Introduction
In the spirit of sonic exploration and musical evolution we bring you the Grendel RA-99 Grenadier, an all-
analog synthesizer with an original and unique tone palette. It implements parallel formant synthesis with a
bank of three voltage controlled filters to generate tones inspired by the human voice, without being
limited by the conventional boundaries of speech modeling. Twenty patch points give you extensive self-
patching options plus creative compatibility with analog modulars, sequencers and keyboard controllers.
Oscillator
The RA-99 sound engine is based on an accurate voltage controlled oscillator with variable wave shape.
The VCO has multiple CV (control voltage) inputs for creative stacking of the various CV sources available
in your studio. There are two 1 volt per octave inputs for melody. It also has a 5 volts per octave input
that is ideal for creating octave modulations from an LFO with 5V output. Finally, the 15 volts per octave
input is suited to narrow pitch modulations like vibrato and pitch bend. The CV inputs of the RA-99 VCO
have wide response bandwidth, allowing FM with audio frequency waveforms.
A subharmonic square wave is generated at a frequency 1 octave below the VCO. Activating the SUB
switch mixes this with the VCO output. Raw subharmonic waveform is available from the SUB OUT jack.
Noise Source
A pink noise generator is included to add complexity to the sound. Pink noise is mixed with the VCO at
the input to the filter bank. Pink noise volume is adjustable with the knob labeled P-NOISE, and by CV
input to the NOISE CV jack. The noise source also adds a subtle amount of jitter to the VCO waveform.
Modulation
The RA-99 modulation section contains a pair of multifunction waveform generators called MOD1 and
MOD2. They can provide (1) gated attack-release envelope, (2) triggered decay envelope, (3) pulse LFO
with variable pulse width, or (4) saw-triangle LFO with variable symmetry. In envelope mode, the output
is a true exponential slope. In addition, RA-99’s MODs can create time delayed gate events, serve as low-
frequency audio VCOs (with limitations), or act as frequency dividers. Both MODs have variable output
level that is sweepable from normal to inverted polarity. Either MOD1 or MOD2 can serve as the main
volume envelope.
Filter Bank
The Grenadier RA-99 filter bank combines one low pass and two band pass filters to produce full-bodied
tones with resonant character of vowels. The filter bank has three control parameters: ALPHA, BETA, and
FILTERS. These parameters are also fully controllable with CV inputs.
Patch Points
Made by Rare Waves® (Texas, USA)
RAREWAVES.NET
Design and Support:
Eric Archer
Manufacturer
Compatibility
CV-Gate In:
Patch cables:
Audio output:
CV output range:
MIDI:
Polyphony:
VCO
1V/oct (x 2), 5V/oct, 15V/oct,
Timbre CV In (controls wave shape)
MOD1
Gate In, Rate CV In, Vari Out, Gate Out
MOD2
Gate In, Rate CV In, Vari Out, Gate Out
Filter Bank
Alpha CV In, Beta CV In, Filter CV In
Audio
Subharmonic Out, VCF audio In,
Mix audio In, Noise VCA CV
Specification
Power Input:
Dimension:
Mass:
Case Material:
RoHS-Compliant:
Lead-free:
12 VDC @ 1.2 Watt
30 x 10 x 6 cm
0.53 kg
Anodized aluminum
YES
YES
1 V/oct, +5V Gate
3.5 mm mono
1/4” analog unbalanced
0 to +5 volts
Not included
Monophonic
Grendel RA-99 Grenadier User Guide | Revision 2020-0103
