This is a very popular dual purpose module. Not only does it feature the classic four stage envelope generator, but it also has a high quality VCA onboard.
This highly useful circuit implementation hardwires the ADSR generator to the control input of the VCA. The signal at the VCA's other input, the IN socket, will then be multiplied by the ADSR waveform. You can use any signal into this input, audio or CV. If you use CV, then the ADSR output level will be governed by the level of the CV. If you use audio, then the ADSR waveform will control the volume of that audio signal.
A typical use would have the IN socket being driven by the velocity CV from a midi-CV convertor. Thus the harder you hit the keys, the greater the ADSR output level. If you use this to control a filter sweep, this can create brilliantly effective touch sensitivity to your patch.
The circuit is configured so that if nothing is plugged into the IN socket, the module will behave as a traditional ADSR module. The output will rise to +5V at the attack peak.
The ADSR is operated by a gate signal, but can also be triggered by slow rising CVs too due to the built in schmitt trigger function. No additional 'trig' input is required.
The ADSR/VCA module is built on one PCB called the VC-ADSR board. Although the 1U panel design does not imply a voltage controlled design, the internal electronics are all voltage controllable. This allows blisteringly fast minimum attack and decay times. And yet, the controls with their true exponential response allow you to adjust the times with ease.
Also on this module is an LED. This gives a visual indication of the output level of the internal ADSR waveform.
Upgradable Design
This module can be upgraded to full voltage control with an addition of an extra PCB called the 'Four pot PCB'. This board takes up 1U of panel space, and is fitted next to the ADSR/VCA to be controlled. The upgrade can be added on at any time and installation is very simple. Two small interconnects behind the front panels allow the two boards to 'talk' to each other. See the VC-ADSR page for more details of the upgrade and the 2U VC-ADSR/VCA module.
Please note: This superb new feature is unfortunately not applicable to older issue ADSR/VCA modules fitted with the green Omeg pots. These older modules use a passive core and are not able to be voltage controlled.
Specifications:
Attack times: 0.75 milliseconds to 12 seconds. Charging voltage +15V, internal attack peak +8.2V. Pseudo linear ramp.
Decay/Release times: 1.8mS to 15s (90% to 10%) Exponential decay slope.
Sustain levels: 0 to 100%
With no jack plug inserted into the IN socket, the attack peak and maximum sustain level is 5V from the OUT+ socket.
An optional switch can be fitted to allow a special extended range. Fitting this switch allows the user to select between the standard A, S and R times as above, or five times these values.
The issue 2 VC-ADSR/VCA board fitted in a 1U panel to make the standard ADSR/VCA module. The optional 'range' switch has not been fitted, but if it were it would connect to the RNG header seen next to the blue capacitor.
Prices
ADSR/VCA full module..................................
125GBP
ADSR/VCA Pre Populated PCB.................... 77GBP
VC-ADSR/VCA issue 2 PCB
........................ 17GBP
ADSR pot kit ....................................................
12GBP
ADSR pot bracket kit
...................................... 4GBP
THAT2180LC VCA ......................................... 4.50GBP
The Pot Kit contains the correct type and quantity of Spectrol 248 or BI TT potentiometers to complete one module.
The Pot Bracket Kit contains the correct type and quantity of Oakley-Spectrol pot brackets and extra Spectrol nuts required to complete 1 module.
Click here for full price list and ordering details. All prices include VAT at UK rates. Shipping and postage is additional to these prices.
Project Downloads
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Front Panel database
A Schaeffer front panel can be made for a 1U wide ADSR/VCA module . The updated database can be found here: adsr.fpd. To read this file you will need a copy of 'Frontplatten designer' from Schaeffer. The program also features on-line ordering, so its now even easier to buy your panels from Scheaffer. The company are based in Berlin in Germany and will send out panels to anywhere in the world. Delivery to the UK normally takes around ten days. For North American users you can also order your Schaeffer panels from Front Panel Express.
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