Steve Duda is a bit of a legend in dance music. Although with an eclectic resume that includes work with artists from Nine Inch Nails to DeadMau5, his skills are broad to say the least. He also has his own in-house label and audio plug-in business, both under the Xfer banner. So far, the plug-ins have been devices which appeal to Steve's own tastes, such as the LFO Tool and the Nerve Drum Machine.
His latest plug-in also follows its own path. Cthulhu has two roles: it's a chord creator and arpeggiator. Each is a MIDI-generating module that shares one plug-in interface—arpeggiator at the top, chords at the bottom. You can use each individually or run them together, in which case the chord module feeds the arp. Deactivating one module folds it away, keeping the interface tidy. Solely a MIDI-generating plug-in, Cthulhu requires you to route its output to an instrument. How you do this varies from host to host (see below). However, it also includes its own sawtooth reference tone as a functional fall-back.
Let's look at how the chord module works. A single incoming note can trigger an output chord of up to eight notes, and each keyboard note can be assigned its own chord. That means you have up to 128 specific slots at your disposal. Used key slots are indicated in blue above the keyboard, with inactive ones in grey. Cthulhu provides two options for displaying and editing each chord's notes: one uses the keyboard, and the other uses the chord panel area just above. Over to the left the thought bubble also turns the current notes into a chord name. The chord panel allows you to scale the chord's notes against the incoming MIDI note trigger (0% to 200%), so your chord has its own velocity spread.
There's also the option to lock one or more of the chord's eight notes as you shift from one chord to the next. This could help if you're trying to hold a particular note as a pedal note, for example. Cthulhu can learn played-in chords in a number of ways, assigning chords sequentially to key slots. You can also copy and paste between slots or generate random chords using the "WTF" button. Once set up, there are various further options for sorting and batch processing your chords—making all chords suspended, for example. If this all seems a little theoretical, there's also around 150 chord presets sourced from the masters (Bach, Mozart, Debussy, et al.), so you have an abundance of chord progressions. Each preset includes a chord cycle laid out sequentially on the keyboard.
Moving onto the arpeggiator, you'll see that it's grid-based—a graph, as they like to call it. Use the graph tabs to select the current parameter, and individual steps are selected for editing (and deactivated if required) along the bottom. Note that the number of steps can be different for each of these tab parameters. Some of the graph tab parameters, such as octave, velocity scale and gate, are pretty self explanatory. However, there are some less obvious additions such as "harmony," which outputs an additional harmonised note, and "late," which adjusts the individual timing of a step. You can also use "random select" to set a degree of note randomness. The pitch tab is particularly interesting, as it lets you select which scale degrees (I, IV, V and so on) will be shifted.
However, the most significant settings are made using the note select tab. Here you'll find a host of typical arpeggiator behaviours (down, up, down/up, up/down, down and up, up and down) as well as the less commonplace "fingered top" and "fingered bottom." These last two replace every other note with highest and lowest chord notes respectively. You can also specify particular notes from the chord using the numerical option. Finally, you can also set a pattern reset on any step or tie steps (these show up as green arrows). It's worth noting these options are all selectable per step if required. Like the chord module, Cthulhu has a bunch of arp presets, and each includes up to 12 separate arp patterns, which are assigned to the letters at the bottom (A to L).
As noted, although Cthulhu loads as an instrument, it requires routing to a sound-generating synth. In Logic this requires you to use the IAC bus, and should you want to play it from a MIDI controller, you'll also have to set up a further routing in Logic's environment. Cthulhu's manual explains this clearly, and I found it easy to set up. Even so, there are still some eccentricities to how the IAC bus operates. (Once I'd found the arp pattern or chords I wanted, I recorded the MIDI part to the instrument track itself and muted Cthulhu.) In Ableton Live you can use the VST version of Cthulhu. This allows for simpler routing, and I found this an all round more enjoyable experience. Cthulhu is still in version 1.0, but there's already a beta update available with some new features. The most useful is drag and drop to DAW for both the currently selected chord and the currently active arp bar.
Cthulhu is one of those unsuspecting plug-ins that you probably don't think you need, but that produces some surprisingly creative results. The step sequencer approach is incredibly powerful, and very quickly I found inspiration from the chord library. Even though I know my way around a keyboard pretty well, being able to focus on rhythmic ideas rather than chord notes is surprisingly refreshing. Also great is the link between the two modules, with chords feeding the arpeggiator. The only slight fly in the ointment is the IAC bus requirement for Logic—not Xfer's fault, of course, but clunky all the same. Even if you only use it on occasions when you're short of inspiration, it's still money well spent.