Circuit Slices Ring+VCA User manual

Circuit Slices, LLC
Ring+VCA
CS045
CS045-UM v1.0| www.circuitslices.com
1
The Circuit Slices Ring+VCA (CS045) is a dual-function module for Eurorack-compatible synthesizers.
Packed in a narrow panel is both a quality classic analog ring modulator circuit and a basic linear VCA.
Ring modulators typically are patched to a VCA –this ring modulator includes the VCA.
Features and Specifications for the CS045 Ring+VCA
The “Ring Modulator” or “Balanced Modulator”or “4-Quadrant Multiplier”, circuit uses a quality Analog
Devices AD633 chip
•Low feedthrough (+/-0.1% Yin and +/- 0.3% Xin typical)
•Low noise (90 µV rms)
•No ‘Nulling’ adjustments are required
•See Analog Devices AD633 data sheet for complete chip specifications
The VCA, or “two-quadrant multiplier” circuit uses a transconductance chip
The VCA is trimmer-adjusted for unity-gain output with a 5V CV input (user adjustable trimmer)
The ring modulator output is “normal” patched to the VCA input
The VCA and Ring Modulator can be used separately –patching to VCA IN disconnects Ring OUT
Includes power cable and case screws
Reverse power protection
Low Power: +12 VDC @ 13 mA, -12 DC @ 13 mA, using a standard Eurorack 10-pin power connection
Connections: Standard 3.5mm jacks
Depth: 32 mm
Narrow panel width: 4 HP

Circuit Slices, LLC
Ring+VCA
CS045
CS045-UM v1.0| www.circuitslices.com
2
Installation
Simply route the supplied ribbon-cable power connector to your power bus and mount the panel using
the supplied screws. Be careful making the connection to your power bus -- the red stripe on the ribbon
cable must be toward the -12V pin on the power bus and the module. We supply a cable that has no
strain-relief on the 10-pin connector. which keeps the module’s overall width narrow.
Using the Ring+VCA
Typically, this module is used for producing bell-like sounds. These are sounds with complex timbers
(often with non-harmonic overtones) created from the sum and difference frequencies applied to the X
and Y inputs of the ring modulator. The ideal ring modulator does not output the original X or Y input
signals –only the sum and difference signals and harmonics. First try using X and Y inputs that are sine
or triangle waveforms of different frequencies. Also, try using an amplified signal from a microphone for
one ring modulator input and a sinewave for the other input for the classic –and a bit cheesy –robot
voice. Better yet, try using the signal from a guitar or other amplified acoustic instrument.
X in
X
Y in
OUT
Sinewave 200 Hz
Sinewave 1000Hz
Inputs
Complex
waveform with
800 Hz and 1200
Hz frequencies
While the ring modulator or 4-quadrant multiplier accepts signals that swing positive or negative, the
VCA, or 2-quadrant multiplier, only accepts positive control voltages (in this case, 0 to 5V). The VCA
input and output signals, are of course bipolar –the standard +/- 5V signal range -- with some
headroom.

Circuit Slices, LLC
Ring+VCA
CS045
CS045-UM v1.0| www.circuitslices.com
3
VCA
IN
CV
OUT
0V
5V
+/- 5V signal from
Ring or external
source
ADSR input +/- 5V signal to other modules
Remember also, that you can patch between the Ring out and VCA in. You might feed the Ring
Modulator output to a VCF and patch the VCF output back to this module’s VCA IN jack.
User Adjustments
While you don’t need to ‘null’the ring modulator (that is, to adjust the circuit so that the inputs are not
passed to the output), there are two circuit board trimmers for the VCA:
•TRIM1 controls the DC offset of the VCA output. Factory-set for minimum DC output
offset.
•TRIM2 controls the VCA’s initial gain. Factory set for a minimum output when 0V is
applied to the CV input. 5V applied to the VCA’s CV input produces unity gain.
The examples above are just the standard ring modulator configuration and only scratch the surface of
the way you might use this device. This affordable little module will greatly expand the capabilities of
any modular synthesizer. We know you will enjoy hours of experimenting, producing wild modulation
sounds and dramatic “clangorous” effects, but try to work these ideas into a finished composition!
This module is limited-warranted for one year with parts, under normal use –not including the
application of reverse or over-voltage power by customer. Return shipping to Circuit Slices from
customer not included. Return to Circuit Slices, LLC for repairs. Circuit Slices, LLC reserves the right to
replace the module if necessary. Please keep your receipt / packing slip for warranty information.
Circuit Slices, LLC
10028 Windjammer Trail
Aurora, OH 44202