Appearances can be deceptive. At first glance, Curve looks like a generic subtractive synth - but get past the austere exterior and you'll find a treasure trove of inspirational features waiting within this plug-in.
Take, for example, the oscillators. There are three of them and each provides the expected selection of controls: pitch, detune, pan and waveform selection. However, instead of the typical handful of squares, saws, sines and so on, Curve offers a custom waveform generator, which occupies the top third of the GUI.
"What looks at first to be yet another subtractive synth is in reality a semi-modular hybrid powerhouse."
Custom waveforms can be drawn using a 'nodes-and-curves' arrangement similar to those found on multi-segment envelope generators. Nodes can be added or deleted, up to 20 per waveform. The wave's partials are displayed in light gray behind the curve. It's a fun and intuitive way to draw in waveshapes, though it might seem a bit fiddly at first.
A collection of buttons below the waveform display enables you to zoom in on the wave, change its position along the horizontal axis, increase or decrease levels as a group, and select from a bunch of pre-rolled 'classic' wave shapes (sine, square, saw, etc).
You can also take snapshots of the waves, which can be copied and pasted between any of the available slots. Any patch can access ten different waveforms, and those waves are saved per-patch. Not bad!
There are five quality modes for the oscillators, and overall the fidelity is great. The waves can take some serious punishment from fast modulation rates, with aliasing only apparent at the most extreme settings. You can also reduce the quality setting for some deliberate PPG-esque aliased grunge.
Putting on the squeeze
Two multimode filters are onboard, each with only two controls (cutoff and resonance, natch). There are ten modes from which to choose, including 6dB, 12dB and 24dB responses, with variations on low-pass, high-pass, peak and notch filters. The filters are hardwired in series, and that brings us to one of Curve's limitations: signal routing.
We wish we could route the three oscillators through one or both (or none!) of the filters as we see fit, rather than being forced to obey a fixed path. Fortunately, some of these limitations are compensated for in the modulation department.
Odds 'n' mods
Parameters can be modulated by a number of sources, including the usual velocity, aftertouch, key-tracking and mod wheel messages. There are a trio of envelope generators onboard, all of which are of the five-stage AHDSR variety (the H being a 'hold' segment).
One of the three envelopes is dedicated to volume, while the other two are available to any modulatable destination. The envelopes are run-of-the-mill but they get the job done.
Curve's LFOs offer some compensation for the pedestrian envelope generator design, and are the key to some of the sequenced presets in the library. On the surface, the four LFOs look like any others, with the ability to sync to host and a speed control. However, they draw upon the same waveforms available to the oscillators, meaning you can draw in some pretty wild custom shapes.
The waveform display offers a note grid with snap-to function, a feature that makes it easy to create musical and rhythmic passages. Additionally, when they're set to a fixed frequency, the LFOs can be cranked up to audible rates, making an ideal arrangement for bizarre modular-style sounds.
To top things off, LFOs 1 and 2 have a Note option, where the LFO's frequency is determined by the incoming MIDI note values. Any of the four LFOs can be synced to the host tempo.
Modulation routing is addressed with an EMS-style modulation matrix. Mod sources are arranged vertically, and destinations are laid out horizontally. Ten sources can be bound to any of nine destinations.
As well as this, there's a dedicated matrix for patching oscillators 1 and 2 and the envelopes into oscillators 3 and 4 for a bit of FM mayhem.
Cableguys have put a lot of emphasis on their intention to involve Curve's userbase in its ongoing development. The synth comes with a substantial package of presets, but users are encouraged to use the built-in browser to download more sounds from the online user library.
At the time of writing, that amounts to 608 additional presets covering a wide range of styles. Of course, being a user library, the sounds can be hit-and-miss - but a good number are excellent.
This isn't the first time a developer has encouraged patch sharing among its users, but Cableguys have made it especially easy to upload and download patches.
In a similar community spirit, Cableguys have decided to make feature requests and bug reports public for all to see and contribute to. The idea is that Curve's growth will be propelled by the desires of its users as much as those of the developer.
While they suggest that not every wished-for feature may be granted, they fact that they're so open about the instrument's development is promising. At the very least, the most requested features and fixes will get bumped to the top of the to-do list.
Again, these guys aren't the first to do something like this, but we applaud their intent to keep Curve's development in the public eye.
Grading on the curve
Our experience with Curve was not entirely without issue. When syncing the preset browser to the online library, we were met with a dialog box that suggested we were using an illegal version of the plug-in (which we weren't, obviously), following which, most of the patches in the library were cleared out.
Fortunately, the diligent developers tracked down and crushed the bug post-haste - within an hour of reporting the issue, in fact. That speaks volumes about the developers' resolve.
We like Curve - we always have. You see, for many years, the beta version was available as a free download - and that may well turn out to be the problem. Curve could be a hard sell for Cableguys. Because it's been freely available for so long, some users might not be easily convinced that it's worth the price of admission.
On top of that, new users might be hard to persuade, given that Curve's best qualities are not obvious at first glance. That's too bad, because what looks at first to be yet another subtractive synth is in reality a semi-modular hybrid powerhouse that can knock out typical analogue-esque tones just as easily as it generates thoroughly modern, digital tones full of motion and interest.
If you tend towards rich, complex timbres, Curve is well worth a look.
Now listen to our audio demos to get an idea of what Curve can do:
Flexible custom waveforms. Excellent sound quality. LFOs share custom waveforms. Growing user library. Developer encourages user community.
Signal path a tad inflexible. Envelopes are limited compare to LFOs.
More than meets the eye, Curve will appeal to those seeking a slightly different take on modern synthesis.
All MusicRadar's reviews are by independent product specialists, who are not aligned to any gear manufacturer or retailer. Our experts also write for renowned magazines such as Guitarist, Total Guitar, Computer Music, Future Music and Rhythm. All are part of Future PLC, the biggest publisher of music making magazines in the world.
Commercial version of the quirky synth that has been available as a free beta for some time