Review – Rapid by Parawave Audio

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Parawave Audio’s new software synth is a deceptively powerful, and easy to use polyphonic synthesizer. We take it for a test drive in this review.


by Rob Mitchell, Jan. 2017


In case you haven’t heard of them yet, Parawave Audio is a new music software company that has released a synth plug-in named Rapid. It is an eight-layer subtractive/polyphonic synthesizer that boasts a large number of features. Many wavetables and multi-samples are available to be loaded into any of the 24 oscillators. For each one of the layers, there are three oscillators, a filter, an insert effect, four envelopes, four LFOs, four sequencers, and multiple effects. You can layer them all together, so you can get a huge lead or pad patch, or you can split up the layers so they are individually triggered by different parts of the keyboard. Another way you might use the layers in your DAW is to have an arpeggiated bass line on one, a drum pattern on another, and a pad on the third layer. In addition to all of the above, it has 32 modulation sources/targets (per layer) that can be used to give your patches more depth and movement.

Now that you have a basic summary of their new product, I’ll go into more of the details. Once you’ve purchased Rapid and have created an account on the Parawave site, you’re able to download it. It is available in VST2 32-bit and 64-bit for the PC, and AU for OS X. The installation on my PC was easy, and it uses a serial number for activation. They also have an alternate method to activate it if your computer is offline.

Once you have it loaded in your DAW, you’ll see the main display. The browser is located on the “Master” page, and is designated with an “M” at the upper-left. Once you open that page, you’ll see the browser with its various categories on the left. The patches that are within the selected category are on the right. The sort order for the bank, type, and preset name columns can be changed from A to Z (or Z to A). This all works very well, but one thing I’d like to see added is some type of “favorites” functionality.

The layers can be selected by using their tabs which extend from left to right. Each layer has an on/off button, so you can disable whichever layers you want so you can hear the others in more detail. Besides being the home for the browser, the Master page is also where you can mix the levels of each layer. In addition, there is a compressor located here which has controls to adjust the gain and threshold for the low, mid, and high frequency bands.  Some useful presets are also available to change the attack and release timing for the compressor’s envelopes.


The Oscillators


The three oscillators in each layer are identical, and every one of them can have up to an eight-voice unison. Detune and Spread controls are available for detuning the unison voices, and spreading them apart in the stereo field. There are bipolar bass and treble controls, and the tuning for the oscillator’s pitch is in semitones (+/- 48) and in cents (+/- 100). To the right of those controls is a switch for note pitch tracking. Balance and Volume controls are here as well.

In the middle of each oscillator is the waveform display. If you have a wavetable loaded, you can click on the waveform in the display to change the view. It will show the waveform shape in a 2D view, but if you click on it, it will then show a 3D view of the wavetable. Along the bottom of the display, you can adjust the wavetable position using the “Morph” control, and change the phase setting with the “Phase” control. The “Random” control lets you set a random amount of change to the starting phase. It can also help with unison voices so they aren’t all playing exactly the same way, though at certain times you may want that phasing effect that occurs.

To load in a wavetable or multi-sample, you click on “Factory” in the upper-left of the oscillator display.  There are many of them to select from (a total of 456), but at the moment, you can’t load in any of your own. However, Parawave Audio did mention that they want to implement this in a future version. The wavetables and multi-samples are setup in several different categories, with names such as Common, Modulation, Harmonic Overtone, and Complex.  “Common” has some of the more simplistic types of wavetables on offer. For example, one of them will blend between sawtooth, triangle, and sine, while another morphs between three different shapes of sawtooth waveforms. In the “Modulation” category, it is all about PWM with different shapes. A few of them are similar to the regular square waves, but many other complex shapes are available that you can modulate in the same type of manner. You may have guessed this already, but the Morph control is what you use to adjust the pulse width. The morphing of the wavetables sounds very good, with a buttery smooth transition between the shapes.

In the Multi-sample categories, there are many types available for your own preset design. They include piano, bell, e-organ, many types of noise, FM plucks, trance-type lead sounds, drums, beach sounds, birds, bass and lead synth sounds, and many more. Some of the others they’ve added are just “attack” types of sounds with a very short duration. That type of sound could be used on one oscillator, and on another oscillator you could use another waveform that uses a longer sample (or a wavetable) for the rest of the patch. It’s really just up to your imagination, and with eight layers available, you can design nearly anything.  A quick note: If you load a multisample, the “Morph” control switches to a “Delay” control, letting you delay the start time of the sample in the oscillator.

In the upper-right of each oscillator there is the FX Insert. These include a tube amplifier, phase and ring modulation, hard sync, pulse-width modulator, phase bend (phase distortion), chaos phase (a type of phase modulation), and noise generator. These effects can definitely broaden the possible sounds you are able to get out of the wavetable/multi-sample library that is included. The controls for these effects are in the lower-right, and they can be modulated by other sources.


Filters, Envelopes, and LFOs


To the right of the first oscillator is the filter section. It has twenty filter types, including a number of variations on Low-pass, High-pass, Bandpass, Peak, Notch, and Comb filters. Depending on the type of filter you select, the controls will change somewhat. Here are a few examples: The 6dB Low-pass has a cutoff and treble control, the Multi Bandpass has cutoff, stereo width, and resonance, while the Acid Low-pass has cutoff, boost, and resonance. I won’t get into all the details of the various controls, as the online documentation covers this subject very well. There is an insert next to the filter, which lets you add an effect or select another filter to contour your sound. Some varied types of distortion effects are here, as well as a ring modulator, and a Time Lag function (delays the left and/or right channels by a certain amount). One way you might use this is to modulate the delay amounts with separate LFO settings on the left and right channels.

Below the filter section you’ll find the controls for the envelopes, LFOs, sequencers, arpeggiator, and voicing controls. Rapid has four ADSR envelopes labelled A thru D.  A is for the amplitude, while envelope B is for the filter. The C and D envelopes can be used for whatever else you’d like. Other controls here are for changing the velocity amount, delay (before the attack), and slope settings.


The LFOs have more than twenty shapes available, and include two sets of the shapes that you can blend between using the “X-Fade” control. The LFO rate can get up to just above 65 Hz, and include phase and “bend” controls. Bend basically warps whatever shape(s) you have selected. Fade and delay adjustments can be made, and there are four different settings for the way the LFO works: Retrigger, BPM Sync, Mono/Arp, and Bipolar. In addition, you can have any combination of these four settings switched on or off.

One of the more useful features in Rapid is its drag-and-drop modulation. When you hold your mouse over a control that can be used as a source for modulation, it will have a “Route +” text that appears right below it. You can then click and drag that to some other control, and it will automatically set it up for modulation. All of the modulation settings show up along the bottom (there are 32 of them per layer), and you’re able to make adjustments to their levels from there. You could also assign sources and targets from that part of the display, or change the assignments you had previously setup. One other way to configure modulation is to right-click on a control, and then assign it from the menu that appears.


Sequencer, Arpeggiator, Effects and More


The Sequence section and Arpeggiator in Rapid give you a high degree of flexibility in spicing up your patches.  There is a large number of sequence patterns from which you can select, or you can design your own using various shapes for each of the steps in the sequence. These patterns you design can be saved to use again whenever you’d like. It works as follows.  For each step, you can  pick a different shape. It might be a rectangular shape, or a down-saw, or more of a curved variety. For most of the shapes, you can adjust the height of the start and end points. These affect whatever you have set up as a target for the modulation. Just about anything can be used as a target. Some of these include filter cutoff, the oscillator’s tuning/volume/panning/morphing, inserts, and the modulators. In case you’re wondering, the modulator   targets include the separate stages of the envelopes, LFO settings, and the sequence’s level and rate. Also, one thing I always wish to have in a synth is included: the effects can be setup as targets as well. 


There are over 100 presets you can choose from to load in to the arpeggiator. If you want to design your patterns, you just click on the grid to place a note where you’d like, or right-click to delete one. Fine tuning and velocity amount for each note is available, and you can adjust the shuffle amount as well as the pattern length (up to 32 steps). Seven different play order modes are on board, including up, up/down, random and four others. The arp can also have up to a four octave range. One of the best features of Rapid is the MIDI file import for the arpeggiator, which just makes your job much easier. This bypasses the 32 step limit, and I was able to import a very long MIDI file with no problems. I am not sure what the note limit is for the import function, but whatever it may be, it sure beats entering each of those notes manually. To top it all off, you can also click and drag the pattern out of the arpeggiator and on to a MIDI track in your DAW.


For the effects section, Rapid has many types to choose from. Some of these include reverb, delay, dual delay (separate settings for the left and right channels), chamber (sounds like a simple delay), three types of distortion, chorus, flanger, sidechain, EQ, trance-gate, and many more. You can have up to seven effects on each layer, and you can drag and drop them into a different order if needed. One of the tricks you can use with Rapid is to have one layer setup with effects on it (with its oscillators turned off) and use sends for the other layers to go to that layer and its effect(s). It essentially becomes an effects bus. This can save on the CPU hit if you have many layers and/or several instances of Rapid running at once.

One last feature I want to mention here is that Rapid includes three macro controls. These let you get quick access to modulation on the fly. For instance, one macro might be set to modulate the first oscillator’s morph setting, detune for the second oscillator, and also affect the reverb amount. It doesn’t stop there however, as this works across all layers. With just one macro, you can set it to affect nearly any part of the eight layers in several different ways.  



There is no doubt that this is one very powerful synth that is definitely very easy to use. Even though the manual was less than halfway done at the time my review, there are tooltips that will appear if you hover over nearly any of its many controls. I still would like to have a full manual of course, but the tooltips really helped out.

Hopefully down the road Parawave Audio will be implementing wavetable and basic sample import into Rapid. That is listed in the “Feature Roadmap” on their website, (along with a Granular oscillator!), as once those features are added, the sky is the limit. I really like the intuitive layout they have designed, but I’d also like to see a resizable display added. This is important when using a monitor that can be set to very high resolution settings. Alternate skins would also be a plus.

This is one really fun synth to use, and you can easily get huge layered sounds from it in no time. Even though it is powerful, I never felt overwhelmed by the interface as it is just so easy to use. With its multiple layers, effects, wavetables and samples, this is the one to watch. It will only improve with time, even though it is already a very capable synth.

Rapid is priced at €179.99 EUR, which works out to be around $190 USD. While I was writing this review, there was a 25%-off intro sale in effect. Hopefully that’s a sign that there will be sales in the future. You can get more information about Rapid and a demo version from their webpage here:







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