CG Noise VCA Manual de usuario

Modular

Noise VCA

Noise Generator with state variable VCF and VCA

1. Introduction

An all-in-one noise 'voice'. A white noise generator followed by a state-variable VCF (switchable

high-, band-, or lowpass characteristic) with adj stable resonance (Q) and a VCA makes this versatile

mod le ideal for most standard noise applications. The integrated filter provides a wide range of rich

and colo rf l noise so nds. The VCF has a 2nd inp t, allowing one to combine external a dio with the noise, or to replace the

VCF's noise inp t completely with an external so rce.

The VCA mode can be switched between exponential or linear characteristic, with a m ting option when the switch is in its middle

position; the 'Offset' knob allows one to shift the VCA's start point by adding a negative or positive voltage to the VCA's CV inp t.

2. Features

–Noise generator with integrated state-variable VCF and VCA

–3 direct o tp ts:

◦White Noise

◦S b F (Random CV)

◦VCF O t (Colo red)

–Switchable VCF characteristic:

◦Highpass

◦Bandpass

◦Lowpass

–Adj stable filter resonance (Q)

–Switchable 2nd VCF signal inp t:

◦White noise only

◦White noise & external signal combined

◦External signal only

–VCA with switchable CV mode:

◦Linear CV

◦0 (m te)

◦Exponential CV

–Available in banana or 3,5mm minijack version

–E rorack mod le

–Width: 10 HP

–Dimensions: 128,5 mm x 50,5 mm

–Depth: ≈40mm

–S pply voltage: ±12V

–Power cons mption: ≈42mA (positive rail)

Banana jack version Minijack version Drawing

Modular

3. Functions

VCF C toff Freq ency The filter's c toff freq ency is adj stable

from ≈ 40 Hz to 15000 Hz.

White Noise O tp t Direct o tp t. The amplit de is ≈ 8-10 Vpp.

S b F (Random) O tp t Direct O tp t. This o tp t provides a

s ba dio random CV for mod lation. The amplit de is ≈8-10Vpp.

The amplit de and characteristic is adj stable with trimmer

23456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

on the

o ter PCB (Please read chapter

4. Adjustment

)

VCF O tp t Direct o tp t for the VCF. Depending on the position of

switch (VCF in), either filtered noise, a filtered external a dio

signal – inp t on socket 'ext. VCF In' - or a combination of both is

available. The filter characteristic can be chosen with the switch 'VCF

Mode' and variied with the knob Q (Resonance)

2 3 456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

; its freq ency

is set with the 'VCF C toff Freq ency' knob and can be mod lated

by an external CV signal applied to the 'VCF CVin' socket

(mod lation depth and polarity adj stable by knob 'VCF CVin' ) or

to the 'VCF 1V/Oct.in' socket .

VCF CV In Polarizing inp t level control knob for the VCF

mod lation voltage applied to the 'VCF CVin' socket . With the

knob in centre position (denter locked), mod lation depth is 0; by

t rning it CW, the mod lation depth will increase; by t rning it CCW

the mod lation depth will increase, however reacting inverted to the CW position.

Q (Resonance) By t rning this knob clockwise the filter resonance increases, p to near self-

oscillation.

VCF CV Inp t VCF c toff freq ency mod lation inp t. Mod lation depth and polarity can be

adj sted by knob 'VCF CVin' .

VCF In VCF a dio inp t selector. With this switch in pper position 'Noise',

white noise

is the inp t

for the filter. With the switch in middle position 'Noise+ext.' , a combination of white noise and the

external a dio signal applied on the 'ext. VCF In' socket feeds the filter's inp t. With the switch

in lower position 'ext.', only the external a dio signal is being processed by the VCF.

VCF Mode Switch Selects the VCF's operation mode:

•Switch in pper position: Highpass filter

•Switch in middle position: Bandpass filter

•Switch in lower position: Lowpass filter

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

2 3 456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

2 3 456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

2 3 456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Modular

VCF 1V/Octave CV Inp t The 1V/oct. tracking can be adj sted precisely by trimmer

23456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

on the o ter

PCB (Please read chapter

4. Adjustment

)

VCA In Signal inp t selector for the VCA. The position of this switch determines which signal is

being processed by the VCA.

•Switch in pper position: White noise

•Switch in middle position: S b F (Random)

•Switch in lower position: VCF O tp t

Ext. VCF In 2nd external signal inp t for the VCF. This inp t allows an external a dio signal to be

fed into the VCF. This signal may replace the internal noise so rce or can be combined with it;

depending on the position of switch 'VCF In' .

Note:

This socket has no extra knob for adj sting its level.

D e to the wide range of possible inp t

signals and filter settings it may happen that the filtered signal is distorted (with high Q setting and

an inp t freq ency which is nearby the VCF's c toff freq ency) or is too low.

VCA CV in Inp t level control knob for the CV so rce applied on 'VCA CVin' controlling the

VCA's amplification (for its inp t signal selectable by switch 'VCA In' ) . In center position (denter

locked) the level is 0 and there is no CV mod lation of the VCA. By t rning the knob clockwise, the

CV will mod late the selected inp t signal. By t rning this knob co nterclockwise, the inverted CV

mod lates the VCA's inp t signal ('polarizer').

Offset VCA offset control. With this polarizing control knob either a positive or negative voltage can

be added to the VCA's CV inp t. In center position (denter locked), the offset voltage is 0. By

t rning the knob CW, a positive voltage with range p to +5V will be added, by t rning the knob

CCW, a negative voltage p to -5V is addable. By t rning this knob CW, the p re, nmod lated

VCA's inp t signal (selectable by switch 'VCF In' ) will be provided on the VCA's o tp t 'VCA O t'

2 3 456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

- with variable amplification. In combination with an applied CV on 'VCA CVIn' , a negative

offset voltage added (t rning the knob CCW) may be sed to shift the VCA's operation point – so

that only from a certain amo nt of positive inp t CV begins to open the VCA (Example see chapter

5. Patches

Example 4).

VCA Mode With this switch the VCA's operation mode can be selected between linear CV or

exponential CV processing and 0 (m te):

•Switch in pper position: Linear

•Switch in middle position: 0 (m ting)

•Switch in lower position: Exponential

VCA CVin Control voltage inp t for the VCA. The amo nt and polarity is adj stable with knob 'VCA

CVin' .

VCA O t O tp t socket for the VCA. The position of switch 'VCA Mode' decides, which inp t

signal is being processed; controllers 'VCA CVin' (for socket 'VCA CVin' ), 'Offset' and switch

'VCA Mode' are responsible for the CV processing.

2 3 456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

2 3 456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

2 3 456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

23456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Modular

Audio routing

4. Adjustment & Settings

The Noise VCA is already caref lly adj sted. No f rther calibrations sho ld be needed. In case of e.g.

nintentional adj stment, here is the description of trimmers and adj stments (o ter PCB):

B s CV off/on Please see Chapter

. Bus CV

VCF c toff freq ency 1V/oct. adj stment

1. Insert a freq ency (preferably sinewave or

triangle) of yo r favorite t ned VCO to 'ext

VCF in' with switch 'VCF In' in lower

position ('ext.'), connect o tp t 'VCF O t'

to an amplifier.

2. Bring the oscillator's freq ency in t ne with

the Noise VCA's VCF c toff freq ency – the

knob 'VCF c toff freq ency' sho ld be

almost in the middle of its range ( on

scale: ≈3-5); with the 'VCF Mode' switch

in center position ('BP') and the 'Q' knob

2 3 456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

widely t rned clockwise (≈ '8' on scale), so

that the filter is resonating slightly. The

oscillator tone m st have its largest

amplit de when it is in pitch with the VCF's

c toff freq ency.

2 3 456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

2 3 456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

Modular

3. Apply a CV so rce (preferably a keyboard) to both the VCF's 1V/Oct CV inp t and the

VCO's 1V/oct. CV inp t.

4. Play or generate 2 alternating notes ( with a distance of 3-4 octaves); e.g. 250 Hz and 2000

Hz.

5. T ne the trimmer

23456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

ntil both alternating notes have the highest amplit de, thereby tracking

the VCF's c toff freq ency – if necessary, readj st the VCF c toff freq ency with knob .

Alternatively, insert a short imp lse signal (e.g. trigger) to 'ext VCF in' with the 'Q' knob

23456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

f lly

t rned p CW, and se the now triggered VCF as a so nd so rce (Example see nder chapter

Patches

Example 3). This generated note yo can compare with a reference VCO's tone by bringing

them in t ne and applying a CV so rce to both 1V/Oct. CV inp ts; then proceed as in step 4. and

adj st trimmer

23456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

S b F amplit de With this trimmer the S b F's o tp t (on socket 'S b F' ) amplit de and

characteristic can be moderately adj sted.

VCA 0-point Offset This trimmer determines the VCA's CV 0-point. With switch 'VCA Mode' in

pper position ('lin.'); switch 'VCA In' in pper position ('White'), the 'Offset' knob in middle

position (center locked) and no CV applied, the VCA's o tp t (socket 'VCA O t'

2 3 456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

) signal sho ld be

as q iet as possible with no

white noise

signal passing thro gh, b t the 'Offset' knob sho ld still

react sensitively when t rned CW.

Exponential Mode 0-point Adj stment of the exponential converter's 0-point. With the 'VCA

Mode' switch in

lower

position ('exp'); the 'VCA In' switch in the pper position ('White'), the

'Offset' knob in the middle position (center locked) and no CV applied, the VCA's o tp t (socket

'VCA O t'

2 3 456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

) signal sho ld be as q iet as possible with no

white noise

signal passing thro gh

(compare to when switch 'VCA Mode' in

middle

position ('0'), b t the 'Offset' knob sho ld still

react sensitively when t rned CW and the

white noise

signal sho ld increase slightly on the VCA's

o tp t).

Exponential Gain Adj sts the exponential converter's amplification. With 'Offset' knob t rned

f lly CW, the o tp t vol me of the VCA sho ld be the same both in 'lin.'and 'exp.' mode (compare

by toggling switch 'VCA Mode' ). With this trimmer yo can adj st the VCA's vol me in 'exp.'

mode.

VCA Inp t Gain Adj stment of the VCA's inp t signal (and therefore the lo dness of the VCA).

With knob 'Offset' f lly t rned CW p, the o tp t vol me of the VCA

2 3 456789

10 11

13 14 15 16 17 18 19

20 22

Objekt in Pfade:

sho ld have nearby the

vol me of the direkt o tp ts , or ; b t also there sho ld be no distortion for very lo d

signals (especially when an external so nd so rce is applied on socket 'ext. VCF in' .

If yo need to recalibrate the

Noise VCA

's VCA section, please follow the adj stment steps in this

order:

23456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

→

23456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

23456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

23456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

2 3 456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

2 3 456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

23456789

10 11 13 14 15 16 17 18 19

20 22

Objekt in Pfade:

Falsche Zahlen

Modular
5.Patches
Simple patches (with other CG Prod cts' mod les)
Patch Description A dio Link
1. Peak & Hold is controlling the Noise VCA 
In this standard patch the Peak&Hold's 
'Release' o tp t controls the VCA with a 
dynamic envelope shape, while the 
Peak&Hold's 'P+H' o tp t is mod lating the 
VCF's c toff freq ency.
Peak&Hold inp t:
Dr m machine
http://www.cg-
prod cts.de/A dio/NoiseVCA_P
-H528.mp3
2. 2 So nds combined
In this example the XR22 VCO FT's 
sq arewave o tp t is applied to 'ext VCF In';
the Peak&Hold is mod lating the Noise 
VCA's VCF c toff freq ency and the VCA. 
Peak&Hold inp t:
Dr m machine
http://www.cg-
prod cts.de/A dio/NoiseVCA_X
R22_PH-530.mp3
3. VCF triggered with imp lses
Short imp lse signals can be  sed to trigger
the VCF, generating 'ping' like so nds. Here 
the Peak&Hold's imp lse o tp t is  sed to 
trigger the VCF; its 'P+H' o tp t is 
mod lating the filter's c toff freq ency. 
Peak&Hold inp t:
Dr m machine
http://www.cg-
prod cts.de/A dio/NoiseVCA_V
CFtriggered-535.mp3
4. VCF & VCA working independently
When  sing the VCA with white noise (or 
S b F) as signal so rce, the VCF can be  sed
completely independent to process another 
signal; or the VCA can generate dynamic 
accents to the 1st (VCF) a dio o tp t - by 
shifting the VCA's offset level. Here the 
VCF's a dio inp t is the imp lse-triggered 
Delay 1022.
Peak&Hold inp t:
Dr m machine
http://www.cg-
prod cts.de/A dio/NoiseVCA_
Delay1022_PH-0539.mp3
5. Sb F mod lating CVs
The 'S b F' o tp t can be  sed to mod late 
the VCF c toff freq ency and/or the VCA - 
random so nds s ch as 'th nder' or 
'crackling' can be generated. 
http://www.cg-
prod cts.de/A dio/NoiseVCA_S
 bF-542.mp3
                                      6  