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<font size="+2" color=#004060><b>TAP</b>-plugins</font><br>
<font color=#004060>Tom's Audio Processing plugins</font><br>
<font size="-1" color=#004060><i>for audio engineering on the Linux
platform</i></font>
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<a href="../ladspa.html">[ LADSPA plugins ]</a>
<a href="../reverbed.html">[ TAP Reverb Editor ]</a>
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<a href="releases.html">[ Releases ]</a>
<a href="general.html">[ General Info ]</a>
<a href="manuals.html">[ Plugin Manuals ]</a>
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<blockquote>
<a href="autopan.html">[ TAP AutoPanner ]</a>
<a href="chorusflanger.html">[ TAP Chorus/Flanger ]</a>
<a href="deesser.html">[ TAP DeEsser ]</a>
<a href="dynamics.html">[ TAP Dynamics (Mono & Stereo) ]</a>
<a href="eq.html">[ TAP Equalizer and TAP Equalizer/BW ]</a>
<a href="doubler.html">[ TAP Fractal Doubler ]</a>
<a href="pinknoise.html">[ TAP Pink/Fractal Noise ]</a>
<a href="pitch.html">[ TAP Pitch Shifter ]</a>
<a href="reflector.html">[ TAP Reflector ]</a>
<a href="reverb.html">[ TAP Reverberator ]</a>
<a href="rotspeak.html">[ TAP Rotary Speaker ]</a>
<a href="limiter.html">[ TAP Scaling Limiter ]</a>
<a href="sigmoid.html">[ TAP Sigmoid Booster ]</a>
<a href="echo.html">[ TAP Stereo Echo ]</a>
<a href="tremolo.html">[ TAP Tremolo ]</a>
<a href="tubewarmth.html">[ TAP TubeWarmth ]</a>
<a href="vibrato.html">[ TAP Vibrato ]</a>
</blockquote>
<h2>TAP Equalizer</h2>
and <b>TAP Equalizer/BW</b><br><br><br>
<img src="tap_eq.png" alt="[TAP Equalizer GUI as shown in Ardour]">
<p>
This plugin is an 8-band equalizer with adjustable band center
frequencies. It allows you to make precise adjustments to the tonal
coloration of your tracks. The design and code of this plugin is based
on that of the DJ EQ plugin by Steve Harris, which can be downloaded
(among lots of other useful plugins) from <a
href="http://plugin.org.uk">http://plugin.org.uk</a>.
</p>
<h3>General information</h3>
<table cellspacing="0" cellpadding="5" border="1">
<tr><th align="left">Unique ID</th><td>2141 [1]</td>
<tr><th align="left">I/O ports</th><td>1 input / 1 output</td>
<tr><th align="left">CPU usage (44.1 kHz)</th><td>4.0% max. (see Notes)</td>
<tr><th align="left">CPU usage (96 kHz)</th><td>8.8% max. (see Notes)</td>
<tr><th align="left">Hard RT Capable</th><td>No</td></tr>
<tr><th align="left">In-place operation</th><td>Supported</td>
<tr><th align="left">run_adding() function</th><td>Provided</td>
</table>
[1] Unique ID for TAP Equalizer/BW is 2151.<br>
<h3>Usage tips</h3>
<p>
The TAP Equalizer is a powerful tool in the hands of a skilled mixing
engineer. The main use of the band frequency controls is to allow to
"tune in" various resonance frequencies of musical instruments, and by
adjusting the gain of these frequencies, to alter the tone of an
instrument in a desired way. For example, the sound of kick drums
consists of two mainly distinct parts: the energy is mainly
concentrated around 80-100 Hz (this is the "boom" part), but there is
another component at around 2.5 kHz which gives the "edge" of the
sound. By adjusting the level of these components, different tonal
results can be achieved.
</p>
<p>
While listening to the track (soloed or not) with this plugin applied,
raise the gain of the appropriate band (that is, the one with the
closest default frequency) by an amount of about 6-12 dB and adjust
the frequency control of the same band until you feel that you "got"
that particular resonant tone of the instrument. Then play around with
the gain settings to achieve the tonal balance you are going for.
</p>
<p>
Since you only pay (in terms of CPU usage) for the bands you actually
use, it is recommended that you set the gains of unneeded bands to
exactly 0 dB (you can do this in Ardour quickly by shift+clicking on
the control fader) since processing of bands with 0 dB gain will be
skipped. So don't leave a band gain at -0.12 dB unless you really need
that -0.12 dB to be there.
</p>
<h3>Summary of user controls</h3>
<table cellspacing="0" cellpadding="5" border="1">
<tr><th>name</th><th>min. value</th><th>default value</th><th>max. value</th></tr>
<tr align="center"><td>Band 1 Freq [Hz]</td>
<td>40</td>
<td>100</td>
<td>280</td></tr>
<tr align="center"><td>Band 1 Gain [dB]</td>
<td>-50</td>
<td>0</td>
<td>+20</td></tr>
<tr align="center"><td>Band 1 Bandwidth [octaves] [2]</td>
<td>0.1</td>
<td>1</td>
<td>5</td></tr>
<tr align="center"><td>Band 2 Freq [Hz]</td>
<td>100</td>
<td>200</td>
<td>500</td></tr>
<tr align="center"><td>Band 2 Gain [dB]</td>
<td>-50</td>
<td>0</td>
<td>+20</td></tr>
<tr align="center"><td>Band 2 Bandwidth [octaves] [2]</td>
<td>0.1</td>
<td>1</td>
<td>5</td></tr>
<tr align="center"><td>Band 3 Freq [Hz]</td>
<td>200</td>
<td>400</td>
<td>1000</td></tr>
<tr align="center"><td>Band 3 Gain [dB]</td>
<td>-50</td>
<td>0</td>
<td>+20</td></tr>
<tr align="center"><td>Band 3 Bandwidth [octaves] [2]</td>
<td>0.1</td>
<td>1</td>
<td>5</td></tr>
<tr align="center"><td>Band 4 Freq [Hz]</td>
<td>400</td>
<td>1000</td>
<td>2800</td></tr>
<tr align="center"><td>Band 4 Gain [dB]</td>
<td>-50</td>
<td>0</td>
<td>+20</td></tr>
<tr align="center"><td>Band 4 Bandwidth [octaves] [2]</td>
<td>0.1</td>
<td>1</td>
<td>5</td></tr>
<tr align="center"><td>Band 5 Freq [Hz]</td>
<td>1000</td>
<td>3000</td>
<td>5000</td></tr>
<tr align="center"><td>Band 5 Gain [dB]</td>
<td>-50</td>
<td>0</td>
<td>+20</td></tr>
<tr align="center"><td>Band 5 Bandwidth [octaves] [2]</td>
<td>0.1</td>
<td>1</td>
<td>5</td></tr>
<tr align="center"><td>Band 6 Freq [Hz]</td>
<td>3000</td>
<td>6000</td>
<td>9000</td></tr>
<tr align="center"><td>Band 6 Gain [dB]</td>
<td>-50</td>
<td>0</td>
<td>+20</td></tr>
<tr align="center"><td>Band 6 Bandwidth [octaves] [2]</td>
<td>0.1</td>
<td>1</td>
<td>5</td></tr>
<tr align="center"><td>Band 7 Freq [Hz]</td>
<td>6000</td>
<td>12000</td>
<td>18000</td></tr>
<tr align="center"><td>Band 7 Gain [dB]</td>
<td>-50</td>
<td>0</td>
<td>+20</td></tr>
<tr align="center"><td>Band 7 Bandwidth [octaves] [2]</td>
<td>0.1</td>
<td>1</td>
<td>5</td></tr>
<tr align="center"><td>Band 8 Freq [Hz]</td>
<td>10000</td>
<td>15000</td>
<td>20000</td></tr>
<tr align="center"><td>Band 8 Gain [dB]</td>
<td>-50</td>
<td>0</td>
<td>+20</td></tr>
<tr align="center"><td>Band 8 Bandwidth [octaves] [2]</td>
<td>0.1</td>
<td>1</td>
<td>5</td></tr>
</table>
[2] These controls appear only in the TAP Equalizer/BW implementation.<br>
<h3>Notes</h3>
<p>
This plugin consists of 8 Peaking EQ filters (which are IIR filters
with an order of two). Filter coefficients are re-computed if and only
if the user changed a control value since the last buffer
run. Furthermore, those filters that are left at 0 dB gain are not
processed at all. For this reason, the CPU demand of this plugin is a
function of the control settings, hence it is not hard RT
capable. However, the CPU demand is still somewhat predictable: moving
all gains away from 0 dB will switch every filter on. The CPU usage
measured in this state will not increase significantly when filter
coefficients are re-computed in response to a changed control. Of
course, if the user sets a gain back to 0 dB, that filter will be
switched off, freeing CPU power. The CPU usage values displayed in the
above table were measured with all filters working.
</p>
<p>
The bandwidth of the Peaking EQ filters is fixed to 1 octave in the
TAP Equalizer implementation. However, because setting individual
bandwidth values may be needed in certain cases, another
implementation called TAP Equalizer/BW is also provided. Using that
plugin, you can set the bandwidth of every filter between 0.1 and 5
octaves. The reason for keeping TAP Equalizer around as well is that
you don't always need the ability to set bandwidth values, and TAP
Equalizer/BW has a large amount of controls which may be disturbing in
this case.
</p>
<p>
Below you can see a Bode diagram of the filter that makes up this
plugin. The three frequencies are 100 Hz, 1 kHz and 10 kHz, with gain
values of -20 and +20 dB and a sampling rate of 44.1 kHz. Bandwidth
was set to 1 octave (which is the default). This plot is also
available as an <a href="tap_eq_bode.eps">EPS file</a>.
</p>
<img src="tap_eq_bode.png" alt="[TAP Equalizer filter Bode diagram]">
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