TDcontroller REFERENCE GUIDE
Linear section
The characteristics of the linear section are independent of signal level, as opposed to the servo control
functions described in next paragraph.
Subsonic and VHF filtering
Low and high-pass filters are used to remove signals out of the usable frequency range, eliminating sub-
and ultra-sonic components that could possibly degrade the performance of the Controller and amplifiers.
These filters are optimized to realize the overall target system response.
Equalizing acoustical response
This equalization section provides the required correction to obtain a flat system response, as the cabinets
are acoustically designed for maximum efficiency in the whole frequency range. Active rather than passive
attenuation allows amplifier voltages to be lowering for a given output SPL and therefore increases the
maximum SPL achievable with the same amplifier.
Active equalization also extends system bandpass, especially at low frequencies where acoustical
performance is limited by cabinet size.
PS / LSub Cross-Over
From input signals summed together, the resulting mono signal is low-pass filtered to feed the Sub-bass
channel. When the channel is turned on (LSub On), main channels (Left & Right) high-pass filters are
reconfigured to filter out signal components below the cross-over frequency. Slopes and other filter
characteristics are optimized using techniques optimized for the actual acoustical data of each driver.
Servo Control section
Servo control of the PS TDcontroller is normally intended to work with amplifier return signals present at
the Sense inputs (monitored by front panel LEDs).
(WARNING : the following paragraph does not apply to PS15TD MKII & PS10 TDcontrollers with serial
numbers below #361)
However, when no signal is detected on a Sense line, an internal signal is automatically substituted for the
actual amplifier signal at the input of the servo control path. This fall-back operation mode allows
protection to be maintained even when Sense lines are accidentally disconnected. It is emphasized that
this fall-back operation mode does not perform with the same accuracy and reliability as actual feedback,
and is intended to maintain some protection in accidental situations only.
VCAs and VCEQs
Each of the 3 Audio channels (Left, Right and Sub-bass) contains two voltage controlled elements driven
by servo signals :
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