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Sub-Bass GAIN control

This

GAIN

control is also

electronically located
behind the limiter circuit,
control range is
-15dB to +15dB.

Sub-Bass phase compensation

The Sub-Bass signal is derived from the lowpass signal by feeding
it through an additional lowpass filter, which, like every similar fil-
ter, produces an inherent phase deviation. This phase distortion
can be compensated for by activating the

LIN PHASE

switch,

which must be operated in the same way as the other switches on
the CCR 24. The yellow

MATCHED

LED indicates that the Sub-

Bass signal is now in phase with the other signals.

Limiter

The built-in limiter circuit keeps the internal signal levels below a
fixed value. When the Gain controls are properly adjusted accord-
ing to the maximum speaker wattage, the limiter circuit will effec-
tively protect your PA system against overload.

Input reference level setting

The CCR 24 is capable of working at two input reference level
standards, 0 dB and +6 dB, selectable by means of an internal
jumper. If you wish to switch to another input level, execute the
following steps in the given order:

•

Always unplug the unit from electrical power as your first step

•

Loosen the screws on the upper side of the unit and remove the

cover

•

Look for the jumper on the PCB board, it`s located at the left

front side (see picture)

•

Plug or unplug the jumper according to your desired input level

(see picture). Plugged jumper means +6 dB, unplugged jumper
0dB input level.

Hints for setting

Like with any other sound processing unit, alteration of the CCR 24
settings should always be approached carefully and with some
thought. When using your ear as a guide, keep in mind that the
human ear quickly adapts to a certain (not necessarily appropriate)
EQ curve and easily becomes fooled into taking this sound as a
new reference. In addition to that, the human ear is insensitive to
signal phase and can only detect phase problems when sound
cancellations occur as a result. If possible, always rely on a fre-
quency analyzer for finding the best crossover setting for your PA
system.
Crossover frequencies should always be selected so that they
match your PA speaker configuration. Always take care that your
high-frequency drivers do not become overstressed by too low
frequencies. Below we`ll give you some general guidelines for speaker
crossover frequencies:

1“ high frequency drivers: not below 2 - 3 kHz
2“ high frequency drivers: not below 1 - 2 kHz
Crossover between 12“ and 18“ speakers: 150 - 250 Hz
Crossover between 10“ and 15“ speakers: 250- 500 Hz

Limiter adjustment

The limiter adjustment procedure requires to run your PA system
at maximum volumes for a short time. To avoid hearing damages,
always wear ear-protective devices during limiter adjustments. To
get the most from the CCR 24’s limiter function, always make
adjustments in the following manner:

Connect your CCR 24 to mixing console and power amplifiers.
Turn only the amplifier(s) for the bass channel on.
Set all gain controls on the CCR 24 to -15dB.
Set all level controls of the amplifier to maximum position.
Send a signal to the CCR 24 by turning up the mixer faders to
maximum position. Bring up the lowpass gain control on the CCR 24
until the amplifier just begins to signalize signal clipping. Rotate the
lowpass gain control counterclockwise until the clipping just stops.
Adjust the mixer master faders for your average sound level.
Now adjust the highpass gain controls to match the bass sigal for
an overall balanced sound.

6. EQ board (optional)

A specialized add-on EQ board is available for the CCR 24 on
request. This board allows to boost or attenuate user-defined fre-
quencies, turning the CCR 24 into a complete EQ unit for your PA
system.
Tuning the board to your specified frequencies is done by solder-
ing the frequency-relevant components to the board. The right
values for the components are provided by a PC program, which is
supplied with the board, along with detailed explanations.
Of course, you can also obtain your personally taylored EQ card
from ZECK on request.

7. Technical specifications

Bandwidth (added):

20 Hz - 30 kHz

Input sensitivity:

0 / +6 dBU

Crosstalk:

-80 dB (15 kHz)

Distortion (THD):

< 0.03 %

S/R ratio:

> 90 dB (+6 dBU)

Input impedance: