SIREN – Stereo MIDI Volume Controller

The Oscillator Devices SIREN is a Stereo MIDI Volume Controller with advanced Tremolo functions. Its two fully analog channels can be independently set from -96dB (Mute) to a whooping +32dB boost. Split the channels before, or mix them after, the volume control. The SIREN has high quality, low-noise buffers and is specifically designed not to color your tone.

The SIREN has two internal LFOs to drive the volume control. That makes it a full-blown MIDI Controlled Analog Stereo Tremolo. Both LFOs operate completely independent. Different waveforms (Sine, Triangle, Rectangle and Ramp in both directions) can either be free running from 100ms to 1.2s, or can be synced to MIDI clock.

On top of that, the SIREN supports Fade and Swell functions. While Fade slowly fades to another volume, the Swell function snaps back to the original volume when done, ready to be triggered again.


  • MIDI Volume Control
  • Fully analog signal path
  • High quality, low noise buffers
  • From -96dB attenuation (Mute) to +32dB boost
  • Split channels before, or mix channels after volume control
  • Tremolo with 5 waveforms, free running or synced to MIDI clock.
  • Fade and Swell functions
  • Both channels can be controlled together, or act completely independent
  • 16 user presets on top of 16 factory presets
  • Compatible with all MIDI 1.0 compliant controllers
  • High-quality Neutrik sockets
  • Developed and handcrafted by Oscillator Devices in Germany
Oscillator Devices Siren - Stereo MIDI Volume Controller

Applications for MIDI Volume Control

Following are some examples how the SIREN can be incorporated into a MIDI guitar or bass rig. It is neither restricted nor limited to these applications, though.

Stereo MIDI Volume Control

This setup controls the volume of a stereo signal chain. You can use an expression pedal connected to your MIDI controller, as MIDI volume pedal, or simply set up patches for song sections with different volumes (lead vs. rhythm).

Mono In/Stereo Out

Split the signal of Channel A to both outputs BEFORE the MIDI volume control. The stereo path after the SIREN can be set to different volumes, for example to push two different drive pedals or two amps in a stereo amplifier setup.

Stereo In/Mono Out

Blend the channels AFTER the MIDI volume control. This can be either to use a stereo setup with a mono amp for small gigs, or to blend two signals, for example a clean blend. When blending two signals, phase issues can occur, when one signal path inverts the signal. For that case, the SIREN can flip the phase of channel A, either with the Phase-Button or MIDI command.

Pre- and Post-Gain FX Loop

In a mono setup, the two channels can be combined to form a FX loop with pre- and post-gain. That way you can dial back or push the volume that’s going into the pedals (pre-gain) and control the volume of the output (post-gain). Of course, you can use one channel as volume control and the other as Tremolo in a different spot at your signal chain.

Input Levels

The SIREN supports a wide range of input signals. You can choose between two input levels. A high gain setting that gives you the full range of boost and is perfect for guitar input levels. With active pickups or line levels, the low gain setting might be better. It gives you more input headroom with decreased maximum boost.

  • High Gain setting: Input headroom 3Vpp, 32dB max. boost.
  • Low Gain setting: Input headroom 9Vpp, 26dB max. boost.


Either one or both channels of the SIREN can act as Tremolo. Use it as beautiful, subtle sine wave tremolo, MIDI clock synced slicer with the rectangle waveform, or automatic swell with the ramp waveform.

When using the SIREN in mono you can cascade both LFOs to create complex waveforms. When using the SIREN as stereo tremolo, you can shift the phase of the Tremolo to create mind bending stereo effects.


  • Sine Wave: A classic, smooth sine wave for that beautiful, subtle Tremolo.
  • Triangle Wave: Almost the same as the sine wave, with a bit more static feel to it.
  • Rectangular Wave: Use the tremolo as slicer with a fast rectangular wave, or sync it with MIDI clock for dramatic on/off effects
  • Ramp: Either as forward or backward ramp. Use it for repeated swells for example.

All Tremolo functions are only accessible via MIDI. Easily explore the functions with the built in factory presets.

Fade and Swell

The Fade and Swell functions are basically a one shot tremolo with a ramp waveform. Use fade to slowly fade to a different volume, fade in, or fade out. Fade stays at the target volume when done. That’s the difference to Swell. Swell snaps back to the source volume, when the ramp is finished, ready to be triggered again. That way you can create slow gear swell effects.


Since the tremolo functions can require multiple commands, they can be wrapped into presets. The SIREN comes with factory presets for easy access when starting out. The most common Tremolo settings can be accessed with a single PC command.

MIDI Connection

The MIDI connections are assigned according to the official MIDI specification of MIDI TRS using MIDI TRS Type A, like pedals from Boss or Wampler. A 1/8″ (3.5 mm) stereo jack plug is used. The MIDI Thru socket is latency free.

1/8″ stereo jack plug to DIN 5-Pin according to MIDI TRS Type A


User ManualSIREN 1.0.1 (December 2023)PDF
Quick StartSIREN 1.0.1 (December 2023)PDF