Technology

Mod is in the details
Beyond the oscillator amp envelopes (which
can’t be reassigned), Bolt ofers a fair amount of
modulation in the shape of three LFOs (in a
tabbed panel) and an assignable ADSR
envelope. Each can be hooked up to four target
parameters from throughout the synth,
although, disappointingly, these don’t include
the efects controls (see below), which could
have been useful for ilter-style EQ modulation.
MIDI velocity can be used to modulate the
Attack and depth of the Mod EG; and the uni/
bipolar LFOs feature phase shift, fade-in, one-
shot mode, envelope retriggering and a couple
of ‘step’ waveforms to aid construction of faux
sequences. The LFOs and Mod EG can modulate
each other, and with the LFOs running at up to
10kHz, all sorts of crazy efects are on the cards.
The Modwheel (two targets) and Aftertouch
(one target) are assignable in the lower section.
Finally, four simple efects modules are on
hand for buing-up and transformative
processing. The one-band EQ switches between
peak and band-pass behaviour; the Chorus
sounds wonderfully lush; the analogue-
modelled Delay feeds back in mono or stereo
and syncs to tempo; and the Reverb includes a
Tone control, and applies compression when the
Size parameter is set towards its maximum.
Fast and furious
What we ind most remarkable about Bolt is how
intuitive it is, thanks to the brilliant operational
simplicity of the oscillators and its zippy (and
freely resizable) one-window interface, which –
tabbed LFOs aside – keeps every parameter,
modulation assignment and efect in view at all
times. The Harmonics and Rollof knobs invite
tweaking and modulation, and small
adjustments to them can have a big efect on
the sound. The toggling oscilloscope/
spectrogram display is perfectly informative,
too, letting you see what’s happening to the
waveform and harmonics as you alter them –
but it’s a shame the same can’t be said of the
modulation system, which doesn’t give any
visual indication of parameter movement.
Other than that niggle, we don’t really have
much in the way of criticism. If we were to pick a
couple of nits, another modulation envelope
wouldn’t go amiss (the LFOs can be substitued
in one-shot mode, but that’s not quite the same);
and while the efect of moving the Harmonics
and Rollof controls is similar to low-pass
iltering, it can’t be made to spoof a high-pass,
band-pass or notch response. In practise, we
didn’t ind this last to be a major issue – and the
EQ has a band-pass option – but for certain
types of sound, those modes might be missed.
Ultimately, while Bolt’s approach is unique in
terms of speciics, it isn’t a gamechanger: this is
a two-oscillator synth that won’t recalibrate your
expectations of what such an instrument can do,
sonically, in any sense. But that’s not really
important – what matters is that this afordable
plugin is supremely easy to get to grips with,
and boasts a powerful, focused sound that’s ripe
for the programming of impressive basses,
leads, keys, pads, FX, percussion and anything
else you could ask of a quality synthesiser.
Web nektartech.com
Verdict
For Novel synthesis method
Easy-to-use, single-window interface
Bright, punchy sound
Very reasonably priced
500 thoroughly usable presets
Against Modulation not visualised
Only one mod envelope
Efects can’t be modulated
‘Low-pass ilter’ only
Bolt’s streamlined oscillator design makes
synthesis straightforward and fun, and
delivers the goods sonically
9/10
Alternatively
Dmitry Sches Thorn
253 » 9/10 » £119
This powerhouse synth lets you get
to grips with individual harmonics
Audio Damage Phosphor
248 » 9/10 » $59
Similarly easy alphaSyntauri-
inspired additive synth
Cooked up by Nektar in collaboration
with Hamburg’s Helmut Schmidt
University, Bolt’s method of synthesis
generates the inal waveform (as it
would appear post-ilter in a
subtractive synth) directly in the
oscillator using just two controls.
Each oscillator outputs a ‘pulse train’
of harmonics, the shape of which is
modulated by the Harmonics and
Rollof knobs. Harmonics is analogous
to a ilter’s cutof frequency control,
attenuating all harmonics when fully
anticlockwise, so that just the
fundamental is heard, and increasingly
raising the levels of the harmonics to
the right as it’s turned clockwise. The
steepness of the amplitude slope is
deined by the Rollof knob, which can
be set to sound like a response of
anything from around 660dB/octave.
Of course, those aren’t actually Bolt’s
only important oscillator parameters,
as the Odd and Deep buttons also have
a profound efect on the harmonics,
enabling squares, saws and other
waveshapes to be invoked.
In general terms, harmonics
synthesis is similar to additive
synthesis. The crucial diference,
however, is that here the harmonics are
generated by a single oscillator, as
opposed to a bank of them, as is the
case with additive.
Harmonics synthesis
Switch the display to spectrum view to see the
amplitudes of the harmonics making up the waveform
Bolt makes all
kinds of waves
with its harmonics
synthesis engine
“Supremely easy to get
to grips with, and
boasts a powerful,
focused sound”
May 2019 / COMPUTER MUSIC / 89
nektar technology bolt / reviews <
CMU268.rev_bolt.indd 89 2/26/19 12:36 PM