DDA Klark Teknik, cs8 User Manual

CS8
Service Manual
Klark Teknik Building
Walter Nash Road
Kidderminster
Worcestershire
Tel: +44 (0) 1562 741515
Fax: +44 (0) 1562 745371
Email: info@uk.telex.com
Website: www.ddaconsoles.com
CS8 Service Manual
Telex Communications (UK) Limited
In line with the company’s policy of continual improvement, specifications and function maybe subject
to change without notice. This Operator Manual was correct at the time of writing. E&OE.
2
Contents
INTRODUCTION ......................................................................................... 4
CS8 SPECIFICA TIONS ................................................................................. 9
OPTIONS ...................................................................................................... 9
CS8 DIMENSIONS AND WEIGHTS ........................................................ 10
DECLARA TION OF CONFORMITY ........................................................ 11
INST ALLA TION GUIDE............................................................................. 12
ATTENTION ............................................................................................... 13
CIRCUIT DESCRIPTIONS .......................................................................... 14
INPUT MODULE (CD1279) ..................................................................... 1 4
INPUT MODULE LINKS ........................................................................... 19
INPUT MODULE BLOCK DIAGRAM ..................................................... 20
THE STEREO INPUT MODULE (CD1302/3).......................................... 21
STEREO INPUT LINKS .............................................................................. 25
STEREO INPUT MODULE BLOCK DIAGRAM ..................................... 26
THE GROUP OUTPUTS (CD1280/CD1286) .......................................... 2 7
GROUP OUTPUT LINKS (MA TRIX)........................................................ 31
GROUP OUTPUT LINKS (RETURN) ....................................................... 32
GROUP OUTPUTS 1-6 BLOCK DIAGRAM ........................................... 33
GROUP OUTPUTS 7-8 BLOCK DIAGRAM ........................................... 34
THE MASTER MODULE........................................................................... 35
MASTER MODULE LINKS ....................................................................... 39
MASTER MODULE BLOCK DIAGRAM................................................. 41
THE BUS LINKING PORT......................................................................... 42
THE METERBRIDGE ................................................................................. 43
THE POWER SUPPL Y ............................................................................... 45
BUS CONNECTOR PIN OUT ................................................................... 47
CS8 MA TRIX CONNECTO R ..................................................................... 48
BUS LINK CONNECTOR .......................................................................... 49
CS8 P AR TS LISTING .................................................................................. 50
SER VICE INFORMA TION ......................................................................... 58
CS8 CIRCUIT DIAGRAMS ........................................................................ 60
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.
© Copyright 1997 EVI Pro Audio Group. All rights reserved.
Manual Version DOC03-CS12M/A.
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INTRODUCTION
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.
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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.
CS8HFLF HF/LF EQUALISER RESPONSE CS8MID MID FREQUENCY EQUALISER BANDWIDTH
ADJUSTMENT
CS8MID1 MID FREQUENCY EQUALISER AMPLITUDE
ADJUSTMENT
CS8MID2 MID FREQUENCY EQUALISER FREQUENCY
ADJUSTMENT
CS8HP HIGH P ASS FIL TER RESPONSE
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AUDIO PRECISION CS8HFLF vs 11 APR 97 11:31:21
20 100 1k 10k 20k
FREQ(Hz)
-20.00
-15.00
-10.00
-5.000
0.0
5.0000
10.000
15.000
20.000
AMPL(dBr)
AUDIO PRECISION CS8HPF vs 11 APR 97 11:43:15
20.000
15.000
10.000
5.0000
0.0
-5.000
-10.00
-15.00
-20.00 20 100 1k 10k 20k
AMPL(dBr)
FREQ(Hz)
THE HIGH AND LOW FREQUENCY EQUALISER RESPONSE
AUDIO PRECISION CS8HIMID vs 11 APR 97 11:37:11
20.000
15.000
10.000
5.0000
0.0
-5.000
-10.00
-15.00
-20.00 20 100 1k 10k 20k
AUDIO PRECISION CS8LOMID vs 11 APR 97 11:41:51
20.000
15.000
10.000
5.0000
0.0
-5.000
-10.00
-15.00
-20.00 20 100 1k 10k 20k
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.
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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
Channel Routing Attenuation > 90dB @ 1kHz Channel Mute Attenuation > 95dB @ 1kHz Channel Fader Attenuation > 85dB @ 1kHz
Distortion
0.005% @1kHz any input to any output at a gain < 50dB.
Noise: -82dBu (24 channels routed and cut) EIN: -127.5dBu ref 200 ohms EIN: -128.7dBu ref 150 ohms
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 transformers Multipole connectors Output transformers Bus linking cable LED Meterbridge Flight case VU Meterbridge Spare power supply with auto Flight Case switchover
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CS8 DIMENSIONS AND WEIGHTS
48 CHANNEL 1930.50mm(76.00")
40 CHANNEL 1681.50mm(66.20")
32 CHANNEL 1432.50mm(56.40")
MASTER AND
OUTPUT SECTION
4
STEREO
MODULES
16 CHANNEL 934.50mm(36.70") 24 CHANNEL 1183.50mm(46.60")
Meterbridge Widths: VU 46.6 inches/1183.5mm (This cannot be fitted to a 16 input console) LED As per corresponding console width.
Console weights (packed):
16 26.4kg/58lbs LED m/b 4.7kg/10.4lbs Combined 31.1kg/68.4lbs 24 36kg/80lbs LED m/b 6.0kg/13.3lbs Combined 42.0kg/93.3lbs 32 45.6kg/100lbs LED m/b 7.4kg/16.3lbs Combined 53.0kg/116.3lbs 40 55.2kg/122lbs LED m/b 8.6kg/19.0lbs Combined 63.8kg/141lbs 48 64.8kg/143lbs LED m/b 10.0kg/22.0lbs Combined 74.8kg/165lbs
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
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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
Signed: ................................ G.M.Squires
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.
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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
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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.
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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
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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.
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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.
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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.
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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).
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INPUT MODULE LINKS
INPUT MODULE PC1394
LIN K FU N CTION
1AUXILIARY CUT ENA BL E YES
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
10 N /A
11 PRE EQ TO DIR OUT YES
12 PO 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
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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.
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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 :-
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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.
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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.
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STEREO INPUT LINKS
STEREO INPUT MODULE PC1418
LINK FU 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)
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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
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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
LF HF
PHASE
EQ
STER
MIX
MONO
7
3
1
2
6
4
5
8
HI
LO
MID
MID
LF HF
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
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OUTPUT
OPTION:
EXTERNAL METER
EXTERNAL MUTE IN/OUT
1
3
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