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8.5 TDcontroller REFERENCE GUIDE
8.5.1 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 / Subbass Cross-Over
From input signals summed together, the resulting mono signal is low-pass filtered to feed the SubBass
channel. When the channel is turned on (Subbass On), main channels (Left & Right) high-pass filters
are reconfigured to filter out signal components below the crossover frequency. Slopes and other filter
characteristics are optimized using techniques optimized for the actual acoustical data of each driver.
8.5.2 Servo Control section
Servo control of the PS TDcontroller is intended to work with amplifier return signals present at the
Sense inputs (monitored by front panel LEDs).
VCAs and VCEQs
Each of the 3 Audio channels (Left, Right and SubBass) contains two voltage controlled elements
driven by servo signals:
•
One operates on the whole frequency range (wide band VCA).
•
The other elements work selectively as dynamic equalizers (LF-VCEQ & HF-VCEQ).
Depending on the nature and origin of the servo signals, either one or the 3 combined elements is used
to process the Audio signal. This feature allows more efficient processing while reducing audible effects.
