Audio, Reviews

BOLT, a bold new synthesiser

bolt synthesiser

Nektar is perhaps best known for its Control and MIDI Keyboards, but now the company has released the BOLT synthesiser, the first Harmonics Synthesiser for VST/AU compatible DAWs. BOLT differs from other synthesisers because it generates a sound’s overtone structure directly in the oscillator, which makes it much faster and simpler to create new sounds – and that, in turn, will stimulate you to experiment.

BOLT uses a new form of synthesis based on a concept by Prof. Dr Udo Zoelzer of Helmut Schmidt University (HSU) in Hamburg, Germany, who is a scientist with decades of experience in digital signal processing.

BOLT’s interface, at first sight, is much more spartan than what you’re used to from others. It has two harmonics oscillators, two sub-oscillators, one modulation envelope generator and three low-frequency oscillators. Each oscillator has its own amplitude envelope.

Its harmonics oscillators let you change a wave’s shape and core sound. It goes from sine to pulse chain just by turning the Harmonics and Rolloff knobs. An Odd switch lets the oscillator create odd harmonics only and if you simultaneously activate Deep, the waveforms on its waveform screen will resemble saw or square shapes.

BOLT furthermore offers four modulation generators. It has three LFOs and one Modulation Envelope Generator. These let you create transients and modulate different aspects of the sound simultaneously. The generators can even modulate each other and none of that requires a PhD in synthesiser sciences as Targets are pre-assigned, so you can experiment by dialling in a target amount to hear an effect.

The modulation envelope generator is modelled after classic ADSR envelopes and covers a range from snappy to lush soundscapes. The four modulation targets can be assigned a large number of destinations, including LFO Frequency and Intensity.

BOLT’s LFOs are special too. They range beyond what you’d expect from 0.01 Hz up to 10 kHz. This allows for some extreme modulation effects, including amplitude and frequency modulation.

There are 13 different waveforms to choose from, including random and stepped waves and if you switch off Cycle, you can use the LFOs as additional auxiliary envelopes. You can also sync each of them differently to create interesting polyrhythms and you can have them cross-modulate each other’s tempo.

Finally, four essential effects processors – EQ, CHORUS, DELAY and REVERB – and a long list of presets round up the capabilities.


Even if you don’t know the first thing about OSC, LFO and other synthesiser acronyms, you’ll be up and running in no time. The reason is that BOLT contains just the right number of controls to let unexperienced users experiment and turn up with something that is actually usable while giving seasoned synthesiser musicians enough power to create pretty much everything they want.

And, actually, BOLT is much more helpful in the creativity department for both types of users than many other synthesisers because the limited number of controls all work together in an almost alchemical way. They allowed me to produce sounds that were wildly apart, some closely resembling existing instruments, while others totally outer-worldly.

Obviously, when you take the time to go through BOLT’s user guide (which is pretty concise) and you learn or know about what each OSC and LFO will do, you can create sounds in a structured way. If you want to create an arpeggiated low or drone-like sound, for example, it suffices to know that you need to have something cycling, something that acts on low frequencies, etc. to create exactly that with BOLT in a fraction of the time it takes with other synthesisers.

And, of course, you can use presets, either by themselves or as a brilliant starting point for your own creations.

But you’ll have the most fun if you start with every module turned off – except for the first oscillator – create a basic sound that you like and then try out all sorts of other modules and module settings and see where all the different settings take you. This is how I created the sound sample you can find here.

Note that I didn’t create the arpeggiating (repeating) effect by hitting keyboard keys, but by manipulating the LFO modulation destinations!

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