New Software Review: Bolt Harmonics Synthesizer by Nektar Technology, Inc.
Bolt is Nektar’s first foray into the world of software synth design—can it carve out its own space in this highly competitive market?
The Bolt Harmonics Synthesizer by Nektar Technology, Inc. is a plugin that old school synth lovers are probably going to want to get their hands on.
It allows you to create lush sounds with the simple turn of the unit’s Harmonics knob. With a clean, yet powerful interface, Bolt allows you to craft thick basses, pads, and leads.
Nektar is best known for their MIDI controllers, but they’ve recently decided to leap into the world of audio synthesis. In an extremely competitive marketplace, Bolt is going to have to provide something truly unique to rise above the noise. Let’s take a look at what Bolt has to offer and see if Nektar’s first attempt at a software synth has paid off.
Features
The bedrock feature of Bolt is its harmonic synthesis engine. It has two main oscillators, two sub oscillators, and two white noise generators that you can shape using one of two ADSR envelopes. When you start a new patch from scratch and turn the Harmonics knob down, you’ll notice on the prominent oscilloscope within Bolt that a sine wave is being played.
The oscilloscope has two views that you can toggle between by clicking on it. The first view locks onto the frequency of the waveform, and the second view transforms the oscilloscope into a spectrogram that enables you to view the harmonic structure of the sound you’re working on.
As you turn up the Harmonics knob, you can hear the harmonic series being constructed above the fundamental. By default, Bolt will add even and odd harmonics at the same time, but by enabling the Odd button, you can cause Bolt to just generate odd harmonics. If you’d like to generate only even harmonics, this can be done by setting up both oscillators with identical settings, and then switching the second oscillator to Odd and Inv; the Odd harmonics are removed from the signal, delivering an almost rhodes-like tonal character.
Right next to the volume fader of each oscillator is a triangular fader that allows you to control the intensity of oscillator distortion. This feature is polyphonic, so unlike other synths, you’ll be able to play a fully distorted chord with each interval intact, and there’s no mud. Nektar chose to use oversampling for the distortion circuit, which allows Bolt to produce a very clean form of distortion. The tradeoff here is that there’s one distortion per voice, meaning this type of processing is CPU intensive.
To further sculpt your sound, you can use the Rolloff knob found within each of the two oscillator sections. This knob controls the slope at which upper harmonic content is rolled off. Higher values produce a more gradual slope, while lower values produce a steeper slope.
The interesting thing about this rolloff feature is that each voice seems to roll off based on the fundamental of the tone it produces, meaning the output from the oscillator isn’t merely getting run through a global low-pass filter. In fact, no filters are used within Bolt at all. When you adjust the Rolloff knob, the slope of the harmonics curve being generated is what you’re manipulating.
Bolt provides a Voice Double section that allows you to control how many voices will play when you press a single note. Ralf Schluenzen, the product manager for Bolt, says that “In this section, when Voices is set to 2, two ‘invisible’ oscillator blocks are added to the signal of each of Bolt’s oscillators—resulting in a total of 3 oscillators active. When you set Voices to 4, you have 5 oscillators active.“ Detune will apply subtle drifting detuning to each voice; this is great for creating “thick” patches. The last notable feature of the Voice Double section is the Width parameter, which spreads the voices across the stereo field.
Bolt offers both a mono and a poly mode. The polyphony count you select (up to a count of 16) determines how many notes you can play at once. The polyphony count only affects the number of notes that will play—not the total number of oscillators that will play. This means you can have up to 160 oscillators playing at the same time.
Some other great features available are frequency modulation (FM) and cross modulation (XM). Engaging FM adds an additional sine wave oscillator that’s used as the modulator for Oscillator 1, and is controlled by the shared FM/XM knob. Engaging XM turns Oscillator 2 into the modulator. Automating the FM/XM knob in your DAW is possible, and allows you to create synth patches that evolve over time.
The LFOs allow you to choose from 13 waveforms that can be mapped to up to 4 various other parameters within Bolt. With rates up to 10kHz, these LFOs are well within the audible range. LFO 1 can modulate LFO 2, and LFO 2 can then modulate LFO 3. Furthering the complexity, you could then choose to have LFO 3 modulate LFO 1. Since the LFOs are beat-syncable, you can create some great accelerating and decelerating effects by cross-modulating LFOs running at different beat divisions.
The Modulation EG section also allows you to apply automation, except it gives you control over an envelope that can be mapped to 4 different parameters. What’s interesting is that you’re able to map the envelope to the frequency and intensity of the LFOs; this allows you to create some very cool evolving modulation effects.
The 4 onboard effects include an EQ, Chorus, Delay, and Reverb. While there aren’t a huge variety of effects, the ones that are included sound really lovely—specifically the reverb. The plugin’s output is also protected with a limiter, allowing you to drive the signal into the ceiling using the Main Volume knob.
Included with Bolt are 500+ factory and artist patches. Most of these patches sound great, and can easily be tweaked to fit the needs of your track. Integrating Bolt into your productions is quick and easy.
In Use
My favorite part about Bolt is that it’s effortless to make usable sounds. I would consider this synth to have a warm tone in general, and I think it’s perfect for basses, pads, and leads.
With software synths, it often seems that patches will only play back well within a certain range of notes. While experimenting with Bolt, I found that I was able to achieve a variety of great tones spanning multiple octaves. This is because Bolt uses harmonic synthesis to generate sounds. The previously mentioned note-dependent rolloff frequencies are a prime example of why patches will play back so well all the way up and down your keyboard.
The following audio clip is something I made with Bolt using the “BOLTRUNNER BELLPAD” patch. I made a couple of adjustments to the patch, ran Bolt’s output audio signal through oeksound’s Soothe to tame some high-end resonance, and applied a touch of compression using FabFilter’s Pro-L2. This audio clip was made using a single instance of Bolt and is a testament to just how much sonic variety you can get out of one patch.
Download the full resolution audio clip here.
When I initially opened up Bolt, I was wondering how it was even going to come close to giving a time-tested synth like Serum a run for its money. After experimenting with Bolt, I realized this wasn’t a fair comparison at all. They perform entirely different types of synthesis and yield significantly different results.
To Be Critical
As much as I love this synth, there are still a couple things I think Nektar can improve on. I was a bit disappointed with the drop-down menus in the LFO and Modulation EG sections. I’ve become quite used to drag-and-drop LFO and envelope assignment using other software synths, which I think provides a superior workflow.
It seems as though Bolt can be quite CPU intensive as well. The previous audio sample was created using Bolt in an empty Ableton session, and while the synth was playing back audio, my CPU Load Meter was reading out consistently around 25%.
It’s crucial that you turn Bolt’s polyphony down to the minimum amount required to accurately play back your patch. Initially, my polyphony count was set to twice that of what I needed it to be and was boosting my CPU Load Meter to 45%.
My computer isn’t the newest model out there, considering it’s a mid 2012 MacBook Pro with Retina display. It contains a 2.6 GHz Intel Core i7 processor with 4 cores and 16 GB 1600 MHz DDR3 memory. These specs aren’t top-of-the-line by today’s standards, so if you have a more powerful computer, you should see decreased CPU load percentages.
I should note that increasing polyphony on any soft synth is going to tax your CPU, and this isn’t solely unique to Bolt. In Ableton, I was actually able to freeze the track I had applied Bolt to and reduce my CPU Load Meter to 0% upon playback. Most soft synths are going to cost a fair bit of CPU since they require your computer to calculate how their output audio will sound, as opposed to just reading audio files off a SSD or HDD in the way that multi-sampled instruments do.
Summing it Up
Bolt was by far one of the most refreshing software synths I’ve used in a long time. It contains a powerful harmonic synthesis engine that’s easy to control and produces rich, warm tones that I think many die-hard analog synth lovers are going to enjoy. Bolt has quickly become one of my go-to synths, and I think this device has the potential to become quite popular within the music industry.
You can purchase Bolt here for $99; it requires MacOS 10.9 or higher, Windows 7, 8, 10 or higher (64bit version only), and supports VST, VST3, and AU.
Charles Hoffman is a Mixing and Mastering Engineer at Black Ghost Audio. After graduating from the University of Manitoba with an English degree, Charles completed his education at Icon Collective in Los Angeles, CA.
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