WEISS DAC202 User manual

OWNERS MANUAL FOR WEISS DAC202 D/A CONVERTER
Page 1 Date: 03/10
DAC202
OWNERS MANUAL

OWNERS MANUAL FOR WEISS DAC202 D/A CONVERTER
Page 2 Date: 03/10
INTRODUCTION
Dear customer
Congratu ations on your purchase of the DAC202 D/A Converter and
we come to the fami y of Weiss equipment owners!
The DAC202 is the resu t of an intensive research and deve opment process.
Research was conducted both in ana og and digita circuit design, as we as
in signa processing a gorithm specification.
On the fo owing pages I wi introduce you to our views on high qua ity
audio processing. These inc ude fundamenta digita and ana og audio
concepts and the DAC202 converter.
I wish you a ong- asting re ationship with your DAC202.
Yours sincere y,
Danie Weiss
President, Weiss Engineering Ltd.
TABLE OF CONTENTS
3 A short history of Weiss Engineering
3 Our mission and product phi osophy
4 Advanced digita and ana og audio concepts
exp ained
4 Jitter Suppression, C ocking
5 Upsamp ing, Oversamp ing and Samp ing Rate
Conversion in Genera
7 Reconstruction Fi ters
7 Ana og Output Stages
7 Dithering
9 The DAC202 D/A Converter
9 Features in a phabetica order
12 Operation, Insta ation
21 Software Insta ation
21 Software Setup
23 Technica Data
26 Contact
Author: Danie Weiss, Weiss Engineering LTD.
Weiss Engineering LTD. reserves the right to make changes to product specification or documentation without prior notice.
Updated manua s and datasheets are avai ab e at our website for down oading. Weiss Engineering LTD. makes no warranty,
representation or guarantee regarding the suitabi ity of its products for any particu ar purpose, nor does part of this manua , and
specifica y disc aims any and a iabi ity, inc uding without imitation consequentia or incidenta damages.
A rights reserved. No part of this pub ication may be reproduced or transmitted in any form or by any means, e ectronic or
mechanica inc uding photocopying, scanning or any information storage or retrieva system without the express prior written
consent of the pub isher.
© Copyright Weiss Engineering LTD., 2010.

OWNERS MANUAL FOR WEISS DAC202 D/A CONVERTER
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A SHORT HISTORY OF WEISS ENGINEERING
After studying e ectrica engineering, Danie Weiss joined the
Wi i Studer (Studer - Revox) company in Switzer and. His work
inc uded the design of a samp ing frequency converter and of
digita signa processing e ectronics for digita audio recorders.
In 1985, Mr. Weiss founded the company Weiss Engineering
Ltd. From the outset the company concentrated on the design
and manufacture of digita audio equipment for mastering
studios. Its first product was the modu ar "102 Series" system.
After 23 years, this system is sti up to date (24 bit / 96kHz)
and is sti being so d. Hundreds of Mastering Studios around the
wor d use it every day.
In the ear y nineties the „Gambit Series“ was aunched, taking
ergonomics and sonic qua ity to new heights. The „Gambit
Series“ consists of stand-a one units ike Equa izer, Denoiser /
Dec icker, Dynamics Processor, A/D converter, D/A converter,
Samp ing Frequency Converter, Dithering etc. 40 bit f oating
point processors and samp ing rates up to 96kHz are emp oyed.
In 2001 we have decided to enter the High-End Hi-Fi market,
which offers a comparab e c iente e to that of the Mastering
Studios. Both consist of critica and discerning isteners, who are
in constant search for the best audio reproduction equipment or
the best audio too s respective y.
Our ist of c ients inc udes big names, ike SONY, BMG, EMI,
Warner, Hit Factory, Abbey Road, Te dec, Te arc, Unite ,
Gateway Mastering (Bob Ludwig), Bernie Grundman Mastering,
Masterdisk, Ster ing Sound, Whitfie d Street, Metropo is and
hundreds more.
For a more comprehensive ist you are invited to visit our pro
audio website at www.weiss.ch.
OUR MISSION AND RODUCT HILOSO HY
The wea th of experience we have gained in over 20 years of
designing products for top Mastering Engineers, we now app y
to the design of outstanding High-End Hi-Fi products.
Our mission is to create equipment, which becomes c assic right
from the outset - outstanding in sonics and design.
These are some of the milestones at Weiss Engineering:
1985 Introduction of the "102 Series", a 24 bit modu ar digita
audio processor for Mastering Studios
1986 Introduction of one of the first samp e rate converters for
digita audio
1987 Introduction of one of the first digita equa izers
1989 Introduction of one of the first digita dynamics processors
1991 Introduction of the "Ibis" digita mixing conso e, bui t for
the mix-down of c assica music
1993 Introduction of the "Gambit" Series of digita audio
processors, which emp oy 40 bit f oating point
processing and sport an extreme y ergonomic user
interface
1995 First 96kHz samp ing rate capab e products de ivered
2001 Introduction of the MEDEA, our High-End Hi-Fi D/A
converter and the first product in our High-End Series
2004 Introduction of the JASON CD Transport

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2007 Introduction of the CASTOR, our High-End Hi-Fi Power
Amp ifier
2008 Introduction of the MINERVA Firewire DAC and the VESTA
Firewire – AES/EBU Interface
2010 Introduction of the DAC202 Firewire DAC, the INT202
Firewire Interface and the ATT202 Passive Attenuator
ADVANCED DIGITAL AND ANALOG AUDIO
CONCE TS EX LAINED
Jitter Suppression and Clocking
What is jitter and how does it affect audio qua ity? In the audio
fie d the term jitter designates a timing uncertainty of digita
c ock signa s. E.g. in an Ana og to Digita Converter (A/D) the
ana og signa is samp ed (measured) at regu ar time interva s;
in the case of a CD, 44100 times a second or every 22.675737..
Microseconds.
If these time interva s are not strict y constant then one ta ks of
a jittery conversion c ock. In practice it is of course not possib e
to generate exactly the same time interva between each and
every samp e. After a , even digita signa s are ana og in their
properties and thus are inf uenced by noise, crossta k, power
supp y f uctuations, temperature etc.
Hence a jittery c ock introduces errors to the measurements
taken by the A/D, resu ting from measurements being taken at
the wrong time. One can easi y observe that the eve of the
error introduced is higher during high audio frequencies,
because high frequency signa s have a steeper signa form.
A good designer takes care that the jitter amount in his/her
design is minimized as we as possib e.
What type of equipment can be compromised by jitter?
There are three types: The A/D Converter as described above,
then there is the D/A Converter where the same mechanism as
in the A/D Converter app ies and the third is the Asynchronous
Samp e Rate Converter (ASRC). The ASRC is not something
usua y found in Hi-Fi systems. It is used by Sound Engineers to
change the samp e rate from e.g. 96kHz to 44.1kHz, or e.g.
for putting a 96kHz recording onto a 44.1kHz CD.
You may now argue that in High-End Hi-Fi there are such things
as „Oversamp ers“ or „Upsamp ers“.
Yes, those are in essence samp ing rate converters, however in
a we -designed system these converters emp oy a synchronous
design, where jitter does not p ay any ro e. Of course a
conversion between 96kHz and 44.1kHz as in the examp e
above, can be done in a synchronous manner as we . An ASRC
in fact is on y required either where one or both of the samp ing
frequencies invo ved are changing over time („varispeed“ mode
of digita audio recorders) or where it is unpractica to
synchronize the two samp ing frequencies.
So basica y in Hi-Fi jitter matters where there are A/D or D/A
converters invo ved. CD and DVD p ayers are by far the most
numerous type of equipment emp oying D/A converters. And of
course stand-a one D/A converters. Jitter, being an ana og
quantity, can creep in at various p aces. The D/A converter bui t
into CD or DVD p ayers can be „infected“ by jitter through
various crossta k mechanisms, ike power supp y contamination
by power hungry motors (spind e / servo) or microphony of the
crysta generating the samp ing c ock or capacitive / inductive
crossta k between c ock signa s etc.
In the standa one D/A converter jitter can be introduced by
inferior cab es between the source (e.g. CD transport) and the

OWNERS MANUAL FOR WEISS DAC202 D/A CONVERTER
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D/A converter unit or by the same mechanisms as described
above except for the motors of course.
In the case of a stand-a one D/A converter (as the DAC202),
one has to take two different jitter contamination paths into
account.
One is the interna path where interna signa s can affect the
jitter amount of the samp ing c ock generator. Here, a the
good o d ana og design princip es have to be app ied. Such as
shie ding from e ectric or magnetic fie ds, good grounding, good
power supp y decoup ing, good signa transmission between the
c ock generator and the actua D/A chip.
The other path is the externa signa coming from the source to
which the samp ing c ock has to be ocked. I.e. the D/A
converter has to run synchronous to the incoming digita audio
signa and thus the frequency of the interna samp ing c ock
generator has to be contro ed so that it runs at the same
samp ing speed as the source (e.g. CD transport). This
contro ing is done by a Phase Locked Loop (PLL), which is a
contro system with error feedback. Of course the PLL has to be
ab e to fo ow the ong term f uctuations of the source, e.g. the
samp ing rate of the source wi a ter s ight y over time or over
temperature, it wi not be a constant 44.1kHz in the case of a
CD. But the PLL shou d not fo ow the short-term f uctuations
(jitter). Think of the PLL as being ike a very s ow-reacting
f ywhee .
In the DAC202 we emp oy a two-stage PLL circuitry, which very
effective y suppresses jitter. A common prob em with most PLLs
used in audio circuitry is that they suppress jitter on y for higher
frequencies. Jitter frequencies that are ow (e.g. be ow 1kHz or
so) are often on y margina y suppressed. It has been shown
that ow frequency jitter can have a arge inf uence on the audio
qua ity though. The DAC202 suppresses even very ow
frequency jitter components.
This means that the DAC202 is virtua y immune to the qua ity
of the audio source regarding jitter. For a CD transport as a
source this means that as ong as the data is read off the CD in
a correct manner (i.e. no interpo ations or mutes) you shou d
hard y hear any difference between different makes of CD
transports or between different pressings of the same CD. A so
„accessories“ ike disk dampening devices or extreme y
expensive digita cab es wi not make any difference in sonic
qua ity. Of course it is a ways a good idea to have a good
qua ity cab e for digita (or ana og) audio transmission - but
within reason.
Upsampling, Oversampling and
Sampling Rate Conversion in
General
In consumer audio circ es the two terms oversamp ing and
upsamp ing are in common use. Both terms essentia y mean
the same, a change in the samp ing frequency to higher va ues.
Upsamp ing usua y means the change in samp ing rate using a
dedicated a gorithm (e.g. imp emented on a Digita Signa
Processor chip (DSP)) ahead of the fina D/A conversion (the
D/A chip), whi e oversamp ing means the change in samp ing
rate emp oyed in today’s modern D/A converter chips
themse ves.
But et’s start at the beginning. What is the samp ing frequency?
For any digita storage or transmission it is necessary to have
time discrete samp es of the signa , which has to be processed.
I.e. the ana og signa has to be samp ed at discrete time
interva s and ater converted to digita numbers. (A so see
"Jitter Suppression and C ocking" above)). This samp ing and
conversion process happens in the so-ca ed Ana og to Digita

OWNERS MANUAL FOR WEISS DAC202 D/A CONVERTER
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Converter (A/D). The inverse in the Digita to Ana og Converter
(D/A).
A physica aw states that in order to represent any given ana og
signa in the digita domain, one has to samp e that signa with
at east twice the frequency of the highest frequency contained
in the ana og signa . If this aw is vio ated so ca ed a iasing
components are generated which are perceived as a very nasty
kind of distortion. So if one defines the audio band of interest to
ie between 0 and 20 kHz, then the minimum samp ing
frequency for such signa s must be 40kHz.
For practica reasons exp ained be ow, the samp ing frequency
of 44.1kHz was chosen for the CD. A samp ing frequency of
44.1kHz a ows to represent signa s up to 22.05kHz. The
designer of the system has to take care that any frequencies
above 22.05kHz are sufficient y suppressed before samp ing at
44.1kHz. This suppression is done with the he p of a ow pass
fi ter, which cuts off the frequencies above 22.05kHz. In
practice such a fi ter has a imited steepness, i.e. if it
suppresses frequencies above 22.05kHz it a so suppresses
frequencies between 20kHz and 22.05kHz to some extent. So in
order to have a fi ter, which sufficient y suppresses frequencies
above 22.05kHz, one has to a ow it to have a so-ca ed
transition band between 20kHz and 22.05kHz where it gradua y
bui ds up its suppression.
Note that so far we have ta ked about the so-ca ed anti-a iasing
fi ter, which fi ters the audio signa ahead of the A/D conversion
process. For the D/A conversion, which is of more interest to
the High-End Hi-Fi enthusiast, essentia y the same fi ter is
required. This is because after the D/A conversion we have a
time discrete ana og signa , i.e. a signa that ooks ike steps,
having the rate of the samp ing frequency.
Such a signa contains not on y the origina audio signa
between 0 and 20kHz but a so rep icas of the same signa
symmetrica around mu tip es of the samp ing frequency. This
may sound comp icated, but the essence is that there are now
signa s above 22.05kHz. These signa s come from the samp ing
process. There are now frequencies above 22.05kHz which have
to be suppressed, so that they do not cause any
intermodu ation distortion in the amp ifier and speakers, do not
burn tweeters or do not make the dog go mad.
Again, a ow pass fi ter, which is ca ed a „reconstruction fi ter“,
is here to suppress those frequencies. The same app ies to the
reconstruction fi ter as to the anti-a iasing fi ter: Pass-band up
to 20kHz, transition-band between 20kHz and 22.05kHz, stop-
band above 22.05kHz. You may think that such a fi ter is rather
"steep", e.g. frequencies between 0 and 20kHz go through
unaffected and frequencies above 22.05kHz are suppressed to
maybe 1/100'000th of their initia va ue. You are right, such a
fi ter is very steep and as such has some nasty side effects.
For instance it does strange things to the phase near the cutoff
frequency (20kHz) or it shows ringing due to the high
steepness. In the ear y days of digita audio these side effects
have been recognized as being one of the main cu prits for
digita audio to sound bad.
So engineers ooked for ways to enhance those fi ters. They
can’t be e iminated because we are ta king aws of physics here.
But what if we run the who e thing at higher samp ing rates?
Like 96kHz or so? With 96kHz we can a ow frequencies up to
48kHz, so the reconstruction fi ter can have a transition band
between 20kHz and 48kHz, a very much re axed frequency
response indeed. So et’s run the who e at 96kHz or even
higher! We – the CD stays at 44.1kHz. So in order to have that
ana og owpass fi ter (the reconstruction fi ter) to run at a
re axed frequency response we have to change the samp ing
frequency before the D/A process. Here is where the Upsamp er
comes in. It takes the 44.1kHz from the CD and upsamp es it to
88.2kHz or 176.4kHz or even higher. The output of the
upsamp er is then fed to the D/A converters, which in turn feeds
the reconstruction fi ter.
A modern audio D/A converter chips have such an upsamp er
(or oversamp er) a ready bui t into the chip. One particu ar chip,

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Page 7 Date: 03/10
for instance, upsamp es the signa by a factor of eight, i.e.
44.1kHz ends up at 352.8kHz. Such a high samp ing frequency
re axes the job of the reconstruction fi ter very much; it can be
bui t with a simp e 3
rd
order fi ter.
So, how come that upsamp ers are such a big thing in High-End
Hi-Fi circ es? The prob em with the upsamp ers is that they are
fi ters again, digita ones, but sti fi ters. So in essence the
prob em of the ana og reconstruction fi ter has been transferred
to the digita domain into the upsamp er fi ters. The big
advantage when doing it in the digita domain is that it can be
done with a inear phase response, which means that there are
no strange phase shifts near 20kHz and the ringing can a so be
contro ed to some extent. Digita fi ters in turn have other
prob ems and of course have quite a few degrees of freedom for
the designer to specify. This means that the qua ity of digita
fi ters can vary at east as much as the qua ity of ana og fi ters
can. So for a High-End Hi-Fi designer it is a question whether
the oversamp ing fi ter bui t into the D/A chips ives up to
his/her expectations. If not, he/she can chose to design his/her
own upsamp er and bypass part of or the who e oversamp er in
the D/A chip. This gives the High-End Hi-Fi designer yet another
degree of freedom to optimize the sonic qua ity of the product.
Reconstruction Filters
Reconstruction fi ters have been mentioned in the "Upsamp ing,
Oversamp ing and Samp ing Rate Conversion in Genera "
paragraph above. If you have read that paragraph you know
what the purpose of the reconstruction fi ter is. The main point
about this ana og fi ter is that its frequency response shou d be
as smooth and f at as possib e in order to have a virtua y inear
phase response. The DAC202 emp oys a 3
rd
order fi ter for that
purpose.
Analog Output Stages
The DAC202 emp oys separate output stages for the main
output and the headphone output. Both stages use state of the
art operationa amp ifiers with high s ew rate. A topo ogy with a
very ow output impedance has been chosen. This assures that
the performance of the DAC202 and the subsequent amp ifier
combination is not compromised by the cab es between the two
or by the input impedance characteristics of the amp ifier.
Dithering
You have probab y not heard the term dithering in conjunction
with audio. Actua y it is a term wide y used in the professiona
audio rea m but not so much in the High-End Hi-Fi market.
What is dithering? Suppose a digita recording has been made
with a 24-bit A/D converter and a 24-bit recorder. Now this
recording shou d be transferred to a CD, which has just 16 bits
per samp e, as you know. What to do with those 8 bits, which
are too many? The simp est way is to cut them off, truncate
them. This, unfortunate y, generates harmonic distortions at ow
eve s, but which nonethe ess cause the audio to sound harsh
and unp easant. The harmonic distortion is generated because
the eight bits, which are cut off from the 24 bits, are corre ated
with the audio signa , hence the resu ting error is a so corre ated
and thus there are distortions and not just noise (noise wou d
be uncorre ated). The dithering technique now is used to de-
corre ate the error from the signa . This can be achieved by
adding a very ow eve noise to the origina 24-bit signa before

OWNERS MANUAL FOR WEISS DAC202 D/A CONVERTER
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truncation. After truncation the signa does not show any
distortion components but a s ight y increased noise f oor. This
works ike magic..... the distortion is rep aced by a sma noise –
much more p easant.
I have given the examp e of a 24-bit recording, which has to be
truncated to 16 bits. Where is the app ication in High-End Hi-Fi
audio? More and more signa processing is imp emented in the
digita domain. Think of digita equa izers, digita vo ume
contro s, upsamp ers, digita pre-amp ifiers, decoders for
encoded signa s on DVD etc. A those app ications perform
some mathematica operations on the digita audio signa . This
in turn causes the word ength of the signa to be increased. E.g.
an input signa to an upsamp er may have a word ength of 16
bits (off a CD), but the output signa of the upsamp er may have
24 bits or even more. This comes from the fact that the
mathematica operations emp oyed in such devices increase the
word ength. E.g. a mu tip ication of two 2-digit numbers resu ts
in a four-digit number. So after the upsamp er the word ength
may be higher than the subsequent processor may be ab e to
accept. In this examp e, after the upsamp er there may be a
D/A converter with a 24 bit input word ength capabi ity. So if
the upsamp er generates a word ength of more than 24 bits it
shou d be dithered to 24 bits for maximum signa fide ity.
I hope these excursions into the theory and practice of audio
engineering has been usefu for you. If you wou d ike to dive
further into those issues I recommend to visit the website of Mr.
Bob Katz, a renowned Mastering Engineer and a Weiss
Engineering customer. He pub ishes artic es on Dithering and
Jitter and many other topics at http://www.digido.com/

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THE DAC202 D/A CONVERTER
Features in alphabetical order
Absolute polarity switch:
The abso ute po arity of the outputs can be inverted for
optimizing the sonic impression.
Audio Inputs:
One XLR, one RCA and one Tos ink connector for AES/EBU or
S/PDIF signa s. Two Firewire connectors for computer
connection.
Audio Outputs:
Two XLR and two RCA connectors for ana og audio output. One
XLR and one RCA connector for AES/EBU and S/PDIF audio
output. One ¼ inch jack socket for headphones.
Backpanel elements from left to right:
• Ana og outputs on XLR and RCA connectors
• Digita outputs on XLR and RCA connectors
• Digita inputs on XLR and RCA connectors
• Wordsync input and output on BNC connectors
• Digita input on Tos ink connector
• Firewire connectors
• Mains connector with fuse
Converters:
Two converters per channe are emp oyed in order to ower the
converter imperfections. Separate converters are used for the
main outputs and the headphone outputs.
Dual / Single Wire modes:
The AES/EBU inputs / outputs of the DAC202 norma y work in
the so ca ed “Sing e Wire” modus, i.e. both audio channe s are
transferred via a sing e cab e. The DAC202 a so supports the
“Dua Wire” modus where the two audio channe s are
transferred via two cab es, i.e. eft channe is on the XLR
connector and the right channe on the RCA connector. This
app ies to both input and output connectors. The Dua Wire
modus, when activated, is active on y at samp ing rates of
176.4 or 192 kHz.
In Dua Wire mode the frequency of the wordc ock
synchronization on the BNC connectors can be chosen to be the

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samp ing rate (i.e. 176.4 or 192 kHz) or ha f the samp ing rate
(i.e. 88.2 or 96 kHz).
Frontpanel elements:
• Standby LED
• IR Receiver
• Headphone socket
• LCD disp ay
• Rotary encoder with switch
Insert mode:
If the insert mode is activated an externa digita audio device
(e.g. a digita equa izer) can be ooped into the signa path via
the XLR input / output connectors. The resu ting signa path
thus ooks as fo ows: Firewire (or RCA or Tos ink) input  XLR
output  externa device  XLR input  DAC chip.
LCD brightness:
The brightness of the LCD can be set with two different choices:
One brightness eve is active when operating the rotary
encoder knob or the remote contro . The other brightness eve
is active when the DAC202 or the remote contro are not
touched. This a ows to dim the LCD when the information on
the LCD screen is not required.
Level Control Main Output:
The output eve of the main output can be adjusted in the
ana og domain in four coarse steps in order to accommodate for
the input sensitivity of the subsequent amp ifier. A higher
reso ution eve contro is imp emented in the digita domain and
operated from the frontpane knob or the remote contro . The
high-reso ution eve contro can be defeated for the main
output in case there is another eve contro avai ab e in the
audio chain.
Level Control Headphone Output:
The output eve of the headphone output can be adjusted in the
ana og domain in four coarse steps in order to accommodate for
the headphone sensitivity. A higher reso ution eve contro is
imp emented in the digita domain and operated from the
frontpane knob or the remote contro .
ower Supply:
A powerfu non-switching power supp y is used. A sensitive
vo tages have their own regu ators.