Grace m802 User manual

owner’s manual
remote microphone preamplifier
Preamplier rmware version 2.2
Remote rmware version 2.0
Manual RevG
all contents © Grace Design/ Lunatec LLC

2
Welcome
Thank you for purchasing the Grace Design m802 preamplier system. With the combination of un-
matched sonic performance, remote control capability and total reliability, the m802 is the ultimate,
state of the art microphone preamplier solution.
We have designed the m802 to be as easy and intuitive to use as possible. However, we strongly recom-
mend that you read this product manual thoroughly to familiarize yourself with the unique features and
capabilities of the m802.
Also, please do not hesitate to contact us directly if you have any questions, comments, or concerns with
your new m802 microphone preamplier system. Thanks for reading and happy recording!!
-The Grace Design Team
Table of Contents
Welcome 2
Important Safety Information 3
Overview 4
Front Panel Diagram 5
m802 RCU Diagram 6
m802 Rearpanel Diagram 6
m802 Rearpanel with A/D Converter Diagram 7
m802 Power Supply Diagram 7
Installation 8
Preamplifier Operation / Modes 11
A/D Converter Sensitivity Calibration 16
Operation within Pro Tools 18
Remote Control Unit Operation 19
Cable Diagrams 22
Specifications 23
Cleaning and Maintenance 24
Warranty Information 25
Manual Revisions 26

3
Important Safety Information
General
• Indoor use only
• Ordinary Protection: This equipment should not be exposed to dripping or splashing.
• Avoid placing objects filled with liquids, such as vases or glasses, on this equipment.
• Class I Equipment (grounded type)
• Electrical rating: 100-120/220-240V~ 50-60Hz 25W
• Mains supply voltage fluctuations are not to exceed ±10% of the nominal supply voltage.
• Pollution Degree 2
• Installation (Overvoltage) Category II for transient overvoltages.
• Maximum Relative Humidity: <80%
• Operation temperature range: 10 °C to 40 °C
• Storage and transportation temperature range –40 °C to 70 °C
• Maximum altitude: 3000m (9843 ft)
• Equipment suitable for continuous operation
• Weight: preamplifier - 6.7kg (14.7lbs) / power supply unit - 2.8kg (6.25lbs)
Safety Marking Symbols
CAUTION: READ ACCOMPANYING DOCUMENTS
This symbol, located on the equipment and in this manual, refers to important in-
structions. Read this manual thoroughly before operating this equipment.
WARNING: ELECTRICAL SHOCK HAZARD
This symbol, located on the equipment and in this manual, indicates the potential
for electrical shock hazard.
DC POWER OUTPUT
This symbol, located on the equipment and in this manual, indicates a DC power
output connection.
Service Information
The Grace Design m802 contains no user serviceable components. Contact Grace Design for repair and
upgrade information. In the event that your Grace Design m802 needs to be returned to the factory,
contact us for a return authorization number.

4
Overview
SYSTEM COMPONENTS
The m802 system consists of an 8 channel preamplier chassis, a power supply chassis, and an optional
remote control unit (referred to as the RCU in the rest of this manual). The preamplier chassis contains
8 audio amplier PCBs, a micro controller PCB, and a front panel control interface. For remote control
communications, the preamplier chassis is equipped with two Philips I2C bus connectors (D-sub 9 pin)
and MIDI IN and OUT connectors. The use of an external DC power supply unit ensures that no power
line interference can compromise the performance of the sensitive microphone amplier circuits.
As well as the standard 48V phantom powered microphone inputs, the m802 can be ordered with op-
tional 130V inputs for use with the DPA (formerly B&K) high voltage microphones. These microphones
employ a high voltage transformerless impedance conversion circuit, which is not subject to the limita-
tions of the 48V phantom powering standard. However, being unbalanced, the DPA 130V microphones
benet greatly from short cable runs from microphone to preamplier.
Additionally, an optional extremely high performance 8-channel analog-to-digital converter module is
available for the m802. This converter module supports sample rates up to 192kHz at 24bit resolution.
The RCU features an expanded version of the preamplier front panel interface and has a single Philips
I2C bus connector as well as a DC power Jack.
REMOTE CONTROL OPTIONS
The m802 preamplier can be controlled by the RCU, via MIDI, or directly from its front panel. The RCU
connects to the preamplier via a Philips I2C serial buss, which makes parallel connections between all
of the devices in the system. In an m802 system, the RCU is the master and all of the preampliers are
slaves. The data on the display of the RCU is echoed back from the preamplier so it shows the actual
status of the preamplier. For instance, when you tell a preamplier to change its gain at the RCU, the
RCU will send the gain change command to the preamplier and then ask the preamplier what its cur-
rent gain setting is. The RCU will then update its own display to reect the change. This gives the user
absolute condence that what is visible on the display is exactly what is happening at the preamplier.
If the RCU is disconnected from the preamplier(s), the data elds in the display will go blank, but the
preampliers will continue to operate normally.
Please Note: The 9pin I2C is a proprietary interface. It is not compatible with RS-232, RS-
422, or any other 9 pin based serial protocol found in the recording studio environment.
The RCU can control up to 8 preampliers (64 channels) by connecting it to one preamplier and then
connecting the remaining preampliers together with I2C cables in a daisy chain fashion. The RCU can
be located up to 1000”(305 meters) away from the preampliers. Using the adapters included with the
RCU, standard microphone cable can be used for this interface. Only one RCU can be connected to a
system at any time.
The m802 can also be controlled via MIDI. When the m802 sees any activity on its MIDI input port, it
automatically switches into MIDI control mode. In this mode, the m802 will emulate a Digidesign® PRE

GRACE DESIGN USA
remote microphone
preamplifier
SETUP
PEAK
+48V
DATA
(push)
GROUP
G
D
E
CF
AB
5
microphone preamplier. After a period of 16 seconds with no activity on the MIDI input port, the m802
will automatically revert back to its normal control mode. See the MIDI Control section of this manual
for more details on the MIDI control mode.
Front Panel Diagram
A
+48 Volt phantom power pushbutton
B
Ø phase reverse pushbutton
C
GROUP pushbutton
D
PEAK indicator reset pushbutton
E
SETUP select pushbutton
F
DATA encoder with pushbutton
G
LCD display 64x240 pixels

48V GROUP VIEW SETUP
GAIN / EDIT
CHANNEL SELECT
remote microphone preamplifier
push
B
G
DE
CF
A
H
J
I
H
H
B
A
G
C
D
F E C
6
m802 Rearpanel Diagram
A
MIC IN XLR Input
B
DPA 130V input (optional)
C
LINE OUT XLR output
D
LINE OUT DB25 output
E
DC Power Input
F
MIDI Output
G
MIDI Input
H
I2C REMOTE IN and OUT
m802 RCU Diagram
A
+48 Volt phantom power pushbutton
B
Ø phase reverse pushbutton
C
GROUP pushbutton
D
VIEW / peak indicator reset pushbutton
E
SETUP select pushbutton
F
7-segment LED display
G
DATA encoder with pushbutton
H
Page Up / Down pushbuttons
I
Channel Select pushbuttons
J
LCD display 64x240 pixels

B
D
A
C
7
m802 Power Supply Diagram
A
LED Voltage indicators
B
Power switch
C
AC line input
D
DC output
front
rear
Digital Output option B incul-
des 2 sets of 8 channel AES3 out-
puts on DB25, Word Clock in and
Out, and 2 8 channel ADAT / Light-
pipe outputs.
Digital Output Option A in-
cludes 2 sets of 8 channel AES3
outputs on DB25, Word Clock in
and Out, and 1 set of AES3-id out-
puts on 4 BNC connectors.
m802 Rearpanel with A/D Converter Diagram

8
Installation
SYSTEM CONNECTION DIAGRAM
PREAMPLIFIER POWER CONNECTIONS
An 8’ (2.8m) DC power cord is supplied to connect the power supply unit to the preamplier unit. This
cord can be identied by the 8 pin circular connectors at each end.
Please note that the DC power cord should be connected before the AC power is turned on. This prevents
incorrect power sequencing which can cause damage to the audio circuits.
Warning: A damaged DC power cord can create a shock hazard as Voltages of
66VDC (148VDC with the DPA Input option) can be present. Do not operate the
m802 with a damaged DC power cord. Replace a damaged DC power cord with
a replacement from Grace Design (WA084) only.
To avoid any interference with the low level audio circuitry, the power supply should be lo-
cated at least 3’(1m) from the preamplier unit.
POWER SUPPLY UNIT CONNECTIONS
A standard AC power cable is included. For safety, the power supply cord must be connected to a
grounded outlet.
AC input voltage settings can be adjusted for 100V, 120V, 220V and 240V operation at 50-60Hz. If your
voltage is 230V, use the 240V setting. From the rear of the power supply unit, open the trap door next
to the IEC power inlet with a small screwdriver. Carefully pull the voltage select cam straight out and
then insert with the desired voltage showing. Do not try to rotate the cam while it is in the power input
module. Replace the fuses with the proper value selected from the fuse value table below (gure 1). Be
sure to use a time delay type fuse with a 250V rating.
m802 Power Supply Unit
m802 Preamplifier Unit
Remote Control Unit
AC Line Input
100/120/220/230-240V~
DC Input
6.0-7.5VDC
DC Power Cord
+6.5,+18,-18,+48VDC
Audio Signal
Inputs/Outputs
push
GRACE DESIGN BOULDER, CO USA
I
O
I2C Interconnect Cord

9
CAM SETTING LINE VOLTAGE FUSE VALUE
100V~ 100V~ 250V~ T 800mA L
120V~ 120V~ 250V~ T 800mA L
220V~ 220V~ 250V~ T 500mA L
240V~ 230V~ 250V~ T 500mA L
240V~ 240V~ 250V~T 500mA L
gure 1 / fuse value table
CHECK LINE VOLTAGE SETTINGS
The power supply unit has been set from the factory to operate at the voltage required for your part of
the world. However, it’s important to double-check this in order to ensure no damage will come to the
unit if power is applied while the setting is incorrect.
TURNING THE POWER ON
The power switch is located on the front panel of the Power Supply Unit. Switching the rocker switch to
the I position turns the mains power on. Switching the rocker switch to the O position turns the mains
power o.
REMOTE CONTROL UNIT POWER CONNECTION
The RCU is powered with the supplied AC wall adapter. It is recommended that the I2C data connec-
tions be made before applying power to the RCU. Simply plugging the 2.1mm barrel connector into the
DC power jack turns the power on. The m802 RCU is rated for 6.0-7.5V / 0.5A DC. (+) is in the center and
(–) is on the outside sleeve.
AUDIO CONNECTIONS
Standard microphone input connections are made via female XLR connectors with pin 2 positive, pin
3 negative and pin 1 ground. 48V phantom power is supplied on pins 2 and 3. DPA® 130V microphone
connections are made via the female 4 pin XLR connectors with audio on pin 4, 130V on pin 3 and
ground on pin 1.
On standard m802 preamp channels, two male XLR output connectors are available with pin 2 positive,
pin 3 negative and pin 1 ground. (There is one male XLR output connector available on 130V DPA cards.)
An additional set of parallel outputs is provided with a 25 pin D-sub connector (See the gure at the
back of the manual – NOTE: this output is not available if the optional A/D converter module is installed).
All output connectors can be used simultaneously.
If the output is to be used unbalanced, pin 1 should be connected to signal ground and pin 2 to signal
hot. Due to the nature of the balanced output stage, pin 3 should be left open for unbalanced operation
(See CABLE DIAGRAMS p. 20). Note: This will provide a signal of positive absolute polarity when the pre-
amplier is being used with a microphone which produces a positive voltage on pin 2 with positive air
pressure on the front of the diaphragm. While a vast majority of microphones conform to this standard
a few do not. Use the phase reverse switch to compensate if necessary.
DIGITAL AUDIO CONNECTIONS
If the optional A/D converter module is installed, multiple digital outputs are available. The routing of
the preamp outputs to the A/D converter is xed. Each preamp channel feeds the corresponding con-

10
verter channel (1-8). The DB25 pin provides 8 stereo AES outputs, which can be congured for single or
dual wire operation. In single wire operation AES outputs 1-4 are copied by AES outputs 5-8 providing
two sets of (8-channel) digital outputs. In dual wire mode, AES outputs 1-4 carry audio channels 1-4
and AES outputs 5-8 carry audio channels 5-8. Please see the digital output table on page 20.
The A/D converter module also has an additional set of outputs. These can be either 4 x AES3id BNC
outputs or 2 x ADAT Lightpipe outputs – (the conguration is determined at time of purchase). The
AES3id outputs each provide 2 channels of audio data in single wire mode or 1 channel of audio data in
dual-wire mode. The ADAT lightpipe outputs provide 8 channels of audio data on each (at base rate). At
dual rates the ADAT S-MUX is enabled and channels 1-4 are available on ADAT output 1, while channels
5-8 are transmitted on ADAT output 2. Quad sample rates are not supported over the ADAT interface.
AES3-id output connector conguration
AES3id connector Audio channels 1-wire mode Audio channels 2-wire mode
1 1-2 1
2 3-4 2
3 5-6 3
4 7-8 4
ADAT output connector conguration
ADAT connector Audio channels Fs = 44.1-48kHz Audio channels Fs = 88.2-96kHz (S-MUX)
Upper 1-8 1-4
Lower 1-8 5-8
gure 2 / digital output conguration
DIGITAL CLOCK CONNECTIONS
The m802 features an external clock input and clock output for syncronization to external clock sources.
The clock input BNC connector can accept a WORDCLOCK signal running at the selected sample rate
or a Digidesign Pro Tools® LOOPSYNC signal. For optimal performance when using the external clock
connection, the m802 must be connected directly to a 75 Ohm clock source. The external clock input is
terminated to 75 ohms within the m802 and thus should not be terminated elsewhere. The clock out-
put connector signal can be derived from two dierent sources, either a buered copy of the incoming
clock signal on the wordclock input connector, or the internally generated WORDCLOCK.
DATA CONNECTIONS
m802 RCU Control: m802 RCU to Preamplier data connections are made with an I2C serial cable.
This cable has a male 9 pin D-sub connector at each end. The data cable can be up to 1000’(304 Meters)
in length. The I2C cable is connected to the 9 pin D-sub connector on the remote unit and to the I2C IN
9 pin D-sub connector on the preamplier. As well, the RCU is supplied with a set of adapters that allow
one to use a standard microphone cable for the serial data link. The microphone cable can be up to 1000’
long. It is not recommended to use a line in a multi-channel snake that contains mic level signals for this
application, because the serial data activity can induce noise into adjacent low level audio signal lines.
However, it is acceptable to include the data signal in a snake that contains only line level signals.
Preamplier-to-Preamplier connections are made by connecting a 9 pin I2C cable from the I2C OUT
connector on one preamplier to the I2C IN connector on another preamplier.
Note: In a multiple preamplier system, all preampliers must be powered on for the RCU to communi-