REQ: Alyjameslab SY-4X Syncussion

The Pearl Syncussion SY-1, introduced in the late 1970s, is a legendary drum synthesizer known for its unique sound shaping capabilities and wide tuning range. At the core you find two identical modules each containing two oscillators, a custom filter, two envelope generators, LFO and Sample & Hold, it also got a noise generator. It has been the secret weapon of many

4 Times the fun

SY-4X provides four Syncussion SY-1 modules in one neat package, with some modules featuring additional modifications like noise direct injection or a Custom Mode A (see Modes below). The four modules allow for creating an 8-voice drum kit, four mono synths (coupled voices = 4 oscillators per module), or a four-voice poly synth (4 x 4 oscillators). You can also mix modes, such as three modules in Drum Kit mode and one in mono synth mode (keyboard controlled). In any play mode, you have full control over every voice parameter—sky's the limit!


Trigger to Modes

SY-4X has an option to use a randomly generated mode sequence synced to each new trigger per drum. This bypasses the analog potentiometer and scrolls through the modes following the generated sequence, which is also kept in memory for perfect recall. You can regenerate the sequence at any time. It supports roughly 50Hz modulation—in case you trigger it 50 times per second! :)

CMOS Oscillators ?

Without getting too technical, this type of VCO uses a CMOS inverter chip and a bias circuit to control the oscillation. If it’s not ideal, one half of the resulting waveform might differ slightly from the other, producing a distorted waveform and extra harmonics. A CMOS parameter in SY-4X is available for each of the 8 voices (2 per module), allowing you to control or enhance this 'defect.' The reset value reflects the original hardware response behavior.

An Unusual Filter

SY-4X models the unique filter design of the Syncussion. It is a 2-stage low-pass SVF with a twist: the control voltage has more effect on the second stage, which is set to a higher cutoff by design. This causes the two filter poles to spread apart depending on the control voltage, creating an almost vowel-like effect. Both cutoff points have a ratio of roughly 4:1, and the CV is at a ratio of 2.13:1. The SPREAD parameter allows you to change or modulate the frequency ratio, controlling how far apart the poles are set.

Envelope 2 Response Control

Envelope 2 controls the VCA, the filter, and, depending on the selected MODE, the tuning. The envelope generator's triggering pulse levels vary with attack strength, providing adequate accent to the output.
SY-4X has a parameter called HOLD. At its lowest, it mimics the original hardware response, but increasing the value changes the envelope response to something more linear. This can be very useful if you need an almost gated response, or, put another way, more body with an ultra-fast decay.

Berserk Mode

An optional mode called BERSERK will turn the whole unit into a nastier beast. Choose between a pre-filter asymmetrical clipping stage or a post-filter crusher stage (roughly 6kHz, variable bit rate). Both Berserk types are tamed by a Stability parameter. This mode can be automated! Use it for subtle crunch or go full Berserk.

Keyboard Modes

The Syncussion could also be controlled from external CV, it could track more or less over 4 octaves and can be used to play actual notes.
SY-4X brings that to another level. By switching a module from Drum Kit mode to Keyboard Mode, you will now control both voices from your keyboard at the same time.

One of the features is that you can optionally switch to near-perfect pitch tracking between oscillators, but not only that: You can now scale the pitch CV to an actual musical pitch following a defined scaling rule of your choice.

The TUNE slider will now be scaled, as will the incoming CV, to either a 1-step scaling (for example: whole tone) or a full scale. This scaling works in both Drum Kit (nice with S&H) and Keyboard Modes. In absolute pitch mode, you define the ROOT of the scale; in relative mode, the current played note will be the root.

8 Preset Modes

The Syncussion offered A, B, C, D, E and F Modes which are a predefined setting for Oscillators Pitch, Frequency Modulation, Volume levels and other modulation sources.
SY-4X adds two additional modes G and H.
Here is a description of each Mode, each one of them is better at producing certain types of sounds than others, experiment with them and you will find out!