Constructional difficulty: moderate
The new 2U wide complete VC-ADSR/VCA module
This is a dual purpose module in a 2U width panel. Not only does it feature the classic four stage envelope generator with full voltage control, 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.
This design features blisteringly fast minimum attack and decay times. And yet, the controls with their true exponential response allow you to adjust the times with ease.
Each CV input is controlled by a dedicated pot. This pot acts as a reversible attenuator, so that the gain of the input is anything from -1 to +1. This means that any inputted CVs can subtract or add to the times, or level, set by the ADSR pots. With any input knob set to its middle position, then that CV channel is effectively turned off.
Also on the module is an LED. This gives a visual indication of the output level of the internal ADSR waveform.
The 2U VC-ADSR/VCA module consists of two printed circuit boards, the VC-ADSR and the 'Four-pot' boards. To build the complete 2U module you will need one of each of these PCBs.
Specifications:
Attack times: 0.75mS to 12s. 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.
This is the 1U wide 'Upgrade' module required for upgrading the standard 1U ADSR/VCA module. This module would sit alongside the ADSR/VCA module either on the right or left of it.
Upgrade the standard 1U ADSR/VCA module for full voltage control
The standard Oakley 1U ADSR/VCA module can be upgraded to full voltage control with an addition of an extra module called the 'ADSR Upgrade module'. This module takes up 1U of panel space, and is fitted next to the standard 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. The ADSR Upgrade module uses the 'Four pot' PCB which is also used on some other Oakley modules.
Each of the four CV inputs is controlled by a dedicated pot. This pot acts as a reversible attenuator, so that the gain of the input is anything from -1 to +1. This means that any inputted CVs can subtract or add to the times, or level, set by the ADSR pots. With any input knob set to its middle position, then that CV channel is effectively turned off.
Please note: This superb feature is unfortunately not applicable to older issue issue ADSR/VCA modules fitted with the green Omeg pots.
Prices
VC-ADSR issue 2 PCB
.................................. 17GBP
ADSR pot kit ....................................................
12GBP
ADSR pot bracket kit
...................................... 4GBP
'Four pot' PCB
................................................. 19GBP
'Upgrade' pot kit
.............................................. 12GBP
'Upgrade' pot bracket kit
................................ 4GBP
THAT2180LC VCA chip ................................ 4GBP
To build the Oakley 2U VC-ADSR, you will need one VC-ADSR PCB and one 'Four-pot' PCB.
See the ADSR page for more details of the standard 1U ADSR/VCA module.
Each pot kit contains four high quality Spectrol 248 pots. Each pot bracket kit contains four Oakley pot brackets and four extra pot nuts. The brackets are especially made for us to hold the PCB mounted Spectrol pots safely to the PCB and cannot be purchased anywhere else. No knobs are provided.
All other parts can be purchased from you usual electronic component supplier.
See the orders page for ordering information, shipping charges and payment methods.
All prices include VAT at UK rates. Shipping/postage is additional to these prices. See also the FAQ page.
Project Downloads
To build the 1U upgrade module only, you need the following documentation:
To build the 2U full VC-ADSR panel, you will need the above and the following additional information:
Use 'save as...' button to download and view the files. IE users need to right hand mouse click and then choose 'save as'. Links to schematics are available to purchasers of the PCB or module and will be sent via e-mail when the board(s) are shipped.
Front Panel database
A Schaeffer front panel can be made for a 2U wide VC-ADSR/VCA module and the 1U VC-ADSR upgrade module. The databases can be found at 2U VC-ADSR and Upgrade.
To read these files 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.
Parts lists for US builders
Builders based in North America can now find full parts lists, complete with order codes, for many of the Oakley modules. Larry Hendry has kindly provided the web space for customers to upload parts lists. Go to www.wiseguysynth.com for full details.
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