Stewart MC850 User guide

MC850 Operation Manual

1 Important safety instructions

1. Please read carefully prior to product installation or operation.

2. Read these instructions.

3. Keep these instructions.

4. Heed all warnings.

5. Follow all instructions.

6. Do not use this apparatus near water.

7. Clean only with dry cloth.

8. Do not block any ventilation openings. Install in accordance with manufacturer’s instructions.

9. Do not install near any heat sources such as radiators, heat registers, stoves, or other

apparatus (including amplifiers) that produce heat.

10. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has

two blades with one wider than the other. A grounding type plug has two blades and a third
grounding prong. The wide blade and/or the third prong are provided for your safety. If the
provided plug does not fit into your outlet, consult an electrician for replacement of the
obsolete outlet.

11. Protect the power cord from being walked on or pinched particularly at plugs, convenience

receptacles, and the point they exit from the apparatus.

12. Only use attachments/accessories specified by the manufacturer.

13. Use only with the cart, stand, tripod, bracket, or table provided by the manufacturer, or sold

with the apparatus. When a cart is used, use caution when moving the cart/apparatus
combination to avoid injury from tip-over.

14. Unplug this apparatus during lightning storms or when unused for long periods of time.

15. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has

been damaged in any way, such as power-supply cord or plug is damaged, liquid has been
spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or
moisture, does not operate properly, or has been dropped.

2 Approvals

This equipment has been tested and found to be compliant with the limits for Class A Digital device

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Voltage

Line plug (according to standard)

110-125 V (US)

UL817 and CSA C22.2 no 42.

220-230 V (EUROPE)

CEE 7 page VII, SR section 107-2-D1/IEC
83 page C4

240 V (UK)

BS 1363 of 1984. Specification for 13 A
fused plugs and switched and
unswitched socket outlets.

pursuant to part 15 of the FCC rules.

This equipment has been tested to UL 60065 and is listed with that agency

3 Warnings

3.1 Explanation of Warning Symbols

3.1.1 Lightning Bolt

The lightning bolt within arrowhead symbol, within an equilateral triangle, is intended to alert the user to
the presence of un-insulated “dangerous voltage” within the product’s enclosure that may be of sufficient
magnitude to constitute a risk of electrical shock to person.

3.1.2 Exclamation Point

The exclamation point within an equilateral triangle is intended to alert the user to the presence of
important operating and maintenance (servicing) instruction in the literature accompanying the appliance.

3.2 Warnings

WARNING: TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT EXPOSE THIS AMPLIFIER TO
RAIN OR MOISTURE. DANGEROUS HIGH VOLTAGES ARE PRESENT INSIDE THE ENCLOSURE. DO
NOT OPEN THE CABINET. REFER SERVICING TO QUALIFIED PERSONNEL ONLY.

Please refer to the following table for AC Line plug information.

3.3 User Responsibility

3.3.1 Mains Connection Grounding

Your amplifier must be connected to a grounded outlet. Do not defeat the safety purpose of the polarized
or grounding-type plug.

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3.3.2 Speaker Output Hazard

Power amplifiers are capable of producing hazardous output voltages, especially constant voltage
amplifiers. To avoid electrical shock, do not touch any exposed speaker wiring while the amplifier
is operating. External wiring connected to the speaker terminals shall be installed by a qualified
person. Do not connect or disconnect speaker wires while the mains power is on. Do not connect
speaker wires together or to ground as this may result in permanent damage to your amplifier.

3.3.3 Radio Interference

This product has been tested and complies with the EMC directive, and with FCC part 15 Class A. If
this product is not used in accordance with these operating instructions, it may cause interference
with to other equipment, such as radio and television receivers.

3.3.4 Speaker Damage

Loudspeakers may be damaged or destroyed if overpowered. Always check the loudspeaker’s

continuous and peak power ratings to prevent such an occurrence. Do not rely solely on the
amplifier’s volume control to reduce output power to a level safe for the loudspeakers.

3.3.5 Maintenance

Clean regularly with a soft cloth to remove dust and debris. Also check that vent holes and slots
are not covered and that there is adequate ventilation for convection cooling.

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4 Table of Contents

1 Important safety instructions ............................................................................................................... 1

2 Approvals .............................................................................................................................................. 1

3 Warnings ............................................................................................................................................... 2

3.1 Explanation of Warning Symbols .................................................................................................. 2

3.1.1 Lightning Bolt ........................................................................................................................ 2

3.1.2 Exclamation Point ................................................................................................................. 2

3.2 Warnings ....................................................................................................................................... 2

3.3 User Responsibility ....................................................................................................................... 2

3.3.1 Mains Connection Grounding ............................................................................................... 2

3.3.2 Speaker Output Hazard ........................................................................................................ 3

3.3.3 Radio Interference ................................................................................................................ 3

3.3.4 Speaker Damage ................................................................................................................... 3

3.3.5 Maintenance ......................................................................................................................... 3

4 Table of Contents ................................................................................................................................. 4

5 Welcome ............................................................................................................................................... 6

5.1 Features ........................................................................................................................................ 6

5.2 Unpacking and Visual Inspection .................................................................................................. 6

5.3 Installation and Setup ................................................................................................................... 6

5.3.1 Rack Mounting ...................................................................................................................... 6

5.3.2 Cooling and Ventilation ........................................................................................................ 6

5.3.3 Operating Voltage ................................................................................................................. 7

6 Rear Panel ............................................................................................................................................. 8

6.1 Operation ...................................................................................................................................... 9

6.1.1 Dante™ Audio ....................................................................................................................... 9

6.1.2 RS-232 Control ...................................................................................................................... 9

6.1.3 Speaker Connections .......................................................................................................... 11

7 MC850 Configuration and Status Application .................................................................................... 13

7.1 MC850 System Status Screen ..................................................................................................... 13

7.1.1 Program Drop-down Menu ................................................................................................ 13

7.1.2 System Drop-down Menu ................................................................................................... 13

7.2 MC850 Device Status Screen ...................................................................................................... 13

7.2.1 Status Tab ........................................................................................................................... 14

7.2.2 Setup Tab ............................................................................................................................ 16

7.2.3 Event Log Tab ...................................................................................................................... 18

7.2.4 Load Test Tab ...................................................................................................................... 18

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8 Specifications ...................................................................................................................................... 19

9 Troubleshooting ................................................................................................................................. 20

10 Warranty Information ........................................................................................................................ 21

10.1 Warranty Summary .................................................................................................................... 21

10.2 Eligibility Requirements .............................................................................................................. 21

10.3 Non-warranty Repairs................................................................................................................. 21

11 Return Procedure ............................................................................................................................... 22

11.1 Shipment Instructions ................................................................................................................ 22

11.2 Packaging Instructions ................................................................................................................ 22

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Operating Mode

Power consumption

(W)

Power dissipated

(W)

Energy dissipated

(BTU/hr)

Standby (non-operational)

4.1

4.1

14

Idle (operational, no input signals)

28

28

96

1/8 rated audio power

103

53

181

50W/channel audio power

585

185

631

5 Welcome

Congratulations on the purchase of your new Stewart Audio MC850 Multi-channel audio amplifier. This
amplifier has been designed and built to provide you with years of high-quality audio performance and
trouble-free operation. If after reading this operation manual you have questions concerning amplifier
installation and operation, please contact your Authorized Stewart dealer, or you may contact us directly
using the contact information provided on the back of this guide.

5.1 Features

The MC850 amplifiers offer 8 channels of audio with nominally 50W output power per channel.
The output power can be allocated up to a maximum of 125W (low impedance) or 100W (constant
voltage) per channel as long as the 200W/ 4 channel limit is not exceeded. (See Section 7.2.2.6 for
more information.) These network-enabled models employ the Dante™ audio transport protocol
to deliver low latency audio over category 5e/6 cables via a 100/1000BaseT network. The low
impedance model (LZ) operate into 4Ω or 8Ω loudspeakers, while the constant voltage or high
impedance model (CV) are designed to be used with one or more high impedance loudspeakers
per channel. The mixed impedance model (MXZ) operates into 6 channels of high impedance
loudspeakers and 2 channels of 4Ω or 8Ω loudspeakers. All models offer control and status via the
Ethernet control port using Stewart Audio’s Multichannel Amplifier Control and Status application.
Output level control is also available over an RS-232 interface for legacy controllers.

5.2 Unpacking and Visual Inspection

Every Stewart Audio product is carefully tested and inspected before leaving the factory and
should arrive in perfect condition. If any damage is discovered, please notify the shipping carrier
immediately. Save the packing materials for the carrier’s inspection and for any future shipping.

5.3 Installation and Setup

5.3.1 Rack Mounting

The MC850 is designed for rack mounting in a standard 19” rack using the rack mount brackets
supplied with the amplifier. The CV and MXZ models weigh in excess of 10 pounds (4.5kg). While
the design places the center of mass of these amplifiers near the front panel, it is strongly advised

that the rear of the enclosure be supported using the #6-32 tpi threaded nut in the center of the
back panel.

5.3.2 Cooling and Ventilation

Ensure that there is sufficient open space around the amplifier to allow for free air flow. The
MC850 contains no fans and thus relies on convection cooling. Do not block the ventilation holes
or slots. Use the following chart to determine cooling requirements for your application.

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Power consumption and energy dissipated

5.3.3 Operating Voltage

The MC850 uses an integral universal power supply that operates on AC mains from 100-240V at
50 or 60 Hz. The power receptacle on the rear panel accepts IEC-60320-C13 power cords. The
MC850 has no power switch. The amplifier will turn on automatically when AC power is
connected to the device.

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③

①

②

④ ⑤ ⑥ ⑦ ⑧

⑨

⑩

6 Rear Panel

1. AC line input – Connect the included IEC power cable.

2. Network audio connectors – Connect one end of a Cat 5e or Cat 6 cable to primary port, and

the other to the 100/1000BaseT switch carrying audio traffic. By default, the two port jack is
configured as a switch, so the other (secondary) jack may be used to “daisy-chain” other
network components. These ports can be configured in Dante Controller as redundant audio
ports, in which case each port should be connected to a switch on a separate audio network.

3. Control and status connector – Connect one end of a Cat5e or Cat 6 cable to this port, and the

other to an Ethernet switch for network control and status. This port can be on the same
network as the audio traffic or on a separate network. Further, if a redundant audio network
is not required, and if the control port can be on the same subnet mask as the audio data, the
two-port audio Ethernet jacks can be configured (via Dante Controller) in switch mode and the
control port can be daisy-chained from the unused audio port. The PC running Stewart Audio’s
MC850 Control and Status application must be on the same network as the control port.

4. Fault indicator – This red LED illuminates in the presence of a fault. A steady LED indicates that

the internal temperature of the device is reaching an unsafe level. A flashing LED indicates that
the amplifier has reached an unsafe internal temperature level and has shut down for
protection. The LED will remain flashing until a safe operating temperature is attained. At that
time, the amplifier will automatically restart. If this condition persists, reassess airflow and
cooling conditions.

5. Power LED – This green LED illuminates whenever AC power is applied. A steady LED indicates

normal operation, while a flashing LED indicates that the amplifier has reached an unsafe
internal temperature and is in a cool down phase.

6. Signal LEDs – The green LED associated with that channel will illuminate when the input signal

level for that channel is greater than -60dBV. There is an approximately 0.5 second hysteresis
at the -60dBV level to prevent excessive flashing.

7. 70/100V Switch (Constant Voltage and Mixed models only) – Select the desired output

voltage (70.7V or 100V) by sliding the switch to the appropriate position in order to meet the
requirements of the country of sale.

8. RS-232 connector – Connect to a standard RS-232 controller using the 3.5mm Euro-style

terminal blocks provided. For RS-232 codes, see Section 6.1.3.

9. Contact Mute – Dry contact closure to mute all amplifier outputs.

10. Speaker outputs – Connect loudspeakers using the 5mm Euro-style terminal blocks provided.

Use 4Ω or 8Ω speakers for low impedance models (–LZ) and the two low impedance outputs (7
and 8) on the mixed impedance models (–MXZ). Use high impedance speakers for the

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constant voltage models (–CV) and the six constant voltage outputs (1-6) of the mixed
impedance models (–MXZ). Observe proper polarity to avoid low frequency cancellation loss.

The sum of the tapped wattage for all speakers connected to a single output should not
exceed 100W

RMS

.

The total tapped wattage for all speakers connected to outputs 1-4 should not exceed
200W
exceed 200W

. The total tapped power for all speakers connected to outputs 5-8 should not

RMS

.

RMS

In normal operation, the DC voltage on the speaker output connectors is approximately
24VDC. Do not connect any speaker output to ground or to the amplifier chassis. Do not
connect speakers across speaker outputs. (Bridge mode is not supported.)

6.1 Operation

6.1.1 Dante™ Audio

MC850 amplifiers utilize Audinate’s Dante™ multi-channel digital media networking technology,
with near-zero latency and synchronization. Routing audio signals from Dante-enabled
transmitters to Dante-enabled receivers is accomplished via the Dante Controller Software
available from Audinate’s web site. Please visit their web site for detailed information regarding
this technology, system and network configuration, troubleshooting, and other support. Note that
the MC850 Series amplifier supports the AES67 standard. To enable the AES67 mode, click on the

AES67 Config tab in the Device View in Dante Controller.

6.1.2 RS-232 Control

An RS–232 port (settings: 9600 baud; 8 n 1) allows remote control of selected amplifier functions.
The RS-232 commands are defined in the following table.

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Command Name and Description

Hex Command

LEVEL UP/DOWN

Changes level by AMOUNT1 on CHAN2

0x12 AMOUNT1 CHAN2 0x03

LEVEL SET

Sets CHAN2 level to LEVEL3

0x12 0x06 CHAN2 LEVEL3 0x03

LEVEL STATUS

Return CHAN2 level in the format
0x06 LEVEL3 0x0A

0x12 0x07 CHAN2 0x03

FORCE MUTE ON

Turn mute on for CHAN2

0x12 0x08 CHAN2 0x03

FORCE MUTE OFF

Turn mute off for CHAN2

0x12 0x09 CHAN2 0x03

TOGGLE MUTE

Toggles mute for CHAN2

0x12 0x10 CHAN2 0x03

MUTE STATUS

Return CHAN2 mute status in the format
0x06 MUTE4 0x0A

0x12 0x11 CHAN2 0x03

FIRMWARE VERSION

Return the current version of the firmware in the format
0x02 0xYY 0xZZ 0x03 where YY = Version; ZZ = Revision

0x12 0x13 0x13 0x03

1

AMOUNT is as follows:
0x01 = Up 1 dB
0x02 = Up 3 dB
0x04 = Down 1 dB
0x05 = Down 3 dB

2

CHAN selects the channel affected as follows:
0x00 = All channels
0x01 = Channel 1
0x02 = Channel 2, etc.

3

LEVEL is in the range of 0 to 100 representing the attenuation in decibels (dB), expressed as a hexadecimal
(0x00 . . . 0x64)

4

MUTE is in the format 0x00 = Unmuted; 0x01 = Muted

Note that the RS-232 level (attenuation) is in addition to the individual channel level and master level. If,
for example, the individual channel level is set at 12 dB and the master level is set at 8 dB, then a 7 dB RS­232 level will result in 27 dB of attenuation relative to full power. Also, the individual channel mute button
and the RS-232 command will mute the channel. Both need to be “unmuted” to restore output to the
loudspeaker. RS-232 settings are retained even if power is removed from and restored to the device.

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Distance

Wire Gauge

Up to 25 ft.

16 AWG

26-40 ft.

14 AWG

41-60 ft.

12 AWG

6.1.3 Speaker Connections

6.1.3.1 Channel-by-Channel Power Allocation (All Models)

Stewart Audio has incorporated channel-by-channel power allocation into the MC850 amplifiers to
further enhance deployment flexibility. Each output can be configured to deliver up to 100W
maximum audio power, with the limitation that the total audio power from outputs 1-4 cannot
exceed 200W, and the total audio power from outputs 5-8 cannot exceed 200W.

6.1.3.2 Low Impedance Models (and Low Impedance Outputs on MXZ Model)

Stewart Audio recommends using high-quality, heavy-gauge speaker wire and connectors to send
the output signal of your amplifier to the speakers. Use the following table as a guideline when
selecting your wire gauge.

Speaker leads connect by means of removable terminal block connectors supplied with the unit.
Strip speaker leads 1/4” and insert into connector observing proper polarity. With a small, flat­blade screwdriver, tighten the screw until the leads are held securely in place. Inspect for possible
shorts or broken wires.

6.1.3.3 Constant Voltage (High Impedance) Models (and High Impedance Outputs on MXZ Model)

Constant voltage amplifiers are designed to facilitate paralleling a number of high impedance
speakers on a single output (channel). Ideally the output signal level is set to deliver nominally

70.7V

RMS

(100V

in Europe) at the output terminals. The output voltage is selected by positioning

RMS

the 70/100V switch on the rear of the device to the appropriate position. Each speaker
transformer is then appropriately tapped to deliver the required volume level for that speaker.
Make certain that the total tapped power from all speakers connected to an output channel does
not exceed the rated power of that channel. A good rule of thumb is to load the channel no more
than 75-80% of rated power.

Care should be used when working around the speaker terminals. Though not officially recognized
as a shock hazard in the UL 60065 Safety Requirements, touching these terminals can be quite
unpleasant and should be avoided.

Because the current flow in constant voltage systems and speakers is much lower than in 4/8Ω
systems, higher gauge (thinner diameter) wire can be used. Please refer to the following table to
choose the appropriate wire gauge for your installation.

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Distance

Wire Gauge

Up to 500ft

22 AWG

500-1000 ft.

20 AWG

Over 1000ft

18 AWG

Speaker leads connect by means of removable terminal block connectors supplied with the unit.
Strip speaker leads 1/4” and insert into connector observing proper polarity. With a small, flat­blade screwdriver, tighten the screw until the leads are held securely in place. Inspect for possible
shorts or broken wires.

NOTE: Class 2 wiring must be used on the speaker terminals to comply with UL
requirements.

CAUTION: Do not connect either speaker terminal to ground. This will cause a short
circuit which may damage the amplifier, speaker, or both. Similarly, do not connect any
speaker terminal to ground.

CAUTION: The speaker terminals represent a shock hazard as they carry 70.7V and 100V
when driven with an audio signal. Disconnect the amplifier from the AC power source
when working on these terminals.

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7 MC850 Configuration and Status Application

The MC850 Configuration and Status application allows the user to set various amplifier
parameters, and receive amplifier status information via a network connection. This application is
available for Windows operating systems from Stewart Audio’s web site.

7.1 MC850 System Status Screen

When the MC850 Configuration and Status
Application is launched, the application
automatically discovers all MC850 devices on the
network and populates the System Status screen.
Selecting the Program and System drop down
menus provide options described below. The
refresh button causes the application to poll and
recreate a list of all MC850 devices on the
network. This list includes the IP address of the
control port (note that the control port may be either on the Dante audio network, or on a separate
network), MAC address, host name, device name, model, and firmware version of the device. To connect
to a specific device, double-click anywhere along the row describing that device.

7.1.1 Program Drop-down Menu

There are two selections on the Program drop-down menu. The
About option provides the version information for the
application. The Exit option exits the application.

7.1.2 System Drop-down Menu

There are three options on the System drop-down menu. The
Select option allows the user to select all or none of the
connected devices for subsequent operation (change mute status
and change run/standby status). If the intent is to change the
status of just some of the connected devices, the status box may
be checked for each individual device.

The Mute option mutes or unmutes all selected devices. The
Standby option changes the run/standby status of all selected
amplifiers. Note that each of these options requires that an
Ethernet socket be opened between the controlling PC and
device before the status change is executed. This typically takes
a few seconds for each device on the network.

7.2 MC850 Device Status Screen

There are four tabs associated with device status: Status, Setup, Event Log, and Load Test. Click on the
desired tab to move to that screen.

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7.2.1 Status Tab

7.2.1.1 VU Meters and Signal Indicators

The Status tab displays VU meters at the top. These may be set to monitor either the input signal level or
the output signal level of all channels by moving the switch to the left of the meters. Just below the meters
are 8 green lights. These mirror the LEDs on the amplifiers and illuminate when an audio signal is present
on that channel.

7.2.1.2 Trim Level Sliders and Level Entry

Below the VU meters and lights are 9 sliders. These trim the level of each channel. There is also a master
slider that trims all channels simultaneously. The master trim and individual channel trims are additive.
These may be set by either moving the slider with the mouse, entering the level in the box below the slider,
or by using the up/down arrows on the right side of each level box. The level can be adjusted in 0.5 dB
steps.

7.2.1.3 RS-232 Settings

The MC850 Series of amplifiers are also equipped with an RS-232 port for volume control and status. The
RS-232 levels for each channel and the master level set by the RS-232 controller are indicated at the bottom
of the Status Tab page. The Reset RS232 button resets all levels to 0dB. This is provided in the event the
RS-232 controller has failed or gotten out of sync with the amplifier.

7.2.1.4 External Mute LED

This LED indicates the status of the external dry contact mute terminal. When illuminated, the amplifier is
muted.

7.2.1.5 Run/Standby, Identify, and Connection Buttons

On the upper right side of the Status tab there is a Run/Standby button. The text in the button indicates
the amplifier status, and the strip at the bottom appears dark green when in the Standby mode and bright

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green when in the Run mode. The Standby mode is recommended when the amplifier will not be delivering
an audio program for extended periods of time. The total power draw in Standby mode is just over 4W (as
compared with 28W in idle mode). There is less than a half second time lag for the amplifier to emerge
from Standby mode. Note that the power to the Dante device remains on during Standby so the amplifier
never drops off the Dante network.

Just below the Run/Standby button is the Identify button. When this button is pressed, the signal present
LEDs on the amplifier will flash for several seconds, providing a visual indicator of the device currently being
controlled and monitored by the application.

To the right of the Run/Standby button is a light that indicates whether the application is connected to or
disconnected from the device.

7.2.1.6 Firmware Version, Device Name, and Fault Indicator

Also to the right of the VU meters is a Connection button which is bright green when the control program is
connected to the amplifier (and dark green when disconnected). Below that the device’s firmware version,
device name (see Setup Tab Section 7.2.2 for details), and model.

7.2.1.7 Channel Status Indicators and Temperature Gauges

To the right of the trim sliders are four Channel Status boxes that illuminate to indicate the amplifier status.
The MC850 actually uses four separate amplifiers, each in BTL mode to provide power to the eight speaker
loads. The status of each amplifier is displayed in the box beside its associated channels. There are five
possible conditions for each amplifier: Normal, Standby, Disabled, Over temperature, and Over current.
When the amplifier is operating normally, the box will appear green. When the amplifier is in Standby, the
box will appear orange. When the amplifier is disabled (the PWM switching has been stopped), the box will
appear yellow. When the amplifier is in danger of exceeding its maximum temperature rating or if it has
exceeded its maximum current rating, the box will appear red.

To the right of the Channel Status boxes are two temperature gauges indicating the approximate
temperature of the PCB in the area of the amplifiers and of the MCU. If these gauges show excessive
temperature, check the ventilation and ambient air temperature surrounding the amplifier. Adjust these
environmental conditions until the temperature indicators are in the green (safe) range.

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7.2.2 Setup Tab

7.2.2.1 Name Section

The amplifier and channel names can be entered in the upper left section of the
Setup Tab. When the Save button below the entry boxes is pressed, the new
channel and device names are propagated through all tabs of the application. To
avoid confusion, it is recommended that these identifiers be the same as those used
in Dante Controller, but the choice is left to the user.

7.2.2.2 IP Address Section

The default condition for the MC850 is to receive a control port IP
address automatically from the DHCP server. However if a static IP
address is desired, this section provides a mechanism to assign
that address. Use care when exercising this option as setting an IP
address that is not in the same subnet as the controlling PC will
result in a failure to discover the device.

7.2.2.3 Channel Control Section

To the right of the Name section is the Channel Control section. Pairs of channels
(corresponding to one of the physical amplifiers) can be enabled or disabled.
When disabled, the PWM switching of the amplifier is halted. While this does not
save a significant amount of energy, it ensures absolute silence at the speakers for
the disabled channel pair.

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7.2.2.4 Sleep Mode Section

To the right of the Channel Control section is the sleep mode section. The
user may set the signal threshold level as desired. When there is no audio
signal greater than the set threshold level at any of the eight inputs for the
time selected, the amplifier will enter the sleep mode. The main power
supplies will be turned off (but not the power to the Dante device) just as in
the standby mode. However, when a signal above the threshold level appears at any channel, the amplifier
will automatically wake from this mode and return to its operating conditions when it entered sleep mode.
There is a short time delay (approximately ½ second) before the amplifier is restored to normal operation.
Sleep mode can be defeated by selecting Never as the time interval.

7.2.2.5 Speaker Impedance Section (–LZ and Channels 7 & 8 of the –MXZ)

The Speaker Impedance section) is to the right of the Sleep Mode section. Select the
impedance that matches the speakers connected to the low impedance outputs. This
ensures that the proper signal levels are delivered to the load to prevent overdriving
the amplifier.

7.2.2.6 Power Allocation Section (–LZ and Channels 7 & 8 of the –MXZ)

The low impedance output models (–LZ Model and Channels 7 & 8 of the –MXZ model) allow the user to
allocate different audio power levels for each channel. As delivered, each channel is allocated 50W

rms

.
Larger spaces may require more power while smaller ones may require less. The Power Allocation Section
provides the means to setting these power levels. However there are certain limitations.

 The total power available to channels 1-4 is 200W
 The total power available for channels 5-8 is 200W
 No channel may be allocated more than 125W

rms

rms

rms

Note that only channels 7 and 8 of the MXZ Model are low impedance. However, the total power
available for channels 5-8 is still 200W

. Subtract the total allocated power for channels 7 and 8 from

rms

200W to determine the maximum tapped wattage for all high impedance speakers attached to channels
5 and 6.

To adjust the power allocated to a channel, select the desired power
level from the dropdown list. Proceed through all channels making
certain that the total allocated power in group 1 (channels 1-4) is less
than or equal to 200W and that the total allocated power in group 2
(channels 5-8) is also less than or equal to 200W.

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Note that for the – MXZ model, only channels 7 and 8 have the power
allocation feature. Please ensure that the total tapped power for
channels 5 and 6 plus the power allocated to channels 7 and 8 does not
exceed 200W.

For the – CV model, there is no power allocation section. However, any
channel can support a maximum to 100W total tapped power as long as
the total tapped power for each group (channels 1-4 and channels 5-8) does not exceed 200W. In practice
it is advisable to keep the total tapped power for the group and the total tapped power for any single
channel to 70-80% of the maximum.

7.2.3 Event Log Tab

The following events are recorded in the Event Log.

1. Entering Standby mode

2. Entering Run mode

3. Device/channels renamed

4. Channels x & y enabled

5. Channels x and y disabled

6. Entering Sleep mode

7. Entering Wake mode

8. Speaker impedance changed

9. Power allocation changed

10. IP Address/mode changed

11. Overcurrent warning

12. Overtemp warning

The system clock is set whenever the application program makes a connection to the device. There is no
internal battery (and thus no internal real-time clock), so the power up time defaults to 01/01/2000
00:00:00. The Event Log file may be cleared, saved, or printed by pressing the appropriate button.

7.2.4 Load Test Tab

Coming soon.

I

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Max. Output Power1 (all channels driven)

MC850 LZ-D

 50W

RMS

x 8 @ 4/8Ω

MC850 CV-D

 50W

RMS

x 8 @ 70.7V/100V (selectable)

MC850 MXZ–D

 50W

RMS

x 2 @ 4/8Ω

 50W

RMS

x 6 @ 70.7V/100V (selectable)

with channel-by-channel power allocation

Performance

Frequency Response (+0, -3dB)

 20Hz – 20kHz 4/8 Ω,
 100Hz – 20kHz 70.7V/100V

THD + N 20Hz – 20kHz @1W @ 8Ω
THD + N 1kHz and full power @8Ω
THD + N 100Hz – 20kHz @1W @70.7V/100
THD + N 1kHz and full power @70.7V/100V

 <0.1%
 <0.1%
 <0.1%
 <0.1%

Signal to Noise Ratio

 >95dB

Channel-to-Channel Isolation (Crosstalk) -----------------

 >95dB

Audio Sampling Rates

 44.1, 48, 88.2, 96, 176.4, 192 ksps

Power Draw Power Saving Mode
Idle
1/8 Power
Full Power

 4.1W (standby)
 28W (operational)
 103W
 585W

Amplifier Class ---------------------------------------------------

 D

Control and Status ----------------------------------------------

 RS-232 and Ethernet

Dante™ Network Audio Input Connectors ---------------

 RJ-45 x 2 (switched or redundant)



Output Connectors ---------------------------------------------

 5mm Euroblock

LED Indicators ---------------------------------------------------

 Power, Fault, Signal (x 8)

Power Supply Input --------------------------------------------

 100-240VAC 50/60Hz (PFC Universal Input)

Construction -----------------------------------------------------

 Aluminum Chassis

Mounting ---------------------------------------------------------

 19” Rack Mount

Cooling ------------------------------------------------------------

 Convection (no fan)

Dimensions (excluding rack mounts) ----------------------

 CV and MXZ models: 1.74” H x 17.3” W x 14.5”

D (44 x 440 x 369mm)

 LZ model: 1.74” H x 17.3” W x 11.0” D (44 x 440

x 280mm)

Weight -------------------------------------------------------------

MC850-LZ-D
MC850-CV-D
MC850-MZ-D

 5 lbs. (2.3kg)
 13 lbs. (5.9kg)
 12 lbs. (5.5kg)

Warranty ----------------------------------------------------------

 3 years

8 Specifications

1

Please refer to Section 6.1.4.1 Channel-by-channel power allocation for additional information.

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9 Troubleshooting

The Power LED is not illuminated

 Verify the integrity of the AC power cable and that it is fully plugged into both a live AC

receptacle and the power inlet.

The LEDs on the RJ-45 jack are not illuminated

 Verify the integrity of the Cat5e/6 cable and that there are no broken wires.
 Verify that the Cat5e/6 cable is connected to an active switch or router.

The Power LED and the LEDs on the RJ-45 jack are illuminated, but there is no sound

 Verify that one or more Dante™ transmitters are routed to the amplifier and that there

is audio coming from the transmitter. A green checkmark at the intersection of the
transmitter and MC850 amplifier receiver in the Network View screen indicates that a
Dante™ subscription has been established. In the Device View screen for the MC850
amplifier, the speaker symbols should be green (not gray) when a signal is routed to
those receive channels and the channels have audio present. See the Dante Help for
more detailed information.

The amplifier (or certain channels) cycles on and off or clicks

 Check speaker connection for loose connections, broken wires or shorts, or a

loudspeaker connection to ground.

In normal operation, the DC voltage on the speaker output connectors is approximately 24VDC. Do not
connect any speaker output to ground or to the amplifier chassis. Do not connect speakers across
speaker outputs. (Bridge mode is not supported.)

 Verify that the total tapped wattage of all loudspeakers on a single channel does not

exceed 100W and that the sum of the tapped power for channels 1-4 and 5-8 does not
exceed 200W.

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Amplifier overheats and/or shuts off.

 Review section 5.3.2 on proper cooling procedures.

Output sound is distorted or cracking.

 Check all cables for damage or loose connections. Replace the cables and loudspeakers

temporarily to see if this resolves the problem. If problem still exists, contact your Authorized
Dealer for service.

10 Warranty Information

10.1 Warranty Summary

All Stewart Audio amplifiers and accessories, unless excluded in this summary, are covered by a 3­year limited warranty on parts and labor from the data of purchase. In order to be eligible for
warranty repairs, the amplifiers and accessories must have been purchased through an authorized
Stewart Audio dealer and submitted by the original purchaser. This warranty is only valid in the
country in which the amplifier was purchased.

10.2 Eligibility Requirements

Stewart Audio warrants against all malfunctions which come as a result of component or
manufacturer defect. The amplifier is also covered from all failures which arise during the
warranty period (3 years from date of purchase) that are not a result of misuse. The following
actions will void your warranty:

 The power cord or AC plug has been damaged through misuse.
 The amplifier has been exposed to moisture or extreme temperatures.
 The amplifier has been dropped, items have been dropped on the amplifier, or the

enclosure has been damaged.

 The amplifier has been opened by the operator.
 The amplifier was improperly packaged when sending to the factory for repair, resulting in

damage.

 Any of the precautions or instructions found in this manual were not followed.

Damages resulting to the amplifier which are not covered under this warranty can be factory­repaired at cost to the customer. Use the contact information below to initiate the repair process.

10.3 Non-warranty Repairs

An estimate for all non-warranty repairs will be provided to the customer once the unit has
been shipped to the factory. The customer is responsible to approve this estimate within 7
days. If the repairs are not approved within 14 days, Stewart Audio reserves the right to
consider the unit scrap and may discard it. Payment for non-warranty repairs must be
submitted to Stewart Audio before the product will be returned to the customer.

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11 Return Procedure

All returns to the factory for service must be accompanied by a Return Authorization (RA) number.
One can be obtained by contacting Stewart Audio at [phone] or via e-mail at
[e-mail].

NOTE: Any defective products received without an RA number will be returned to sender at
their expense.

If Stewart Audio is unable to contact the sender in 14 days, the merchandise will be considered
scrap and may be disposed of.

11.1 Shipment Instructions

 If Stewart Audio requests that you ship the defective product back to their service center,

please refer to the guide below. To ensure prompt warranty service, be sure to follow all
instructions.

 Return Authorization (RA) is required for product being sent to the factory for service.
 See packing instructions in Section 9.2.
 Ship the defective product using a method which provides for order tracking or order

confirmation. The service center is located at the following address:

Stewart Audio
14335 Cuesta Court Suite C
Sonora, CA 95370

 Use a bold black marker and write the RA number on three sides of the box.

Record the RMA number for future reference. The RA number can be used to check the repair
status.

11.2 Packaging Instructions

Should Stewart Audio request that you ship your product to their service center, these instructions
must be followed in order to ensure safe delivery. If they are not followed, Stewart Audio assumes
no responsibility for damaged goods and/or accessories that are sent with your unit.

1. Please write the RA number on three sides of the box. Include the Stewart Audio RA

number inside the box and a brief description of the problem.

2. You will be advised during the RA process what accessories should be included with the

amplifier (power supplies, connectors, cords, etc.). This is dependent on the failure
assessment.

3. When shipping your amplifier, it is important that it has adequate protection. We

recommend you use the original packing material when returning the product for repair. If
you do not have the original box, see number 4.

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4. If you provide your own shipping pack, use materials adequate to prevent damage during

transit. Make certain that the amplifier is NOT free to move within the package, as this is
the most common cause of damage.

5. Securely seal the package with an adequate carton sealing tape.

6. Do not use light boxes or “peanuts”.

NOTE: Damage caused by poor packaging will not be covered under warranty.

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