ACMT - Applied Computer Music Technologies Ltd

ACM520X1 Product Operating Guide
 
Access to plug-in parameters is provided by a fully resizable graphical user interface. Your host application may also provide access to parameter adjustments and additional configuration. Graphical User Interface
 
The plug-in settings are adjusted by clicking and dragging on the rotary controls or buttons. Some controls may have detents – these manifest themselves as areas in the rotation where the reluctance to move is increased such that you have to drag them a bit harder. They are intended to behave similarly to real controls which may have a 'click stop' at 0dB for example.
 
You can also adjust the controls by placing the mouse pointer over them and using the scroll wheel. In this case the detent has no effect.
 
Control Modes
 
The control mode determines the way in which the rotary controls respond to mouse movement. This can normally be configured via the host application preferences. Please refer to your host application documentation for details.

• Circular. In this mode, clicking on a control will move it immediately to the mouse pointer’s angular position. To adjust the control, drag the mouse pointer in a circle or an arc.
• Relative Circular (Default). This is the default mode unless changed by host application settings. Similar to circular mode, however moving the mouse will adjust the control relative to its current setting.
• Linear. In this mode, the control responds to vertical mouse movement. Drag up to increase the value, turning the control clockwise, or down to decrease the value, turning the control anticlockwise.

In all modes, double clicking the centre of a control will return it to its default position.
 

Control Functions
 
1. Gain Reduction Meter
 
The gain reduction meter shows the amount of gain reduction (attenuation) being applied to the signal as it passes through the compressor. The amount of attenuation is dependent on the threshold and ratio settings. Increasing amounts of gain reduction mean the compressor is having to act more strongly to control the signal level.
 
2. Threshold
 
The threshold control sets the point at which the compressor begins to act. If a signal larger than the threshold enters the compressor, it will be progressively attenuated depending on the ratio control setting. In this compressor design, the threshold will also be automatically adjusted for different ratio settings, in order to maintain perceived loudness.
 
3. Make-up Gain
 
The make-up gain control provides additional gain at the compressor output to compensate for the effect of lowering the threshold setting. At high ratio settings with a low threshold, the compressor output will not be much higher than the threshold level therefore additional make-up gain may be required to match the unprocessed signal. Switch the compressor in and out of circuit while adjusting the control until the processed and unprocessed signal levels are matched.
 
4. Attack (ms)
 
The attack control sets the speed with which the compressor reacts to signals which are louder than the threshold. The shorter the time, the quicker the compressor will respond to changes in input level and reduce loud signals. Set the attack to fast (anticlockwise) to aggressively control loud signals without any of the initial transients getting through.
 
5. Release (sec)
 
The release control sets the speed with which the compressor recovers after reducing a loud signal. Longer release times with shorter attack settings may lead to audible pumping of the output level, whereas shorter release times with longer attack may be better suited to more subtle dynamic control, for example mastering.
 
5a. Auto-Release
 
In addition to the four release time-constants, the ‘auto’ setting provides a program-dependent release time. This ensures the compressor reacts quickly to rapidly changing dynamics, while retaining an underlying amount of gain reduction determined by a longer average of the signal level.
 
6. Ratio
 
The ratio control sets the amount of compression applied to audio which is louder than the threshold. In simple terms, the ratio is the ratio of the change in input level to the change in output level, so for example, if the compression ratio is set to 10:1, a change of 10dB in the input signal (assuming it is already above the threshold) will only result in a 1dB change in the output level.
A ratio of 1:1 is equivalent to having no compressing action, in this case a change in input of 10dB results in a change in output of 10dB.
 
This compressor design is characterised by an intentional change of threshold for different ratio settings, in order to maintain a constant perceived loudness. The ratio setting also affects the compressor ‘knee’ – that is, how quickly the input vs output curve transitions from 1:1 below the threshold to the selected compression ratio above it. For a ratio of 2:1 the onset of gain reduction will be gradual, and the threshold will be lowest. For higher ratios such as 4:1 or 10:1, the threshold will increase and the onset of gain reduction will be more abrupt.
 
7. Effect In / Out
 
This is the plug-in bypass switch. With the switch on, the plug-in will be in the signal path. With the switch off, signals pass through unaffected.
 
8. Side-Chain Highpass Filter
 
This places an 80Hz highpass filter into the signal path feeding the compressor side-chain. This can be useful when using the compressor on the master bus, to prevent a bass-heavy mix from triggering the compressor unnecessarily, while still controlling the upper and mid-range dynamics effectively.
 

ACM520X1 Technical Specification:
 
1. System Requirements (64bit Linux)

• Linux x86-64/AMD64 64bit e.g. Ubuntu 20.04 LTS or newer.
• A Linux VST, VST3 or CLAP compatible host application.

2. Product Specifications

• Linux VST, VST3, JACK and CLAP compatible.
• Mono or stereo operation.
• Interpolated controls for smooth parameter changes with no 'zipper' noise.
• -18dBFS reference level for 0dBu.
• Threshold: -15dBu to +15dBu, also dependent on ratio settings.
• Attack time: 0.1, 0.3, 1, 3, 10 and 30ms.
• Release time: 0.1, 0.3, 0.6, 1.2 seconds, and auto-release.
• Compression ratio: 2:1, 4:1 or 10:1
• Output make-up gain: -5dB to +15dB.
• Switchable side-chain highpass filter (6dB / octave at 80Hz).
• Polarity invert switch.
• Output level trim (+/-6dB).

Please note: In the interest of continual product improvement, specifications may be subject to change without notice.

ACM520X1 Download Free Demo
 
1. System Requirements (64bit Linux)

• Linux x86-64/AMD64 64bit e.g. Ubuntu 20.04 LTS or newer.
• A Linux VST, VST3 or CLAP compatible host application.

2. Free Demo Limitations

• Every 60 seconds the plug-in will fade to silence momentarily. To remove this limitation you will need to have purchased a product activation code.
• To remove the demo limitations, open the plug-in in your host application and click the lock button at the top left of the plug-in GUI to open the license entry dialogue. Type (or paste) your product activation code into the text box. You will then need to restart your host application to complete the process.

3. Product Support

• All downloads include their own installer, manual, and installation instructions. Easy to install with just a few clicks.
• If you need help downloading or installing the software please use our contact form to let us know.