ACMT - Applied Computer Music Technologies Ltd

ACM-2A 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. Low Frequency Shelf - Boost
 
The Boost control positioned on the left hand side of the front panel controls the amount of low frequency boost. This is adjustable over a range from 0dB to approx 13.5 dB dependent on the other control settings. Similar to vintage hardware equalizers, there may be some interaction between the controls.
 
2. Low Frequency Shelf - Attenuate
 
The Atten control positioned on the left hand side of the front panel controls the amount of low frequency attenuation. This is adjustable over a range from 0dB to approx 17.5 dB dependent on the other control settings. Note that increasing the attenuation results in more low frequency cut. As mentioned previously, the controls will interact with each other - which can also be used advantageously to replicate some of the classic boost / cut curves from vintage EQ hardware.
 
3. Mid-High Peak - Boost
 
The amount by which the peak filter boosts the selected frequency range is adjusted by the Boost control on the right hand side of the front panel. The peak filter provides a range of approximately 0dB to 18dB of boost. It does not provide the ability to attenuate or cut selected frequencies. The maximum available boost will depend upon the bandwidth settings, with approximately 18dB available at 'Sharp' and 10dB at 'Broad'.
 
4. High Frequency Shelf - Attenuate
 
The Atten control positioned on the right hand side of the front panel controls the amount of attenuation provided by the high frequency shelving filter, covering a range from 0dB to approximately 16dB. Similar to the low frequency attenuator, increasing the setting results in more high frequency cut.
 
5. High Frequency Shelf - Atten Sel
 
The Atten Sel control selects the high shelf filter frequency, from either 5kHz, 10kHz or 20kHz. All frequencies above the selected setting will be attenuated by the amount set with the Atten control. The high shelf filter does not provide the ability to boost selected frequencies.
 
6. Power Switch
 
The power switch provides a 'clean bypass'. With the switch off, the EQ and the tube amplifier emulation will be completely out of circuit and signals will pass through unaffected. With the switch on, the EQ will operate normally, where the tube amplifier emulation remains in the signal path even when the EQ filters are bypassed ('EQ In' switch [10] set to off).
 
7. Mid-High Peak - Frequency
 
The High Frequency switch on the right hand side of the front panel sets the centre frequency of the mid-high peak filter, adjustable in steps from 3kHz (KCS) to 16kHz (KCS).
 
8. Mid-High Peak - Bandwidth
 
The bandwidth control determines the width of the mid-high peak filter boost. It is continuously variable from the 'sharp' setting, providing a narrow peak, to 'broad', providing a wider peak. The exact bandwidth may also depend upon other control settings.
 
9. Low Frequency Shelf - Frequency
 
The Low Frequency control selects the frequency at which the LF Boost and / or LF Attenuate takes place. As this section is a shelving filter, all frequencies below the selected setting are boosted or attenuated. The control is not continuously variable, instead having four fixed positions at 20Hz, 30Hz, 60Hz and 100Hz. In keeping with original vintage EQ front panels, the control settings are indicated in cycles per second (equivalent to Hz).
 
10. EQ In
 
This is the EQ filter bypass switch. With the switch on, the filters will be in the signal path and affecting the output. With the switch off, the filters will be out of the signal path.
 
Note that vintage hardware EQs such as the original Pultec units often had passive filters, followed by a transformer-coupled valve (tube) amplifier stage to make up for signal loss in the filter. Even with the filters bypassed, the amplifier stage remained in circuit. While this does not affect the signal level, it does mean that there is still extra valve 'warmth' even with the EQ switched out.

ACM-2A Technical Specification:
 
1. System Requirements (64bit Linux)

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

2. Product Specifications

• Linux VST and VST3 compatible.
• Mono or stereo operation.
• Interpolated controls for smooth parameter changes with no 'zipper' noise.
• -18dBFS reference level for 0dBu.
• THD: 0.15% at +10dBu.
• Max. LF Boost: 13.5dB dependent on control interaction.
• Max. LF Attenuate: 17.5dB dependent on control interaction.
• Max. Mid-high Boost: 18dB (sharp bandwidth) / 10dB (broad bandwidth).
• Max. HF Attenuate: 16dB.
• Filter slope: 6dB / Octave.
• Filter types:
  • Low frequency shelf (boost / attenuate).
  • Mid-high peak (boost).
  • High frequency shelf (attenuate).
• Filter frequency ranges:
  • Low shelf: 20Hz, 30Hz, 60Hz and 100Hz.
  • Mid-high peak: 3kHz, 4kHz, 5kHz, 8kHz, 10kHz, 12kHz, 16kHz.
  • High shelf: 5kHz, 10kHz and 20kHz.
• Filter bandwidth (mid-high peak): 1.5 - 2.5 octaves, dependent on control interaction.
• Polarity invert switch.
• Output level trim (+/-6dB).

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

ACM-2A Download Free Demo
 
1. System Requirements (64bit Linux)

• Linux x86-64/AMD64 64bit e.g. Ubuntu 20.04 LTS or newer.
• A Linux VST or VST3 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.