Rega DAC Wolfson WM8742 User Manual
CONTENTS
INTRODUCTION 1
TECHNOLOGY 2
FRONT PANEL INDICATORS & CONTROLS 3
BACK PANEL 4
IN USE & DIGITAL OUTPUT 5
FILTER SETTINGS 6
CONNECTIVITY 7
USB CONNECTIVITY 8
96kHz-192kHz OPERATION 9
TECHNICAL SPECIFICATIONS 10
TROUBLESHOOTING 11
TROUBLESHOOTING 12
GLOSSARY OF TERMS 13
INTRODUCTION
TECHNOLOGY
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 IC’s and 5 user selectable digital filters, two isolated Co-axial
inputs, two Toslink SPDIF 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.
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 parallelconnected Wolfson WM8742 DAC’s, which are driven via a buffer stage, which
ensures the integrity of the data being fed to the DAC IC’s – similar to the
arrangement used in the Isis (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 IC
control signals ensuring the control data noise is kept to a minimum.
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2
FRONT PANEL INDICATORS AND CONTROLS
BACK PANEL
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 Input 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 Input Locked is on)
32K – Indicates the incoming sample rate is 32kHz
44.1/48K – Indicates the incoming sample rate is 44.1 or 48kHz
88.2/96K – Indicates the incoming sample rate is 88.2 or 96kHz
192K – Indicates the incoming sample rate is 176.4 or 192kHz
3
Digital Inputs
USB - type B connector/Isolated
Optical Digital Input 1 - Optical/Toslink
Optical Digital Input 2 - Optical /Toslink
Co-Ax Digital Input 3 - Isolated 75Ω Co-axial Phono
Co-Ax Digital Input 4 - Isolated 75Ω Co-axial Phono
Digital output (via receiver & PLL) -SPDIF
Optical Toslink
Co-axial/Phono Isolated 75Ω
Analogue Output Left and Right Phono
Power Mains/line input IEC C5 type
Fuse Fuse holder
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