the filter.
This
article has looked at the three basic
features common to most famous "bass
synths" such as fast envelope speed,
proper filter implementation, and versatile,
gutsy oscillators with a flexible mixer.
By carefully choosing a synth that is
optimized for creating bass tones you
will have gone a long way towards overcoming
some of the problems with creating a
good bass sound. It is amazing how much
your playing and sound will improve
by playing bass lines on a synth proper
for the job.
Until
next time.
James Meeker
