ACMT - Applied Computer Music Technologies Ltd

ACM210X1 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 the marker points for each band, modifying the filter response curve. Filter types are selected by right-clicking and choosing from the context menu. Filter bands can be individually activated or deactivated by double clicking the associated marker. Filter Q can be adjusted using the scroll-wheel with the mouse pointer positioned over the corresponding marker, or in the filled area under the curve.
 
The user interface is fully resizable, while for fine parameter control the display can be zoomed up to 2X normal size using the scroll-wheel with the mouse pointer positioned over any part of the graphical display background.
 
Adding a new filter band
 
In the default configuration, there are no active EQ bands. To add a new filter band, click on the response curve baseline [7] and a new marker will appear. Drag the marker left and right to adjust the frequency, or up and down to set the gain. The default type is the dB / 2 peak filter, if necessary this can be changed by right-clicking and selecting from the context menu. Up to ten bands can be active at any time.
 
Adjusting filter parameters
 
To adjust the filter parameters, click on a filter band marker [10] and drag left or right with the mouse to set the frequency, or up and down to adjust the gain (boost or cut). The filter Q can be changed using the scroll-wheel with the mouse pointer in the filled area under the response curve, or over the associated marker.
 
Activating or deactivating a filter band
 
To activate or deactivate an individual filter, double click the filter band marker. When the selected band is active there will be a filled area under its associated frequency response curve.
 
Stereo Placement
 
Starting with version 3.1.4, the context info pop-up associated with the active EQ band consists of two parts. The right-hand side shows information about the frequency, gain and bandwidth settings for the selected band, while the left-hand side contains a toolbar for selecting stereo placement and solo options.
 
Clicking the left placement icon assigns the current band to the left side of the stereo image. A tab will be visible on the marker for the selected band indicating its channel assignment, and its effect will be shown in the global yellow EQ curve.
 
Clicking the right placement icon assigns the current band to the right side of the stereo image. A tab will be visible on the marker for the selected band indicating its channel assignment, and its effect will be shown in the global white EQ curve.
 
Clicking the stereo placement icon assigns the current band to both the left and right side of the stereo image (default). The band’s effect will be visible in both the global yellow and white EQ curves.
 
Soloing an EQ Band
 
Clicking the headphone icon places the selected band in solo mode. Only a single band can be in solo at any one time. In solo mode, only the range of frequencies affected by the selected band is audible. For peak filters this equates to a band-pass, for low and high shelf filters this equates to low and high-pass respectively. For the low and high-pass (high and low cut) filters, the range of frequencies being cut by the filter is audible.
 

Control Functions
 
1. EQ In
 
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.
 
2. FFT On / Off
 
The FFT switch activates or deactivates the FFT spectrum analyser. Note that the plug-in is likely to use more CPU with the spectrum analyser active.
 
3. FFT Source
 
The FFT Pre / Post switch selects the spectrum analyser signal source, monitoring the frequency spectrum either before or after the filters.
 
4. FFT Slope
 
The FFT slope switch adjusts the spectrum analyser display using a 3dB / octave slope. Because human hearing does not respond to all frequencies equally, the slope helps ensure that programme material which sounds balanced also appears balanced on the display.
 
5. EQ Flat
 
The Flat switch resets all currently active EQ bands to 0dB, returning the plug-in to a flat response.
 
6. EQ Clear
 
The Clear switch clears the plug-in settings and removes all active EQ bands, resetting it to its initial configuration.
 
7. EQ curve baseline
 
To add a new filter band, click on the EQ curve baseline and a new marker will appear. Drag the marker left and right to set the frequency, or up and down to adjust the gain. The default type is the dB / 2 peak filter, if necessary this can be changed by right-clicking and selecting from the context menu.
 
8. Shelving filter 'Q'
 
The low and high frequency shelving filters have adjustable resonance / Q. In this case, the 'Q' determines both the steepness of the filter slope, and the amount of overshoot or undershoot at the filter corner frequencies. The Q can be adjusted using the scroll-wheel while placing the mouse pointer in the filled area beneath the frequency response curve, or over the filter band marker [10].
 
9. Peak filter Q
 
Peak filter Q can be adjusted using the scroll-wheel while placing the mouse pointer in the filled area beneath the frequency response curve, or over the filter band marker [10]. Higher Q values correspond to a narrow bandwidth peak, with lower values corresponding to a broader bandwidth. The plug-in provides several peak filter types:

• Peak dB / 2: The filter Q is determined using frequency points at which the filter gain in dB is half that of the peak. The filter provides symmetrical boost and cut responses.
• Peak -3dB: The filter Q is determined using frequency points at which the filter response is 3dB below that of the peak. The filter provides symmetrical boost and cut responses.
• Peak +3dB: The filter Q is determined using frequency points at which the filter response is 3dB above unity (0dB) for boost, or 3dB below unity for cut. The filter provides symmetrical boost and cut responses.
• Asymmetric: The filter Q is determined using frequency points at which the filter response is 3dB below the peak for boost or 3dB below unity (0dB) for cut. The filter provides asymmetrical boost / cut responses in which the cut is much narrower than the boost, for the same Q setting.
• Inverse asymmetric: The filter Q is determined using frequency points at which the filter response is 3dB above unity (0dB) for boost or 3dB below the peak for cut. The filter provides asymmetrical boost / cut responses in which the boost is much narrower than the cut, for the same Q setting.

10. Filter band marker
 
Each band has an associated marker which can be dragged using the mouse, modifying the filter parameters. Drag up or down to change the amount of boost or cut, and left or right to adjust the filter frequency. Use the mouse scroll-wheel with the pointer positioned over the marker to adjust the filter Q. Double clicking the marker activates or deactivates the filter band. The presence of a filled area under the response curve indicates that the band is active.
 
11. Combined frequency response
 
In addition to the individual filter response curves, the graphical user interface also shows the combined response of all currently active filter bands, as indicated by the white line.
 
12. FFT Spectrum analyser display
 
The realtime FFT provides a visual indication of the frequency spectrum. In conjunction with the FFT source select [3], the display can show either the input, before the EQ, or the output, after the EQ.
 

De-Cramped Analogue Modelled Filters:
 
At commonly used sample rates such as 44100Hz and 48000Hz, conventional digital EQs can cause frequency response cramping as the filter frequency approaches its upper limit. Conventional solutions such as oversampling can be CPU intensive, introducing other artefacts and additional latency. The ACM210X1 uses innovative analogue filter modelling technology to provide a zero latency de-cramped response, accurately replicating that of an equivalent analogue filter without requiring oversampling.
 

 
The cramping effect of a conventional EQ can clearly be seen below as the filter frequency is increased (yellow and red traces). In this instance the shelf slope becomes significantly steeper and the resonant peak becomes narrowed.
 

 

ACM210X1 Technical Specification:
 
Product Specifications

• Windows & Linux VST, VST3, and CLAP compatible.
• Mono or stereo operation.
• Interpolated parameters for smooth changes with no 'zipper' noise.
• -18dBFS reference level for 0dBu.
• Equalizer:
  • Number of filter bands: 10.
  • Filter Q (peak filters): 0.3 to 5.0
  • Filter Q (shelf / low and high-pass): 0.7 to 1.4
  • Maximum boost or cut: 18dB.
  • Filter types:
    • High-pass: 2-pole with adjustable resonance.
    • Low-pass: 2-pole with adjustable resonance.
    • Band-pass: Unity gain band-pass with adjustable Q.
    • HF Shelf: High frequency shelf with adjustable resonance.
    • LF Shelf: Low frequency shelf with adjustable resonance.
    • Peak dB / 2: Peak filter with Q determined using frequency points at which the filter gain in dB is half that of the peak. The filter provides symmetrical boost and cut responses.
    • Peak -3dB: Peak filter with Q determined using frequency points at which the filter response is 3dB below that of the peak. The filter provides symmetrical boost and cut responses.
    • Peak +3dB: Peak filter with Q is determined using frequency points at which the filter response is 3dB above unity (0dB) for boost, or 3dB below unity for cut. The filter provides symmetrical boost and cut responses.
    • Asymmetric: Peak filter with Q determined using frequency points at which the filter response is 3dB below the peak for boost or 3dB below unity (0dB) for cut. The filter provides asymmetrical boost / cut responses in which the cut is much narrower than the boost, for the same Q setting.
    • Inverse Asymmetric: Peak filter with Q determined using frequency points at which the filter response is 3dB above unity (0dB) for boost or 3dB below the peak for cut. The filter provides asymmetrical boost / cut responses in which the boost is much narrower than the cut, for the same Q setting.
  • Internal processing: 64Bit floating point.
  • Algorithm: Analogue filter modelling coefficient generator provides filter responses which closely model analogue equivalents, without requiring high sample rates or internal upsampling.
• FFT Spectrum analyser:
  • Algorithm: Windowed Fast Fourier Transform.
  • FFT Window function: Blackman - Harris.
  • FFT Resolution: 1024 Frequency bins covering 0 to Fs interpolated to 4096 bins during the FFT process, where Fs is the sample rate.
  • FFT Latency: 1024 samples.
  • FFT Slope:
    • 3dB per octave (slope switch enabled).
    • Flat (slope switch disabled).
  • FFT Source: Pre or post EQ, average of left and right stereo channels.
• Polarity invert switch.
• Output level trim: +/-6dB

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

ACM210X1 Download Free Demo
 
1. System Requirements - Windows

• 64bit Windows 7 or newer.
• A VST, VST3 or CLAP compatible host application.

2. System Requirements - Linux

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

3. 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.

4. 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.