manual/include/bundled-plugins-filters.html

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<h2 id="ace-compressor">ACE Compressor</h2>
<p>
The job of this filter is to make an audio recording perceivably louder by
reducing the dynamic range, that is, the difference between the loudest and
the quietest parts. ACE compressor lowers the volume of loud sounds above a
user-defined threshold measured in dB, then the gain of all the sound gets
increased to make up for lost loudness.
</p>
<figure>
<img style="width:50%;" src="/images/a-compressor.png" alt="ACE Compressor">
<figcaption>
ACE Compressor
</figcaption>
</figure>
<p>Available settings are:</p>
<ul>
<li><strong>Threshold</strong>. This setting defines the loudness at which the compressor
will start working.</li>
<li><strong>Knee</strong>. Whether the transition from uncompressed to compressed is soft
or hard. The effect is more noticeable with larger ratios.</li>
<li><strong>Ratio</strong>. How much the gain is reduced above a certain threshold.
If the ratio is e.g. 5:1, 5dB will become 1dB.</li>
<li><strong>Attack</strong>. How long (in ms) it takes to apply maximum compression.</li>
<li><strong>Release</strong>. How long it takes to return to zero compression.</li>
<li><strong>Makeup Gain</strong>. How much the overall level should be increased after
reducing loud sections.</li>
<li><strong>Sidechain</strong>. Whether the effect should be activate by the loadness
of audio signal in another track passing a certain threshold.</li>
</ul>
<p>The plugin also provides an opt-out inline display that shows input signal,
threshold, and resulting gain reduction:</p>
<figure>
<img style="width:75%;" src="/images/a-compressor-inline.png" alt="Inline ACE Compressor display">
<figcaption>
Inline display
</figcaption>
</figure>
<h2 id="ace-expander">ACE Expander</h2>
<p>
Contrary to compressors, expanders increase the dynamic range either
by making quite sounds quieter (downward expanders) or by making loud
sounds louder (upward expanders). <em>ACE Expander</em> is a downward
expander. It reduces the level of a signal below a user-defined threshold
by user-defined ratio, then optionally increases the overall gain to make
up for lost loudness.
</p>
<figure>
<img style="width:50%;" src="/images/a-expander.png" alt="ACE Expander">
<figcaption>
ACE Expander
</figcaption>
</figure>
<p>Available settings are:</p>
<ul>
<li><strong>Attack</strong>. How long (in ms) it takes to apply maximum
reduction of the quiet sections.</li>
<li><strong>Release</strong>. How long it takes to stop reducing the quiet
signal at all.</li>
<li><strong>Knee</strong>. Whether the transition from non-reduced to
reduced signal level is soft or hard. The effect is more noticeable with
larger ratios.</li>
<li><strong>Ratio</strong>. How much the gain is reduced below a certain
threshold. If the ratio is e.g. 3:1, -10dB will become -30dB.</li>
<li><strong>Threshold</strong>. The loudness at which the expander will
start working.</li>
<li><strong>Makeup Gain</strong>. How much the overall level should be
increased after reducing quiet sections.</li>
<li><strong>Sidechain</strong>. Whether the effect should be activated by
the loudness of audio signal in another track passing a certain threshold.</li>
</ul>
<p>
<em>ACE Expander</em> also comes with an inline widget for mixer channels
that displays the input signal level, the threshold, and the amount of
reduced signal.
</p>
<figure>
<img style="width:75%;" src="/images/a-expander-inline.png" alt="Inline ACE Expander display">
<figcaption>
Inline display
</figcaption>
</figure>
<h2 id="ace-delay">ACE Delay</h2>
<p>
Delay effects repeat original signal after a user-defined interval.
In <em>ACE Delay</em>, the interval is calculated from the tempo and the
divisor&nbsp;&mdash; a musical time unit like a 1/4th note or a dotted 1/16th note.
When using a delay in music production, it's usually best to sync to
project's tempo, especially if there are tempo ramps in a song.
</p>
<figure>
<img style="width:50%;" src="/images/a-delay.png" alt="ACE Delay">
<figcaption>
ACE Delay
</figcaption>
</figure>
<p>Available settings are:</p>
<ul>
<li><strong>Tempo</strong>. Amount of beats per minute.</li>
<li><strong>Sync</strong>. This toggles the syncing to project&#39;s
tempo.</li>
<li><strong>Divisor</strong>. The interval between the original sound and
its delayed copy, expressed in whole or fractional notes
(1/4th, 1/8th etc.)</li>
<li><strong>Dotted</strong>. When enabled, adds half the divisor unit
to the delay interval, e.g. a 1/8th note becomes a dotted 1/8th note.</li>
<li><strong>Time</strong>. The final delay time expressed in milliseconds.</li>
<li><strong>Feedback</strong>. How much of the processed signal goes back
into the delay effect&#39;s input.</li>
<li><strong>Low-Pass Filter (LPF)</strong>. This helps simulating analog
delay effects where the repeated signal gets dull.</li>
<li><strong>Invert</strong>. This option inverts the polarity of the output
signal.</li>
<li><strong>Output Gain</strong>. Reduces or increases the level of the
output signal.</li>
</ul>
<h2 id="ace-reverb">ACE Reverb</h2>
<p>A reverb effect emulates sound waves reflecting off the walls in a closed
space which could be a a small room or a cathedral. The effect is usually
applied to a &quot;dry&quot; audio recording, that is, one typically made in a
very small room with acoustic absorption treatment so that there are little-to-no
reflections. That way, a reverb effect makes the most sense as it gives you a
clean slate and more freedom to shape your sound.</p>
<p>The <em>ACE Reverb</em> effect is a very simple one, based on early research to
artificial reverberation by Manfred Schroeder and Ben Logan (<a href="https://ccrma.stanford.edu/~jos/pasp/Schroeder_Reverberators.html">see
here</a> for technical details). There are just two controls:</p>
<ul>
<li><strong>Blend</strong>. This control changes the mix in favour
of either &quot;dry&quot; unprocessed signal that is being fed into the
effect or the &quot;wet&quot; processed by the effect. 0 means you only
hear the unprocessed signal, 1 mean you only hear the processed signal.</li>
<li><strong>Room Size</strong>. This control changes the size of the virtual
room and therefore the amount of decay.</li>
</ul>
<h2 id="ace-high-low-pass-filter">ACE High/Low Pass Filter</h2>
<p>
High-pass and low-pass filters reduce the signal below and above a certain
frequency respectively. The <em>ACE High/Low Pass</em> filter combines the
two filters in one.
</p>
<figure>
<img style="width:50%;" src="/images/a-lpf-hpf.png" alt="Inline ACE High/Low Pass Filter display">
<figcaption>
ACE High/Low Pass Filter
</figcaption>
</figure>
<p>Each of the two bandpass filters has three controls:</p>
<ul>
<li><strong>Steepness</strong>. How much the filter reduces the signal per
each step (12dB/oct to 48dB/oct). Setting steepness to <em>Off</em>
disables the filter entirely.</li>
<li><strong>Cutoff frequency</strong>. The base frequency where the filter
begins cutting off the data.</li>
<li><strong>Resonance</strong>. How much the signal around the cutoff
frequency is suppressed (lower values) or emphasized (higher values).
The plugins defaults to 0.707 which roughly translates to "do nothing".</li>
</ul>
<p>
The plugin also comes with an inline display visualizing the effect that
the filters have.
</p>
<figure>
<img style="width:75%;" src="/images/a-lpf-hpf-inline.png" alt="Inline ACE High/Low Pass Filter display">
<figcaption>
Inline display
</figcaption>
</figure>
<h2 id="ace-eq">ACE EQ</h2>
<p>
Equalizers are commonly used to shape the sound, change timbre of an
instrument and generally help it sit better in a mix.
</p>
<p>
ACE EQ is a simple 4-band equalizer with a low and a high shelves.
All bands and shelves are optional and can be disabled by clicking on
the outer border of respective parameters boxes.
</p>
<p>
For each band it's possible to set the base frequency, the gain level,
and the bandwidth. The latter defines how much frequencies around the base
frequency are affected by the gain adjustment. In an example below, the first
band has the narrowest bandwidth of 0.1, and the third band has the default
banwidth of 1.0. While both bands have a gain of +10dB, the first one is very
narrow, but the third one is wide enough so that changes begin affecting
frequencies that belong to neighboring frequency bands.
</p>
<figure>
<img style="width:50%;" src="/images/a-eq-bandwidths.png" alt="ACE EQ bandwidths">
<figcaption>
ACE EQ bandwidths
</figcaption>
</figure>
<p>There are three ways to adjust both frequency, gain, and bandwidth:</p>
<ol>
<li><p><strong>Directly on the diagram</strong>. Dragging the band mark
(1 through 4) left and right changes the frequency, dragging it up and down
changes the gain. Scrolling the mouse wheel over the band mark changes the
bandwidth.</p>
</li>
<li><p><strong>In the bottom parameters boxes</strong>. Scrolling the mouse
wheel over a setting changes its value. This is also where and how the master
output can be adjusted.</p>
</li>
<li><p><strong>Numerically via the generic plugin UI</strong>. This user
interface can be displayed by right-clicking on the plugin in the mixer
channel and choosing the <em>Edit with generic controls…</em> option.</p>
</li>
</ol>
<p>ACE EQ also provides an inline display for mixer channels:</p>
<figure>
<img style="width:75%;" src="/images/a-eq-inline.png" alt="Inline ACE EQ display">
<figcaption>
Inline display
</figcaption>
</figure>
<h2 id="ace-notch-bank">ACE Notch Bank</h2>
<p>
This is a very basic harmonic filter that suppresses a user-defined number
of harmonics (stages) starting at a user-defined base frequency. The filter
is mostly useful as a demonstration for Ardour's built-in biquadratic filter
that can be used in Lua scripts.
</p>
<figure>
<img style="width:50%;" src="/images/ace-notch-bank.png" alt="ACE Notch bank">
<figcaption>
ACE Notch Bank
</figcaption>
</figure>
<p>
An example below is a sine wave at 120Hz with added harmonics, each
at a lower magnitude than the previous one. Applying the ACE Notch Bank
filter starting at 120Hz with 8 stages completeles silences the signal
(the purple line for processed signal is not even visible):
</p>
<figure>
<img style="width:75%;" src="/images/ace-notch-bank-before-after.png" alt="Results of applying ACE Notch Bank">
<figcaption>
Results of applying ACE Notch Bank
</figcaption>
</figure>