Grass Valley 8920DAC User Manual

8920DAC

AES/EBU TO ANALOG AUDIO CONVERTER

Instruction Manual

071-0614-02

FIRST PRINTING: JULY 1999

REVISED PRINTING: SEPTEMBER 2000

2.0software release

Contacting Grass Valley Group

Region Voice Fax Address Web Site

North America [phone]

530-478-4148

Pacific Operations [phone]

Support: 852-2585-6579
U.K., Europe, Asia, Middle East [phone] [phone]
France [phone]
Germany [phone] [phone]

Copyright © Grass Valley Group. All rights reserved.

This document may not be copied, in whole or in part, or otherwise reproduced, except as specifically
permitted under U.S. copyright law, without the prior written consent of Grass Valley Group, P.O. Box
599000, Nevada City, CA 95959-7900 USA. GRASS VALLEY GROUP is a registered trademark and
Grass Valley is a trademark of Grass Valley Group. All registered trademarks and trademarks are prop­erty of their respective holders. Grass Valley Group products are covered by U.S. and foreign patents,
issued and pending. Product options and specifications subject to change without notice. The informa­tion in this manual is furnished for informational use only, is subject to change without notice, and
should not be construed as a commitment by Grass Valley Group. Grass Valley Group assumes no re­sponsibility or liability for any errors or inaccuracies that may appear in this publication.

[phone] Grass Valley Group

[phone]

P.O. Box 599000
Nevada City, CA 95959-7900
USA

www.grassvalleygroup.com

Contents

Preface

About This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

8920DAC AES/EBU to Analog Audio Converter

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Module Placement in the 8900 Frame. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Frame Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Cabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Loop-through Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Power Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Operation Indicator LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Local Onboard Module Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Configuring Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Level Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

20/24-bit DAC Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Remote Control Lockout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Remote Configuration and Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Module Configuration Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Software Update Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Signal Configuration Displays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Digital Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Control and Routing FPGA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

CPU (Controller) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Digital/Analog Converter (DAC), Filter, Gain, and Output Stages . . . . . . . . . 18

Regulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Index

8920DAC Instruction Manual iii

Contents

iv 8920DAC Instruction Manual

Preface

About This Manual

This manual describes the features of a specific module of the 8900 Series
Modular Products family. As part of this module family, it is subject to
Safety and Regulatory Compliance described in the 8900 Series frame and
power supply documentation (see the

Instruction Manual

8900TX/8900TF/8900TFN Frames

).

8920DAC Instruction Manual v

Preface

vi 8920DAC Instruction Manual

8920DAC AES/EBU to Analog Audio Converter

Introduction

The 8920DAC converts digital audio to analog audio and provides true 20­bit performance. Its various modes can modify the outgoing signal to
provide channel swapping, channel summing, tones, and phase inversion.
When used in an 8900 frame supporting network control, the 8920DAC
supports remote mode selection. The module uses 24-bit delta-sigma
digital-to-analog converters (DACs) with 128 times over-sampling and
noise shaping which offer superior performance with lower idle tones, and
excellent sonic performance and resolution.

8920DAC features include:

■

Support for 32 kHz, 44.1 kHz, and 48 kHz sampling rates

■

Jumper selectable 20-bit or 24-bit DAC mode

■

One 75
One pair of balanced analog outputs available on terminal block

■

outputs using BNC adapter board

■

Input sampling frequency, emphasis, and error LED indicators
Output range selection from +14 dBu to +24 dBu with jumper selectable

■

maximum level

Ω

loop-through AES-3id/EBU input

■

Channel level control using an on-board, multi-turn trim potentiometer

■

Auto detection of emphasis and engagement of de-emphasis to flatten
frequency response

Module is part of the 8900 family of audio and video modules

■

■

Supports remote control in 8900 networking frames

■

Offers remote control lockout using an on-board jumper

8920DAC Instruction Manual 1

8920DAC AES/EBU to Analog Audio Converter

Installation

Installation of the 8920DAC module is a process of:

Placing the module in the desired frame slot,

■

■

Cabling and terminating signal ports, and

■

Configuring the module.

The 8920DAC module can be plugged in and removed from an 8900 Series

frame with power on. When power is applied to the module, LED indica-

tors reflect the initialization process (see Power Up on page 5 ).

Module Placement in the 8900 Frame

There are ten cell locations in the frame to accommodate either analog or

digital modules. These are the left ten locations. Refer to Figure 1.

The two cells on the right are allocated for the power supplies. For addi-

tional information concerning the Power Supply module, refer to the 8900

Power Supply manual.

The third cell from the right is allocated for the Frame Monitor or Network

Interface controller modules. These modules provide health monitoring

and control options.

Figure 1. 8900 Series Frame

Any 8900 Module

Frame Monitor Module or
Network Interface Module

Power

Supplies

(only)

0614-04r1

2 8920DAC Instruction Manual

1.

3.

8900 modules are interchangeable within the module cells. There are 10
BNC connectors in each cell’s I/O group. The functional assignment of
each connector in a group is determined by the module that is placed in
that cell. The maximum number of modules an 8900 frame can accept is ten.

Figure 2 illustrates the rear connector plate for an 8900 Series frame.

Frame Capacity

The maximum number of 8900 modules allowed in a frame is determined
by frame cooling capacity. Table 1 provides the power capacity, cooling
capacity, and maximum module count for the 8920DAC in each frame type.

Table 1. Power, Cooling, and Module Capacity of 8900 Frames

Power (W) 60 60 100 100 100
Recommended Module Cooling (W) 30 60 30 90 90
8920DAC Modules 10 10 10 10 10

Capacity Calculated

8900T2

Frame

8900T2-F

Frame

8900TX

Frame

8900TF

Frame

Installation

8900TFN

Frame

DA10

J1 J2

O

J3 J4

U
T

J5 J6

J7 J8

J9 J10

IN

DA9

J1 J2

J2

O

J3 J4

J4

U

T

J5 J6

J6

J7 J8

J8

J9 J10

IN

Note

Module capacity figures assume no other modules are in the frame. If the
maximum number of modules a frame can handle is less than ten, provide as
much space between the modules as possible.

Figure 2. 8900 Series Frame Rear Connectors

DA8

J1 J2

O

J3 J4

U
T

J5 J6

J7 J8

J9 J10

IN

DA7

J1 J2

J2

O

J3 J4

J4

U

T

J5 J6

J6

J7 J8

J8

J9 J10

IN

DA6

J1 J2

O

J3 J4

U
T

J5 J6

J7 J8

J9 J10

IN

DA5

J1 J2

J2

O

J3 J4

J4

U
T

J5 J6

J6

J7 J8

J8

J9 J10

IN

DA4

J1 J2

O

J3 J4

U

T

J5 J6

J7 J8

J9 J10

IN

DA3

J2

J1 J2

O

J4

J3 J4

U

T

J6

J5 J6

J8

J7 J8

J9 J10

IN

DA2

J1 J2

O

J3 J4

U

T

J5 J6

J7 J8

J9 J10

IN

DA1

J1 J2

O

J3 J4

U

T

J5 J6

J7 J8

J9 J10

IN

8900 modules can be inserted and removed while the frame is powered. To
install a module in the frame:

Insert the module, connector end first, with the component side of the
module facing to the right and the ejector tab to the top.

2.

Verify that the module connector seats properly against the backplane.

0614-03

Press the ejector tab in to seat the module in place.

8920DAC Instruction Manual 3

8920DAC AES/EBU to Analog Audio Converter

Cabling

Note

At the back of this manual are overlay cards that can be placed over the rear
connector BNCs to identify the specific 8920DAC connector functions.

Loop-through Input

Connect an input signal to one of the loop-through input connectors, J9 or
J10 (see Figure 3). The 8920DAC input will accept AES-3id/EBU audio. Ter­minate the unused connector into 75 Ω if the signal is not looped to other
equipment.

Figure 3.

J1

J3

J5

L+

GND

L–

8920DAC

Grass Valley

DAx

Adaptor

O

Input/Output Connectors

R+

J2

J2

GND

R–

U
T

J4

J6

J4

J6

Analog balanced
output adapter

Not Used

AES/EBU

Loopthrough Input

Outputs

J8

J7

J9 J10

IN

J8

0614-02

The 8920DAC provides one stereo analog, differential pair output through
the plug-in adapter connected to BNCs J1- J4.

4 8920DAC Instruction Manual

Power Up

Operation Indicator LEDs

Power Up

The front LED indicators and configuration switches are illustrated in

Figure 4. Upon power-up, the green PWR LED should light and the yellow

CONF LED should illuminate for the duration of module initialization.

With factory default configuration and a valid input signal connected, the
green PWR LED should be on and the yellow REM OVER LED should be
off. (Refer to Table 2 on page 6 and Table 3 on page 7 to see a complete list
of possible operating conditions and the resulting indicator status.)

Audio input presence is indicated by the 32, 44.1, or 48 LED which indi­cates the corresponding input signal sample rate has been detected. The
REM OVER LED indicates that the Function Switch is being overridden by
remote control.

Figure 4. LEDs and Configuration Switches

Ejector Tab

FAULT – Red diagnostic LED is off during normal operation

COMM – Yellow LED on during remote control communication
CONF – Yellow LED on when module is initializing or

processing control data
PWR – Green diagnostic LED on indicates power OK

32 – Green LED on indicates active sample rate

44.1 – Green LED on indicates active sample rate

48 – Green LED on indicates active sample rate
REM OVER – Yellow LED on indicates local switches and

jumper settings are overridden by remote control

5

6

4

7

3

8

2

9

1

A

0

B

F

C

E

D

16-position Rotary switch
selects output mode

EMPH – Yellow LED on indicates module is performing de-emphasis

0614_06

GND

8920DAC Instruction Manual 5

8920DAC AES/EBU to Analog Audio Converter

A red FAULT LED indicates an error situation and, when noted with the
other indicator LEDs, can indicate a specific problem area. Table 2 describes
signal output and LED indications for the various input/reference combi­nations and user settings.

Table 2. Indicator LEDs and Conditions Indicated

LED Indication Condition

Off Normal operation

Fault

(red)

COMM

(yellow)

CONF

(yellow)

PWR

(green)

32

(green)

44.1

(green)

48

(green)

REM

OVR

(yellow)

EMPH

(yellow)

On continuously Module has detected internal fault

Long flash Configuration problem: FPGA not responding to CPU, Input not present, AES/EBU out of lock

Short flash Other AES/EBU error

Off No activity on frame communication bus
Long flash Location Command received by the module from a remote control system
Short flash Activity present on the frame communication bus

Off Module is in normal operating mode

On continuously Module is initializing, changing operating modes or updating firmware

Off No power to module or module’s DC/DC converter failed

On continuously Normal operation, module is powered

Off Sample rate is not near 32 kHz

On Continuously Sample rate is 32 kHz ±400 ppm

Flashing Sample rate is 32 kHz ±4%

Off Sample rate is not near 44.1 kHz

On Continuously Sample rate is 44.1 kHz ±400 ppm

Flashing Sample rate is 44.1 kHz ±4%

Off Sample rate is not near 48 kHz

On Continuously Sample rate is 48 kHz ±400 ppm

Flashing Sample rate is 48 kHz ±4%

Off Module configuration is by the module’s on-board switches and jumpers

On continuously Module configuration is by remote control and on-board switch settings are overridden

Off Module is not performing de-emphasis

On continuously Module is performing de-emphasis

6 8920DAC Instruction Manual

Table 3 provides the possible input and output conditions that result from

different inputs and settings.

Table 3. Possible Operating Conditions

Audio Input Condition Output Condition

Any AES-3id with sample rate between 32 kHz to 48 kHz

Any AES-3id with sample rate between 32 kHz to 48 kHz
with Function Switch is set to E (1 kHz Tone)

No AES-3id input

No AES-3id input with Function Switch is set to E (1 kHz Tone) No tone at output and output will be muted.

Audio will be converted at any sample rate between the minimum and maximum
rates. Sample rate LEDs will only light if rate is within 4% of any standard.

1 kHz tone with frequency of tone accurate only at 32 kHz, 44.1 kHz or 48 kHz
sample rates.

No sample rate LEDs will be lit, output will be muted, Fault LED flashing, signal to
noise level should be greater than or equal to maximum signal to noise level.

Power Up

8920DAC Instruction Manual 7

8920DAC AES/EBU to Analog Audio Converter

Configuration

The following parameters must be set on the 8920DAC module:

Control mode – Local/Remote or Local control only (remote lockout),

■

■

Output gain – coarse and fine adjustment,

■

20-bit or 24-bit DAC mode, and

■

Output mode – channel swapping, summing, and phase inversion.

The Control Mode, Output Gain and DAC modes must be configured
locally using onboard jumpers and switches. Output mode can be set
locally with the front rotary switch or can be configured remotely with the
network interface.

Local Onboard Module Configuration

The 8920DAC module must be configured locally to set certain parameters
using the on-board components shown in Figure 5 on page 9. The CONF
LED indicates status of the configuration process.

These components perform the following:

Jumper JP1 – sets control mode for Local only or Remote and Local.

■

■

Jumpers JP5 – sets the D-to-A conversion mode to 20- or 24-bits.

■

Jumper JP6 and JP7– set coarse output gain level adjustment for left and
right channels.

Left and Right Fine Adjust Potentiometers – provide fine adjustment of

■

the left and right channel output gain levels.

■

Function (rotary) switch – selects a desired output configuration (0
through 9, A through F), although not all positions are used.

CONF (configuring) LED – when on, indicates the module is initial-

■

izing or processing configuration information. Whenever the Function
Switch is changed, the CONF LED will flash to indicate configuration
is being performed.

Note

Function switch positions 0 and F (Factory defaults) can be used to return the
module configuration to the original factory settings.

8 8920DAC Instruction Manual

CONF – configuration processing LED

Rotary
switch

JP1

JP7

HighLow

HighLow

JP6

0614-05r1

LOCAL –

REMOTE –

jumper across these pins
(5 – 6) locks out remote control

jumper across these pins
(4 – 5) enables remote
and local control

Level Adjustments

Remote Control Lockout

Left Coarse

Right Coarse

Left

Fine

Adj.

Right

Fine

Adj.

JP5

24-bit signal

20-bit signal

20/24-bit DAC Operation

1

1
3

6

Figure 5. 8920DAC Module Settings and Adjustments

Configuration

Configuring Output Mode

The 8920DAC provides thirteen possible output configurations as shown
in Table 4. The module can be configured using the rotary switch shown in

Figure 5 or by remote control (see

make a configuration setting simply rotate the switch to the desired output
configuration. The 16-position rotary switch selects one of 13 possible

8920DAC Instruction Manual 9

output modes. Positions B and C are not used and positions 0 and F select
the same mode (Factory default).

Table 4. 8920DAC Output Mode Configuration

Switch

Position

0 Factory default – No phase inversion, channel swapping or summing
1 Channel swap – Left and Right
2 Both channels phase inverted
3 Left channel phase inverted
4 Right channel phase inverted
5 Right channel to both channel outputs
6 Left channel to both channel outputs

Mode Description

Input Status/Output Mode on page 13

). To

8920DAC AES/EBU to Analog Audio Converter

Table 4. 8920DAC Output Mode Configuration

Switch

Position

7 Left + Right to both channel outputs (-6dB mono sum)
8 Left - Right to both channel outputs
9 Left + Right to Left channel output and Left- Right to Right channel output
A Left + Right to both channel outputs and both channels phase inverted
B Not Used (Digital Silence)
C Not Used (Digital Silence)
D Tone 1 to all channels (Digital Silence)
E Tone 2 to all channels (1 kHz, -20 dBFS)
F Factory default – No phase inversion, channel swapping or summing

Level Adjustment

The gain stage of each output channel (right and left) has two means of
adjustment—fine and coarse (refer to Figure 5 on page 9).

The Coarse jumpers (JP6 and JP7) select the range of adjustment either:

■

High range—19 to 24 dBu, or

■

Low range—14 to 20 dBu.

Mode Description

Fine control within those ranges is set using the multi-turn potentiometers
(Left and Right Fine Adj.) providing ±3 dBu gain adjustment (do not exceed
24 dBu). This combination gives a maximum range of full-signal settings
from +14 dBu to +24 dBu.

20/24-bit DAC Operation

Jumper block JP5, pins 1 to 3, determine whether the DAC is in 24-bit or
20-bit mode (see Figure 5 on page 9). With the jumper across pins 1 and 2,
the DAC is in 20-bit mode and will mask the lower four bits of information.
With the jumper across pins 2 and 3, the DAC is in full 24-bit mode.

Remote Control Lockout

When a jumper is placed across pins 5 and 6 of jumper block JP1, module
output mode settings are adjustable from the on-board switches only. To
have both Local and Remote access, set the jumper across pins 4 and 5 (see

Figure 5 on page 9).

10 8920DAC Instruction Manual

Remote Configuration and Monitoring

8920DAC monitoring and some module configuration can be performed
remotely using the 8900NET interface in 8900TF or TFN frames (see

Figure 6). This section describes the GUI access to the module configura-

tion functions. Refer to the 8900NET Network Interface Module Instruction
Manual for information on setting up and operating the 8900 frame net­work.

For remote access, make sure the jumper block on the module is set for both
Local and Remote access (Figure 5 on page 9).

Configuration

Note

Figure 6. 8900NET GUI

The physical appearance of the menu displays shown in this manual repre­sent the use of a particular platform, browser and version of 8900NET
module software. They are provided for reference only. Displays will differ
depending on the type of platform and browser you are using and the version
of the 8900NET software installed in your system.

The links section lists the frame and its current modules. The selected link's Status
page is first displayed and the sub-list of links for the selection is opened. The sub-list
allows you to select a particular information page for the selected device.

Content display section displays information for the selected
frame or module (frame slot icons are also active links).

8920DAC Instruction Manual 11

8920DAC AES/EBU to Analog Audio Converter

The 8900 modules can be addressed by clicking on a specific module icon
in the frame status display or on a module name or slot number in the link
list on the left.

The 8920DAC will indicate a SMPTE Alarm fault on the Frame Status
display for the following alarms:

■

Unlocked or missing audio input, or

■

Board Failure.

Module Configuration Displays

The 8900 GUI provides the following links and displays for the 8920DAC
module (Figure 7):

■

Module Configuration displays showing status and slot configuration
information (location and user assigned names),

■

Signal Configuration displays, and

■

Software Update display.

The Module Configuration displays are the same for all remote controllable
8900 modules. Refer to the 8900NET manual for more information on these
displays. Some functions listed may not be supported by a particular
module. These will be indicated as not supported.

Figure 7. 8920DAC Display Links

Module Configuration

Displays

Signal Configuration

Display

Software Update

Display

Software Update Displays

The Software Update display allows you to download new software ver­sions for the module. Refer to the 8900NET manual and the Grass Valley
Group website at http://www.grassvalleygroup.com for complete details
and new software versions.

Signal Configuration Displays

This section discusses the Signal Configuration Displays available remotely
to set and monitor the 8920DAC module parameters. All other module
parameters not set remotely must be set locally using the on-board jumpers
and switches (see Local Onboard Module Configuration on page 8 ).

12 8920DAC Instruction Manual

Configuration

Use
This
Link

Input Status/Output Mode

The Input Status/Output Mode menu display will report the following
items under Input Status (Figure 8):

■

Module name – as defined in the main Status menu.

■

Frame location – indicates the frame name and slot number.
20/24-Bit operation – indicates whether the module is set for 20- or 24-

■

bit operation at jumper J5 on the circuit board. (Refer to 20/24-bit DAC

Operation on page 10

■

Input Sample Rate – indicates the current sample rate being detected by
the module as one of the following: Out of Range, 32K, 32K 4%, 44.1K,

44.1K 4%, 44.056K, 48K or 48K 4%).

■

Input Error – indicates any input error conditions present as either
Validity, CRC, Parity, Bi-phase, No Lock or No Error.

■

De-emphasis Left and Right – indicates whether de-emphasis is being
applied to the left and right audio channels.

Left and Right Ch Data – indicates type of incoming data (audio or non-

■

audio) to the left and right channels.

Under Output Mode, set the desired output for the module from the thir­teen selections listed below and shown in the menu display in Figure 8.
After making the selection, hit the Apply button to activate it.

.)

Default – factory default with no phase inversion, channel swapping or

■

summing.

■

L/R Swap – swaps left and right channel outputs.
L/R Invert – both left and right channel outputs phase inverted.

■

L Invert – left channel output phase inverted.

■

■

R Invert – right channel output phase inverted.

■

R Mono (R to L/R) – right channel to both channel outputs.
L Mono (L to L/R) – left channel to both channel outputs.

■

■

L plus R to L/R – left plus right to both channel outputs.

■

L minus R to L/R – left minus right to both channel outputs.
L plus R, L minus R – left plus right to left channel output and left

■

minus right to right channel output.

■

(L plus R) Inv to L/R – left plus right to both channel outputs with both
channel outputs phase inverted.

■

Silence – digital silence on both channel outputs.
1K@ -20dBFS – tone to both channel outputs.

■

8920DAC Instruction Manual 13

8920DAC AES/EBU to Analog Audio Converter

Figure 8. Input Status/Output Mode Menu Display

Input sample rate
values include:
Out of Range
32K
32K, 4%

44.1K

44.1K, 4%

44.056K
48K
48K, 4%

Types of input
errors include:
Validity
CRC
Parity
Bi-phase
No Lock

14 8920DAC Instruction Manual

Specifications

Table 5. 8920DAC Specifications

Parameter Value

Digital Input

Signal type AES-3 id-1992, transformer coupled, loop-through
Number of inputs 1 loop-through
Connector type 75 Ω BNC
Common mode range +12/-7 V
Differential voltage range 200 mV to 12 V p-p
Sampling rates 32 kHz, 44.1 kHz, 48 kHz
Input return loss >15 dB (100 kHz to 10 MHz)
Maximum jitter <200 ps RMS

Outputs

Number of outputs 1 stereo (two-channel)
Signal type Balanced analog audio
Signal level for full-code input +14 to +24 dBu max
Output impedance 50 Ω single-ended, 100 Ω differential
Connector type Terminal block through BNC adapter board
Drive capability +24 dBu into 10 k

Performance (24 dBu into 10 kΩ load)

Signal-to-noise ratio >107 dB unweighted 22 kHz filter, >110 dB “A” weighted
THD+noise (20-22 kHz) <0.004%, 22 kHz filter, +24 dBu/10 kΩ/7.5 nF
Interchannel crosstalk <-100 dB, 20 Hz to 20 kHz
Intermodulation distortion <0.006%, CCIF two-tone test, 19 kHz and 20 kHz tones
Frequency response ±0.1 dB, 20 Hz to 20 kHz
DC offset <± 1 mV
De-emphasis 50/15 µsec, automatic
Delay (input to output) 650 µsec

Environmental

Frame temperature range 0 to 45 degrees C
Operating humidity range 10 to 90% non-condensing
Non-operating temperature -10 to 70 degrees C

Mechanical

Frame type 8900 Series

Power Requirements

Supply voltage ±12 V
Power consumption < 3 Watts

Ω

Specifications

8920DAC Instruction Manual 15

8920DAC AES/EBU to Analog Audio Converter

Service

The 8920DAC modules make extensive use of surface-mount technology
and programmed parts to achieve compact size and adherence to
demanding technical specifications. Circuit modules should not be ser­viced in the field unless directed by Customer Service to do so.

If your module is not operating correctly, proceed as follows:

■ Check frame and module power and signal present LEDs.

■ Check for presence and quality of input signals.

■ Verify that source equipment is operating correctly.

■ Check cable connections.

Refer to Figure 4 on page 5 for the location of PWR LED and Table 2 on

page 6 for proper LED indications.

If the module is still not operating correctly, replace it with a known good
spare and return the faulty module to a designated Grass Valley repair
depot. Call your Grass Valley representative for depot location.

Refer to the Contacting Grass Valley Group at the front of this document for
the Grass Valley Customer Support Information number.

16 8920DAC Instruction Manual

Functional Description

Refer to the block diagram in Figure 9 while reading the following func­tional description.

Figure 9. 8920DAC Block Diagram

Control bus

from back-plane

4-bit rotary

CPU

(Controller)

FPGA

Routing and Control

Processor

Digital

Input

AES/EBU

Receiver

switch

Option

jumpers (4)

Audio

Clocks

Stereo

24-bit

DAC

Differential

Input

Receivers

and LPFs

Functional Description

Final Gain

Stage and

Z Matching

Differential

Output
Drivers

Right Main

Left Main

+

–

+

–

Digital Input

Sample

Rate,

Error,
Emphasis,
and Mode

LEDs

AES/EBU audio data is fed into the 8920DAC through an isolation trans­former to the receiver. The receiver extracts the audio signal (left/right), as
well as clock (bit clock, L/R clock and master clock), sample rate, emphasis
and error information. The signal, clock and other decoded information is
then passed to a FPGA (field-programmable gate array) for further
decoding and routing.

0614_01

8920DAC Instruction Manual 17

8920DAC AES/EBU to Analog Audio Converter

Control and Routing FPGA

The FPGA receives its programming and control information from the CPU
at power up. It also is able to receive mode commands from a four-bit
rotary switch. The FPGA receives an digital audio serial stream from the
receiver and sends its outputs to the output DAC. The FPGA also performs
the following functions:

■ Decodes and drives the front panel LEDs,

■ Passes clock and audio information to the DAC for analog decoding,

■ Enables the appropriate emphasis filter for both channels for the

received sample rate on the DAC, and

■ Enables a soft mute that ramps up/down in about 20 ms (depending on

sample rate).

CPU (Controller)

The primary purpose of the CPU is to provide remote monitoring capa­bility for the 8920DAC. It receives information about:

■ Sample rate,

■ Emphasis,

■ Error,

■ Mode selection, and

■ Digital signal present

This information is passed through the frame controller to a remote moni­toring location. A removable jumper is provided to allow disabling of
remote control.

Digital/Analog Converter (DAC), Filter, Gain, and Output Stages

The DAC consists of a single, stereo, 24-bit, 128x over-sampling DAC. The
outputs of the DACs are differential. They are received by a differential
receiver, which also serves as a Low Pass Filter. The signal then passes
through to the gain stage.

The output drivers provide precision signal balance and output common
mode rejection.

18 8920DAC Instruction Manual

Regulator

Functional Description

The 8920DAC’s power is fed from ±12V rails of the frame’s power supply.
Power comes into the module, is fused, and then split into analog and
digital paths.

Each stage of the DAC receives its own separate, highly regulated and fil­tered power source. The following power feeds are produced:

■ Digital +5V for micro-controller,

■ Digital +3.3V for FPGA, DAC and other digital sections,

■ PLL +5V for AES receiver,

■ DAC analog +5V

■ Analog ±10V for filter and differential receiver stage, and

■ Analog±12V for final gain and driver stage.

8920DAC Instruction Manual 19

8920DAC AES/EBU to Analog Audio Converter

20 8920DAC Instruction Manual

Index

Numerics

20/24-bit DAC 10

jumper 10
remote indication 13

32 kHz LED 6

44.1 kHz LED 6
48 kHz LED 6

B

backplane 3
block diagram 17

C

COMM LED 6
CONF (configuration) LED 6, 8
configuration 8

local onboard 8
remote 12

connectors 3

input/output 4
consumption, power 15
controller module 2
CPU 18

errors

input

13

F

factory default 5
FAULT LED 6
fault report 12
field-programmable gate array (FPGA) 17
frame 2, 15

cell 2

frame status display 11

G

gain 18
GUI 11, 12

I

indicators 6
inputs

cabling
specification 15

4

L

D

de-emphasis

local indication

remote indication 13
Displays

Input Status/Output Mode

6

13

E

EMPH LED 6
environmental specifications 15

8920DAC Instruction Manual Index-1

LEDs 6
loop-through 4

M

module

controller
installation 2
power supply 2
slots 3

2

N

T

network 11

O

operational modes 6
output mode

configuration

local

9

remote 13

outputs

analog
cabling 4
D1 serial digital 15
HD 15
level adjustment (gain) 10
specification 15

overlay 4

15

P

poteniometers (gain) 10
power regulator 19
power requirements 15
power supply 2

termination 4
troubleshooting 16

V

voltage 15

R

REM OVR (remote override) LED 5, 6
remote control

configuration

remote control

remote control jumper 10
repair 16
rotary switch 9

11

S

sample rate 5

local indication 5

remote indication 13
SMPTE alarm 12
software updates 12
specifications 15

Index-2 8920DAC Instruction Manual