sheet ALC4-ST_def
technical specifications ALC4(-ST)
The ALC4 is a combination of a speaker controller
and power amplifier. The ALC units are designed
to guarantee the best speaker drive, with maximum
sound quality and operating reliability.
The amplifier stage consists of a 2x 2kW (2 ohms
RMS) Class G design. The combination of double
conventional power supplies with a massive 400
Joules capacitor bank makes the ALC4 deliver
dynamic and sustained very high power output.
The controller section consist of several stages; On
the input stage the SDP circuit and on the output
stage the SIS circuit ensure easy, reliable and optimised speaker response.
SDP Speaker Drive Processor™
The SDP circuit can be seen as the “brain” of
the amplifier. By means of speaker-specific modules, that are located in 2 front-accessible slots,
the characteristics of the connected speaker are
loaded into the amplifier. With this, the amplifier
is “tailor-made” to the speaker, regardless of the
power output specifications of the amplifier. This
can be done with either the analogue SDP modules, or the DDP digital drive processor™.
Multiple processing functions are operating at the
same time:
Protection: The speaker is protected against
damage from over-excursion and power overload.
Due to Alcons Audio continuous R&D, all specifications are subject to change without prior notice.
Dedicated filtering: The fixed cross-over settings
cater for the best system performance.
Optimised power response: The SDP module
adjusts the RMS and peak values to the speakers
capacity, giving maximum system power output.
System equalising: This circuit equalises the
system response, with utilising the maximum
component efficiency. This results in higher overall system sensitivity and reduces the need for
active filtering while offering efficient amplifier
usage (passive system).
The DDP™ also offers level control, mute and a
user-controllable 4-band parametric equaliser and
(up to) 340ms delay.
By placing the modules in the slots, the SDP circuit is automatically activated, without the need for
changing switches/jumpers (“plug&play”). Taking
out the modules, bypasses the SDP circuit and converts the ALC into a “standard” stereo power amplifier, for use with traditional speaker systems.
SIS Signal Integrity Sensing™
data port
The SIS circuit extends the control-loop of the
amplifier to the input terminals of the speaker, by
means of two additional (sense) wires, compensating for the influence of speaker cables.
SIS offers cable-length independent damping,
resulting in a virtually infinite damping under all
conditions (up to an almost immeasurable value of
over 10.000).
The Data port located on the back of the unit, is the
connection for ALC remote-control function.
Furthermore SIS maintains signal level by detecting
the amount of signal loss at the end of the cable.
As a result of pre-compensation of the self-induction of the cable, non-linear harmonic + intermodulation distortion are reduced substantially by SIS,
while offering a more linear frequency response
(reduced linear distortion).
SIS offers a significantly tighter and more accurate
low and mid response. Without connection of the 2
extra sense wires, the ALC units can also be used
as any normal amplifier in combination with nonSIS speaker systems.
ATCM Advanced Thermal and
Clip Management™
ATCM has a number of sensors within the amplifier, that constantly monitor both operating temperature, in and output signal. For the temperature
section of ATCM, the input signal stage is regulated
when dangerous temperature increase is sensed;
In this way, the amplifier stays in operation, instead
of switching into “heat protection”.
Through the 15-pin D-connection to remote processor, function includes indication of operating
status; Temperature per channel, bridge/parallel
mode, AC power level, output power read-out,
impedance check for speaker damage, clip/protect
indication, level control, etc.
For cinema application, the Data-port is completely
compatible with existing D-pin connected cinema
monitors. In that application, the signal in/out connection also caters for reduced set-up and installation time and standardised in/output levels.
The ALC4 amplifier has in addition a number of
user-friendly features, that make the ALC the ideal
Alcons speaker companion.
All relevant switches (bridge and parallel input) are
conveniently located on the front behind the cover.
When switching to bridge-mode, there is no need
for using different SDP modules. Furthermore, in
bridge-mode, the amp is controlled by only one
The parallel-mode input switch: With this switch,
the input of channel 1 is also send to input channel 2. Therefore there is no need for external “loop
wires” (Y-cables) from link output 1 into input 2.
The clip limiter section reduces the signal input
level to the safest maximum level, when continuous clipping is detected. In this way the high frequency drivers are protected against damage from
harmonics and also the amplifier remains cooler.
The limiter has a “Soft-knee clipping characteristic”
for inaudible, but safe operation.
ATCM offers ease-of-operation and guarantees
operation under all conditions.
Due to Alcons Audio continuous R&D, all specifications are subject to change without prior notice.
evolutionary audio solutionsTM
technical specifications ALC4(-ST)
The ALC features PowerCon™ AC power connection, for quick and efficient exchange of rack
mounted ALC’s.
The ALC4-ST is the “stealth” version of the ALC4.
It has potentiometers that are located behind the
front lid, preventing unwanted changing of gainsettings.
dimensional drawing
technical specifications
Input sensitivity
2,1 Vrms(+8.6dBu) for full RMS
power in 4 ohms
Max. input level
Input impedance
20k Ohm
Frequency range
@ 250W into 8 ohms
10 Hz .. 20kHz +0..-0.1dB
10 Hz .. 50kHz.+0..-3dB
Channel separation
32dB (40x)
>75 dB @ 1kHz., 250W into 8 ohms
>50 dB @ 20kHz., 250W into 8 ohms
Total harmonic distortion
<0.007% @ 1kHz., 250W into 8 ohms
<0.2% @ 20kHz., 250W into 8 ohms
<0.04% @ 2kHz.-10kHz.,
250W into 8 ohms
Signal-to-noise ratio
Slew rate
Damping factor
Output power (RMS/peak)
>111dB A-weighted
>40V /uS
10.000 @ 1kHz., 8 ohms
@ 1kHz. < 0,5% THD
2x 1150W / 2x 1270W @ 8 ohms
2x 1720W / 2x 1960W @ 4 ohms
2x 2250W / 2x 2760W @ 2 ohms
Output power bridge mode
@ 1kHz. < 0,5% THD
1x 2300W / 1x 2540W @ 16 ohms
1x 3440W / 1x 3920W @ 8 ohms
1x 4500W / 1x 5520W @ 4 ohms
Main supply voltage
stated at rear of amplifier
Power consumption
75 VA (standby)
2200 VA 1/8 of maximum output
power pink noise in 2 ohms
A : Alcons Audio B.V.
De Corantijn 69
1689 AN Zwaag
The Netherlands
[email protected]
+31 (0)229 28 30 90
+31 (0)229 28 30 99
Weight (approx.)
19 inch rack mount, 3 HU,
457mm/18 in. deep behind mounting
surface, without connectors
Dimensions (HxWxD)
132 x 482 x 457 mm / 5.2 x 19 x 18 in.
without connectors and rack handles
Due to Alcons Audio continuous R&D, all specifications are subject to change without prior notice.
35,4kg (78lb)
3 years
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