ZS-40 V2 — two updates on a synth based on a classic

Most of the original patch notes still apply, so they are copied below.

This patch requires firmware 2.0. (https://empresseffects.freshdesk.com/support/solutions/articles/1000275389-updating-firmware-on-the-zoia)

When working on an update for the ZS-40, I found myself at a crossroads: the built-in plate reverb is nice, but it consumes a lot of CPU. Sometimes I want it; sometimes I want what I could achieve with the extra CPU. Whatever was a patcher supposed to do? Fork it!

So, there are two forks included in the zipped folder (along with the original for archival purposes): “ZS-40 V2” and “ZS-40 V2 FX.”

Let’s run down what new features they share:

RING MOD! There is a ring mod added to both; its frequency is controlled by an envelope, triggered by the first note played (this is the same design used in Yamaha’s CS line). You can set its FREQ (from sub-audio tremolo/phasing to audio rate ring mod mayhem), its LEVEL (or mix, from subtle parallel processing to everything running through the ring mod), the ENVELOPE DEPTH (positive or negative, so that the ring mod’s frequency rises and falls or falls and rises — try sweeping from sub-audio to audio rate ring modulation or vice versa), and the ATTACK and DECAY of the envelope. The sounds it creates are fantastic! It adds a whole new palette to the patch, allowing for cinematic soundscapes and atonal nightmares; it can be subtle or cacophonous, harmonic or abrasive. I’m pretty jazzed about this.

VELOCITY! Both patches’ amps respond to velocity. You can also bypass this by pushing the button at the end of the ADSR row controls.

SEPARATE OSCILLATOR 2 CONTROLS! Before the second oscillator’s detune was controlled exclusively by the mod wheel, but now you can also set it via the control page, with COARSE and FINE control (for that thick detune action).

MOD WHEEL ASSIGNMENTS! You can assign the oscillator 2 frequency to the mod wheel and set its range (the previous version’s default), or you can assign the filter frequency to the mod wheel, or both!

MINOR UNDER THE HOOD IMPROVEMENTS!

V2 w/ no effects sacrifices the plate reverb but adds the following:

12 dB/OCTAVE FILTERS! Using two stacked low-pass filters, we have a topology much more closely resembling the CS (low-pass) filter.

GLOBAL HIGH PASS FILTER! Okay, the CS uses a per-voice low- and high-pass filter to create a powerfully versatile band-pass. I didn’t have the CPU for that, but I did add a global high-pass which is terrific for shaping the timbre.

FILTER VELOCITY! Like the amp counterpart, this can be toggled off and on via a pushbutton.

KEY-TRACKING! Set how the filter responds to note position.

INDIVIDUAL PITCH BEND RANGES! For each oscillator. I took this idea from how the expression pedal controls ZS-30G, my guitar port of this patch (https://patchstorage.com/zs-30g-a-pitch-tracked-adaptation-of-zs-40/). Have one oscillator bend up, while the other bends down! Set them to bend into an interval! Lots of fun ways to employ this.

======ORIGINAL PATCH NOTES==========

Which is the Yamaha CS-80. Does it come close to modeling the sophistication of one of the most complex, expressive, and unique synthesizers ever made? With highly specialized envelopes, two signal paths, polyphonic aftertouch….. etc. the list goes on. Nope. Ha. Nope. It doesn’t even use velocity.

Instead, I went for something evocative, rather than authentic; specifically evocative of Vangelis’s use of the CS-80 for the Bladerunner soundtrack.

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Rev 1.1 notes: As suggested by u/ChalkHorseNIck in this post (https://www.reddit.com/r/ZOIA/comments/jnuod0/trifecta_a_chilled_tune_for_a_notsochilled_day/), I added a stereo audio input, which passes into the plate reverb. Thanks, Nick! And check out his track!

Also a few very very minor under the hood modifications.

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Here, we have a four-voice synth, with two sawtooth oscillators per voice. The second oscillator can be detuned, via the mod wheel (CC1), to create thick pads or even pitch sweeps (the range of the mod wheel is defined on the first page, because it’s meant to be manipulated; saw it to a small increment for detuning and larger values for pitch sweeps). The first oscillator alone is controlled by the pitch wheel, allowing it to sweep above or below the second oscillator.

Combined with lots and lots of plate reverb and a dint of pitch modulation from a stereo spread, the sound, to me, is quite a lot like some of those gorgeous CS-80 pads, even if it is nowhere near an exact replica.

I would like, I think, to take a go at a more faithful reproduction, particularly of those envelopes (fascinating envelopes) at some point, but it would require sacrificing the effects (most of you have other sources of reverb, though, I figure). Still, it’s on my “maybe one day” list.

Controls:

Stompswitches:

Left — switches between two different rates, super slow (.333 Hz), and slow (.8 Hz), the stereo spread modulation.

Front page:

The top row of controls deals with the ADSR. The A, D and R stages are limited to 15 seconds, and they are linearly controlled. So, .1 = 1.5 seconds, .5 = 7.5 seconds, etc.

The middle row of controls governs the filter. The filter is key-tracked 100%, so it follows pitch. You can add to this base frequency with the frequency control. The envelope amount is bipolar; the filter and VCA share an envelope. Resonance is free and open, but I think it sounds best kept very low.

The bottom row has controls for the reverb and for the mod wheel amount. Pitch bend is sent to oscillator 1 (+/- 1 octave). Mod wheel is sent to oscillator 2. You can use it to detune the second oscillator for thick pads, or to have the two oscillators glide past one another, a little like the ribbon controller of the CS-80.

The “efx audio out” page has the audio output stage. The voices enter a modulated stereo spread, to add even more thickness, before reaching the plate reverb. The left stompswitch selects between two rates for the stereo spread modulation, from real slow to pretty slow. You could adjust that here, as well as the range. The plate reverb is also EQ’d to accentuate highs and cut lows, but you could change that, too, if you wanted, on this page.

The “midi” page has all the MIDI modules. If you want to change the channel (default is 1), this is the page to do it at. There is a control for the mod wheel (CC1), pitch bend, MIDI notes, and aftertouch. Aftertouch maxes the reverb mix to 100%.