No matter how big your Eurorack case is, space is always at a premium, and it can be difficult to make room for everything you need. Often, the best value in terms of rack space is found in a module that can be tapped for different tasks.
Similarly, musicians who like having a traditional synthesizer setup (e.g., VCO -> VCF -> VCA) will often buy a module that provides a complete voice. Not only does this maximize case real estate, the plug-and-play aspects of a semi-modular panel simplify the process of getting a playable sound, especially when gigging.
Tidal Wave ($465) from Snazzy FX fits both scenarios. As a 20HP, skiff-friendly utility module, it includes a voltage controlled mixer/ crossfader, a waveshaper, a VCA, a VCF, and an LFO, all of which you can tap into individually. Flip a few switches and you’ve got a remarkably powerful and rich-sounding semi-modular synthesizer voice.
The biggest hurdle is figuring out the module’s interface, which takes a bit of study if you want to get the most out it. I will start by describing the basic functionality that Tidal Wave provides and then explain how the features can be combined to do very interesting and useful things.
The Tidal Wave has a pleasant sounding, 4-pole resonant lowpass filter with enough control capabilities to give it some attitude. Knobs are provided for filter cutoff and Q, while the VCF CV and Q CV inputs have bidirectional controls to set modulation level. I love resonant VCFs that give you the option of dialing in negative modulation, because things can get especially glurpy when you put the filter on the verge of resonance. A linear FM input and a direct VCF output are also included.
SINE WAVE OSCILLATOR
Next, you can turn up the Q to make the filter resonate, which changes the VCF into a surprisingly malleable sine wave oscillator. Use the filter cutoff knob and VCF 1/V input to control pitch. There are three Q Modes: Comp levels out the sound as the Q knob is increased; NRML lets the resonant tone’s volume decrease naturally as Q is increased; and High-Q/Sine mode increases the range and intensity of the resonant tone and works in conjunction with the routing switch (in its down position) to send the sine wave through the wavefolder. (More on this in a moment.)
You can use the LFO on its own or incorporate it into the synth voice using the bus switches. Sine, triangle, and square wave shapes are provided, and a CV input allows you to modulate the speed.
With the VCA, you get Attack and Decay knobs to shape the retriggering envelope while the LFO knob controls the speed. Use the Envelope Trigger Source switch to select a triangle, square, or random waveform. When an external signal is patched into the VCA’s CV input, the normaled connection is interrupted, though you can still use it internally as a control source.
In addition to a gain/offset control, you have three interactive knobs—Crest, Tide, and Floor—to sculpt the wave shape of an external audio signal or the internally generated sine wave. The bipolar WS Mod knob determines the amount of modulation coming from the internal LFO and/or an external CV.
With the Tidal Wave’s voltage-controlled cross-fader and mixer, we start to see some of the module’s upper-level functionality. Depending on the position of the Mix Source switch, you can fade between the waveshaped and filtered signal, or move between one of those choices and whatever is patched to the Input jack. If no input is present at the Input jack, you can mix between silence and either the waveshaped or filtered signal. Overall, this feature is designed to give you the ability to crossfade between two timbres using externally or internally generated signals, and it yields very interesting results.
For example, I patched a drone into the audio input and sent the VC Mix output to my mixer. I set the Mix Source switch to VCF/Dry and switched the LFO Bus to the lowest position in order to use a sine wave to control the VC Mixer. With the LFO speed set to a slow rate and the VC Mixer knob to the 11 o’clock position, the module crossfaded between a filtered version of the drone and the unprocessed signal (favoring the latter).
Next, I patched a stepped LFO into the VCF CV input and placed the Filt Mod control to 11 o’clock to exaggerate harmonics in the filtered sound. The result was a rising and falling set of filtered bell tones that crossfaded in and out of the original drone.
By switching the Mix Source to Dry/WS, I could then crossfade between a waveshaped version of the drone and the unprocessed input. At this point, the external CV added subtle pulses to the waveshaped side while the WS Mod control allowed me to inject a bit of modulation into the distortion using the internal LFO.
Switching Mix Source to VCF/WS allowed me to crossfade between the stepped bells of the filter and the modulated waveshaping timbre. Because the VC Mixer is normalized to the VCA Input, you can take any these signals from the VCA Output and adjust the attack and decay times to add more variety to the signal.
Just for fun, I patched a different waveform from the same oscillator into the Tidal Wave’s VCA input, sending the VCA output to another mixer channel: I wanted to see what happens when you use different functions of the module separately. When I set the Env Trig Source to triangle or square, the internal LFO opened the VCA in time with the panning speed of the VC Mixer.
However, when I set the trigger source to Random, the output became rhythmically varied. By adjusting the Random Trigger Threshold control, I could pulse the VCA in more complex ways than simply opening and closing it in time with the panner (though not in a chaotic sample-and-hold way that I had expected). The Random setting also worked well when I patched the crossfaded signals out of the VCA and adjusted the attack and decay.
All of this may sound complex, but it really isn’t. It is the type of thing you might do with a collection of single-function modules. But here, it can all be done within a single panel.
Now it’s time to combine the Tidal Wave’s internal signal routing features, which can increase timbral complexity. For example, using the Routing switch you can place the VCF before or after the wavefolder, whether you are processing an external audio signal or the internally generated sine wave.
Even more interesting is that the internal CV busing matrix patches the envelope to one destination and the selected LFO shape to the other. Whichever side you set the CV Bus switch, that CV is sent to the Filter Mod while the opposite side goes to Q Mod. For example, if you set CV Bus to Env, the envelope gets patched to Filter Mod, while the LFO goes to the Q mod.
On the left side of the LFO Bus switch you will see three choices—sine wave, triangle, and Off— used to control the VC Mix. I integrated all of these selections in the crossfading example above.
In a final push toward sonic madness, the Tidal Wave includes a Feedback switch that sends the output of either the filter or VC Mixer back into the waveshaper. Once you engage the Feedback circuit, you can have fun setting the Random Trigger Threshold to build rhythmic variations between various parts of the patch.
There is a lot to wrap your head around here and it will take you some time to grasp fully how signals are bused to different places within the module. But if you put in the effort to learn the Tidal Wave’s more esoteric features, you will soon realize the module is not a one-trick pony: It’s an entire circus!
Crank everything up and the module excels as a noise machine. Yet, it cleans up very well to provide warm and juicy timbres. With all the useful things it can do, you’ll find that the Tidal Wave is a great way to spend 20HP of your modular case.
Special thanks to Guy Taylor of I/O Music Technologyfor loaning us the module for this article.