StandardCLIP Manual

StandardCLIP is a new advanced clipping-plugin. You can use StandardCLIP in two ways:

• as a dynamic tool in your master effects chain to increase the volume
• as a harmonic generator to add odd harmonics to your signal

You can adjust the way the clipping is done easily, like a hard-limiting brick wall or smooth soft-saturated.
Since clipping is a non-linear process, clipping adds always new harmonics to the signal, and if it's done without oversampling, harmonics above the Nyquist-frequency will be folded back in the frequency spectrum and that's called aliasing. Oversampling reduces aliasing. StandardCLIP offers high quality oversampling up to the factor 256. It also offers very versatile oversampling options: You can choose between minimum phase mode (without additional latency) and linear phase mode (adds latency to the signal, but preserves phase-shift), and change the filter quality and cut-off frequency of the filter which is used for the oversampling process.

This is a 2000Hz sinus signal running through the clipping unit without oversampling. What you see is that odd harmonics (3rd = 6 kHz, 5th = 10 kHz, 7th = 14 kHz) are added to the signal, this is what naturally happens when you limit any kind of signal.
But we also see unwanted side effects, called aliasing. Because the new odd harmonics will also continue beyond the Nyquist-frequency. These harmonics can not be recreated with the used sampling rate and will be folded back to the signal. StandardCLIP reduces the aliasing by oversampling the source signal to a higher sample rate. Then it processes the clipping, removes unwanted frequency content above the source Nyquist-frequency and finally down-samples it to the source sample rate again.
This is another example of clipping with and without oversampling. The source signal is a sine sweep from 800Hz to 20kHz.



The quality of the oversampling depends not only on the oversampling-factor. Also the quality of the filters which are used for up and down sampling is essential (steepness, phase linearity).
StandardCLIP offers total control over the used filters.

Open the dmg-File you have downloaded and double-click on the containing pkg-File. Select "continue" on the welcome screen. If you see the "Select the Destination" screen, you can click "continue" as well. Then, select "Install" and enter your admin password. The actual setup software will start afterwards.

Please click on the "I agree" button if you agree to the "License and Legal Information".

If this is a first-time installation, the license key will be requested at this point. First, copy the license key from the mail you received after purchasing the software. If you can't find your license key, please make use of our License-Key Recovery Tool.

Select the license key and press the key combination "Command" + C, so that you can copy it. To paste the license key into the input field of the installer, press the key combination "Command" + V.

This picture shows an example of what the setup application looks like after the license key has been inserted. The license key consists mainly of letters and numbers. For some products it also contains the email address and special characters. In the product delivery email, the license key is a separate block of monospace characters. (The license key on this screenshot is generated for demonstration purposes only and does not work).

The correct plugin paths for VST, VST3 and AAX plugin formats are pre-configured automatically. If you want, you can change them manually, but that is not recommended. Press "Install Now!" and confirm the installation settings.

Open the zip-File and double-click on the containing setup executable-file.

The unpacking process may take a while. Once it's over, you'll see a Windows notification asking "Do you want to allow this app to make changes to your device?" Please select YES.

Please click on the "I agree" button if you agree to the "License and Legal Information".

If this is a first-time installation, the license key will be requested at this point. First, copy the license key from the mail you received after purchasing the software. If you can't find your license key, please make use of our License-Key Recovery Tool.

Select the license key and press the key combination "Control" + C, so that you can copy it. To paste the license key into the input field of the installer, press the key combination "Control" + V.

Choose the correct plugin paths for VST, VST3 and AAX plugin formats. If you are not sure where the plugin directory of your DAW software is located, please look into the manual, or use the settings dialog of your DAW. Please make sure that the host is using the same architecture (32bit/64bit) as the plugin.

Download the installation package and double-click on the containing PKG File, then click on:

"Continue" -> "Install"

The custom de-installation process starts afterwards.

Accept the license agreement and click on the "Uninstall"-button at the top right corner. To finalize the process, click the "Uninstall Now!" button.

Open the setup-application, accept the license agreement and select "Uninstall" on the top right. To finalize the process, click the "Uninstall Now!" button.

The setup uninstall routine will remove all major files (plugin binaries and content library) from your computer. However, a few very small files, which store configuration properties like the license key, will reside on the machine. If you want to get rid of these files, you can find them in these directories:

/Users/username/Music/Audio Music Apps/SIR Audio Tools

%APPDATA%\SIR Audio Tools

Amplification before the clipping stage.
Increase the input gain to drive the signal into the clipping barrier.

Adjust the clipping level.

Amplification after clipping stage.
This is the main output-volume control. If you use the StandardCLIP as last plugin in your signal-chain, the computed clip-level (clip-fader * output gain fader, small red arrow) should be always 0 dBFS or lower. Because of the oversampling process, signal peaks higher than computed clip-level can occur.

The output gain assistant helps you find a reasonable headroom between the computed clip level (clip-fader * output gain fader, small red arrow) and the ceiling level.
Due to the oversampling process, some signal peaks can appear above the computed clip level. In order to avoid aliasing, it is important that the signal level never overshoots the ceiling level.
This assistant adjusts the output gain fader to the highest possible value, which guarantees that no output sample level will be higher than the ceiling level. Please play the loudest part of your project while the assistant is open.
Click on "Apply New Output Gain" to set the new output gain.

Use ceiling only if you want to use StandardCLIP as final plugin of your master chain, to prevent samples higher than a defined threshold which is usually under or equal 0 dBFS. The ceiling threshold should never be lower than the computed clip level (small red "CLIP" arrow), because the ceiling occurs after the oversampling stage and will create aliasing then. Usually the ceiling is just a few dBs higher than the computed clip level, to limit the few samples above output-gain which can occur because of the oversampling process.

StandardCLIP has a switch to select several different clipping modes. The different clipping modes, represent different clip curves (as you see in the diagram), depend on the setting it can sound more or less saturated. Each mode has a different chracterisic.

This is the default algorithm. This mode changes the signal over the entire dynamic range.

This mode has a slightly different characteristic. It compresses a dynamic range by half. A line in the function diagram shows the level at which the saturation begins. Dynamic integrity is maintained below this threshold.

25% - compresses the last 6 dB into 3 dB, and adds 3 dB
50% - compresses the last 12 dB into 6 dB, and adds 6 dB
75% - compresses the last 18 dB into 9 dB, and adds 9 dB
100% - compresses the last 24 dB into 12 dB, and adds 12 dB

Cuts the audio at the clipping level without soft-saturation. This is often used to trim a few peaks from the signal before it enters a limiter, for more transparent limiting.

Intensity of soft-clipping function. You can adjust seamlessly between hard-clipping and soft saturated clipping.

Use oversampling to minimize aliasing artifacts.
The higher the oversampling factor, the more you reduce aliasing caused by the clipping process. But it will also cause more CPU consumption.

To get an impression how the oversampling affects the processing, here are some frequency spectrum-graphs. A two kHz sinus-test signal, which is processed by StandardCLIP with different oversampling factor settings.

To open the advanced settings, click on the oversampling-button -> Expert settings, or use the Preferences button on the top -> Oversampling Configuration

The filter is an important part of the up and down-sampling process. You can choose between two filter-types:

• linear-phase (adds latency to the signal, but doesn’t induce phase shifting to the signal. This type is preferred for most applications (including mastering)
• use minimum-phase filter (adds no latency to the signal, but induces phase-shifting to the signal) for live usage

This can be used to have a higher oversampling factor while bouncing (whether or not this is supported, depends on the host). When using an offline oversampling factor, which differs from the online oversampling factor, the online oversampling factor has to be at least 2. This is important for various reasons. (Among other things, online/offline have to share the same latency setting)
This function has been successfully tested with:

• Pro Tools 12 (File -> Bounce To -> Disk), the „AudioSuite“ clip rendering function from the menu still uses the online oversampling factor
• Logic Pro X (File -> Bounce -> Project or Section)
• Cubase 8 (File -> Export -> Audio Mixdown)
• Ableton 11 (File -> Export Audio/Video)

The lower the filter-cut off the less harmonics above Nyquist-frequency will cause aliasing, but the more effect on the signal the filter has.

Generally speaking the steeper the filter is, the better the oversampling result will be. But keep in mind that bigger filter-kernels also cause more latency, CPU consumption and potential pre-ringing artifacts in the transitional region. On the other hand, bigger filter-kernels have a smaller transition region.

The higher the order, the steeper the oversampling filter, but also the higher the CPU-consumption. Also there will be more phase-shifting in the transitional region.

This button resets all oversampling related settings to their default value.

Some older host-software will not open the plugin with the right number of channels, which will waste CPU-power. With this option you can adjust the right number of channels the plugin should use. This setting is no longer necessary with modern DAWs.

To save CPU-consumption the silence bypass will be automatically activated if the input audio level is below -190 dB. You can turn off this behavior via the options menu.

Adjust the whole plugin-GUI size.

StandardCLIP visualizes the clipping function as logarithmic and linear function plot. To switch between the linear and logarithmic function plot, click on it. A small red point in the diagram shows the current peak-value.

This is a preview of how the output or input waveform looks like, using the maximum level of all channels as input source.

The output preview includes the pre-reduction level (red), relative to the output-level (white). If you use no soft-clipping the maximum output-level (white) will match the clipping level (If output gain is 0dB). The more soft-clipping is used, the higher the pre-reduction level (red), because of the inclusive amplification of the saturation function.

The thin line represents the 0dB boundary.

You are able to switch between a full waveform preview or a half waveform preview, for a more precise overview.

Its also possible to switch between slow and fast scrolling.

Shows the all-time maximum peak and maximum RMS level. You can reset both levels with a mouse click.

This is a peak-meter, a peak-hold meter and an RMS-meter. Simply control the input/output gain of your signal. The peak meter indicates visually the instantaneous level of an audio signal. A big red block on the top signals the output going above 0 dBFS. This is especially important if you use StandardCLIP as the final plugin in your mastering chain.

The RMS value is used to measure the perceived loudness of the signal. Percussive signals have a higher distance between peak and RMS. Change the range of the scale via the options menu.

The Gain Difference Meter shows the RMS (red, Root Mean Square) or peak (green) difference between the input and output of the oversampled clipping process. The output gain and ceiling level have no effect on this display. Change the minimum and maximum scale values via the options menu.

Special thanks to all beta-testers and to Matthias Kahlmann and Conor Boyle for having helped me with the manual.