Rega Dac wolfson wm8742 User manual

CON EN S

NTRODUCT ON 1

TECHNOLOGY 2

FRONT PANEL ND CATORS & CONTROLS 3

BACK PANEL 4

N USE & D G TAL OUTPUT 5

F LTER SETT NGS 6

CONNECT V TY 7

USB CONNECT V TY 8

96kHz-192kHz OPERAT ON 9

TECHN CAL SPEC F CAT ONS 10

TROUBLESHOOT NG 11

TROUBLESHOOT NG 12

GLOSSARY OF TERMS 13

ECHNOLOGY

The input stage comprises a Wolfson digital receiver with a high stability low

jitter clock driving the receiver PLL. The receiver and PLL have their own

dedicated power supplies. The DAC stage comprises of a pair of parallel-

connected Wolfson WM8742 DAC’s, which are driven via a buffer stage, which

ensures the integrity of the data being fed to the DAC C’s – similar to the

arrangement used in the sis (Rega’s reference CD player).

The output amplifier employs a discrete differential multiple feedback filter and

output amplifier, with a high cut-off frequency for use with higher sample rates.

We decided not to use a sample rate converter and process the data at the

incoming sample rate which keeps the signal processing to a minimum. Jitter

was minimised by synchronously clocking the digital data with our receiver PLL

(removing any jitter from the input signal).

All the capacitors associated with the analogue signal path are Nichicon FG

bypassed with MMK polyester capacitors, and low impedance conductive

polymer capacitors are used for DAC decoupling. The power supply utilizes a

toroidal transformer, fast rectifier diodes and again Nichicon FG capacitors.

There is a power supply for the control microcontroller, separate from the

digital & analogue audio stages. Special attention being paid to the inter C

control signals ensuring the control data noise is kept to a minimum.

IN RODUC ION

The Rega DAC is a 16/20/24-bit at 32kHz to 192kHz digital to analogue

converter incorporating an enhanced version of the Rega designed circuit.

Developed to be simple to set up and use, the Rega DAC is designed to optimise

performance from any two channel PCM digital audio source.

With the PC (although a somewhat contentious issue in hi-fi circles) now widely

accepted as a creditable medium for storing and streaming music. The use of

high quality lossless files such as WAV, FLAC and ALAC offer performance

through the DAC equal to and in some cases better than red book CD. Great

care has been taken to remove noise generated by the PC and other input

sources. During development this was identified as a major drawback with

many DAC’s on the market today.

The Rega DAC housed in a custom aluminium and steel case boasts a pair of

Wolfson DAC C’s and 5 user selectable digital filters, two isolated Co-axial

inputs, two Toslink SPD F inputs and an isolated USB input.

The Rega DAC has been designed and engineered to achieve the highest

performance in its class. We hope you enjoy this Rega product for many years

to come.

BACK PANEL

Digital Inputs

USB - type B connector/ solated

Optical Digital Input 1 - Optical/Toslink

Optical Digital Input 2 - Optical /Toslink

Co-Ax Digital Input 3 - solated 75Ω Co-axial Phono

Co-Ax Digital Input 4 - solated 75Ω Co-axial Phono

Digital output (via receiver & PLL) -SPD F

Optical Toslink

Co-axial/Phono solated 75Ω

Analogue Output Left and Right Phono

Power Mains/line input EC C5 type

Fuse Fuse holder

FRON PANEL INDICA ORS AND CON ROLS

Power on/off (button above Rega logo) When the power button is pressed

the Rega logo illuminates to indicate power is on.

Input Locked indicator This indicates the digital input signal is valid and the

PLL in the receiver is locked. When the nput Locked LED is off the soft mute is

activated.

Input This button selects the 5 available digital inputs. Push to advance to the

next input as follows:

USB Optical 1 Optical 2 Co-axial 3 Co-axial 4

Sample rate LED’s (only valid when nput Locked is on)

32K – ndicates the incoming sample rate is 32kHz

44.1/48K – ndicates the incoming sample rate is 44.1 or 48kHz

88.2/96K – ndicates the incoming sample rate is 88.2 or 96kHz

192K – ndicates the incoming sample rate is 176.4 or 192kHz

FIL ER SE INGS

The cut-off points of the filters are in the upper end of the frequency range.

However, due to complex technical phenomena, this will have an effect lower in

the frequency band. For further description see the glossary of terms. These

settings are a matter of personal taste and may only offer subtle changes. We

suggest using Filter setting 1 and trying different settings with various

equipment.

Filter setting switch & LED’s Push to advance to the next filter.

Filter settings 1 – 5

(low sample rates 32/44.1/48K)

1 Linear phase half-band filter

2 Minimum phase soft-knee filter

3 Minimum phase half-band filter

4 Linear phase apodising filter

5 Minimum phase apodising filter

Filter settings 1 – 5

(medium & high sample rates 88.2/96 & 176.4/192K)

1 Linear phase soft-knee filter

2 Minimum phase soft-knee filter

3 Linear phase brickwall filter

4 Minimum phase apodising filter

5 Linear phase apodising filter

IN USE

Power-up the DAC using the power switch on the front panel. After a few

seconds you will hear an audible click from the output mute relay and the

analogue audio will be active. Please note: The front panel will display the

previously selected setting’s displayed before the unit was last powered down.

f the currently selected input has an active source connected the Input Locked

LED along with the appropriate incoming sample rate LED will illuminate. Unless

the Input Locked LED is lit the sample rate indication is irrelevant. By pressing

the input selection switch you can select any one of the inputs. When the Input

Locked LED is off, or there is a transmission error the internal soft mute is

activated automatically.

By pressing the Filter selection switch you can select any one of the 5 available

digital filters 1,2,3,4 or 5. (The exact properties of these filters are outlined on

the opposite page).

DIGI AL OU PU

The digital output mirrors the selected input. For example when input 2 has

been selected the digital output will be the signal present on input 2 but cleaned

up and re-clocked, this can be used to drive an auxiliary piece of equipment if

so desired.

USB CONNEC IVI Y

Connect a USB A-B type lead (as illustrated) from the DAC USB to a USB output

on your PC. The standard Windows ‘

found new hardware

’ dialogue will be

displayed on your PC in the bottom right hand corner of the screen.

USB A-B lead (not supplied)

The DAC will be recognised as ‘USB AUD O DAC’. nstallation should be

automatic as no driver disc is required. After a short period

‘your new

hardware is installed and ready to use’

should appear to confirm that

connection and installation has been successful.

t is recommended to switch off any other system sounds emitted by the PC via

the control panel. The DAC will automatically become the default for your PC

whilst connected. Once disconnected the previous default will be restored. f

this does not happen you can manually reset as follows :

Windows XP

- Control panel/Sounds and audio devices/Audio/Sound Playback

Windows Vista/Windows 7

- Control Panel/Hardware and Sound/Manage Audio

Devices/select ‘USB AUD O DAC’ from list.

Mac OS

- System Preferences/Sound Output/Select Audio USB DAC.

CONNEC IVI Y (examples)

1 USB A-B/ 2 OP ICAL/3 CO-AXIAL

This page offers ‘suggested connectivity’, with so many products offering a

number of options it is important to check the manual of the product your are

connecting, for the appropriate or optimum output connection and settings

required to operate properly.

Note: This unit only accepts two-channel PCM digital audio. You cannot connect

a Dolby Digital 5.1/7.1 or a DTS signal as they will not be recognised. f you wish

to connect a DVD or similar device, please ensure that the sound output of your

player is set to two-channel PCM.

ECHNICAL SPECIFICA IONS

DAC Wolfson WM8742

Frequency Response (100KΩ load)

Low data rate 44.1/48KHz Filter 2 = 10Hz -0.05dB to 20KHz -0.1dB

Medium data rate 88.2/96KHz Filter 2 = 10Hz -0.05dB to 30KHz -1dB

High data rate 176.4/192KHz Filter 2 = 10Hz -0.05dB to 41KHz -1dB

otal Harmonic Distortion (24bit 96KHz) = 0.006% @ 1KHz

Signal o Noise Ratio -105dB

(relative to maximum output level with a 100Hz to 22KHz bandwidth)

Maximum output level = 2.175V into 100KΩ load

Bit resolution 16 to 24bit (USB is limited to 16bit)

Supported data rates = 32, 44.1, 48, 88.2, 96, 176.4, 192KHz

Digital inputs

USB solated (16bit 32/44.1/48KHz)

Input 1 Optical/Toslink (24bit 32/44.1/48/88.2/96/176.4/192KHz)

Input 2 Optical /Toslink (24bit 32/44.1/48/88.2/96/176.4/192KHz)

Input 3 solated 75Ω Co-axial (24bit 32/44.1/48/88.2/96/176.4/192KHz)

Input 4 solated 75Ω Co-axial (24bit32/44.1/48/88.2/96/176.4/192KHz)

Digital output (via receiver & PLL) - SPD F

Optical Toslink solated 75Ω

Co-axial/SPD F

Power 230v/115v/7.6W

Dimensions in cm W 21.5 x D 27 x H 8

Weight 4.0 Kg

96kHz & 192kHz OPERA ION

The Rega DAC can operate at 192kHz when used with a capable soundcard

connected via the Co-axial or optical input. Due to the limitations of some

operating systems the exact configuration and set-up can vary from one

PC/Laptop to another.

f you are constructing a high sample rate music server, we recommend that

the frequency response and THD of the final unit complete with the DAC,

soundcard and player is checked using high frequency test tones with suitable

measuring equipment to ascertain the playback chain is capable of true 96 &

192K operation.

This test will require specialist test tones and equipment. Loudspeakers should

not be used as certain frequencies could potentially damage the drive units.

Please note: Some PC/Laptop or disc players are only capable of a maximum

sample rate of 48kHz. The USB will only work at 32/44.1/48kHz 16-bit even if

you have a 96kHz & 192kHz playback configuration.

11 12

ROUBLESHOO ING

No power - no LED’s illuminated

s the mains supply connected and the socket

switched on?

s the front panel on/off switch fully

depressed?

Has the fuse in the mains plug blown?

n the mains socket live?

(plug in another appliance to check)

Replace with the same

rated fuse

Check household fuse or

contact an electrician

Correct the fault (contact

Rega dealer if faulty)

Contact your Rega dealer

Are the output connections

connected correctly?

Are the matching inputs on the amplifier

correclty selected?

s the correct input on the DAC selected and

the input locked LED illuminated?

Check connected digital product is

working properly

Select correct input

on the DAC

Correct the fault

Check setup and settings

Contact your Rega dealer

ROUBLESHOO ING

Power ON - No output

Correct the fault

Yes

GLOSSARY OF ERMS

PLL

Phase lock Loop

PCM

Pulse code modulation

SPDIF

Sony Philips digital interface protocol

SOF MU E

Software mute (not output mute)

SOF KNEE FIL ER

Filter with a large transition band which reduces dispersion and delay

HALF BAND

Filter where the transition region is centred at one quarter of the sampling rate

APODISING FIL ER

Filter exhibiting a smooth roll off

BRICKWALL FIL ER

Filter exhibiting a steep roll off

FLAC/ALAC

Lossless audio formats

DIGI AL FIL ER

Device or process that removes unwanted features from a signal.

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OWNERS LOG

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