RME DMC-842 User manual
User’s Guide
DMC-842
The Digital Microphone Interface
MultiMode
SyncAlign
™
8-Channel Digital Microphone Interface with Line Outputs
8-Channel AES to Analog / ADAT Interface
AES/EBU Format and Sample Rate Conversion
Optional 64-Channel MADI Interface
24 Bit / 192 kHz Digital Audio
™
I64 Option Slot™
SteadyClock
™
SyncCheck™
MIDI Remote Control
AES-3
AES-10
24 Bit Interface
AES42
Important Safety Instructions..................................4
General
1 Introduction ...............................................................6
2 Package Contents.....................................................6
3 Brief Description and Characteristics.....................6
4 First Usage – Quick Start
4.1 Controls - Connectors - Displays............................7
4.2 Quick Start ..............................................................9
5 Accessories...............................................................9
6 Warranty...................................................................10
7 Appendix..................................................................10
Usage and Operation
8 Front Panel Controls
8.1 Select Key and Rotary Encoder (SET) ................14
8.2 Clock Section.......................................................15
8.3 Analog Out...........................................................15
8.4 Remote.................................................................16
9 The Input Channel in Detail
9.1 General ................................................................16
9.2 Gain......................................................................16
9.3 Digital Phantom Power ........................................16
9.4 Mode 2 .................................................................17
9.5 Stereo / Inactive...................................................17
9.6 M/S Processing....................................................17
9.7 SRC......................................................................18
9.8 PAR......................................................................18
9.9 Sync .....................................................................18
10 The Setup Menü
10.1 General ................................................................19
10.2 ID (Id) ...................................................................19
10.3 Bank (bA).............................................................19
10.4 Auto ID (Au) .........................................................20
10.5 Delay Compensation (dC)....................................20
10.6 Follow Clock (FC).................................................21
10.7 Word Clock Out (Co)............................................21
10.8 Peak Hold (Ph).....................................................21
10.9 Digital Output (do)................................................21
10.10 Analog Output (Ao) ..............................................22
10.11 Gain (GA).............................................................22
10.12 Control Pulse (Cp)................................................22
10.13 Sync Pulse (SP)...................................................22
10.14 Special (Sp)..........................................................23
11 The Parameter Menu
11.1 General ................................................................23
11.2 Low Cut................................................................24
11.3 Directivity Pattern.................................................24
11.4 Pre-Attenuation....................................................24
11.5 Mute .....................................................................24
11.6 Peak Limiter.........................................................24
11.7 Command Type....................................................24
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12 Remote Control
12.1 MIDI .....................................................................25
12.2 MIDI over MADI ...................................................25
12.3 Remote Control Software ....................................26
12.4 RS232..................................................................28
Inputs and Outputs
13 Digital Inputs
13.1 XLR......................................................................30
13.2 D-Sub – AES/EBU Sync......................................30
14 Digital Outputs
14.1 AES / EBU ...........................................................31
14.2 ADAT Optical.......................................................32
14.3 I64 MADI Card.....................................................33
14.4 Differences DMC-842 / ADI-642..........................34
15 Analog Outputs.......................................................35
16 Word Clock
16.1 Word clock Input and Output...............................36
16.2 Technical Description and Background...............37
16.3 Cables and Termination.......................................38
17 MIDI...........................................................................38
Technical Reference
18 Technical Specifications
18.1 Analog..................................................................40
18.2 Digital Inputs........................................................40
18.3 Digital Outputs .....................................................41
18.4 Digital...................................................................41
18.5 MIDI .....................................................................41
18.6 General................................................................42
18.7 Firmware..............................................................42
18.8 MADI User Bit Chart ............................................42
18.9 Connector Pinouts...............................................42
19 Technical Background
18.1 Terminology.........................................................44
18.2 Lock and SyncCheck...........................................45
18.3 Latency and Monitoring .......................................46
18.4 DS – Double Speed.............................................47
18.5 QS – Quad Speed ...............................................47
18.6 AES/EBU – SPDIF...............................................48
18.7 MADI Basics ........................................................49
18.8 SteadyClock.........................................................50
20 Block Diagram.........................................................51
21 MIDI Implementation DMC-842
21.1 Basic SysEx Format ............................................52
21.2 Message Types ...................................................52
21.3 Table....................................................................53
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Important Safety Instructions
ATTENTION! Do not open chassis – risk of electric shock
The unit has non-isolated live parts inside. No user serviceable parts inside.
Refer service to qualified service personnel.
Mains
• The device must be earthed – never use it without proper grounding
• Do not use defective power cords
• Operation of the device is limited to the manual
• Use same type of fuse only
To reduce the risk of fire or electric shock do not expose this device to rain or
moisture. Prevent moisture and water from entering the device. Never leave
a pot with liquid on top of the device. Do not use this product near water, i. e.
swimming pool, bathtub or wet basement. Danger of condensation inside –
don't turn on before the device has reached room temperature.
Installation
Surface may become hot during operation – ensure sufficient ventilation.
Avoid direct sun light and do not place it near other sources of heat, like radiators or stoves. When mounting in a rack, leave some space between this
device and others for ventilation.
Unauthorized servicing/repair voids warranty. Only use accessories
specified by the manufacturer.
Read the manual completely. It includes all information necessary
to use and operate this device.
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User’s Guide DMC-842 © RME
User’s Guide
DMC-842
General
User’s Guide DMC-842 © RME
5
1. Introduction
The DMC-842 is both an AES/EBU interface as well as a controller for digital microphones. The
unique device allows for connection and control of up to 8 digital microphones, and converting
their signals to ADAT, AES/EBU, analog and (optional) MADI. Eight switchable hi-end sample
rate converters offer a flexible clocking and further usage options.
When developing the DMC-842, RME worked closely with the microphone manufacturers to
secure maximum compatibility and best functionality. As a result the DMC-842 is the most flexible and most compatible AES42 interface available – a true milestone for the broad acceptance
of the new digital microphone technology.
2. Package Contents
Please check that your DMC-842 package contains each of the following:
• DMC-842
• Power cord
• Manual
• RME Driver CD
• 1 optical cable (TOSLINK), 6.6 ft (2 m)
3. Brief Description and Characteristics
The DMC-842 is an 8-channel interface for AES42 digital microphones, with full remote controllability and optional MADI I/O. In a standard 19" box with 2 unit height the device offers numerous extraordinary features like MultiMode, Intelligent Clock Control (ICC), SyncCheck, SteadyClock, MIDI over MADI, and remote control via AES, MADI and MIDI.
• 8 XLR AES/EBU inputs
• 8 balanced XLR line outputs
• 8-channel 24 bit sample rate conversion
• Fully compatible to AES42
• Digital Phantom Power switchable per input
• Supports Mode 1 and Mode 2
• Gain adjustable per channel, even in asynchronous Mode 1
• Future-proof by flash updates
• LED level meter with 13 LEDs per channel
• Noise suppression on power-on and power-off at the analog outputs
• M/S decoding/encoding
• Fully remote controllable
• Word clock input and output
• SyncCheck tests and reports the synchronization status of the clock signals
• SyncAlign guarantees sample aligned and never swapping channels
• MIDI I/O
• 4 x AES/EBU Out per D-sub, 8 channels @ 192 kHz
• 2 x ADAT Out, 8 channels @ 96 kHz
• Optional MADI I/O (I64 MADI Card)
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User’s Guide DMC-842 © RME
4. First Usage – Quick Start
4.1 Controls - Connectors - Displays
The front of the DMC-842 features eight LED level meter, eight
numerical LED displays, eight Select keys, a rotary encoder,
further keys for more specific configuration options, and 69
LEDs providing a detailed status display.
Each channel has a dedicated configuration area on the front
plate. The display GAIN shows the currently set amount of
amplification. The 13-segment LEVEL meter with switchable
Peak Hold function shows the incoming digital level.
The SELECT button is used for a per-channel activation / deactivation of:
GAIN Amount of amplification
DPP Digital Phantom Power
STEREO Stereo mode
M/S Mid/Side encoding
SRC Sample Rate Converter
The LEDs MODE 2 and SYNC are skipped, as these are
status displays only. The also skipped LED PAR stands for the
Parameter settings mode (see below).
Pushing the knob SET several times lets you access all functions consecutively. The rotary
encoder is a highly intuitive multifunctional device. It is used to set the gain, to select the desired
function, to deactivate the function of one or all channels, to select various options in the Setup
menu and to perform the setting of the parameters.
The key ANALOG OUT defines the
analog reference level at the analog
outputs. This level is reached at full
scale of the DA-converters, thus
matching the front panel level meter's
level indication.
REMOTE defines the source for MIDI
remote control operation (Option Slot
/ MADI, D-sub AES1, MIDI DIN jack,
RS232).
After pressing the SETUP button the device enters the Setup menu, where many more options
can be configured. More information can be found in chapter 10.
After pressing the PAR button the device enters the Parameter menu. More information can be
found in chapter 11.
In the CLOCK SECTION the current clock reference and frequency multiplier is chosen.
User’s Guide DMC-842 © RME
7
The rear panel of the DMC-842 has eight AES42 inputs, eight analog outputs, mains power,
MIDI I/O, word clock I/O, the I64 Option Slot, and all digital inputs and outputs (AES/ADAT).
DIGITAL MICROPHONE – AES/EBU INPUTS (XLR): Eight balanced AES42 inputs with
switchable digital phantom power (DPP). These inputs are compatible to AES3 and AES/EBU.
ANALOG LINE BALANCED OUTPUTS (XLR): Eight balanced line outputs with up to +27 dBu
level.
AES I/O (25-pin D-sub): The D-sub connector provides four AES/EBU outputs and one
AES/EBU input (clock synchronization). The 25 pin D-sub connector is wired according to the
widely spread Tascam standard (pinout see chapter 18.9). The AES I/Os are transformercoupled.
ADAT OUT (TOSLINK): Optical ADAT outputs. These provide the same signals as the
AES/EBU outputs, but in ADAT format.
WORD IN (BNC): A push switch allows to activate internal termination (75 Ohms).
WORD OUT (BNC): Standard word clock output.
MIDI I/O (5-pin DIN): MIDI input and output via 5-pin DIN jacks. Used to remote control the
DMC-842, and – with installed MADI Card - to transmit MIDI data via MADI.
IEC receptacle for power connection. The specially developed, internal hi-performance switch
mode power supply lets the DMC-842 operate in the range of 100V to 240V AC. It is shortcircuit-proof, has an integrated line-filter, is fully regulated against voltage fluctuations, and suppresses mains interference.
With installed I64 MADI Card:
MADI I/O optical: Standard MADI ports.
MADI I/O koaxial (BNC): Standard MADI ports.
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User’s Guide DMC-842 © RME
4.2 Quick Start
After connection of all cables and power-on of the device, the configuration of the DMC-842
begins in the CLOCK section. Choose a clock source and a sample rate. The next step is the
configuration of the input channels. When using digital microphones DPP (digital Phantom
power) must be activated. In Mode 1 the SRCs have to be activated as well as soon as more
than one microphone is connected.
The next step is the GAIN setting. This can be done in two ways:
• Individually: Hit the SELECT button of one or several channels. The corresponding GAIN
displays start flashing. Select the desired value with the rotary encoder. Or:
• Globally: Push the encoder knob once. All GAIN displays start flashing. Select the desired
value with the rotary encoder.
The flashing stops automatically after about six seconds. The LEVEL meter serves as comfortable tool to check whether gain is sufficient or already overloading the input.
To activate a function, press the SET knob repeatedly until the corresponding LEDs are flashing. Pressing once all GAIN displays start flashing (gain setting), pressing twice selects all DPP,
then STEREO and so on. To activate or deactivate a specific function per channel, the corresponding SELECT button is used. They are therefore also labeled ON/OFF.
The DMC-842 stores all settings before switching off, and sets them automatically when switching on the next time. The storing process is triggered about 4 seconds after the last change.
Using the included Windows software, the device’s complete state can be stored and archived.
5. Accessories
RME offers several optional components for the DMC-842:
Part Number Description
OK0050 Optical cable, Toslink, 0.5 m (1.7 ft)
OK0100 Optical cable, Toslink, 1 m (3.3 ft)
OK0200 Optical cable, Toslink, 2 m (6.6 ft)
OK0300 Optical cable, Toslink, 3 m (9.9 ft)
OK0500 Optical cable, Toslink, 5 m 16.4 ft)
OK1000 Optical cable, Toslink, 10 m (32.8 ft)
BO25MXLR4M4F1PRO Digital Breakout Cable Pro, AES/EBU
25-pin D-sub to 4 x XLR male + 4 x XLR female, 1m (3.3 ft)
BO25MXLR4M4F3PRO same, 3 m (9.9 ft)
BO25MXLR4M4F6PRO same, 6 m (19.8 ft)
BO25M25M1PRO Digital D-sub Cable Pro, AES/EBU
25-pin D-sub to 25-pin D-sub, 1m (3.3 ft)
BO25M25M3PRO same, 3m (9.9 ft)
BO25M25M6PRO same, 6m (19.8 ft)
User’s Guide DMC-842 © RME
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I64 MADI Card MADI module featuring thru-input, Delay Compensation, Auto ID, MIDI
over MADI, remote via MADI
BOB32 BOB-32, Universal breakout box, 19" 1 Unit height. The professional
digital AES/EBU breakout solution
6. Warranty
Each individual DMC-842 undergoes comprehensive quality control and a complete test at IMM
before shipping. The usage of high grade components should guarantee a long and trouble-free
operation of the unit.
If you suspect that your product is faulty, please contact your local retailer.
Audio AG grants a limited manufacturer warranty of 6 months from the day of invoice showing
the date of sale. The length of the warranty period is different per country. Please contact your
local distributor for extended warranty information and service. Note that each country may
have regional specific warranty implications.
In any case warranty does not cover damage caused by improper installation or maltreatment replacement or repair in such cases can only be carried out at the owner's expense.
No warranty service is provided when the product is not returned to the local distributor in the
region where the product had been originally shipped.
Audio AG does not accept claims for damages of any kind, especially consequential damage.
Liability is limited to the value of the DMC-842. The general terms of business drawn up by Audio AG apply at all times.
7. Appendix
RME news and further information can be found on our website:
http://www.rme-audio.com
Distributor: Audio AG, Am Pfanderling 60, D-85778 Haimhausen, Tel.: (49) 08133 / 91810
Manufacturer:
IMM Elektronik GmbH, Leipziger Strasse 32, D-09648 Mittweida
Trademarks
All trademarks and registered trademarks belong to their respective owners. RME, Hammerfall
and DIGICheck are registered trademarks of RME Intelligent Audio Solutions. MultiMode,
SteadyClock, DMC-842, I64 Option Slot, I64 MADI Card, SyncAlign, SyncCheck, ZLM and Intelligent Clock Control (ICC) are trademarks of RME Intelligent Audio Solutions. Alesis and ADAT
are registered trademarks of Alesis Corp. ADAT optical is a trademark of Alesis Corp. S/MUX is
copyright Sonorus.
Copyright © Matthias Carstens, 12/2014. Version 1.1
All entries in this User's Guide have been thoroughly checked, however no guarantee for cor-
rectness can be given. RME cannot be held responsible for any misleading or incorrect information provided throughout this manual. Lending or copying any part or the complete manual or its
contents as well as the software belonging to it is only possible with the written permission from
RME. RME reserves the right to change specifications at any time without notice.
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User’s Guide DMC-842 © RME
CE / FCC Compliance
CE
This device has been tested and found to comply with the limits of the European Council Directive on the approximation of the laws of the member states relating to electromagnetic compatibility according to RL2004/108/EG, and European Low Voltage Directive RL2006/95/EG.
FCC
This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses,
and can radiate radio frequency energy and, if not installed and used in accordance with the
instructions, may cause harmful interference to radio communications. However, there is no
guarantee that interference will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which can be determined by turning
the equipment off and on, the user is encouraged to try to correct the interference by one or
more of the following measures:
- Reorient or relocate the receiving antenna.
- Increase the separation between the equipment and receiver.
- Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.
- Consult the dealer or an experienced radio/TV technician for help.
RoHS
This product has been soldered lead-free and fulfils the requirements of the RoHS directive.
ISO 9001
This product has been manufactured under ISO 9001 quality management. The manufacturer,
IMM Elektronik GmbH, is also certified for ISO 14001 (Environment) and ISO 13485 (medical
devices).
Note on Disposal
According to the guide line RL2002/96/EG (WEEE – Directive on Waste
Electrical and Electronic Equipment), valid for all european countries, this
product has to be recycled at the end of its lifetime.
In case a disposal of electronic waste is not possible, the recycling can
also be done by IMM Elektronik GmbH, the manufacturer of the DMC-
842.
For this the device has to be sent free to the door to:
IMM Elektronik GmbH
Leipziger Straße 32
D-09648 Mittweida
Germany
Shipments not prepaid will be rejected and returned on the original sender's costs.
User’s Guide DMC-842 © RME
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User’s Guide DMC-842 © RME
User’s Guide
DMC-842
Usage and Operation
User’s Guide DMC-842 © RME
13
8. Front Panel Controls
8.1 Select Key and Rotary Encoder (SET)
The rotary encoder SET is a highly intuitive multifunctional device. It is used to set the gain, to
select the desired function, to deactivate the function of one or all channels, to select various
options in the Setup menu and to perform the setting of the parameters.
To activate a function, press the SET knob repeatedly until the corresponding LEDs are flashing. Pressing once all GAIN displays start flashing (gain setting), pressing twice selects all DPP,
then STEREO and so on.
To activate or deactivate a specific function per channel, the corresponding SELECT button is
used. They are therefore also labeled ON/OFF.
Each channel offers the following functions:
GAIN Amount of amplification
DPP Digital Phantom Power
MODE 2 Status display, not selectable
STEREO Only odd channels: Stereo mode
INACTIVE Only even channels: when Stereo mode had been activated
M/S Mid/Side encoding
SRC Sample Rate Converter
PAR Parameter configuration, not selectable
SYNC Sync state display, not selectable
The LEDs MODE 2 and SYNC are skipped, as these are status displays only. The also
skipped LED PAR stands for the Parameter settings mode (see chapter 11).
Setting the GAIN can be done in two ways:
• Individually: Hit the SELECT button of one or several channels. The corresponding GAIN
displays start flashing. Select the desired value with the rotary encoder. Or:
• Globally: Push the encoder knob once. All GAIN displays start flashing. Select the desired
value with the rotary encoder.
When adjusting several channels at the same time, the relation between individual channels will
be retained. So the gain of multiple channels can be increased or decreased without them loosing their level relations. In case one of the linked channels reaches the highest or lowest gain
value (0 or +63 dB), the gain relationship gets lost.
Turning the encoder knob to the left initiates a global OFF command for all selected (flashing)
channels. For example, DPP can be switched off for all channels by pressing the encoder knob
twice and then turning it to the left by four ticks. The corresponding global ON command (a turn
to the right by at least four ticks) is also implemented.
For safety reasons, the DMC-842 will leave the selected function after 6 seconds. This may
seem cumbersome when changing the gain frequently, because the gain function will have to
be selected every time via the Select button or the encoder first. On the other hand, the DMC842 is absolutely safe from accidental changes.
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User’s Guide DMC-842 © RME
8.2 Clock Section
The source and frequency of the unit's clock is configured in the CLOCK SECTION. The button
CLOCK lets you step through the options external clock (Word, AES, Option = MADI) and internal clock. The button SAMPLE RATE sets the sample rate for both external and internal clock.
WCK, AES, OPTN (Slave Mode)
Defines the corresponding input as clock reference. A missing or invalid clock source signal is
indicated by flashing of the corresponding LED.
INT (Master Mode)
Activates the internal clock.
With a setting of INT (internal clock) it is mandatory that the clock rate of the sources is
synchronous to the DMC-842. Therefore the external device has to be synchronized to the
DMC-842's word clock output or AES/ADAT/MADI output.
The DMC-842 thus has to be master, all devices connected to it must be slave. In order to avoid
clicks and drop outs due to faulty or missing synchronicity, a special process called SyncCheck
compares the incoming data and the DMC-842's internal clock. The SYNC state is indicated by
a flashing (error) or turned off (OK) LED.
44.1, 48
Activates the internal clock at 44.1 kHz or 48 kHz.
DS, QS
With the DS LED additionally lit, the sample rate will be 88.2 or 96 kHz, with QS lit it will be
176.4 or 192 kHz.
A selection of DS and QS is also possible when using external clock (Slave). If the DMC-842
should operate at 192 kHz, but receives a synchronous word clock of 48 kHz, the button
SAMPLE RATE allows to activate DS or QS mode. This way, AD-conversion and digital outputs
are configured to operate in the frequency ranges Single Speed, Double Speed or Quad Speed.
Single Speed
All outputs carry a signal in the range of 32 kHz up to 48 kHz.
DS (Double Speed)
The AES outputs 1-8 carry a signal in the range of 64 kHz up to 96 kHz. ADAT and MADI stay
at no higher than 48 kHz, with the data transmitted in the S/MUX format.
QS (Quad Speed)
The AES outputs 1-8 carry a signal in the range of 176.4 kHz up to 192 kHz. ADAT and MADI
stay at no higher than 48 kHz, with the data transmitted in the S/MUX4 format. Therefore ADAT
is limited to 4 channels (2 per optical output) in this mode.
8.3 Analog Out
The button ANALOG OUT is used to set the analog reference level at the analog outputs. This
level is reached at full scale of the DA-converters, thus matching the front panel level meters
level indication.
Reference 0 dBFS @ Analog Headroom
+24 +24 dBu 3 dB
+19 +19 dBu 8 dB
+13 +13 dBu 14 dB
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8.4 Remote
REMOTE defines the source of MIDI remote control commands. Choices are the MIDI DIN jack,
the D-sub AES1 and the MADI input of the I64 MADI Card (Option Slot). A firmware update
added a fourth option, RS232, signaled by the LEDs OPTN and MIDI flashing alternately. Nevertheless RS232 is currently not functional.
Note
: Via MIDI remote control, all front panel controls can be locked (Lock Keys). An exception
is the REMOTE key. In Off-state Lock Keys is deactivated. Therefore a locking of all the
controls can be revoked directly at the unit at any time.
9. The Input Channel in Detail
9.1 General
Each channel has a dedicated configuration area on the front plate. The display GAIN shows
the currently set amount of amplification. The 13-segment LEVEL meter with switchable Peak
Hold function shows the digital signal level after Gain control, but before SRC, stereo and M/S
processing, as shown in the block diagram (chapter 20). The SELECT button is used to select a
channel, but also to activate/deactivate the different functions (DPP, STEREO etc).
9.2 Gain
The DMC-842's GAIN can be set individually per channel over a range of 0 db up to +63 dB, in
steps of 1 dB. The device has its own gain control, operational even in the asynchronous Mode
1, and – as shown in the block diagram – is placed in front of the SRCs. When the microphone
signals support for gain control, the DMC-842’s gain stage is deactivated automatically by setting it to 0 dB internally.
The gain can not be set directly for inactive channels. Therefore in Stereo mode the gain display of the right channel is turned off.
9.3 Digital Phantom Power
The LED DPP indicates activated digital phantom power for the XLR input. Phantom power
should only be activated when using digital microphones.
Connecting and disconnecting microphones while phantom power is active causes a voltage surge, which can destroy components. Switch phantom power off before connecting/disconnecting any external device.
As called for in the AES42 standard, the DMC-842 provides a common mode voltage of 10
Volts on both input pins. When connecting fully balanced AES/EBU outputs, this voltage theoretically stays without effect. Nevertheless we strongly recommend to switch off DPP in such
cases. When connecting unbalanced outputs (AES-ID or SPDIF) a current is expected to flow
through the output stage of the feeding device!
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User’s Guide DMC-842 © RME
9.4 Mode 2
In Mode 1 the digital microphone is clock master, operating from the internal and fixed frequency. When connecting more than one microphone, the usage of sample rate converters for
clock-decoupling is unavoidable.
In the newer Mode 2 the digital microphone is clock slave. The DMC-842 determines the frequency and generates a digital control signal for each microphone. A sample rate conversion is
not required in this case.
The microphone signals the supported mode, the DMC-842 switches its input accordingly. The
LED MODE 2 therefore is a state display only.
: Not every digital microphone supports Mode 2. With regard to the outstanding SRC built
Note
into the DMC-842 Mode 1 can be seen as equally good alternative. However the SRCs delay
the audio signals by about 141 samples. At 44.1 kHz, this equals about 3 ms.
9.5 Stereo / Inactive
The DMC-842 has 8 single AES/EBU compatible inputs, being a 2-channel (stereo) input each.
At the time of printing this manual, digital stereo microphones not yet exist. A digital microphone
therefore provides only the information of one channel per input. For maximum flexibility the
operation mode can be switched between 2-channel and 1-channel. The labeling of the input
XLR connectors has been done to signal this flexibility. The odd ones are labeled Stereo (1/2),
the even ones Mono (2).
When an odd channel is switched into STEREO mode, the according even channel’s INACTIVE
LED lights up automatically. The gain can not be set directly for inactive channels. Therefore in
Stereo mode the gain display of the right channel is turned off.
9.6 M/S Processing
The DMC-842 includes a digital M/S processor. The channels have a fixed assignment: all odd
ones are M, all even ones are S. The front panel shows an according labeling:
Channel 1 M
Channel 2 M/S
The mid/side principle is a special positioning technique for microphones, which results in a mid
signal on one channel and a side signal on the other channel. The DMC-842’s M/S processor
transforms these information back into a standard stereo signal. The process sends the monaural mid channel to left and right, the side channel too, but phase inverted (180°) to the right
channel. For a better understanding: the mid channel represents the function L+R, while the
side channel represents L-R.
The M/S-Processing automatically operates as M/S encoder or decoder, depending on the
source signal format. When processing a usual stereo signal, all monaural information will be
shifted into the left channel, all stereo information into the right channel. Thus the stereo signal
is M/S encoded. This yields some interesting insights into the mono/stereo contents of modern
music productions. Additionally some very interesting methods of manipulating the stereo base
and generating stereo effects come up, as it is then very easy to process the side channel with
Low Cut, Expander, Compressor or Delay. The most basic application is to change the level of
the side channel: this allows to manipulate the stereo width from mono to stereo up to extended
in a stepless way.
/S (D)
(D)
User’s Guide DMC-842 © RME
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