The information in this manual has been carefully verified and is believed to be
correct, however, EVI Pro Audio reserves the right to modify the product
described in this manual at any time. This document may not be copied or
reproduced by any method whatsoever, whether in part or in whole, without
the written permission of EVI Pro Audio.
The CS8 console has been designed to provide the consultant,
contractor, installer and user with a cost effective system which
will perform to accepted professional standards, be simple for the
untrained user to operate, and be tolerant of wiring and installation
problems. There can be no excuse for a system which is over sensitive
to the wiring and installation conventions used, and hums at every
opportunity.
High quality balanced inputs and outputs are only part of the story.
Equally important is the way in which the console grounding system
works, because it is through the console ground that all the noisy
ground currents from the cable screens will flow. Any part of the
audio signal path which shares the cable screen to console ground
path within the console will effectively have the cable screen noise
added to that signal path. The current flowing in cable shields in
typical installations has be shown to be substantial (in the order of
100mA and above) and is caused by the difference in potential
between the ground connection at each end of the cable screens.
Of comparable importance to any system performance is the power
supply. Internal linear power supplies may be less expensive, but
are usually responsible for inducing noise into the audio and
generating substantial amounts of heat, making it uncomfortable
for the operator. Internal switch mode supplies may be cool running,
but are usually even more of a problem with regard to noise.
Another often overlooked point with internal power supplies is
how to provide auto-switchover between 2 supplies without
extensive modification thereby nullifying the warranty. Internal
supplies are also a potential problem from a maintenance point of
view.
Most service technicians can easily fault find and repair a linear
supply with commonly found components, but a switch mode supply
does not make use of common off the shelf components. Although
more expensive, a separate and generously rated linear power
supply is used with the CS8 keeping heat and noise away from the
console. Rack mounting ears are available for permanent
installations, and the supply is UL and CSA approved.
At this point it is useful to look at some of the features of the CS8.
PAN AND ROUTING
The pan pot can be switched between stereo panning mode, and
left/centre/right panning mode. Left-centre-right panning to the
master outputs provides much improved spatial positioning. The
technique has been used for many years in the film industry where
its benefits are well known.
4
In music systems the centre channel generates a more solid centre
image, especially for the “star” of the show, and helps to maintain
a stereo image across a wider sound stage. In mixed media
productions and in church applications the use of a speech optimised
centre cluster can improve intelligibility without compromising the
music system performance.
If only a stereo system is being run, and the pan pot is switched to
stereo mode, then the centre output is individually assignable from
each input or the from a sum of the left/right mix to provide a
separate mono output for broadcast/film feeds etc.
Another unique feature for a mixer in this class is individual sub
group routing instead of the inconvenient and inflexible paired
routing which always requires the use of the pan pot to route a
channel to a single sub group. There is always a crosstalk
performance compromise involved and it is done solely for economic
rather than for operational reasons, as it halves the number of
routing switches and removes the need for a pan in/out switch.
The CS8 allows routing to the sub groups either individually or in
pairs via the pan pot.
EQUALISATION
The CS8 input module has a 4 band equaliser with high and low
frequency boost/cut controls and two swept frequency middle
sections. There is more than two octaves of overlap between the
frequency ranges of the mid equalisers while the frequency span
extends to from 70Hz to 10kHz.
AUXILIARIES
The CS8 has 8 full time auxiliary send controls allowing easy session
setup. These are normally post fade but can be switched pre fade.
Normally the pre fade signal is pre fade post cut but byusing internal
links it can be changed to the pre equaliser signal. Auxiliaries 7 and
8 can be used in stereo where stereo foldback, for example, is
required.
CHANNEL CUT
The channel cut is a silent FET switch which can be remotely
controlled through a connector on the rear of each channel by a
simple connection to ground. In addition, when the channel cut
switch is pressed, another contact is grounded on the Mute Remote
connector. This can be used to control a Midi Mute controller, cue
lights, or even to control another channel on the mixer by linking
the mute out pin of one channel to the mute in pin of any other
channel(s). Such an application could be a podium switch which
would allow the speaker to override other channels for example.
5
SOLO/PFL MONITORING
While it is normal to find PFL/AFL on almost all mixers, the CS8
goes a step further. The input solo is arranged to have priority over
the output solo. This means that there is no need to de-select an
output solo when selecting one or more input solo controls, and
when the input solo is released, the output solo is re-established. A
master solo level trim control is located on the master module for
level matching, and the level of the solo signal is displayed on the
left mix bargraph.
An additional solo feature provided is Solo In Place. In this mode,
soloing any input channel will cause all other input channels to be
cut, thereby allowing only itself to be heard in the mix, correctly
panned and at the right level, along with any stereo effect return
channels. This is of great benefit during set-up and rehearsal and is
much more useful than the standard PFL. A switch on the master
module selects Solo In Place mode.
SIGNAL LED’s
The value of effective metering of signal levels throughout the
signal path cannot be overestimated. Signal present and 0dB LED’s
on all input channels give confidence to the operator while peak
overload LED’s indicate when the channel is being driven close to
clipping. However, it is unusual to find a peak overload LED at the
very place where it is most needed, at the summing bus mix
amplifiers, operating independently of the output meters. If the
mix amplifier is overloaded and starts to clip, the only thing that
can be done to rectify the situation is to pull down all input faders.
On the CS8, there are overload warning LED’s on each of the sub
group mix amplifiers as well as on the left, centre and right mix
amplifiers. When the output meters are switched to observe the
matrix outputs the bus peak leds also monitor the matrix bus.
INSERTS
Inserts are used to patch in external pieces of equipment such as
equalisers, limiters etc. and are provided on all channels, group
outputs, mix outputs and auxiliary outputs. To be useful and
useable, the inserts should be at a level which is compatible with
this external equipment. Sadly, this is often not the case. Some
mixers have inserts at odd levels which will preclude their efficient
use because of the noise penalty. All inserts on the CS8 are at a
consistent level which is at the internal operating level of 0dBu.
AUXILIARY INSER TS
In most installations, it is quite normal to place an equaliser in the
stage monitor sends, but this is normally external to the mixer. This
of course means that the only way of listening to the monitor sends
(internal to the mixer) is via the solo system.
6
Herein lies a problem. The operator does not hear the effect of the
external equalisation. Also, any noise introduced by the external
device is constant and not proportional to the setting of the send
control. The ideal place to insert an external device is pre the send
master control and this is the case in the CS8.
EQUALISER CUR VES
The following graphs illustrate the equalisation and filtering
responses of the CS8 console.
CS8HFLFHF/LF EQUALISER RESPONSE
CS8MIDMID FREQUENCY EQUALISER BANDWIDTH
ADJUSTMENT
CS8MID1MID FREQUENCY EQUALISER AMPLITUDE
ADJUSTMENT
CS8MID2MID FREQUENCY EQUALISER FREQUENCY
ADJUSTMENT
CS8HPHIGH P ASS FIL TER RESPONSE
7
AUDIO PRECISION CS8HFLFvs11 APR 97 11:31:21
201001k10k20k
FREQ(Hz)
-20.00
-15.00
-10.00
-5.000
0.0
5.0000
10.000
15.000
20.000
AMPL(dBr)
AUDIO PRECISION CS8HPFvs11 APR 97 11:43:15
20.000
15.000
10.000
5.0000
0.0
-5.000
-10.00
-15.00
-20.00
201001k10k20k
AMPL(dBr)
FREQ(Hz)
THE HIGH AND LOW
FREQUENCY EQUALISER
RESPONSE
AUDIO PRECISION CS8HIMIDvs11 APR 97 11:37:11
20.000
15.000
10.000
5.0000
0.0
-5.000
-10.00
-15.00
-20.00
201001k10k20k
AUDIO PRECISION CS8LOMIDvs11 APR 97 11:41:51
20.000
15.000
10.000
5.0000
0.0
-5.000
-10.00
-15.00
-20.00
201001k10k20k
AMPL(dBr)
AMPL(dBr)
FREQ(Hz)
FREQ(Hz)
THE HI-MID FREQUENCY
EQUALISER RESPONSE
SHOWING FREQUENCY
RANGE
THE LO-MID FREQUENCY
EQUALISER RESPONSE
SHOWING FREQUENCY
RANGE
THE HIGH PASS FILTER
RESPONSE.
8
CS8 SPECIFICA TIONS
Nominal Operating Level +4dBu with a unity gain structure.
Frequency Response 20Hz - 20kHz +/-0.5dB any input to any output
at a gain < 50dB.
EQ range
HF +/-15dB @ 10kHz shelving
LF +/-15dB @ 100Hz shelving
Hi Mid +/-15dB 470Hz - 15kHz, Q = 1.4
Lo Mid +/-15dB 70Hz - 2.2kHz, Q = 1.4
Maximum output level:+20dBu into a bridging load
Output impedance:<75R
Maximum input level:+30dBu
Phono connector levels: Nominal -10dBV
Signal present threshold: -21dBu
Peak led threshold:3dB below clipping
Power consumption:< 600 Watts
OPTIONS
Input transformersMultipole connectors
Output transformersBus linking cable
LED MeterbridgeFlight case
VU MeterbridgeSpare power supply with auto
Flight Caseswitchover
VU Meterbridge 6.5kg/14.5lbs (Add to weight without LED meterbridge)
These weights assume a fully fitted console. Meterbridges are shipped in with
the console but not mounted on the console.
Power Supply Weight (packed): 7.8kg(17.2lbs)
Dimensions: 2U Rack Mounting with a depth of 265mm(10.43")
DIMENSIONS AND WEIGHTS
10
Declaration of Conformity
The Manufacturer of the Products covered by this Declaration is
Klark Teknik Building, Walter Nash Road, Kidderminster,
Worcestershire, DY11 7HJ.
The Directives Covered by this Declaration.
89/336/EEC Electromagnetic Compatibility Directive, amended by 92/31/EEC & 93/68/EEC
73/23/EEC Low Voltage Equipment Directive, amended by 93/68/EEC.
The Products Covered by this Declaration.
Model CS3 Mixing Console.
Model CS8 Mixing Console.
Model CS12M Mixing Console.
The Basis on which Conformity is being Declared
The products identified above comply with the protection requirements of the EMC Directive and with the principal elements of the safety objectives of the Low Voltage Directive, and the manufacturer has applied the following standards:
EN 55013 : 1990
Limits and methods of measurement of radio disturbance characteristics of Broadcast
Receivers and Associated Equipment.
EN55020 : 1988
Sound and Television Broadcast Receivers and Associated Equipment, Electromagnetic
Compatibility.
EN 60065 : 1994
Safety requirements for mains operated electronic related apparatus for household
and similar general use.
The technical documentation required to demonstrate that the products meet
the requirements of the Low Voltage Directive has been compiled by the
signatory below and is available for inspection by the relevant enforcement
authorities. The CE mark was first applied in 1996
Authority: Product Support Manager.
Date:1st, January 1997.
Attention
The attention of the specifier, purchaser, installer, or user is drawn to special
measures and limitations to use which must be observed when these products
are taken into service to maintain compliance with the above directives.
Details of these special measures and limitations to use are available on
request, and are also contained in product manuals.
11
INST ALLA TION GUIDE
There are a number of points to consider when installing a mixing
console. Many of these points will have been addressed before the
console is even unpacked but it is worth repeating them again.
POSITION
The console should be located in a convenient space commensurate
with the use to which the console is being put. Ideally a cool area is
preferred not in close proximity to power distribution equipment
or other potential sources of interference. Provision should be made
for some flat surface surrounding the console to prevent people
using it as a table top. One of the worst fates that can befall a
console is for a cup of coffee to be tipped into it by someone resting
it on the control surface!
POWER
The power supply should be located as far from the console as the
connecting cable will allow, a 5 metre power cable is supplied with
the console. It should be set for the appropriate line voltage and
plugged into the mains outlet using the supplied cable. If the power
supply is rack mounted then be sure to leave space above for
ventilation - 2U is suggested.
SLEEVE TIPRING
TIP CO NN EC TI ON
RING CON N ECTION
SLEEV E CONNECTION AND CABLE CLAM P
1/4 INCH TRS 'A' GAUGE JA C K PLUG
FEM A LE XLR-3MALE XLR-3
12
3
12
3
PHONO SO CK ETS
PHONO PLU G
12
WIRING
The console uses four different connector styles:TRS jack sockets, XLR male connectors, XLR female connectors and
phono connectors.
The cables used should be of as high a quality as possible. Many
installation problems can be traced back to poor or faulty cables
and connectors.
There are two different conventions for the wiring of XLR
connectors. The international convention uses pin 2 as the hot pin
while the older American convention uses pin 3 as the hot pin.
When going from balanced input to balanced output this is of little
consequence but when unbalanced signals such as those found on
the insert points are used then phase reversal can result. The CS8
and all DDA products are wired PIN 2 HOT.
ATTENTION
CABLES
This product should only be used with high quality, screened twisted
pair audio cables, terminated with metal bodied 3-pin XLR
connectors. The cable shield should be connected to Pin 1. Any
other cable type or configuration for the audio signals may result
in degraded performance due to electromagnetic interference.
ELECTRIC FIELDS
Should this product be used in an electromagnetic field that is
amplitude modulated by an audio frequency signal (20Hz - 20kHz),
the signal to noise ratio may be degraded. Degradation of up to
60dB at a frequency corresponding to the modulation signal may
be experienced under extreme conditions (3V/m, 90% modulation).
No permanent damage or degradation of performance will be
caused by these conditions.
13
CIRCUIT DESCRIPTIONS
The following gives a brief description of each module as an aide
to understanding the signal flow within the console. Many
references are made to the circuit diagrams with the reference
number for the appropriate diagram being given at the beginning
of each module. The master module uses two circuit boards
requiring four circuit diagrams.
INPUT MODULE (CD1279)
The input module contains eight input channels mounted on a
common set of metalwork. The channels are identical and a console
is constructed by using 2 or more input modules together with an
output module and a master module within a frame.
THE INPUT ST AGE(CD1279)
The same input stage is used for both the microphone and the line
input. CON2, an XLR style connector, is used for the microphone
input which is wired to the inner contacts of CON3, the line input
TRS jack. With nothing inserted into the jack socket the signal
connects to the normal contacts and is then fed to an attenuator
which is activated by selection of the line input. Resistors R2 and
R3 feed phantom power to the microphone input and this is DC
blocked from the line input amplifier by C2 and C3. SP1, SP2 and
SP6 are filters providing protection from high frequency signals
entering the inputs. Additional filtering is carried out by capacitors
C37, C38, C39 and C40. CON9 (optional) is wired in parallel with
the XLR which allows for wiring the input to a multipole connector
mounted on the console frame.
Resistors R7, R8 and R9 form an attenuator when the line input is
selected, reducing the input signal by 30dB. C45 and C46 again
provide DC isolation and there is provision at this point for the
insertion of an input balancing transformer. Note that if a
transformer is fitted R14 should be changed to 1k. Where a
transformer is not fitted two 10R resistors (R10, R11) carry the signal
through to the input amplifier. D1, D2, D3 and D4 provide clamping
for excessive input voltages and the signal is applied to the bases
of transistors Tr5 and Tr7. VR1 is the front panel gain control and
this is connected through the MIC/LINE switch such that in the MIC
position the gain range is 20 to 70dB while in the LINE position it is
-10 to 20dB.
Signal is taken from the collectors of Trs 5 and 7 and applied
differentially to the input of IC1A. The output from here is fed
back to the emitters of the input transistors through 56k resistors
with one side being phase inverted by IC1B. The phase reverse
14
switch, SW3, selects either the normal or the phase inverted signal
and feeds it to the high pass filter stage. This is a three pole high
pass filter operating at 80Hz giving a roll off of 18dB per octave.
When not required this can be completely bypassed by SW4. The
output of SW4 after buffering by IC8B is known as PRE1 and is the
pre equaliser signal. PRE1 is a source for the auxiliary sends which
will be referred to later.
THE EQUALISER
The signal is presented to the equaliser which is a four band design.
The high and low frequency sections are built around IC2B with
VR7 providing low frequency boost and cut while VR2 provides
high frequency boost and cut. The middle frequency sections are
built around IC3 and use a Wein bridge as the frequency
determining network. VR3 selects the frequency of operation and
VR4 determines the amount of boost or cut given to the hi mid
signals while VR5 alters the frequency and VR6 the boost or cut for
the lo mid signals. The output from the equaliser connects to SW5
the EQ IN/OUT switch where either the pre equaliser sinal or the
equalised signal can be selected to be passed to the insert send.
CON5, a Tip, Ring and Sleeve jack, is used for the insert point with
the Tip being used as the send. SP3 and SP4 are filters preventing
noise from entering the console. The insert return signal is buffered
by IC7A and is then presented to the channel fader. The output
from the fader feeds the channel cut circuit.
The pre fader signal feeds the auxiliary cut circuit, the solo bus
when a solo is requested and finally the 3 led signal meter which is
driven from IC6, a quad comparator. There are SIGNAL PRESENT,
0dB and PEAK indicators which are powered from a current source
built around Tr8. The auxiliary cut allows the creation of a PRE
FADE POST MUTE signal, which can be defeated if required, in
addition to the POST FADE POST MUTE signal.
THE MUTE CIRCUIT
Tr1 is the CHANNEL MUTE fet which is buffered by IC4A and
following this the signal is known as POST. This signal routes to the
groups when panning is not used and also feeds the auxiliary sends
when selected as POST. The pre fade signal goes through a second
AUXILIARY MUTE circuit built around Tr2 to give a PRE FADE POST
MUTE signal called PRE2. LK1 is normally installed allowing the
PRE FADE signal to be muted when the channel mute is operated.
By removing LK1 and installing LK2 the PRE FADE signal will not
mute with operation of the channel mute switch.
15
In order to improve the attenuation of the mute circuits a small
amount of signal is fed forward to cancel with any residual from
the output of the fets. Resistors R140, R141 and R142 perform the
feed forward for the channel signal while R99, R100 and R101 are
used for the auxiliary cut circuit.
The mute circuit can be remotely controlled either through the
external remote connector or from the four mute groups provided.
A SAFE button allows the mute groups to be disabled on the
module. When the local mute button is pressed a ground is placed
onto the remote control connector. This can be used to operate
external equipment such as a midi sequencer or it could be
connected to other channels so that when one channel is muted
others will also mute. Led 1 indicates a MUTE whether it is local or
remote. In every case a MUTE request grounds the base of Tr6
causing it to switch off and hence its collector to go high. This is
applied to the gates of Tr1 and Tr2 causing them to switch off since
they are P channel fets. Tr4 will also turn off causing Tr3 to turn off
allowing led 1 to indicate the mute condition.
THE P AN CIRCUIT
The POST signal next goes to the pan circuit. This circuit can be
switched between stereo (L/R) and left/centre/right (LCR) modes
using SW15. The output of the pan pot can be routed to the mix or
the groups. If panning to groups is not selected then the groups
receive the POST signal while, with panning selected, they receive
the output of the pan pot (PANL and PANR). If LCR panning is
selected then assigning to mix (SW13) will send signal to the left
centre and right buses.
If L/R mode is selected no signal will appear on the centre output
except by pressing the MONO button (SW27) when the POST signal
will be routed to the centre bus. The groups can only use the left
and right pan pot outputs and therefore if LCR panning is selected,
panning to groups will not function in the expected manner.
The pan pot is built around VR16, a dual pot, and IC5. When in L/R
mode only one section of the pot (VR16A) is used and it simply
reduces the resistance to ground of the left or right signal
depending upon the direction of rotation. This reduces the
amplitude of the signal on one side while increasing it on the other
to create the panning effect.
When LCR mode is selected the input signal is fed to a centre tap
on VR16A. Signal can thus only appear on the left or right output
of this section of the pan circuit (but not both together) with the
amplitude depending again on the rotation of the pan pot.
16
The centre output is derived from the same input signal and VR16B
is used to control its amplitude by decreasing the resistance to
ground when the pot is rotated away from its central position.
IC5B buffers the centre signal.
THE AUXILIARY SENDS
The auxiliary sends can use the following three signals :PRE1, PRE2 and POST.
PRE1 is the pre equaliser signal, PRE2 is the pre fader post mute
signal and POST is the post fader post mute signal.
All auxiliaries will normally receive the POST signal, however, there
are PRE switches associated with the auxiliaries allowing the pre
fader signal to be selected. The default condition is that PR2 shall
be the pre signal although links allow this to be changed to the
PRE1 signal. Only one link of a pair should ever be inserted.
Auxiliaries 1, 2, 3
Link 4 PRE1
Link 3 PRE2
Auxiliaries 4, 5, 6
Link 5 PRE1
Link 6 PRE2
Auxiliaries 7, 8
Link 7 PRE1
Link 8 PRE 2
THE SOLO FUNCTION
SW22 is the solo or PFL switch. When operated it places DC onto
the IPCUEDC bus which is detected by the master module. The audio
signal INS_RET is fed onto the IPCUE bus and fed to the monitoring
system on the master module. If Solo In Place mode is selected
then the module initiating the solo will have its solo switch
depressed and the incoming SIP signal will have no effect. If the
module did not originate the solo in place the solo switch will not
be depressed and the SIP signal will cause the channel to mute.
THE DIRECT OUTPUT
The direct output is available at CON5, a jack connector. The signal
is unbalanced, at a nominal level of 0dBu and by default is the
POST signal. SW28 allows the PRE1 signal to be used.
17
Switches 9, 10, 11, 12, 23, 24, 25 and 26 route the signal to the
groups. Switch 27 routes signal to the MONO (CENTRE) bus and
SW13 routes to the stereo MIX bus.
ROUTING AND MUTE GROUPS
Switches 18, 19, 20 and 21 select the mute group buses. They are
combined through diodes D11 through D14 and then go to the
SAFE switch SW17 before combining with the local and remote
MUTE signals.
GROUNDING
All routing to buses is through 10k resistors. All connectors are
grounded to the metalwork (chassis) ground. This is connected to
0V by a 100R resistor in parallel with a 10n capacitor. BUSREF is
taken from 0V through a 10k resistor.
There is provision for an external meter output on CON8 (option).
18
INPUT MODULE LINKS
INPUT MODULE PC1394
LIN KFU N CTION
1AUXILIARY CUT ENA BL EYES
2AUXILIARY CUT DISA BLE
3PRE FA D ER TO AUX 1-3YES
4PRE EQ TO AUX 1-3
5PRE EQ TO AUX 4-6
6PRE FA D ER TO AUX 4-6YES
7PRE EQ TO AUX 7-8
8PRE FA D ER TO AUX 7-8YES
9N/A
10N /A
11PRE EQ TO DIR OUTYES
12PO ST EQ TO DIR OUT
FI TTED AS
SU PPLI ED
NOTES
INSTALL
ONLY ONE
LINK
INSTALL
ONLY ONE
LINK
INSTALL
ONLY ONE
LINK
INSTALL
ONLY ONE
LINK
INSTALL
ONLY ONE
LINK
19
MONO
MIX RIGHT
MIX LEFT
INPUT MODULE BLOCK DIAGRAM
MUTE GROUP 4
MUTE GROUP 3
MUTE GROUP 2
MUTE GROUP 1
PFL
AFL
AUXILIARY 8
AUXILIARY 7
AUXILIARY 6
AUXILIARY 5
AUXILIARY 4
AUXILIARY 3
AUXILIARY 2
AUXILIARY 1
GROUP 8
GROUP 7
GROUP 6
GROUP 5
GROUP 4
GROUP 3
GROUP 2
GROUP 1
56
12
34
ROUTING
78
TO GROUPS
PAN
+/-
15dB
freq.
4 BAND EQUALISER
HI
LO
GAIN
20 to 70dB
-10 to20dB
GAIN
OPTIONAL TX
INPUT
OPTION:
INPUT
MULTIPOLE CONNECTOR
MONO
EQ
HFLF
HI
MID
LO
MID
HPF
PHASE
LK11
LK12
48V
MIX
SIS
PAN
FADER
OUTPUT
EXTERNAL METER
PRE
DIR
SIS
+10dB
PEAK
0dB
DIRECT OUTPUT
LK1,2
SIGNAL PRESENT
1
PRE
LK3
PFL
EXTERNAL MUTE IN/OUT
CHANNEL
1
INSERT POINT
2
LK4
MUTE
3
SAFE
3
PRE
6
4
7
5
8
PRE
LK6
LK5
LK8
LK7
123
4
MUTE GROUP 1
MUTE GROUP 3
MUTE GROUP 2
MUTE GROUP 4
20
THE STEREO INPUT MODULE (CD1302/3)
THE INPUT ST AGE
The same input stage is used for both microphone and line inputs.
Looking at the left signal path, CON2, an XLR style connector, is
used for the microphone input which is wired to the inner contacts
of CON3, the line input TRS jack. With nothing inserted into the
jack socket the signal connects to the normal contacts and is then
fed to an attenuator which is activated by selection of the line
input. Resistors R2 and R3 feed phantom power to the microphone
input and this is DC blocked from the line input amplifier by C2
and C3. SP1, SP2 and SP3 are filters providing protection from high
frequency signals entering the inputs. Additional filtering is carried
out by capacitors C37, C38, C39 and C40.
Resistors R7, R8 and R9 form an attenuator when the line input is
selected, reducing the input signal by 30dB. C45 and C46 again
provide DC isolation and there is provision at this point for the
insertion of an input balancing transformer. Note that if a
transformer is fitted R14 (R214) should be changed to 1k. Where a
transformer is not fitted two 10R resistors (R10, R11) carry the signal
through to the input amplifier. D1, D2, D3 and D4 provide clamping
for excessive input voltages and the signal is applied to the bases
of transistors Tr4 and Tr5. VR1A is the front panel gain control and
this is connected through the MIC/LINE switch such that in the MIC
position the gain range is 20 to 70dB while in the LINE position it is
-10 to 20dB.
Signal is taken from the collectors of Trs 4 and 5 and applied
differentially to the input of IC1A. The output of IC1A is fed back
to the emitters of the input transistors through 27k resistors with
one side being phase inverted by IC1B. The phase reverse switch
SW28 (located in the left signal path only) selects the normal or
phase inverted signal and passes it to the high pass filter formed
around IC2A. This is a three pole high pass filter operating at 80Hz
giving a roll off of 18dB per octave. When not required this can be
completely by-passed by SW3. The output of SW3 passes through
SW19, the MONO R switch to become PRE-L1 which is the pre
equaliser signal (left). It is a source for the auxiliary sends which
will be referred to later.
SUMMING AMPLIFIER
IC11A sums the left and right signals together to create a mono
signal which has its polarity restored by IC11B before being
presented to switches SW19 and SW20 (the left and right signal
cut switches). When Mono R (switch 19) is pressed the left signal is
cut and replace by the right signal. Similarly when Mono L (switch
20) is pressed the right signal is cut and replaced by the left signal.
If both switches are pressed the output of IC11B (a mono signal) is
fed to both left and right signal paths.
21
THE EQUALISER
PRE1 L1 is presented to the equaliser which is a four band design.
The high and low frequency sections are built around IC9A with
VR6 providing low frequency boost and cut while VR2 provides
high frequency boost and cut. The lo middle frequency section is
built around IC8/IC202A. VR15 selects the frequency of operation
and VR14 determines the amount of boost or cut given to a signal.
The hi middle frequncy section is built around IC15B and IC16A.
VR17 determines the frequency of operation while VR18 determines
the amount of boost or cut. The equaliser output feeds the EQ IN/
OUT switch, SW29 allowing the pre or post equaliser signal to be
selected.
IC7A buffers the equaliser output and feeds it to the fader. The
equaliser output is also used to derive the PFL signal and to drive
the SIGNAL PRESENT, 0dB and PEAK indicators.
THE CUT CIRCUIT
The signal path splits at this point to go through two cut circuits.
This allows the creation of a PRE FADE POST MUTE signal (which
can be defeated if required) in addition to the POST FADE POST
MUTE signal. Tr1 is the CHANNEL MUTE fet and the post cut signal
is buffered by IC4A. The signal leaving IC4A is the POST FADE signal
which is then fed through a pan pot that can be routed to the
groups or the L/R mix. The pre fade signal goes through an
AUXILIARY MUTE circuit built around Tr2 to give a PRE FADE POST
MUTE signal called PRE2. LK1 is normally installed allowing the
PRE FADE signal to be muted when the channel mute is operated.
By removing LK1 and installing LK2 the PRE FADE signal will be
unaffected by operation of the channel mute switch. IC12A is used
to combine the left and right post fade signals for sending to the
auxiliaries. IC12B is used to combine the left and right pre fade
signals for sending to the auxiliaries.
As with the input module a small amount of signal is fed forward
to cancel any residual from the fets to improve the mute
attenuation.
THE BALANCE CIRCUIT
The post fade signal next goes to the balance circuit. The output of
the balance pot can be routed to the mix or the groups. The groups
normally receive the mono post fade signal but with the PAN switch
depressed they will receive the outputs of the balance pot built
around VR16. By default the balance control works as a pan pot
with full attenuation of the unwanted side. A more limited range
of adjustment can be obtained by changing the circuit as follows :-
22
Move R140 to R141 and R341 to R340 leaving the positions for
R140 and R341 blank.
Make R142 and R342 both 10k (they are 0R links).
This will then give a balance range of +3/-6dB.
PEAK AND SIGNAL PRESENT LEDS
A PEAK indicator and a SIGNAL PRESENT indicator are driven from
the post equaliser signal. IC14 is used as a voltage comparator and
directly drives leds 5 and 6. A reference voltage is applied to pins 5
and 7 while audio is applied to pins 3 and 5. The PEAK led comes
on 3dB before clipping while the SIGNAL PRESENT led comes on
with a signal level higher than -18dBu.
THE AUXILIARIES
With the exception of auxiliaries 7 and 8 the auxiliaries work in
mono using mixed left and right signals which are derived either
pre or post fade. The following three signals are available :PRE1, PRE2 and POST.
PRE1 is the pre equaliser signal, PRE2 is the pre fader post cut signal
and POST is the post fader post cut signal.
When PRE is selected the PRE2 signal is the factory default setting.
Links enable the default settings to be changed.
AUX 1-3
Remove link 3 and install link 4 for PRE1.
AUX 4-6
Remove link 6 and install link 7 for PRE1.
AUX 7-8
Remove link 11 and install link 12 for PRE1.
Auxiliaries 7 and 8 may be used as a stereo pair by depressing SW22,
the STEREO switch.
23
THE CUT CIRCUIT LOGIC
SW6 is the mechanically latching CUT switch which when operated
places a ground on the cathode of D15 causing the base of Tr3 to
go low and therefore the collector to go high. D9 will now stop
conducting enabling LED1 to illuminate indicating a cut. The
collector of Tr3 is applied via R118 and R98 to the gate of Tr1, an P
channel FET, causing it to stop conducting hence muting the signal.
D10 is used to create different on and off switching times for the
FET.
As the attenuation of the FET is not perfect a feedforward technique
is used to cancel any residual signal. A small fraction of the channel
signal is fed to the non inverting input of IC4A where it will sum
with the residual but in anti-phase to it thus cancelling it completely.
The operation of the AUXILIARY CUT is similar to that of the
CHANNEL CUT. Links 1 and 2 exist to disable the auxiliary cut if
required. In this case Link 1 should be removed and Link 2 installed.
An external input and output are available for the CUT function.
The external cut output simply extends a ground onto the connector
when the cut switch is depressed. The external cut input requires
to ground the cathode of D7 which then has the same effect as the
cut switch grounding D6. A simple latching switch contact is
sufficient.
THE SOLO FUNCTION
SW18 is the solo or PFL switch. When operated it places DC onto
the IPCUEDC bus which is detected by the master module enabling
it to replace the selected monitor signal with signal from the solo
bus (IPCUE). The equaliser outputs are mixed to mono for use as
the solo signal. If Solo In Place mode is selected then the module
initiating the solo will have its solo switch depressed and the
returned SIP signal from the master module will have no effect. If
the module did not originate the solo in place the solo switch will
not be depressed and the SIP signal will cause the channel to mute.
Thus only the module initiating the solo will be left uncut. In this
mode no change takes place on the master module and only the
module initiating the solo in place will be heard through the
monitoring system.
There is provision for an external meter on connector CON4 (option).
ROUTING AND GROUNDING
All routing to buses is through 10k resistors. All connectors are
grounded to the metalwork (chassis) ground. This is connected to
0V by a 100R resistor in parallel with a 10n capacitor. BUSREF is
taken from 0V through a 10k resistor.
24
STEREO INPUT LINKS
STEREO INPUT MODULE PC1418
LINKFU NCTION
1
2
3
4
6
7
11
12
AUXILI ARY CUT
ENA BLE (LEFT)
AUXILI ARY CUT
DISA BLE (LE F T )
PRE FA D ER MONO
TO AUX 1-3
PRE EQ MONO TO
AUX 1-3
PRE FA D ER MONO
TO AUX 4-6
PRE EQ MONO TO
AUX 4-6
PRE FA D ER MONO
TO AUX 7-8
PRE EQ MONO TO
AUX 7-8
FI TTED AS
SU PPLI ED
YES
YES
YES
YES
NOTES
INSTA LL ONLY
ONE LINK
INSTA LL ONLY
ONE LINK
INSTA LL ONLY
ONE LINK
INSTA LL ONLY
ONE LINK
17
18
21
22
201
202
PRE EQ LEFT TO
AUX 7-8
PRE EQ RIGHT TO
AUX 7-8
PRE FA D ER LEFT
TO AUX 7-8
PRE FA D ER RIGHT
TO AUX 7-8
AUXILI ARY CUT
ENA BL E (RIGHT)
AUXILI ARY CUT
DISA BLE (RIGHT)
25
FI T AS A PA IR
YES
FI T AS A PA IR
YES
YES
INSTA LL ONLY
ONE LINK
STEREO INPUT MODULE BLOCK DIAGRAM
MUTE GROUP 4
MUTE GROUP 3
MUTE GROUP 2
MUTE GROUP 1
PFL
AFL
AUXILIARY 8
AUXILIARY 7
AUXILIARY 6
AUXILIARY 5
AUXILIARY 4
AUXILIARY 3
AUXILIARY 2
AUXILIARY 1
GROUP 8
GROUP 7
GROUP 6
GROUP 5
GROUP 4
GROUP 3
GROUP 2
GROUP 1
MONO
MIX RIGHT
MIX LEFT
8
1234567
FADER
ROUTING
+/-
15dB
freq
4 BAND EQUALISER
R BOTH
HI
LO
GAIN
20 to 70dB
-10 to20dB
GAIN
INPUT
OPTION:
MULTIPOLE CONNECTOR
HI
LO
HPF
MID
MID
LFHF
PHASE
EQ
STER
MIX
MONO
7
3
1
2
6
4
5
8
HI
LO
MID
MID
LFHF
L BOTH
PRE
HPF
PRE M1
BALANCE
PRE
POST M
PRE M2
PRE
STEREO
GAIN
PEAK
123
PRE L1
PRE R1
PRE L2
PRE R2
SIGNAL
OdB
MUTE
SAFE
4
PFL
LEFT INPUT
48V
RIGHT INPUT
INPUT
OPTION:
MULTIPOLE CONNECTOR
26
OUTPUT
OPTION:
EXTERNAL METER
EXTERNAL MUTE IN/OUT
1
3
THE GROUP OUTPUTS (CD1280/CD1286)
There are two different kinds of output module. Numbers 1 - 6
carry a matrix section and auxiliary output while numbers 7 and 8
carry a stereo return section and an auxiliary output in addition to
the group output stage.
THE GROUP OUTPUT (CD1286)
Links 1, 2, 3, 4, 14, 15, 24 and 25 determine which of the group
buses will be assigned to the output. Only one link should ever be
installed. IC7B mixes the bus signals and presents them to IC7A
which simply phase inverts the signal before feeding the group
insert point, CON4. This is unbalanced and the send signal is applied
to the tip of the jack. When no plug is inserted the signal is
normalled through the RING contact and sent to the group fader.
This is followed by a buffer (IC8A) with 10dB of gain in order that
the fader can be run with 10dB of gain in hand.
A BUS PEAK indicator is fed from the pre insert signal to give
warning of high signals on the group bus. D5 half wave rectifies
the audio signal which is then presented to IC11B. This is used as a
voltage comparator and drives LED13 when the signal exceeds the
voltage on pin 6 of IC11B. Any signal greater than 3dB below
clipping level will cause an indication.
An AFL feed to the solo system is taken from the output of the
fader buffer. It is fed to the OPCUE bus through switch SW9 which
also applies DC to the OPCUEDC bus.
The group signal goes to the MUTE switch, SW8, from where it
splits off to the meter, the group output, and the sub mix circuitry.
The balanced output stage built around IC10 will simulate a
transformer so that it may be used into unbalanced loads without
any ill effect. Links 7 and 8 are used to bypass the output transformer
connector (CON10) and must be removed if a transformer is used.
CON15 may optionally be fitted where the output is to be wired to
a multipole connector.
The meter is built around IC12, a BA683A, giving a 12 segment
display with a range of +12dB to -21dB. PR1 is used to calibrate the
0dB point while PR2 is used to set the DC offset for the low end of
the scale. SW1 selects the group or the matrix signal to the meter.
Note that the BUS PEAK indicator is also switched between the
group and the matrix.
CON17 may optionally be fitted to provide signals for a meterbridge.
CON17 is switched by SW1 to carry the group or the matrix meter
signals.
27
There is a feed to an matrix connector (CON7) and links 5 and 6
determine whether the signal is pre or post fade. Link 5 is normally
installed giving a POST FADER signal to the matrix. Link 13 is used
to select the matrix bus.
The group can be sub mixed onto the main L/R and centre buses of
the console. A pan control is required to pan the mono group signal
onto the L/R and centre buses and this is constructed around VR15,
a dual pot, and IC9. When in L/R mode only one section of the pot
is used and it simply reduces the resistance to ground of the left or
right signal depending upon the direction of rotation. This reduces
the amplitude of the signal on one side while increasing it on the
other to create the panning effect. When LCR mode is selected the
input signal is fed to a centre tap on the pot. Signal will thus only
appear on the left or right output of this section of the pan circuit
with the amplitude depending again on the rotation of the pan
pot.
The centre output is derived from the same input signal as the left
and right outputs. VR15B is used to control the amplitude of the
centre signal and it is buffered by IC8B. The output of IC8B is fed to
the centre bus of the console when LCR mode is selected and the
MIX switch, SW6, is pressed. The POST signal may be fed to the
centre output of the console by pressing SW5 (MONO) which will
over ride the centre output of the pan pot in LCR mode.
AUXILIARY MASTER (CD1286)
Links 9, 10, 11, 12, 20, 21, 22 and 23 determine which of the auxiliary
buses will be sent to the output. Only one link should ever be
installed. IC4B mixes the bus signals and presents them to IC4A
which simply phase inverts the signal before feeding the auxiliary
insert point CON11. This is unbalanced and the send signal is applied
to the TIP of the jack through SUP11. With no plug inserted the
signal is normalled through the RING contact and sent to the
auxiliary master level control, VR1. This is followed by a buffer
(IC11A) with 10dB of gain in order that the level control can be run
with 10dB of gain in hand. An AFL feed to the solo system is taken
from the output of the buffer. It is fed to the OPCUE bus through
switch SW2 and DC is applied to the OPCUEDC bus.
The buffer output feeds the balanced output stage built around
IC6. This stage will simulate a transformer so that it may be used
into unbalanced loads without any ill effect. Links 18 and 19 are
used to bypass the output transformer connector (CON2) and must
be removed if a transformer is used. Components labelled SUP are
provided for the purposes of interference suppression and are fitted
to all input and output connections.
28
CON16 may be optionally fitted to feed a meterbridge.
THE MATRIX SECTION (CD1286)
A 12 by 6 matrix is formed by output modules 3 through 8. The
groups account for eight of the inputs with remainder being used
by the left, centre and right mixes and an external input.
CON12, a TRS jack, is used as the external input feeding IC1A which
unbalances the signal and feeds VR2, the level control. The output
of VR2 is combined with the group and mix inputs to the matrix at
IC2A with IC2B being used to phase invert the group/mix signals
which are simply brought in through level control pots VR3-VR10.
The combined signal goes to the matrix insert point, CON3, before
going through the matrix output level control, VR14. This is followed
by a buffer with 10dB of gain allowing the fader to be used with
10dB of gain in hand. The output of the MUTE switch is used to
feed the AFL switch, SW4, in addition to feeding the balanced
output stage built around IC3.
This stage will simulate a transformer so that it may be used into
unbalanced loads without any ill effect. Links 16 and 17 are used
to bypass the output transformer connector (CON9) and must be
removed if a transformer is used. Components labelled SUP are
provided for the purposes of interference suppression and are fitted
to all input and output connections.
STEREO INPUT (CD1280)
The stereo input is a line level stereo input which can be routed to
the group, auxiliary and mix outputs of the console. Note that if a
mono input is available then only the left input need be used as it
will be normalled to the right signal path if no jack is inserted into
the right input. IC1 forms the stereo balanced input from where
the signal goes through a gain control stage using IC2 and VR1
followed by the two band equaliser using IC3. The output of the
equaliser is summed to mono to create the PRE-M signal used to
feed PFL through SW8 and the auxiliaries. When SW8 is operated
DC is fed onto the IPCUEDC bus to signal the master module that a
solo has been requested and audio is placed on the IPCUE bus.
The equaliser is followed by the MUTE switch, SW14, and from
there the signal goes through a stereo fader. This is followed by a
buffer stage with 10dB of gain in order that the fader can work
with 10dB of gain in hand.
29
The post fader stage is presented to a balance control constructed
around VR4 and is mixed to mono to create the POST-M signal
used to feed the auxiliaries. The balance control is buffered by IC5
giving unity gain with the control in its central position. With the
control rotated to the right, for example, the right signal will
increase by 3dB while the left signal will be fully attenuated.
The output of the buffer is fed to the MIX switch, SW2 and the
group routing switches, SW4 through SW7. The feed to the mono
bus is through SW3 using the POST-M signal. Auxiliaries 5 through
8 can be accessed by the stereo input.
The PRE switch, SW1, allows the auxiliaries to be sent pre fade
mono signal rather than the post fade mono signal. The STEREO
switch, SW13, allows auxiliaries 7 and 8 to be used as a stereo
auxiliary using either the pre or post fade stereo signals.
THE GROUP OUTPUT (CD1280)
Links 1 and 2 determine which of the group buses will be assigned
to the output. Only one link should ever be installed. IC7B mixes
the bus signals and presents them to IC7A which simply phase inverts
the signal before feeding the group insert point. This is unbalanced
and the send signal is applied to the TIP of the jack. When no plug
is inserted the signal is normalled through the RING contact and
sent to the group fader. This is followed by a buffer with 10dB of
gain in order that the fader can be run with 10dB of gain in hand.
A BUS PEAK indicator is fed from the pre insert signal to give
warning of high signals on the group bus. D5 half wave rectifies
the audio signal which is then presented to IC11B. This is used as a
voltage comparator and drives LED18 when the signal exceeds the
voltage on pin 6 of IC11B. Any signal greater than 3dB below
clipping level will cause an indication.
An AFL feed to the solo system is taken from the output of the
fader buffer. It is fed to the OPCUE bus through switch SW12 which
also applies DC to the OPCUEDC bus. The group signal then goes to
the CUT switch SW10 from where it splits off to the meter, the
group output, and the sub mix circuitry.
The balanced output stage built around IC10 will simulate a
transformer so that it may be used into unbalanced loads without
any ill effect. Links 7 and 8 are used to bypass the output transformer
connector (CON5) and must be removed if a transformer is used.
30
GROUP OUTPUT LINKS (MA TRIX)
GROUP MOD U LE 1-6 PC1398
LINKFUNCTION
1BUS 3 SELEC T
2BUS 4 SELECT
3BUS 5 SELECT
4BUS 6 SELECT
5MATRIX PO ST FA D ERY ES
6MATRIX PRE FA D ER
7
8
9AUX 3 SELECT
10AUX 4 SELECT
11AU X 5 SELECT
12AUX 6 SELECT
13M ATRIX ASSIGN
14N /A
GROUP OUTPUT
TRAN SF O RM ER BYPASS
GROUP OUTPUT
TRAN SF O RM ER BYPASS
FITTED AS
SU PPLIED
YES
YES
NOTES
M ODULE PO SITION
D EPEN DEN T
REM OVE IF AN
O UTPU T
TRA N SFORM ER IS
FITTED
M ODULE PO SITION
D EPEN DEN T
15N /A
16
17
18
19
20AU X 1 SELECT
21AUX 2 SELECT
22AU X 7 SELECT
23AU X 8 SELECT
24BU S 1 SELECT
25BU S 2 SELECT
MATRIX OUTPUT
TRAN SF O RM ER BYPASS
MATRIX OUTPUT
TRAN SF O RM ER BYPASS
AUXILI ARY OUTPUT
TRAN SF O RM ER BYPASS
AUXILI ARY OUTPUT
TRAN SF O RM ER BYPASS
31
YES
YES
YES
YES
REM O VE IF
TR A N SFO RM ERS
ARE USED
M ODULE PO SITION
D EPEN DEN T
GROUP OUTPUT LINKS (RETURN)
GROUP MODULE 7-8 PC1395
LINKFUNCTION
1BUS 7 SELECT
2BUS 8 SELECT
3
4
5MATRIX PO STYES
6MATRIX PRE
7
8
MATRIX GROUP 7
ASSIGN
MATRIX GROUP 8
ASSIGN
TRA NSF ORM ER
BYPASS
TRA NSF ORM ER
BYPASS
FITTED AS
SU PPLI ED
YES
YES
NOTES
MODULE PO SI TION
DEPENDENT
MODULE PO SITION
DEPENDENT
INSTALL ONLY ONE
LINK
REM OVE BOTH
WHEN AN OUTPUT
TRA N SFO RM ER IS
USED
32
GROUP OUTPUTS 1-6 BLOCK DIAGRAM
MIX LEFT
MIX RIGHT
MONO
GROUP 1
GROUP 2
GROUP 3
GROUP 4
GROUP 5
GROUP 6
GROUP 7
GROUP 8
AUXILIARY 1
AUXILIARY 2
AUXILIARY 3
AUXILIARY 4
AUXILIARY 5
AUXILIARY 6
AUXILIARY 7
AUXILIARY 8
BUS
PEAK
AFL
PFL
GROUP FADER
GROUP OUTPUT
AUXILIARY
OUTPUT
EXTERNAL INPUT
TO METER
MUTE
AFL
EXT
1
2
3
4
5
6
7
8
L
R
C
TX OPTION
PAN
TX OPTION
AFL
TO METER
TO METER
MATRIX OUTPUT
GROUP INSERT
POINT
OPTION:
MULTIPOLE CONNECTOR
OUTPUT
GROUP OUTPUT
MIX
SIS
AUXILIARY INSERT
POINT
OPTION:
MULTIPOLE CONNECTOR
AUXILIARIES 1-6
BUS
MATRIX INSERT
PEAK
MUTE
TX OPTION
AFL
MONO
OUTPUT
POINT
GROUP SUMMING
AMPLIFIER
MATRIX SUMMING
AMPLIFIER
AUXILIARY
MULTIPOLE CONNECTOR
GROUP
MATRIX
OPTION:
OUTPUT
GROUP
MATRIX
BUS PEAK
METER
EXTERNAL METER
OUTPUT
33
N
GROUP OUTPUTS 7-8 BLOCK DIAGRAM
I
SIS
OUTPUT
EXTERNAL METER
METER
TX OPTION
MUTE
PAN
AFL
BUS PEAK
GROUP FADER
GROUP OUTPUT
PFL
AFL
AUXILIARY 8
AUXILIARY 7
AUXILIARY 6
AUXILIARY 5
AUXILIARY 4
AUXILIARy 3
AUXILIARY 2
AUXILIARY 1
GROUP 8
GROUP 7
GROUP 6
GROUP 5
GROUP 4
GROUP 3
GROUP 2
GROUP 1
MONO
MIX RIGHT
MIX LEFT
1/2
3/4
5/6
ROUTING
7/8
MIX
MONO
POST L
MUTE
STEREO INPUT FADER
EQUALISER
BALANCE
6
5
STEREO
PRE
POST R
PRE MONO
PRE L
STEREO INPUT
7
POST MONO
PRE R
8
PFL
LEFT/MONO
34
RIGHT
THE MASTER MODULE
The Master Module supports a number of functions including the
main mix outputs, two auxiliary outputs, a tape return input and
the monitoring system. Two circuit boards are used with signals
passing between them when required.
AUXILIARY SENDS(CD1281)
Auxiliaries 7 and 8 are located on the master module and their
function is identical to the auxiliary masters located on the group
modules.
Looking at Auxiliary 7 IC1A mixes the auxiliary 7 bus signals and
presents them to IC1B which simply phase inverts the signal before
feeding the auxiliary insert point. This is unbalanced and the send
signal is applied to the TIP of the jack. When no plug is inserted the
signal is normalled through the RING contact and sent to the
auxiliary master level control, VR1. This is followed by a buffer with
10dB of gain in order that the level control can be run with 10dB
of gain in hand. An AFL feed to the solo system is taken from the
output of the buffer. This is fed to the OPCUE bus through switch
SW1 and DC is applied to the OPCUEDC bus.
The output of the buffer feeds the balanced output stage built
around IC3. This stage will simulate a transformer so that it may be
used into unbalanced loads without any ill effect. Links 1 and 2 are
used to bypass the output transformer connector (CON13) and must
be removed if a transformer is used.
LEFT , CENTRE AND RIGHT MIX (CD1281/2)
IC4A mixes the left bus signals and presents them to IC4B which
simply phase inverts the signal before feeding the auxiliary insert
point. This is unbalanced and the send signal is applied to the TIP
of the jack. An unbalanced feed to a tape recorder is also taken
from this point and is suitable for machines operating at -10dBV. A
feed of the CENTRE or MONO mix is also summed with the left and
right signals for sending to the tape recorder outputs. When no
plug is inserted in the insert jack the signal is normalled through
the RING contact and sent to the master fader. A BUS PEAK indicator
is fed from the pre insert signal to give warning of high signals on
the master bus. D11 half wave rectifies the audio signal which is
then presented to IC7A used as a voltage comparator to drive LED13.
Any signal greater than 3dB below clipping level will cause an
indication.
35
The master fader is followed by a buffer with 10dB of gain in order
that the fader can be run with 10dB of gain in hand. The output of
the buffer feeds the balanced output stage built around IC8. This
stage will simulate a transformer so that it may be used into
unbalanced loads without any ill effect. Links 3 and 4 are used to
bypass the output transformer connector (CON14) and must be
removed if a transformer is used. A feed of the fader buffer output
is also used to feed the centre output of the console when SW8 is
depressed.
The signal paths for the RIGHT and CENTRE signals are identical to
that described for the left signal.
MONITORING
There are left, centre and right outputs for speakers, a stereo
headphone output and 3 master meters. Solo audio is automatically
switched on to the monitor outputs when a solo is active and there
is an external tape input which can be assigned as a monitor source
or to the left and right outputs of the console.
T APE PLA Y INPUT(CD1283)
The external tape input is unbalanced and buffered by IC5 having
a non inverting gain of 5.5dB. The signal passes through CON11
(CD1283) to CON10 (CD1282) and from there to the level control
VR2. The inputs to the level control are also taken to the TAPE
switch SW6. The outputs of the level control feed IC13 which has
6dB of gain before being presented to switches SW2 and SW3 which
route it the L/R and MONO outputs of the console. The signals are
applied to the fader buffers and hence the master faders will not
affect the level of the tape signal when assigned to the mix outputs
of the console. This means that a tape can be played through the
console outputs with the main faders closed to suppress other signal
sources and is known as an intermission playback facility.
In addition to the TAPE switch the monitor path has a MIX TO MON
switch (SW4) and a CENTRE TO MON switch (SW5). The selected
source is applied to fets Tr1, Tr2 and T18 which will normally pass
the signal. If a solo is active then Tr1, Tr2 and Tr18 will cease to
conduct and Tr3, Tr4 and Tr19 will conduct to allow the solo bus to
be fed to the monitor outputs of the console. LMON, RMON and
CMON are the signals presented to the monitor outputs.
SOLO LOGIC(CD1282)
There are two solo DC buses, IPCUEDC and OPCUEDC which allow
input and output solos to be treated differently.
If an input solo is requested the IPCUEDC bus will go high causing
Tr7 to turn on and hence its collector to go low.
36
This switches off Tr8 which allows Led 16 to turn on indicating an
input solo. The collector of Tr7 is connected through SW7 (the SIP
switch) to the gate of Tr6, causing Tr6 to switch off.
The effect of this is to disable any output solo audio that is active,
giving the console input solo priority. The cathode of D7 is now
low causing Trs 1, 2, 12 and 18 to turn off. Tr11 inverts the output
of Tr7 causing Trs 3, 4, 13 and 19 to turn on.
Thus the normal monitor source is silenced while the solo audio is
allowed onto the monitor outputs in addition to the left meter
now showing solo audio level instead of the left mix signal. The
operation of an output solo is very similar other than for the fact
that it cannot disable input solos. During a solo the centre and
right meters are muted by fets Trs 5 and 6 (CD1283). Solo audio is
mixed by IC11B and this is where the solo meter feed is derived.
Signal can be adjusted in level by VR3 before going to the monitor
system without affecting the meter readings.
A Solo In Place mode can also be selected and when this is the case
the output of Tr7 feeds Tr14 causing it to turn on and therefore
Tr15 to turn on. This causes a logic low to be placed on the SIP bus
which mutes any input module not having its solo switch depressed.
The master meters are built around BA683A ICs, giving a 12 segment
display with a range of +12dB to -21dB.
Auxiliary 8 and the centre output are as for auxiliary 7 and the left
output description previously given.
THE MONITOR OUTPUTS (CD1284)
The selected monitor signals LMON, RMON and CMON are fed to a
volume control VR4 which is buffered by IC10/11. A PHONES switch
(SW14) selects the headphone or loudspeaker outputs. The
loudspeaker outputs are built around IC12, IC13 and IC14 and are
similar to the balanced outputs used for the main outputs of the
console. Transformer balancing is not available for the monitor
outputs.
The headphones outputs are designed to feed a low impedance
load and have a transistor output stage. IC17, transistors 1 through
4 and associated components form the stereo headphone amplifier.
TALKBACK
IC15 is the talkback microphone amplifier with gain being
adjustable by VR3. Link 1 may be installed if a phantom powered
microphone is to be used. When the talkback key is pressed Rs 114,
115 and 116 connect with the monitor signals to form a DIM circuit
of around 15dB.
37
Talkback can be routed to the auxiliaries, the mix or the groups.
There are also sine and pink noise generators. They can be switched
on using SW7 and the appropriate source selected by SW6. The
routing for these generators is as for the talkback. VR2 is a level
control for the selected oscillator.
Pink noise is generated from diodes D16 and D17 which are
differentially applied to IC7A. The output from IC7 is taken through
the ON switch, SW7, and then applied to IC7B for amplification
before filtering by resistors R86—R91 and capacitors C45—C49. The
output of the filter is buffered and amplified by IC6B from where
it goes to the SINE/PINK selector switch, SW6.
A 1kHz sine wave is generated by IC16 with D18 and D19 being
used to stabilise the amplitude.
IC16A along with C53, C54 and R97 form a bandpass filter
determining the frequency of oscillation.
38
MASTER MODULE LINKS
MASTER MODULE PC1396
LINKFUNCTION
AUXILI ARY 1
1
2
3
4
5
6
TRA NSF ORM ER
BYPASS
AUXILI ARY 1
TRA NSF ORM ER
BYPASS
LEFT MIX
TRA NSF ORM ER
BYPASS
LEFT MIX
TRA NSF ORM ER
BYPASS
RIGHT MIX
TRA NSF ORM ER
BYPASS
RIGHT MIX
TRA NSF ORM ER
BYPASS
FI TTED AS
SU PPLIED
YES
YES
YES
YES
YES
YES
NOTES
REM OVE WHEN
FI TTING AN
OUTUT
TRA NSF ORM ER
REM OVE WHEN
FI TTING AN
OUTUT
TRA NSF ORM ER
REM OVE WHEN
FI TTING AN
OUTUT
TRA NSF ORM ER
CENTRE MIX
7
8
9METER ENA BLEYES
TRA NSF ORM ER
BYPASS
CENTRE MIX
TRA NSF ORM ER
BYPASS
YES
YES
39
REM OVE WHEN
FI TTING AN
OUTUT
TRA NSF ORM ER
REM OVE WHEN
M ETERBRIDGE IS
FITTED
COM M S MODULE PC1397
LINKFUNCTION
TALKBACK
1
MICROPHONE
PHA NTO M PO W ER
AUXILI ARY 2
2
TRANSFORM ER
BYPASS
AUXILI ARY 2
3
TRANSFORM ER
BYPASS
FI TTED AS
SU PPLI ED
YES
YES
NOTES
REM OVE WHEN
FITTING OUTPUT
TRA NSF ORM ERS
40
MASTER MODULE BLOCK DIAGRAM
LEFT/SOLO METER
OUTPUT
EXTERNAL METER
R POST
L POST
C POST
AUX
OUTPUT
OPTION:
MULTIPOLE CONNECTOR
AUXILIARY OUTPUT 1
PHONES
MONITOR LEVEL
OUTPUT
LPOST
OPTION:
MULTIPOLE CONNECTOR
MIX OUTPUT LEFT
LOCAL MONITOR L
-
+
MIXTAPE
LOCAL MONITOR R
-
+
C
CENTRE
RPOST
LOCAL MONITOR C
-
+
TALKBACK
CENTRE METER
OUTPUT
OPTION:
MULTIPOLE CONNECTOR
MIX OUTPUT RIGHT
HEADPHONES
INPUT
TALKBACK MICROPHONE
AUX 1-3
AUX 4-6
AUX 7-8
MIX
BUS
SINE
OUTPUT
OPTION:
MULTIPOLE CONNECTOR
MIX OUTPUT CENTRE
ON
PINK
SOLO LOGIC
TX
OPTIONAL
+
INSERT POINT
BUS PEAK
TX
OPTIONAL
-
MUTE
CUT
-
+
L/R
TO CENTRE
TAPE LEVEL
INSERT POINT
BUS PEAK
L
AUXILIARY OUTPUT 2 IS SIMILAR TO AUXILIARY 1
AUX 1
TAPE
SEND RET
L
L+R TO
CENTRE
L/R
OPTIONAL
INSERT POINT
41
TX
MUTE
BUS PEAK
R
TX
OPTIONAL
-
+
-
+
MUTE
SOLO LEVEL
INSERT POINT
BUS PEAK
C
INPUT SOLO
OUTPUT SOLO
R
C
I/P SOLO
O/P SOLO
IPCUEDC
OPCUEDC
SIP
THE BUS LINKING POR T
The bus linking port enables two consoles to be used together in a
master slave configuration. The bus structure is broken between
the input modules and the group modules although in normal use
a shielded connector is used to join the two sections. If the console
is to be used as a master the connector is removed and the master
end of a link cable put in its place. This retains the link between
the buses and connects the input modules of the slave console to
the buses of the master console. If the console is to be used as a
slave the slave end of the link cable is used which breaks the link
between the buses and feeds the input modules over to the master
console. This of course means that the group and master modules
of the slave console are not used as only one master per function
can be allowed access to the bus.
During unlinked operation a blanking plug must be inserted to
connect the input and output buses.
CD1308
This shows the Bus Link Blanking Plug.
CD1306
This shows the Bus Link PCB. There are two input connectors to
allow consoles where the master modules are located in the centre.
and one output connector. The output and input connectors are
connected by the blanking plug during normal (unlinked)
operation.
GROUND
STU D
BUS LINK PORT
BUS LINK PORT
GROUND
INPUT BUSOUTPUT BUS
MASTER CONSOLE
STU D
INPUT BUSOUTPUT BUS
SLA V E CONSO LE
42
THE METERBRIDGE
VU METERBRIDGE (CD1310)
The VU Meterbridge carries 11 meters indicating the three main
console outputs in addition to either the matrix, group or auxiliary
outputs of the console.
Signal selection is carried out by switches SW1 — SW3 while C1
ensures that on power up the GROUP signals will be displayed.
IC1 is a dual SR Flip Flop and normally the Reset input will be held
low by the pull down resitor R3. The Set input is wired to Vss and is
thus always low. When SW1 is pressed, or C1 is charging immediately
after switch on, Vdd is connected through D1 and R3 to Vss. Current
therefore flows and a voltage is created across R3 which is enought
to make the Reset input if IC1a see a logic high. The Q output is
thus set to a logic low while the Qbar output will be a logic high. A
similar situation will arise on IC1b and therefore the A and B control
inputs of the 4052 multiplexers will both be low allowing the X0
and Y0 input signals through which are the group signals. IC12a
also reads the control lines. As both are low and the IC is connected
as an invertor the output will go high causing LED1 to illuminate.
If neither or only one of the control lines is low the output will not
go high enough to turn on LED1.
If the matrix output is required then SW2 should be pressed. This
will cause C2 to charge through R1 creating a +ve pulse on the
clock input of IC1A. Assuming that we are in GROUP mode the
Data input will see the logic high from the Qbar output and this
will be clocked through to the Q output. The A control line now
goes high while the B control line stays low causing the multiplexers
to allow through the signals on the X1 and Y1 inputs which are the
matrix signals.
If the auxiliary outputs are required then SW3 should be pressed.
IC1B is clocked by a +ve going pulse from C3. Again the Data input
which is high will be clocked through to the Q output causing the
B control line to go high. The multiplexers will now allow through
signals connected to the X3 and Y3 inputs which are the auxiliary
output signals. The B control line is connected through to the RESET
pin of IC1A and when the auxiliary signal is selected a pulse will be
created through C6 causing IC1A to reset. When the auxiliary signals
are deselected the B control line will go low causing a -ve going
pulse. To prevent this from causing damage to the circuit
components it is clamped by D3 and thus prevented from driving
the reset pin more than 0.6V below ground. C7 and D4 perform
similar functions on IC1B.
43
When the A control line is high the output of IC11b will go low
causing the MATRIX indicator to illuminate while if the B control
line is high the output of IC12b will go low causing the Auxiliary
indicator to illuminate.
The outputs of the multiplexers are fed through buffer amplifiers
with some gain adjustment to allow for calibration of the meters.
Resistors attenuate the signal input to the multiplexers when a
signal is not selected in order to prevent breakthrough of any high
level audio signals. The signals for the left, centre and right mixes
do not travel through any multiplexers and are permanently
selected. There are of course only 6 matrix outputs and meters 7
and 8 will therefore not indicate during the period that the
meterbridge is being used to indicate MATRIX signals.
LED METERBRIDGE OUTPUT SIGNAL PROCESSING (CD1312)
The signal input to the led meterbridge output section is identical
to that of the VU meterbridge. Selection can be made between the
group, matrix and auxiliary signals. In this case the outputs from
the multiplexers are fed to quad comparator ICs of the type LM2901.
These rectify the audio signals and define the ballistics of the
resulting signal that is fed to the display board (CD1311).
LED METERBRIDGE OUTPUT DISPLA Y BOARD (CD1311)
Each meter is identical and is constructed from 3 quad comparator
ICs of the type LM2901 creating a 12 segment meter. A resistor
chain is used to set the threshold voltage for each comparator and
this determines the point at which an led will switch on. The leds
are driven from constant current sources formed from transistors
TR1 through TR8.
LED METERBRIDGE INPUT DISPLA Y BOARD (CD1307)
The meteres are identical to those used on the output display board
(CD1311). There is no need for a ballistics and rectifier section in
the meterbridge as the signal is taken from after the ballistics and
rectifier section of the meter driver on the module. Further LM2901
ICs (IC25 and IC26) are used to buffer the module signals before
being presented to the meters.
44
THE POWER SUPPL Y
The power supply is a linear type supplying +/-18 volts and +48
volts DC to the console. It may be rack mounted and a space of 2U
above the unit is recommended for ventilation.
The positive and negative rail regulators are identical in operation
thus only the positive rail is described.
Diodes D11 through D14 rectify the incoming AC from the
transformer and feed the main reservoir capacitors C9 and C10. A
small plug in module contains the series pass transistor and
associated regulating circuit. Q002 is the series pass transistor and
is driven from Q001 which in turn receives a control signal from
IC001, a 723. The output from the series pass transistor is passed
directly to the power supply output. D15 indicates that the supply
is functioning.
Diodes D1 through D4 rectify the AC used for the phantom voltage
supply. This is smoothed by C1, C2 and C4 from where it is fed to a
TL783C, the regulator. R1, R2 and R4 are used to derive a
programming voltage which is applied to the TL783C. D5 and D6
will protect the regulator from inverse voltages that may be applied
to it. C5 and C15 smooth the regulated output which is applied to
the output connector of the power supply. D7 indicates that the
phantom supply is working.
There is a delayed output from the power supply which may be
used to activate relays in a console. This facility is not used when
connected to the CS8 console.
There is no connection within the power supply between 0V and
mains earth (chassis). There is a ground lift switch which, when
operated, will allow the console to float completely free from
ground. If the ground is lifted then the console chassis is connected
to 0V Audio in the power supply.
The chassis wire is bonded to the frame and also to a large
ground post on the rear panel of the console. In accordance with
current good practice pin 1 of the XLR connectors is taken to
chassis ground as is the sleeve connection from jack sockets.
46
BUS CONNECTOR PIN OUT
PINSIGNALDESCRIPTION
1BUS 8GROUP 8 BUS
2MUTE 1MUTE GROUP 1 BUS
3BUS 7GROUP 7 BUS
4MUTE 2MUTE GROUP 2 BUS
5BUS 6GROUP 6 BUS
6MUTE 3MUTE GRO UP 3 BUS
7BUS 5GROUP 5 BUS
8MUTE 4MUTE GROUP 4 BUS
9BUS 4GROUP 4 BUS
10IPCU EINPUT CUE AUDIO
11BU S 3GROUP 3 BUS
12IPCUEDCINPUT CUE CO NTRO L
13BUS 2GROUP 2 BUS
14O PCUEO UTPU T CUE AUDIO
15BU S 1GROUP 1 BUS
16O PCU ED CO UTPUT CUE CO N TRO L
17M IX RMIX RIGHT BUS
18SIPSOLO IN PL ACE
19M IX C
20BU SREFBU S REF ERENCE
21M IX LLEFT MIX BUS
22+18V+18 VOLTS
23AU X 8AUXILIARY 8 BUS
24+18V+18 VO LTS
25AU X 7AUXILIARY 7 BUS
26+18V+18 VOLTS
27AU X 6AUXILIARY 6 BUS
280VA U D IO GROUND
29AU X 5AUXILIARY 5 BUS
300VA U DIO GROUND
31A UX 4AUXILI ARY 4 BUS
320VA UDIO GRO UND
33AU X 3AUXILIARY 3 BUS
34-18V-18 VOLTS
35AU X 2AUXILIARY 2 BUS
36-18V-18 VOLTS
37A U X 1AUXILIARY 1 BUS
38-18V-18 VOLTS
39M W KGRO UN DCHA SS IS
40+48VPHA NTO M PO W ER
CENTRE OR MONO MIX
BUS
39
1
40
2
VIEW OF BUS RIBBON
CONNECTOR LOOKING
INTO THE CONSOLE
47
CS8 MA TRIX CONNECTO R
PINSIGNALDESCRIPTION
1MTX 4MATRIX 4 BUS
2M YX 5MATRIX 5 BUS
3MTX 3MATRIX 3 BUS
4MTX 6MATRIX 6 BUS
5MTX 2MATRIX 2 BUS
6MTX 7MATRIX 7 BUS
7MTX 1MATRIX 1 BUS
8MTX 8MATRIX 8 BUS
9MTX RMATRIX RIGHT BUS
10REC-CCENTRE RECORD FEED
11M TX CMATRIX CENTRE BUS
12CM ONCENTRE MONITO R FEED
13M TX LMATRIX LEFT BUS
1 4GNDAUDIO GR OUND
13
1
14
2
VIEW OF BUS RIBBON
CONNECTOR
LOOKING INTO THE
CONSOLE
48
BUS LINK CONNECTOR
DIN 41612 CO NN ECTO R
SIGNALABSIGNAL
BU S 811BUS 8
BU S 722BUS 7
BU S 633BUS 6
BU S 544BUS 5
BU S 455BUS 4
BU S 366BUS 3
BU S 277BUS 2
BU S 188 BUS 1
MIX R99MIX R
MIX C10 10MIX C
MIX L11 11MIX L
AUX 81212AUX 8
AUX 71313AUX 7
AUX 61414AUX 6
AUX 51515AUX 5
AUX 41616AUX 4
This listing contains all the parts used in the assembley of a CS8 console. Where
possible both a DDA part number and an EVI part number are given and ultimately all
part numbers should be of the EVI type.
DDA No.DESCRIPTIONEVI AUDIO P AR T NUMBER
ACBL17-005 .EART H LOOMACBL17-1446-3
ACBL17-006 .EART H LOOMACBL17-1447-3
ACBL17-009 .MASTER/COMMS WFMACBL17-1450-3
ACBL17-010 .PSU XLR WFMACBL17-1437-3
ACBL17-011 .LITTLITE XLR WFMACBL17-1438-2
ACBL17-012 .HEADPHONE WFMACBL17-1439-2
ACBL17-017 ..FADER W F MACBL17-017-3
ACBL24-006 . M A TRIX LOOMACBL24-1479-1
ACBL24-007 .MASTER/COMMS LINK WFMACBL24-1440
ACBL24-008 .LITTLITE XLR’S WFMACBL24-1504
ACBL24-010 ..F ADER W F MACBL24-555
ACBL24-011 ..FADER W F MACBL24-485
ACBL24-012 ..FADER W F MACBL24-250
ACBL24-013 ..FADER W F MACBL24-300
ACBL24-020 .O/P LED MTR WFMACBL24-1480-1
ACBL24-021 .16CH L/H LED MTR WFMACBL24-1481-1
ACBL24-025 .O/P VU MTR WFMACBL24-1485-1
ACBL24-026 .VU METERBRIDGE WFMACBL24-1486-1
ACBL24-030 .LOOM I/P 16CH LHACBL24-1505-1
ACBL24-031 .LOOM I/P 24CH LHACBL24-1506-1
ACBL24-032 .LOOM I/P 16CH RHACBL24-1507-1
ACBL24-034 .LOOM I/P 24CH RHACBL24-1509-1
ACBL24-035 .LOOM O/PACBL24-1510-1
AMDL24-001 .STD I/P
AMDL24-004 .4+4 MONO/STEREO
AMDL24-012 .O/P & MASTER
APCB24-420 .CS8 BUS LINK - BLKG.PLUG
APCB24-421 .CS8 BUS LINK
CAP01-5002 ..33PF 50V 10%(5MM PITCH)CAP02-GK233050
CAP01-5003 ..100PF 5OV 10%(5MM PITCH)CAP02-GK310050
CAP01-5004 ..470PF 50V 10%(5MM PTCH)CAP02-GK347050
CAP01-5005 ..680PF 50V 10%(5MM PITCH)CAP02-GK368050
CAP01-5009 ..10PF 50V 5% (5MM PITCH)CAP02-GK210050
CAP01-5013 ..22OPF 50V 10%(5MM PITCH)CAP02-GK322050
CAP01-5014 ..150PF 50V 10%(5MM PTCH)CAP02-GK315050
CAP04-0010 ..220U 25V 20% (5MM PITCH)CAP43-322025
CAP04-0016 ..1000U 10V 20%(5MM PITCH)CAP43-410010
CAP04-0017 ..1000U 25V 20%(5MM PITCH)CAP43-410016
CAP04-5003 ..2U2 63V 20%(5MM PITCH)CAP43-122063
CAP04-5005 ..100U 16V 20%(5MM PITCH)CAP43-310016
CAP04-5006 ..22U 25V 20%(5MM PITCH)CAP43-222025
CAP04-5012 ..33U 63V 20%(5MM PITCH)CAP43-233063
CAP04-5026 ..2U2 50V 20%(5MM PITCH)LPCAP43-122050LP
With the exception of the meters there are no adjustments within
the CS8 console.
SAFETY
Always switch off the console before carrying out any work on it.
TOOLS
No special tools are required in order to service the CS8. An
oscilloscope and multimeter will allow fault finding to component
level in the unlikely event of a fault. A module extension cable,
ACBL99-023, is supplied with the console to enable individual
channels to be powered when removed from the frame. If a
complete block of 8 channels is to be serviced then ACBL99-024, an
8 way extension cable, should be used.
MODULE REMOVAL
Remove the twelve screws retaining a module and ease it out of
the frame. There are four screws at the bottom of the module,
four screws at the top of the module and four screws at the rear of
the console at the base of the connector panel. The recommended
method is to raise the front of the module and to push the module
a little towards the front of the console from the rear connector
panel. Lift the module, holding it at the front edge and rear
connector panel. Keep it parallel to the front plane of the console
and disconnect the ribbon cable from each of the 8 boards before
pulling the module completely clear.
MODULE DISASSEMBL Y
Remove the screws mounting the XLR to the connector panel.
Remove the screws holding the circuit board to the top panel and
pull the circuit board clear.
MODULE REASSEMBL Y
This is a reverse of the disassembly process and care must be taken
that leds are not damaged through misalignment with their panel
holes.
MODULE REPLACEMENT
Place the module over its final position and reconnect the ribbon
cable to all the boards. Gently ease the module back into the frame
taking care not to crush or otherwise damage the ribbon cable.
Insert the 12 retaining screws.
ST A TIC PRECAUTIONS
Electronic equipment can be very sensitive to static discharges and
care should be taken to avoid static in the work area. Where possible
work on a bench where you can be grounded through a wrist strap.
58
If boards have to be shipped then they should be wrapped in
conductive plastic bags or conductive plastic sheeting.
PAR TS
In the interests of safety always use genuine replacement parts.
Safety approvals will be invalidated by use of non standard
components.
METER ALIGNMENT
An audio test set is required to accurately measure the level of the
output for which the meter is being adjusted.
Master Left and Right Meters
With 0dBu at the console outputs adjust PR1 to read 0dB and with
-21dBu at the console output adjust PR2 such that the bottom led
is just on. These adjustments should be repeated until both readings
are accurate as they are interactive to some extent.
Centre Meter
PR15 should be used to set the 0dB point while PR25 should be
used to set the -21dB point following the above procedure.
Group Meters
PR2 should be used to set the 0dB point while PR3 should be used
to set the -21dB point following the above procedure.
If a meterbridge is fitted then some additional calibration work
will be required as follows:-
VU Bridge
Calibrate the console meters as above and then use PR1 through
PR7 to calibrate the VU meters. The adjustment is the same for
whichever signal source is selected and it is therfore probably easiest
to set the meters to read GROUP. Set the group outputs to +4dBu
(0VU) and adjust PR1 for group 1 so that the meter reads 0VU.
Calibrate the remaining meters using PR2 through PR8.
The master meters can be set in the same fashion having set the
output levels to +4dBu. PR9 will calibrate the left meter while PR10
and PR11 will calibrate the centre and right meters respectively.
LED Bridge
There are no adjustments in the led meterbridge.
CD1303PC1418/19
GROUP MODULE(1-6)CD1286PC1395
GROUP MODULE(7-8)CD1280PC1398
MASTER MODULE(MASTER MIX)CD1281PC1396
MASTER MODULE(T APE/SOLO)CD1282PC1396
MASTER MODULE(CENTRE MIX)CD1283PC1397
MASTER MODULE(T/B MONITOR)CD1284PC1397
CENTRE METERCD1273PC1385
POWER SUPPL YCD1271PC1386
BUS LINKCD1306PC1421
BUS LINK BLANKING PLUGCD1308PC1420
LED INPUT METERCD1307PC1423
LED OUTPUT METERCD1311PC1424
LED OUTPUT METER SUB PCBCD1312PC1425
VU METERCD1310PC1426
METER CONNECTORCD1309PC1422
60
MIC
CON2
NC3FAHL
R3
6K8R26K8
231
SP6
CM-CHOKE
12
34
CON9
3
2
1
3WAY
MH
CON5
1/4JACKSL
DIRECT
OUT
R87
100R
C30
10N
213456
EXTERNAL
CUT
MUTE1
MUTE2
MUTE3
MUTE4
CON3
1/4JACKSL
LINE
213456
SP1
1N
SP2
1N
DIRECT
PRE
SW28
2PSUJ
SP5
1N
CUT
SW16
2PSUJ
CON7
1
2
3
3WAY
MHR/A
SAFE
SW17
2PSUJ
MUTE 1
SW18
2PSUJ
MUTE 2
SW19
2PSUJ
MUTE 3
SW20
2PSUJ
MUTE 4
SW21
2PSUJ
This drawing is split across the following two pages to aid readability .
+48V
R4
SW1
47K
+48V
R1
R5
10K
10K
1 2
1 2
SP3
1N
SP4
1N
470R
C1
MIC/
2U2
63V0.2
LINE
GAIN
R7
C45
4K7
100U
16V0.2
R6
LK11
LK12
D8
1N4148
SW2
R9
300R
4PSUJ
C46
R8
100U
16V0.2
4K7
NOTE: IF T1 IS FITTED
R14 CHANGES TO 1K AND
R10 AND R11 ARE NOT FITTED.