Prism sound DREAM DA-1 User Manual

Prism

Dream

Operation Manual

Issue 1.1 12 February 1996

Prism Media Products Limited

William James House

Cowley Road

Cambridge

CB4 4WX

UK

Phone: [phone]

Fax: [phone]

Email: [e-mail]

Prism Media Products Limited Dream
Operation Manual

CONTENTS

1. INTRODUCTION ............................................. 4

2. SUMMARY OF DA-1 FEATURES ................................ 4

3. GETTING STARTED .......................................... 5

3.1. Un-packing your DA-1 .................................... 5

3.2. Using the DA-1 for the first time ............................ 5

3.3. DA-1 product concept and capabilities ....................... 7

3.4. Dynamic Range Enhancement (DRE) ........................ 7

4. OPERATION ................................................ 7

4.1. Normal mode controls .................................... 8

4.2. Set inputs mode ........................................ 9

4.3. Set level mode ......................................... 9

4.4. Set master mode ....................................... 10

5. FRONT-PANEL INDICATORS ................................. 11

5.1. Input selection or maximum output level setting indicators ....... 11

5.2. 32kHz, 44.1kHz and 48kHz indicators ...................... 12

5.3. `Other' indicator ........................................ 12

5.4. `Master' indicator ....................................... 12

6. CONNECTORS ............................................. 13

6.1. Analogue output connections ............................. 13

6.2. Interconnect screens - the pin 1 conditions ................... 13

6.3. Connector table ........................................ 14

7. SPECIFICATION ............................................ 15

7.1. Digital Inputs .......................................... 15

7.2. Synchronization ........................................ 18

7.3. Digital Outputs ......................................... 19

7.4. Analogue Outputs ...................................... 23

7.5. Performance Specification ............................... 23

7.6. Power ............................................... 26

7.7. Physical Dimensions .................................... 26

8. INTERNAL CONFIGURATION OPTIONS AND FUSES .............. 26

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8.1. Fuses ............................................... 26

8.2. PCB jumper links ....................................... 27

8.3. Mains transformer voltage selection ........................ 27

9. ELECTROMAGNETIC COMPATIBILITY .......................... 27

10. REFERENCES ............................................. 28

Manual Revision History

6 September 1995 Version 1.0 First issue
12 February 1996 Version 1.1 Hardware revision C

Product Revision History

February 1996 Hardware revision C
Note that prior to revision C the DA-1 had a different output configuration from that

described in this manual. If your unit serial number is less than 090 and the serial number
label does not state "Rev C" (indicating that the unit has been upgraded to hardware
revision C) then this manual is not appropriate. Please ask your supplier for a version 1.0
manual. If in doubt as to the revision status of your unit the older configuration can be
identified by a short circuit between the analogue output XLR pin 1 and the chassis.

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Prism Media Products Limited Dream
Operation Manual

1. INTRODUCTION

The Dream converter is intended for professional audio use in applications where
a very high performance is required for monitoring; for example in the production of high
quality 16-bit CD masters - where noise shaping can provide a weighted dynamic range
of more than 110dB, or for conditions such as live recording where a large amount of
headroom may be required.

The Prism Dynamic Range Enhancement (DRE) system is also incorporated for use with
monitoring and/or decoding a DRE encoded source.

2. SUMMARY OF DA-1 FEATURES

Ž 24 bit input resolution
Ž 115 dB A-weighted dynamic range
Ž -104 dB THD+N at full scale (0.0006%)
Ž Flat low frequency response (-0.05 dB at 5.0 Hz)
Ž Floating balanced outputs
Ž Calibrated maximum output level adjustment:

+5 dBu to +28 dBu in 1 dB steps
fine trim in steps of 0.05dB

Ž DRE decoding to analogue and digital outputs
Ž Input selection from 7 inputs
Ž Digital inputs in AES3, SPDIF, Optical, AES-3ID coax, and SDIF-2 formats
Ž Digital outputs in AES3, SPDIF, Optical, and SDIF-2 formats simultaneously
Ž Digital interface format conversion
Ž Mute control on front panel
Ž Invert control on front panel
Ž De-emphasis of emphasised signals (Both CD and J17 characteristics)
Ž Low jitter, high precision clock with:

Capture range better than IEC958 consumer specification (±1500ppm)
Excellent jitter tolerance ( >200ns at 2kHz)
Excellent jitter rejection (-60dB at 500Hz)

Ž Clock master mode for use with digital audio workstations

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3. GETTING STARTED

It is not necessary to read all the manual before being able to use the Dream . This
section contains all the information required for you to get going straight away.

3.1. Un-packing your DA-1

Check that you have the following items and that they are undamaged:

" Dream converter unit
" Dream operation manual (this book)
" IEC320 type mains lead with appropriate plug for your supply

Check that your unit carries a label on the rear panel indicating the correct mains voltag e
for your application area and that the plug fitted to the mains lead is of the correct type. If
not, DO NOT CONNECT THE MAINS SUPPLY, but contact your distributor.

Please keep the packaging for re-use in the event that the unit should be shipped to
another location or in the event that it should ever need to be returned to the manufacturer
for repair or upgrade.

3.2. Using the DA-1 for the first time

Connect a source of digital audio to an appropriate input connector on the DA-1. Note that
if the source is in the Sony Digital Interface Format (SDIF-2) then the three BNC inputs,
labelled L, R and WCK need to be used, otherwise only one connector is required.

The analogue outputs of the DA-1 are wired as follows:

pin 1 Screen and mid-point of balanced output
pin 2 Balanced output (Hot or `+')
pin 3 Balanced output (Cold or `-')

Conventional connections to a balanced analogue input should use a screened twisted
pair lead. The DA-1 output pins 2 and 3 should be wired to the two conductors of the pair
and pin 1 to the cable screen. The other end of the cable should be connected in a similar
manner.

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The DA-1 can also connect to unbalanced inputs. For optimum performance the DA-1
should be connected to an unbalanced input using only pins 1 and 2. Pin 2 should connect
to the signal conductor and pin 1 should connect to the ground or return. The signal level
is then halved. (It is possible to drive unbalanced inputs from pins 2 and 3 but this
unbalances the output and can lead to hum. In any case do not connect the three output
pins to each other).

Connect the mains supply and switch on the DA-1 unit.
The front-panel lights should all illuminate momentarily; if any of them fails to light it may be

faulty. If so then check again by turning the unit off and on. If the problem is still evident
contact your distributor.

After the unit has initialised one of the seven input selection lights on the left of the front
panel will illuminate to indicate the selected input. This indicator will be steadily on if the
signal at the selected input is being decoded without error. It will flash if a signal is not
detected, and briefly extinguish when individual errors are detected. To select a different
input press the round select push-button on the left hand side of the front panel.

When you have selected the input you require then, if the signal is decoded correctly and
the unit is configured to the factory default settings, then only the appropriate sample rate
indicator and the input selection indicator will be steadily on. This indicates that the unit
is now operating correctly. If the output level needs adjustment refer to section 4.3.

NOTE: If you are having problems with any of these controls it may be because the configuration has been altered
from the factory defaults. If you wish to return all the DA-1 settings to the factory defaults then switch the unit on
while pressing all four of the right hand buttons during the whole of the start-up cycle - this takes approximately
six seconds.

In the default configuration the indicators for the four right hand side controls should not be on. If the set button
indicator is on then press the button to leave `set' mode. If any of the other control button indicators are on then
press the respective control buttons to toggle them off.

If you are still having problems setting the unit into the standard configuration described above, then refer to the
descriptions of the set inputs (section 4.2), or set master (section 4.4) controls.

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3.3. DA-1 product concept and capabilities

The Dream is designed to provide a very high quality of digital to analogue
conversion without sampling jitter or data truncation - whatever the resolution or timing
accuracy of the source.

Two other useful features are also provided. These are a set of jitter filtered digital outputs
and a Dynamic Range Enhancement (DRE) decoder.

The digital outputs normally provide the same data as present on the selected digital input,
translated into the appropriate format, and any incoming jitter is filtered off. This means
that the Dream is also a digital audio format convertor, corrector and de-jitterer.

3.4. Dynamic Range Enhancement (DRE)

DRE is a process designed for the increasing the dynamic range of 16 bit recording
channels, such as DAT, CD-R, or 1630+U-matic, when further post-processing is
required. It requires an encode process on recording and a decode process on playback.
It is suitable for applications where 20-bit dynamic performance is desired of the recorder
but only a 16-bit recorder is available, and where the requirement for a decode process
is not a problem. The Prism Sound Dream AD-1 20-bit analogue to digital converter can
encode DRE signals from digital or analogue sources, and can also decode them (in
digital to digital mode) to transfer the high resolution signal, encoded on a 16-bit tape, onto
a 20 bit digital audio workstation. The Dream can be used with the AD-1 to provide
analogue monitoring of the encoded signal, as well as to perform the digital to digital
decoding function required for transfers to the `linear' or `non-DRE' domain.

4. OPERATION

There are five control buttons. Four of them operate in two ways, and the fifth, SET, button
switches their function. For normal use they operate in isolation to select the digital
source, MUTE the output, INVert the output and turn on the DRE decode function. The
configuration settings - which are intended to be set and then left alone - can be modified
from one of the three `set' modes: set inputs, set level and set master . The SET button
is illuminated to indicate one of these modes.

All the control settings are saved in permanent memory so that they are remembered when
the unit is off.

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4.1. Normal mode controls

The following functions apply to the controls only if the SET control is not illuminated. This
shows that the unit controls are in the normal mode. The unit is always in normal mode
after being switched on.

4.1.1. Select
Pressing this button causes the selected digital input to switch to the next enabled input.

NOTE If this control does not have any effect, or it will not select the required input, this may be because some
inputs have been disabled. Refer to the description of the SET inputs control, section 4.2, to change this.

4.1.2. MUTE
This control is used to mute the analogue output. The digital outputs are unaffected.

4.1.3. INV
This control is used to invert the polarity of both analogue outputs. The digital outputs are

unaffected.

4.1.4. DRE
This control is used to switch on the DRE decoding function on the digital input (DRE is

described in section 3.4). Both the analogue and digital outputs are affected by this
control.

4.1.5. SET
Holding this button down while pressing one of the three adjacent switches puts the unit

into one of the following control modes: Either Set Inputs, Set Level, or Set Master, as
described by the red text. These modes allow the user to modify the configuration of the
DA-1. In normal use they are not required.

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4.2. Set inputs mode

The set inputs mode is used to enable or disable the selection of digital inputs. This
avoids cycling through unused inputs when switching between sources. An input will be
skipped if it is "disabled". This mode is indicated by both the MUTE/Inputs and the SET
controls being lit. (Note in this mode the MUTE button has the function of enabling the
inputs. For that reason it is referred to as the MUTE/Inputs control.)

To enter set inputs mode from the normal mode (ie. if the SET control is not illuminated)
hold the SET button down and press the MUTE/Inputs button.

To enter set inputs mode from one of the other set modes (ie. if the SET control is
illuminated) just press the MUTE/Inputs button.

The seven input indicators on the left of the unit illuminate to indicate the inputs that are
enabled. One of the indicators will be flickering to show the input that would be affected
by the MUTE/Inputs control. Press the MUTE/Inputs control to toggle the enabled state
of this input. The flickering will toggle between fast and mostly on, indicating enabled, to
slow and mostly off, indicating disabled.

Press the small round select button to cycle through the other inputs.
To leave set inputs mode then either select another of set modes by pressing INV/Level

or DRE/Master, or change to normal mode by pressing SET.

4.3. Set level mode

Set level mode is used to adjust the maximum analogue output level. This is the output
level corresponding to an digital input at full scale. It can be set to any value between
+5dBu to +28dBu in 1dB steps. A fine trim, in 0.05dB steps, is also possible.

Set level mode is indicated by both the INV/Level and the SET controls being illuminated.
(Note that in this mode the INV button has the function of enabling the inputs. For that
reason it is referred to as the INV/Level control.)

To enter set level mode from the normal mode (ie. if the SET control is not illuminated)

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