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audio engineering on the Linux platform.">
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<meta name="keywords" content="TAP-plugins TAP Reverb Editor
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Reverberator Equalizer EQ Vibrato Tremolo Echo Tom Szilagyi LADSPA
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JACK Plugin Linux Audio">
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<meta name="author" content="Tom Szilagyi">
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<font size="+2" color=#004060><b>TAP</b>-plugins</font><br>
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<font color=#004060>Tom's Audio Processing plugins</font><br>
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<font size="-1" color=#004060><i>for audio engineering on the Linux
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<a href="../index.html">[ Home ]</a>
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<a href="../ladspa.html">[ LADSPA plugins ]</a>
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<a href="../reverbed.html">[ TAP Reverb Editor ]</a>
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<a href="releases.html">[ Releases ]</a>
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<a href="general.html">[ General Info ]</a>
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<a href="manuals.html">[ Plugin Manuals ]</a>
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<a href="deesser.html">[ TAP DeEsser ]</a>
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<a href="dynamics.html">[ TAP Dynamics (Mono & Stereo) ]</a>
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<a href="eq.html">[ TAP Equalizer and TAP Equalizer/BW ]</a>
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<a href="doubler.html">[ TAP Fractal Doubler ]</a>
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<a href="pinknoise.html">[ TAP Pink/Fractal Noise ]</a>
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<a href="pitch.html">[ TAP Pitch Shifter ]</a>
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<a href="reflector.html">[ TAP Reflector ]</a>
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<a href="reverb.html">[ TAP Reverberator ]</a>
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<a href="rotspeak.html">[ TAP Rotary Speaker ]</a>
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<a href="limiter.html">[ TAP Scaling Limiter ]</a>
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<a href="sigmoid.html">[ TAP Sigmoid Booster ]</a>
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<a href="echo.html">[ TAP Stereo Echo ]</a>
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<a href="tremolo.html">[ TAP Tremolo ]</a>
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<a href="tubewarmth.html">[ TAP TubeWarmth ]</a>
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<a href="vibrato.html">[ TAP Vibrato ]</a>
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<h2>TAP Reverberator</h2>
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<img src="tap_reverb.png" alt="[TAP Reverberator GUI as shown in Ardour]">
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<b>TAP Reverberator</b> is unique among reverberators freely available
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on the Linux platform. It supports creating no less than 43
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reverberation effects, but its design permits this to be extended even
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further by the user, without doing any actual programming. Please take
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a look at <a href="../reverbed.html">TAP Reverb Editor</a>, a separate
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JACK application for more information about this.
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The design is based on the comb/allpass filter model. Comb filters
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create early reflections and allpass filters add to this by creating a
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dense reverberation effect. The output of the set of comb and allpass
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filters (also called the reverberator chamber) is processed further by
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sending it through a bandpass filter. The resulting band-limited
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reverberation is very similar to the natural reverberation that occurs
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in acoustic rooms. To achieve an even more natural-sounding effect,
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all comb filters have high-frequency compensation in their feedback
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loop. This is to model that the reflection ratio of acoustic surfaces
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is the function of frequency: higher frequencies are attenuated more,
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and thus decay time of higher frequency components is significantly
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To enhance the reverberation sound even further, a special option
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called <i>Enhanced Stereo</i> is provided. When turned on (which is
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the default), it results in an added spatial spread of the reverb
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sound. This feature is most noticeable when applying the plugin to
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mono tracks: the sound of these tracks will "open up" in space.
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<h3>General information</h3>
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<table cellspacing="0" cellpadding="5" border="1">
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<tr><th align="left">Unique ID</th><td>2142</td>
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<tr><th align="left">I/O ports</th><td>2 inputs / 2 outputs</td>
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<tr><th align="left">CPU usage (44.1 kHz)</th><td>10.7% max. (see Notes)</td>
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<tr><th align="left">CPU usage (96 kHz)</th><td>24.8% max. (see Notes)</td>
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<tr><th align="left">Hard RT Capable</th><td>No</td></tr>
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<tr><th align="left">In-place operation</th><td>Supported</td>
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<tr><th align="left">run_adding() function</th><td>Provided</td>
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Despite the rather complex algorithm of this plugin, usage is
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relatively simple and the user is required to adjust only a limited
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number of global controls. This is achieved by defining "presets"
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called Reverb Types which actually mean larger sets of internal
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control values. When choosing a Reverb Type, the plugin loads all
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values associated to that type, and operates according to the newly
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loaded values. (If you want access to the internals of a Reverb Type,
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please check out <a href="../reverbed.html">TAP Reverb Editor</a>.)
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The most important global variable of the whole effect is the decay
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time. By adjusting this, you can create the feel of a larger acoustic
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space (set the decay to more than 2-3 seconds for this), as well as a
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"tight", relatively dry effect (for which you should set a much lower
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value). But you should be aware of the fact that not every
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reverberation type sounds good at any decay setting (see the table
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below for recommended decay values). For example, a <i>Room
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(Small)</i> will not sound too good when you set the decay to a very
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large value, and vice versa, a <i>Hall (Large)</i> will not sound
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optimal at very small decay settings. However, when choosing a more
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artificial type of reverberation (<i>Afterburn</i>,
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<i>Pulse Chamber (Reverse)</i> or <i>Warble Chamber</i>, for example),
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there is no "natural" decay time: set it as you see fit according to
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the effect you are trying to achieve.
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General advice about adjusting the dry and wet signal levels: the wet
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level should be about 3 to 15 dB lower than the dry level, according
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to the reverb type you are using. Of course if you want to create an
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artificial sounding effect, you can decrease the dry level, even down
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to -70 dB if that is what you want. However, one thing to know is that
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you shouldn't set the wet level to a very high value (generally not
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above 0 dB) because the output level of the plugin may become too high
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and you may overdrive the next plugin in the chain, or you may cause
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signal clipping in the master output of your multitrack. Furthermore,
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because the wet signal is added to the incoming dry signal, you should
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decrease the dry level as well by a few dB-s (and then set the wet
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level according to this) so as not to raise the overall loudness of
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Usually, when trying to create a natural-sounding reverberation
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effect, all components (comb filters, allpass filters, the bandpass
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filter and the stereo enhancement mode) should be switched
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on. However, to create artificial effects, it is possible to turn off
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any of these components. For example, if you only want the sound of
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multiple echoes, you can turn off everything but the comb filters; if
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you want to create a more unnatural, harsh effect, turn off the
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bandpass filter processing. (Also note that bandpass filters of
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different Reverb Types have different low and high cutoff frequencies,
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since this filtering also affects the nature of the reverberated sound
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very much.) Naturally, components that are switched off don't consume
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As mentioned earlier, not all Reverb Types sound good with any decay
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setting. The following table contains decay time settings adequate for
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particular Reverb Types. Decay times are shown in seconds. As a rule of
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thumb, when decay times are above 3 seconds, the "Wet Level" should be
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at least 6 or more decibels below the "Dry Level". <i>The values
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below are only general advice, and they are provided merely as a
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starting point for your experimentation. You are free to use any value
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that sounds good for your mix.</i>
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<h3>Recommended decay times</h3>
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<table cellspacing="0" cellpadding="5" border="1">
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<tr><th>Reverb Type</th><th>Decay Time</th></tr>
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<tr><td>AfterBurn</td><td>2.8</td></tr>
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<tr><td>AfterBurn (Long)</td><td>4.8</td></tr>
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<tr><td>Ambience</td><td>1.1</td></tr>
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<tr><td>Ambience (Thick)</td><td>1.2</td></tr>
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<tr><td>Ambience (Thick) - HD</td><td>1.2</td></tr>
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<tr><td>Cathedral</td><td>10</td></tr>
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<tr><td>Cathedral - HD</td><td>10</td></tr>
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<tr><td>Drum Chamber</td><td>3.6</td></tr>
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<tr><td>Garage</td><td>2.3</td></tr>
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<tr><td>Garage (Bright)</td><td>2.3</td></tr>
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<tr><td>Gymnasium</td><td>5.9</td></tr>
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<tr><td>Gymnasium (Bright)</td><td>5.9</td></tr>
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<tr><td>Gymnasium (Bright) - HD</td><td>5.9</td></tr>
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<tr><td>Hall (Small)</td><td>2.0</td></tr>
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<tr><td>Hall (Medium)</td><td>3.0</td></tr>
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<tr><td>Hall (Large)</td><td>5.1</td></tr>
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<tr><td>Hall (Large) - HD</td><td>5.1</td></tr>
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<tr><td>Plate (Small)</td><td>1.7</td></tr>
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<tr><td>Plate (Medium)</td><td>2.6</td></tr>
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<tr><td>Plate (Large)</td><td>5.7</td></tr>
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<tr><td>Plate (Large) - HD</td><td>5.7</td></tr>
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<tr><td>Pulse Chamber</td><td>3.1</td></tr>
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<tr><td>Pulse Chamber (Reverse)</td><td>3.1</td></tr>
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<tr><td>Resonator (96 ms)</td><td>4.0</td></tr>
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<tr><td>Resonator (152 ms)</td><td>4.2</td></tr>
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<tr><td>Resonator (208 ms)</td><td>5.1</td></tr>
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<tr><td>Room (Small)</td><td>1.9</td></tr>
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<tr><td>Room (Medium)</td><td>2.8</td></tr>
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<tr><td>Room (Large)</td><td>4.4</td></tr>
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<tr><td>Room (Large) - HD</td><td>4.4</td></tr>
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<tr><td>Slap Chamber</td><td>2.3</td></tr>
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<tr><td>Slap Chamber - HD</td><td>2.9</td></tr>
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<tr><td>Slap Chamber (Bright)</td><td>3.4</td></tr>
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<tr><td>Slap Chamber (Bright) - HD</td><td>3.7</td></tr>
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<tr><td>Smooth Hall (Small)</td><td>1.8</td></tr>
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<tr><td>Smooth Hall (Medium)</td><td>3.0</td></tr>
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<tr><td>Smooth Hall (Large)</td><td>5.9</td></tr>
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<tr><td>Smooth Hall (Large) - HD</td><td>5.9</td></tr>
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<tr><td>Vocal Plate</td><td>3.1</td></tr>
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<tr><td>Vocal Plate - HD</td><td>3.1</td></tr>
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<tr><td>Warble Chamber</td><td>4.0</td></tr>
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<tr><td>Warehouse</td><td>6.0</td></tr>
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<tr><td>Warehouse - HD</td><td>6.0</td></tr>
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<b>Q:</b> <i>What is that HD in the name of some Reverb Types?</i>
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<b>A:</b> HD stands for <i>High Density</i>. Reverb Types marked with
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this are enhanced versions of other types, for example <i>Hall (Large)
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- HD</i> is derived from <i>Hall (Large)</i>. Enhancement means
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additional comb and/or allpass filters, which result in an even
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smoother reverberation effect. However, more filters mean more CPU
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usage, so it's up to you to decide whether to choose them or not. If
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CPU usage is not a great concern, it is recommended to use the HD
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versions where available.
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<h3>Summary of user controls</h3>
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<table cellspacing="0" cellpadding="5" border="1">
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<tr><th>name</th><th>min. value</th><th>default value</th><th>max. value</th></tr>
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<tr align="center"><td>Decay [ms]</td>
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<tr align="center"><td>Dry Level [dB]</td>
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<tr align="center"><td>Wet Level [dB]</td>
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<tr align="center"><td>Comb Filters</td>
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<tr align="center"><td>Allpass Filters</td>
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<tr align="center"><td>Bandpass Filter</td>
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<tr align="center"><td>Enhanced Stereo</td>
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<tr align="center"><td>Reverb Type</td>
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The maximum number of filters is 20 combs and 20 allpass
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filters. Actually it is double this much because every filter exists
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in two instances for the two channels. This amount allows for the
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creation of very dense, very smooth-sounding Reverb Types.
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Comb filters are implemented as first-order IIR filters with a
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biquadratic low-pass filter in the feedback loop, which has its cutoff
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frequency determined by the frequency response parameter of the comb
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filter. Allpass filters are implemented as ordinary first-order IIR
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When <i>Enhanced Stereo</i> is enabled, parameters of the two
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instances of the same filter are set to slightly different values.
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Without this option, the two input channels are processed in the exact
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same way. It is absolutely recommended to turn this on when applying
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the plugin to mono tracks, but it is also useful on stereo tracks.
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Because the varying complexity of Reverb Types and the fact that
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options can be switched on/off individually, CPU usage is a function
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of user settings. For this reason, this plugin is not hard RT
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capable. The CPU usage was measured with all options turned on, and
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the Reverb Type set to <i>Ambience (Thick) - HD</i>, which is the most
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complex one at the moment. Other Reverb Types with fewer
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comb/allpass filters utilize proportionately less CPU.
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$Id: reverb.html,v 1.3 2004/08/17 13:05:16 tszilagyi Exp $
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doc/ladspa/reverb.html
