WEISS INT202 User manual

Weiss Engineering Ltd.
Florastrasse 42, 8610 Uster, Switzerland
www.weiss-highend.co
INT202
OWNERS MANUAL

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 2 Date: 03/10
INTRODUCTION
Dear Custo er
Congratulations on your purchase of the INT202 Firewire
Interface and welco e to the fa ily of Weiss equip ent
owners!
On the following pages I will introduce you to our views
on high quality audio processing and interfacing. These
include funda ental digital and analog audio concepts
and the INT202 Firewire Interface.
I wish you a long-lasting relationship with your INT202.
Yours sincerely,
Daniel Weiss
President, Weiss Engineering Ltd.

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 3 Date: 03/10
TABLE OF CONTENTS
4 A short history of Weiss Engineering
5 Our ission and product philosophy
6 Advanced digital and analog audio concepts
explained
6 Jitter Suppression, Clocking
8 Upsa pling, Oversa pling and Sa pling
Rate Conversion in General
10 Dithering
11 Firewire vs USB
13 The INT202 Firewire Interface
13 Features
16 Operation / Installation
21 Technical Data
22 Contact
Author: Daniel Weiss, Weiss Engineering LTD.
Weiss Engineering LTD. reserves the right to ake changes to product specification or docu entation without prior
notice. Updated anuals and datasheets are available at our website for downloading. Weiss Engineering LTD. akes
no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does
part of this anual, and specifically discali s any and all liability, including without li itation consequential or
incidental da ages.
All rights reserved. No part of this publication ay be reproduced or trans itted in any for or by any eans,
electronic or echanical including photocopying, scanning or any infor ation storage or retrieval syste without the
express prior written consent of the publisher.
© Copyright Weiss Engineering LTD., 2010.

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 4 Date: 03/10
A SHORT HISTORY OF WEISS ENGINEERING
After studying electrical engineering, Daniel Weiss joined
the Willi Studer (Studer - Revox) co pany in
Switzerland. His work included the design of a sa pling
frequency converter and of digital signal processing
electronics for digital audio recorders.
In 1985, Mr. Weiss founded the co pany Weiss
Engineering Ltd. Fro the outset the co pany
concentrated on the design and anufacture of digital
audio equip ent for astering studios. Its first product
was the odular "102 Series" syste . After 23 years,
this syste is still up to date (24 bit / 96kHz) and is still
being sold. Hundreds of Mastering Studios around the
world use it every day.
In the early nineties the „Ga bit Series“ was launched,
taking ergono ics and sonic quality to new heights. The
„Ga bit Series“consists of stand-alone units like
Equalizer, Denoiser / Declicker, Dyna ics Processor, A/D
converter, D/A converter, Sa pling Frequency
Converter, Dithering etc. 40 bit floating point processors
and sa pling rates up to 96kHz are e ployed.
In 2001 we have decided to enter the High-End Hi-Fi
arket which offers a co parable clientele to that of the
Mastering Studios. Both consist of critical and discerning
listeners, who are in constant search for the best audio
reproduction equip ent or the best audio tools
respectively.
Our list of clients includes big na es, like SONY, BMG,
EMI, Warner, Hit Factory, Abbey Road, Teldec, Telarc,
Gateway Mastering (Bob Ludwig), Bernie Grund an
Mastering, Masterdisk, Sterling Sound, Whitfield Street,
Metropolis and hundreds ore.
For a ore co prehensive list you are invited to visit our
pro audio website at www.weiss.ch.

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 5 Date: 03/10
OUR MISSION AND PRODUCT PHILOSOPHY
The wealth of experience we have gained in ore than
20 years of designing products for top Mastering
Engineers, we now apply to the design of outstanding
High-End Hi-Fi products.
Our ission is to create equip ent which beco es
classic right fro the outset; - outstanding in sonics and
design.
The e are ome of the mile tone at Wei
Engineering:
1985 Introduction of the "102 Series", a 24 bit odular
digital audio processor for Mastering Studios
1986 Introduction of one of the first sa ple rate
converters for digital audio
1987 Introduction of one of the first digital equalizers
1989 Introduction of one of the first digital dyna ics
processors
1991 Introduction of the "Ibis" digital ixing console,
built for the ix-down of classical usic
1993 Introduction of the "Ga bit" Series of digital audio
processors, which e ploy 40 bit floating point
processing and sport an extre ely ergono ic
user interface
1995 First 96kHz sa pling rate capable products
delivered
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
2007 Introduction of the CASTOR, our High-End Hi-Fi
Power A plifier
2008 Introduction of the MINERVA Firewire DAC and the
VESTA Firewire – AES/EBU Interface
2009 Introduction of the INT202 Firewire Interface, the
ATT202 Passive Attenuator, the DAC202 D/A
Converter

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 6 Date: 03/10
ADVANCED DIGITAL AND ANALOG AUDIO
CONCEPTS EXPLAINED
Jitter Suppre ion and Clocking
What is jitter and how does it affect audio quality? In the
audio field the ter jitter designates a ti ing uncertainty
of digital clock signals. E.g. in an Analog to Digital
Converter (A/D) the analog signal is sa pled ( easured)
at regular ti e intervals; in the case of a CD, 44100
ti es a second or every 22.675737.. icroseconds.
If these ti e intervals are not strictly constant then one
talks of a jittery conversion clock. In practice it is of
course not possible to generate exactly the sa e ti e
interval between each and every sa ple. After all, even
digital signals are analog in their properties and thus are
influenced by noise, crosstalk, power supply fluctuations,
te perature etc.
Hence a jittery clock introduces errors to the
easure ents taken by the A/D, resulting fro
easure ents being taken at the wrong ti e. One can
easily observe that the level of the error introduced is
higher during high audio frequencies, because high
frequency signals have a steeper signal for .
A good designer takes care that the jitter a ount in
his/her design is ini ized as well as possible.
What type of equip ent can be co pro ised by jitter?
There are three types: The A/D Converter as described
above, then there is the D/A Converter where the sa e
echanis as in the A/D Converter applies and the third
is the Asynchronous Sa ple Rate Converter (ASRC). The
ASRC is not so ething usually found in Hi-Fi syste s. It
is used by Sound Engineers to change the sa ple rate
fro e.g. 96kHz to 44.1kHz, or e.g. for putting a 96kHz
recording onto a 44.1kHz CD.
You ay now argue that in High-End Hi-Fi there are such
things as „Oversa plers“ or „Upsa plers“.
Yes, those are in essence sa pling rate converters,
however in a well designed syste these converters
e ploy a synchronous design, where jitter does not play
any role. Of course a conversion between 96kHz and
44.1kHz as in the exa ple above, can be done in a
synchronous anner as well. An ASRC in fact is only
required either where one or both of the sa pling
frequencies involved are changing over ti e („varispeed“
ode of digital audio recorders) or where it is unpractical
to synchronize the two sa pling frequencies.
So basically in Hi-Fi jitter atters where there are A/D or
D/A converters involved. CD and DVD players are by far
the ost nu erous type of equip ent e ploying D/A
converters. And of course stand-alone D/A converters.
Jitter, being an analog quantity, can creep in at various
places. The D/A converter built into CD or DVD players
can be „infected“ by jitter through various crosstalk

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 7 Date: 03/10
echanis s, like power supply conta ination by power
hungry otors (spindle / servo) or icrophony of the
crystal generating the sa pling clock or capacitive /
inductive crosstalk between clock signals etc.
In the standalone D/A converter jitter can be introduced
by inferior cables between the source (e.g. CD player)
and the D/A converter unit or by the sa e echanis s
as described above except for the otors of course.
In the case of a stand-alone D/A converter (as the
MINERVA), one has to take two different jitter
conta ination pathes into account.
One is the internal path where internal signals can affect
the jitter a ount of the sa pling clock generator. Here,
all the good old analog design principles have to be
applied. Such as shielding fro electric or agnetic
fields, good grounding, good power supply decoupling,
good signal trans ission between the clock generator
and the actual D/A chip.
The other path is the external signal co ing fro the
source to which the sa pling clock has to be locked. I.e.
the D/A converter has to run synchronous to the
inco ing digital audio signal and thus the frequency of
the internal sa pling clock generator has to be
controlled so that it runs at the sa e sa pling speed as
the source (CD transport). This controlling is done by a
Phase Locked Loop (PLL) which is a control syste with
error feedback. Of course the PLL has to be able to follow
the long ter fluctuations of the source, e.g. the
sa pling rate of the source will alter slightly over ti e or
over te perature, it will not be a constant 44.1kHz in the
case of a CD. But the PLL should not follow the short
ter fluctuations (jitter). Think of the PLL as beeing like
a very slow-reacting fly-wheel.
Jitter handling in the INT202 Firewire Interface in
more detail
The Jitter Eli ination Technologies (JET) PLL on the chip
used in the INT202 feature state-of-the art jitter
rejection abilities and extre ely low intrinsic jitter levels.
Like all phase-locked loops, JET PLL use feedback to lock
an oscillator to a ti ing reference. They track slow
reference changes, but effectively free-run through rapid
odulations of the reference (i.e. flywheel like). Fro a
jitter transfer point of view, they provide increasing jitter
attenuation above so e chosen corner frequency.
Jitter attenuation is just one aspect of PLL design. Other
considerations include frequency range and intrinsic
jitter. It can be shown that conventional designs are
bound by a funda ental tradeoff between these three
aspects. For exa ple, specifying a frequency range of
one octave eans using a low-Q oscillator. But that
akes for high intrinsic jitter when the loop corner
frequency is held down. Conversely, good jitter
attenuation and low intrinsic jitter can be had by using a
voltage-controlled crystal oscillator (VCXO). But the
frequency range is then tiny. A further consideration is
that only low-Q oscillators are easy to integrate on chip.
JET PLL sidestep the above- entioned tradeoff. It
incorporates two loops. One is largely or wholly nu eric,

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 8 Date: 03/10
and has its corner frequency set low enough to give good
reference-jitter attenuation. The other regulates the
analog oscillator and has its corner frequency set uch
higher, to oderate the intrinsic jitter. The two corner
frequencies ight be around 10 Hz and 100 kHz, for
exa ple. Another benefit of having a high corner
frequency in the analog loop is that interference, e.g. via
the oscillator's supply rail, is ore-effectively
suppressed. JET PLL requires a fast, stable, fixed-
frequency clock. It is this that gives it stability in the
band between the two corner frequencies. (Equally, in
this band any jitter on this clock passes straight through
to the JET PLL's clock output.) The stable clock is usually
derived fro a free-running crystal oscillator. JET PLL
contains a nu ber-controlled oscillator, which can also
be called a fractional frequency divider. Like the analog
oscillator, this injects jitter. Typically, spectru shaping
is used to push ost of that jitter up to frequencies
where it will be heavily attenuated by the analog loop. As
well as frequency-locking the analog oscillator to the
provided reference, JET PLL can also phase-lock an
associated fra e sync to the reference.
Up ampling, Over ampling and
Sampling Rate Conver ion in
General
In consu er audio circles the two ter s oversa pling
and upsa pling are in co on use. Both ter s
essentially ean the sa e, a change in the sa pling
frequency to higher values. Upsa pling usually eans
the change in sa pling rate using a dedicated algorith
(e.g. i ple ented on a Digital Signal Processor chip
(DSP)) ahead of the final D/A conversion (the D/A chip),
while oversa pling eans the change in sa pling rate
e ployed in today’s odern D/A converter chips
the selves.
But let’s start at the beginning. What is the sa pling
frequency? For any digital storage or trans ission it is
necessary to have ti e discrete sa ples of the signal
which has to be processed. I.e. the analog signal has to
be sa pled at discrete ti e intervals and later converted
to digital nu bers. (Also see "Jitter Suppression and
Clocking" above)). This sa pling and conversion process
happens in the so called Analog to Digital Converter
(A/D). The inverse in the Digital to Analog Converter
(D/A).
A physical law states that in order to represent any given
analog signal in the digital do ain, one has to sa ple
that signal with at least twice the frequency of the
highest frequency contained in the analog signal. If this
law is violated so called aliasing co ponents are
generated which are perceived as a very nasty kind of
distortion. So if one defines the audio band of interest to
lie between 0 and 20 kHz, then the ini u sa pling
frequency for such signals ust be 40kHz.
For practical reasons explained below, the sa pling
frequency of 44.1kHz was chosen for the CD. A sa pling

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 9 Date: 03/10
frequency of 44.1kHz allows to represent signals up to
22.05kHz. The designer of the syste has to take care
that any frequencies above 22.05kHz are sufficiently
suppressed before sa pling at 44.1kHz. This suppression
is done with the help of a low pass filter which cuts off
the frequencies above 22.05kHz. In practice such a filter
has a li ited steepness, i.e. if it suppresses
frequencies above 22.05kHz it also suppresses
frequencies between 20kHz and 22.05kHz to so e
extent. So in order to have a filter which sufficiently
suppresses frequencies above 22.05kHz one has to allow
it to have a so called transition band between 20kHz and
22.05kHz where it gradually builds up its suppression.
Note that so far we have talked about the so called anti-
aliasing filter which filters the audio signal ahead of the
A/D conversion process. For the D/A conversion, which is
of ore interest to the High-End Hi-Fi enthusiast,
essentially the sa e filter is required. This is because
after the D/A conversion we have a ti e discrete analog
signal, i.e. a signal which looks like steps, having the
rate of the sa pling frequency.
Such a signal contains not only the original audio signal
between 0 and 20kHz but also replicas of the sa e signal
sy etrical around ultiples of the sa pling frequency.
This ay sound co plicated, but the essence is that
there are now signals above 22.05kHz. These signals
co e fro the sa pling process. There are now
frequencies above 22.05kHz which have to be
suppressed, so that they do not cause any
inter odulation distortion in the a plifier and speakers,
do not burn tweeters or do not ake the dog go ad.
Again, a low pass filter, which is called a „reconstruction
filter“, is here to suppress those frequencies. The sa e
applies to the reconstruction filter as to the anti-aliasing
filter: Pass-band up to 20kHz, transisition-band between
20kHz and 22.05kHz, stop-band above 22.05kHz. You
ay think that such a filter is rather "steep", e.g.
frequencies between 0 and 20kHz go through unaffected
and frequencies above 22.05kHz are suppressed to
aybe 1/100'000th of their initial value. You are right,
such a filter i very steep and as such has so e 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 early days of digital audio these
side effects have been recognized as beeing one of the
ain culprits for digital audio to sound bad.
So engineers looked for ways to enhance those filters.
They can’t be eli inated because we are talking laws of
physics here. But what if we run the whole thing at
higher sa pling rates? Like 96kHz or so? With 96kHz we
can allow frequencies up to 48kHz, so the reconstruction
filter can have a transition band between 20kHz and
48kHz, a very uch relaxed frequency response indeed.
So let’s run the whole at 96kHz or even higher! Well –
the CD stays at 44.1kHz. So in order to have that analog
lowpass filter (the reconstruction filter) to run at a
relaxed frequency response we have to change the
sa pling frequency before the D/A process. Here is
where the Upsa pler co es in. It takes the 44.1kHz

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 10 Date: 03/10
fro the CD and upsa ples it to 88.2kHz or 176.4kHz or
even higher. The output of the upsa pler is then fed to
the D/A converters which in turn feeds the reconstruction
filter.
All odern audio D/A converter chips have such an
upsa pler (or oversa pler) already built into the chip.
One particular chip, for instance, upsa ples the signal by
a factor of eight, i.e. 44.1kHz ends up at 352.8kHz. Such
a high sa pling frequency relaxes the job of the
reconstruction filter very uch, it can be built with a
si ple 3
rd
order filter.
So, how co e that upsa plers are such a big thing in
High-End Hi-Fi circles? The proble with the upsa plers
is that they are filters again, digital ones, but still filters.
So in essence the proble of the analog reconstruction
filter has been transferred to the digital do ain into the
upsa pler filters. The big advantage when doing it in the
digital do ain is that it can be done with a linear phase
response, which eans that there are no strange phase
shifts near 20kHz and the ringing can also be controlled
to so e extent. Digital filters in turn have other
proble s and of course have quite a few degrees of
freedo for the designer to specifiy. This eans that the
quality of digital filters can vary at least as uch as the
quality of analog filters can. So for a High-End Hi-Fi
designer it is a question whether the oversa pling filter
built into the D/A chips lives up to his/her expectations.
If not, he/she can chose to design his/her own
upsa pler and bypass part of or the whole oversa pler
in the D/A chip. This gives the High-End Hi-Fi designer
yet another degree of freedo to opti ize the sonic
quality of the product.
Dithering
You have probably not heard the ter dithering in
conjunction with audio. Actually it is a ter widely used
in the professional audio real but not so uch in the
High-End Hi-Fi arket.
What is dithering? Suppose a digital recording has been
ade with a 24 bit A/D converter and a 24 bit recorder.
Now this recording should be transferred to a CD which
has just 16 bits per sa ple, as you know. What to do
with those 8 bits which are too any? The si plest way
is to cut the off, truncate the . This, unfortunately,
generates har onic distortions at low levels, but which
nonethless cause the audio to sound harsh and
unpleasant. The har onic distortion is generated
because the eight bits which are cut off fro the 24 bits
are correlated with the audio signal, hence the resulting
error is also correlated and thus there are distortions and
not just noise (noise would be uncorrelated). The
dithering technique now is used to de-correlate the error
fro the signal. This can be achieved by adding a very
low level noise to the original 24 bit signal before
truncation. After truncation the signal does not show any
distortion co ponents but a slightly increased noise
floor. This works like agic..... the distortion is replaced
by a s all noise – uch ore pleasant.

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 11 Date: 03/10
I have given the exa ple of a 24 bit recording which has
to be truncated to 16 bits. Where is the application in
High-End Hi-Fi audio? More and ore signal processing is
i ple ented in the digital do ain. Think of digital
equalizers, digital volu e controls, upsa plers, digital
pre-a plifiers, decoders for encoded signals on DVD etc.
All those applications perfor so e athe atical
operations on the digital audio signal. This in turn causes
the wordlength of the signal to be increased. E.g. an
input signal to an upsa pler ay have a wordlength of
16 bits (off a CD), but the output signal of the upsa pler
ay have 24 bits or even ore. This co es fro the fact
that the athe atical operations e ployed in such
devices increase the word length. E.g. a ultiplication of
two 2 digit nu bers results in a four digit nu ber. So
after the upsa pler the word length ay be higher than
the subsequent processor ay be able to accept. In this
exa ple, after the upsa pler there ay be a D/A
converter with a 24 bit input word length capability. So if
the upsa pler generates a word length of ore than 24
bits it should be dithered to 24 bits for axi u signal
fidelity.
I hope these excursions into the theory and practice of
audio engineering have been useful for you. If you would
like to dive further into those issues I reco end to visit
the website of Mr. Bob Katz, a renowned Mastering
Engineer and a Weiss Engineering custo er. He
publishes articles on Dithering and Jitter and any other
topics at http://www.digido.co
Firewire v . USB
Firewire is a peer-to-peer protocol, eaning that every
device on a Firewire network is equally capable of talking
to every other device. Two video ca eras on a Firewire
network can share data with each other. A Firewire audio
interface could save sound data directly to a Firewire
hard drive. Your co puter is just another peer on this
network, and has no inherent special status.
Firewire is always i ple ented in hardware, with a
special controller chip on every device. So the load it
puts on your CPU is uch lighter than USB
co unications load, and you're uch less likely to lose
any sound data just because you're running fifteen things
at once. Specialized hardware usually akes things
faster and ore reliable, and this is one of those ti es.
But the real reason Firewire is ore reliable than USB is
ore funda ental than that. It's because Firewire allows
two operating odes. One is asynchronous, si ilar to
what USB uses. The other is isochronous ode, and it
lets a device carve out a certain dedicated a ount of
bandwidth that other devices can’t touch. It gets a
certain nu ber of ti e slices each second all its own.
The advantages for audio should be obvious: that strea
of data can just keep on flowing, and as
long as there isn't ore bandwidth de and than the wire
can handle (not very likely) nothing will interfere with it.
No collisions, no glitches. Fro a practical perspective,

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 12 Date: 03/10
this also akes it safer to send a lot ore audio via
Firewire. That's why ost of the ultichannel interfaces
(18 channels, 24 channels, etc.) are Firewire devices,
and USB devices usually just send a two channel stereo
signal.
For hooking up your ouse, keyboard or thu b drive,
USB is plenty fast and plenty cheap. For hard drives,
either one will do (although Firewire is so ewhat ore
reliable). For audio devices, USB will do fine if no other
devices are co peting with it and if you have processor
roo to spare. But Firewire will always be able to handle
ore load with lower latency and no glitches, because it
has resources it can set aside to ake sure your audio
gets where it needs to go.

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 13 Date: 03/10
THE INT202 FIREWIRE INTERFACE
Feature
Input :
There are two Firewire connectors in order to be able to
chain ore Firewire based units on a single Firewire bus.
Which of the two Firewire connectors is used for the
connection to the co puter is not relevant. The accepted
sa pling frequencies are 44.1, 48, 88.2, 96, 176.4 or
192 kHz.
Output :
There are two AES/EBU outputs on a pair of XLR and a
pair of RCA connectors. The XLR and RCA connectors are
fed fro the sa e source, but have separate output
stages. They can be used si ultaneously.
The single / dual wire switch allows to switch the
AES/EBU output to the so called dual wire for at. If
switched to dual wire, the two XLR connectors beco e
channel 1 and channel 2 respectively of the audio signal
(sa e with the RCA connectors). This is the case only at
176.4 or 192 kHz sa pling rates. All other rates are not
influenced by the single / dual wire switch, i.e. the
for at is single wire. Certain equip ent (CD transports,
DACs) support 176.4 / 192 kHz sa pling rates only via
the dual wire interfaces. In single wire ode all four
connectors carry the sa e signal. All four can be used
si ultaneously.
Synchronization:
The synchronization aster always is the INT202 device,
i.e. the co puter is slaved to the INT202. The sa pling
rate is set via the Weiss Firewire IO window. On a Mac
syste the sa pling rate set in AudioMidi sets the one in
the Weiss Firewire IO window and vice versa. With the
proper (advanced) player software the sa pling rate of
the INT202 is switched auto atically depending on the
track played. For ore infor ation on this topic see the
paragraph on bit transparency checking. The INT202’s
intrinsic jitter is very low.
Power Supply:
The power can be either supplied fro the Firewire bus
or fro the external power supply supplied with the
INT202.
Firewire bus power ay or ay not be available with the
particular co puter used. Refer to the co puter anual
to find out. If the Firewire connector at the co puter is a
4 pin type then bus power is not available by definition.
With the other types of connectors (6 pin or 9 pin) bus
power ay be available.

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 14 Date: 03/10
If the INT202 powers up with the co puter connected
and with no external power supply connected, then there
obviously is bus power available. If preferred, the
external power supply ay still be connected in that
case. The INT202 then auto atically switches over to the
external power supply.
A 4 pin Firewire socket looks like this:
Software feature :
The software in the INT202 allows for level control and
for absolute phase reversal. These features are only
accessible via the (optional) Re ote Control unit. If the
re ote control unit is not used, the gain stays at 0dB as
set at the factory. 0dB eans a fully bit transparent
transfer. The absolute phase is set to 0°, i.e. the phase is
not changed.
The level control is properly dithered, i.e. there are no
artefacts due to the level control. A paper on the topic of
digital level control (including sound exa ples) can be
found here:
http://www.weiss-
highend.ch/co puterplayback/Digital_Level_Control.pdf
In addition the software allows for the testing of the bit
transparency of the usic player progra running on the
co puter. This is useful to find out the proper settings /
configuration of the player progra to achive bit
transparency. Bit transparency eans that the bits fed
fro the harddisk to the INT202 are not changed in any
anner.

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 15 Date: 03/10
Frontpanel / Backpanel element :
• Single Wire / Dual Wire odes select switch
• Power on switch
• Power / Bit Transparency check LED
• Infrared receiver
• Bit Transparency check switch
• Two XLR connectors, single wire ode: OUT1 and
OUT2 carry the sa e stereo signal, dual wire ode:
OUT1 = left channel, OUT2 = right channel
• Two RCA connectors, single wire ode: OUT3 and
OUT4 carry the sa e stereo signal, dual wire ode:
OUT3 = left channel, OUT4 = right channel
• Two 6 pin Firewire 400 sockets, which one is used
does not atter
• Power socket for an external power supply.

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 16 Date: 03/10
Operation / In tallation
Unpacking and Setup of the INT202
Carfully unpack the INT202. The following ite s should
be enclosed:
• The INT202 Firewire Interface unit
• A Power Supply
• A CD with the necessary Firewire drivers for Windows
and OSX and with the Bit Transparency check files.
• This Owners Manual
• A Certificate of Guarantee
• Optionally: An IR Re ote Control
Firewire and Power Connection
First install the software on your co puter as described
in a separate chapter below.
Then connect the co puter to the INT202 via an
appropriate Firewire cable. There are three types of
cables applicable:
- 4 pin Firewire 400 (co puter side) to 6 pin Firewire
400 (INT202 side)
- 6 pin Firewire 400 (co puter side) to 6 pin Firewire
400 (INT202 side)
- 9 pin Firewire 800 (co puter side) to 6 pin Firewire
400 (INT202 side)
Chose the proper cable as required by your co puter.
Make ure to plug in the Firewire cable in the
proper orientation! If the connector i plugged in
rever ed the INT202 can be di troyed becau e of
the bu power on the Firewire bu .
After connecting the INT202 to the co puter and
switching the co puter on and switching the INT202
power switch to “on”, the power LED at the INT202 ay
be lit. If this is the case then the INT202 is powered fro
bus power on the Firewire bus.
If you connect an external power supply to the INT202
then the Firewire bus power is auto atically switched off
and the INT202 is powered fro the external power
supply.
AES/EBU or S/PDIF Connection
The output of the INT202 has to be connected to your
D/A Converter or any other digital audio device. Use
either the XLR or RCA connectors as applicable. There
are two sets of XLR and RCA connectors available for the
support of the so called “dual wire” for at. This for at is
used by so e D/A converters for higher sa pling rates.

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 17 Date: 03/10
The INT202 can be switched to the “dual wire” for at
and then outputs audio with a sa pling rate of 176.4 or
192 kHz in the dual wire for at. All other sa pling rates
are not affected by the dual / single wire switch and are
output in single wire for at.
If your DAC requires the 176.4 or 192 kHz sa pling
rates to be in dual wire for at then switch the INT202 to
“dual wire” and connect OUT1 (or OUT3) to the left input
of your DAC and OUT2 (or OUT4) to the right input.
If your DAC can handle all sa pling rates in single wire
for at then switch the INT202 to “single wire” and
connect any of the four outputs of the INT202 to the
input of your DAC. All four outputs can be used
si ultaneously, i.e. you ay connect ore than one DAC
at the sa e ti e.
Note that any change of the “dual wire / single wire”
switch setting takes effect only after the INT202 has
been switched off (Power LED not lit) and switched on
again (Power LED lit).
Bit Tran parency Check
If the bit transparency check switch (TRSP CHECK
switch) is on, then the INT202 is uting the outputs and
is entering the bit transparency check ode. It is looking
for specific bit patterns co ing fro the firewire source.
I.e. in order to test the bit transparency of the player
software on the co puter the enclosed WAV files (see
driver CD) have to be ripped to the co puter and played
fro the player progra . If the INT202 then sees the
expected bits co ing fro such a file, it flashes the
power LED continuously, indicating that the player is bit
transparent. If the LED stays lit the player is not bit
transparent.
There are a total of 12 files supplied. One set for 16 bit
and one set for 24 bit transparency checking. One set
includes all supported sa pling rates, na ely 44.1, 48.0,
88.2, 96.0, 176.4, 192.0 kHz. This allows to ake sure
the player is bit transparent for all sa pling rates. We
suggest to check first with the 24 bit files. If those yield
a bit transparent result then it is not necessary to check
with the 16 bit files.
If the player does not see to be bit transparent then
this can have several causes, like:
- a volu e control not at 0dB gain
- a equalizer
- a sa pling rate conversion
- a “sound enhancer” feature and ore
Make sure all those processing ele ents are bypassed.
Particularly the sa pling rate conversion can creep in
“unnoticed”. I.e. the sa pling rate in the Weiss Firewire
IO window has to atch the sa pling rate of the file
played, else a conversion is going on in the operating
syste . For iTunes there is another thing to know:
Whenever the sa pling rate is changed in the AudioMidi
setup or the Weiss Firewire IO window, the iTunes
progra has to be restarted to gain bit transparency
again. For iTunes running on a Mac co puter a progra

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 18 Date: 03/10
like Sonic Studio’s “A arra” is highly reco ended.
With A arra it is possible to switch the sa pling rate in
AudioMidi (i.e. in the INT202) auto atically depending
on the sa pling rate of the file played. A arra works in
conjunction with iTunes.
On a Windows based syste the use of ASIO or WASAPI
is highly reco ended. These syste s ake it si ple to
achieve bit transparent playback. In addition the
sa pling rate of the INT202 is switched auto atically
depending on the sa pling rate of the file played.
Remote Control
If you also have bought the Re ote Control for the
INT202 then you can control the volu e and the phase
of the digital signal transferred by the INT202. The
volu e up / down switches control the volu e
accordingly. The axi u gain is 0 dB (a gain factor of
1.0), i.e. the INT202 can not a plify the signal and thus
akes sure that there are no “overs” occuring within the
INT202. The “ ute” switch allows to toggle between fully
off ( uted) and the volu e set with the volu e control.
Absolute Phase control:
Pressing the ute switch for a few seconds toggles the
operation ode to phase control. In that ode the ^ key
switches the phase to 0° and the v key switches to 180°
(i.e. inverted phase). Press the ute key for a few
seconds again to get back to the volu e control ode.
The phase set before is retained when switching back to
volu e control ode. When changing the phase with the
^ and v keys you notice a short uting of the audio. This
prevents fro any clicks caused by the phase switching
and also is an indication that the switching has actually
taken place.
The volu e setting is retained when switching the
INT202 off / on, while the phase is reset to “not inverted”
after a power cycle.
Software in tallation
Perfor the following installation procedure before
connecting the INT202 to the co puter. The necessary
files are supplied on the enclosed drivers CD.
Window :
0. Do not connect the device.
1. Double click "WeissFirewireInstaller.exe"
2. Click "Next"
3. Select the directory where you'd like to install the
tools. Usually you can use the default values and click
"Next"
4. Select if you'd like to create a desktop icon. "Next"
5. Click "Install"
6. You will be asked if you'd like to continue the
installation because the driver/software didn't pass the
Windows-Logo-Test. Select "Continue".
7. Select "Yes, restart the co puter now" and click
"Finish"

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 19 Date: 03/10
Mac:
0. Mount the WeissFirewire.d g diski age by double
clicking it
1. Fro the ounted drive double click WeissFirewire-
3.3.3.3586.pkg (the version nu bers can be different of
course)
2. Click "Continue"
3. Select the drive (usually you leave it at the defaults)
4. Click "Continue"
5. Click "Upgrade" or "Install"
6. You'll be asked to login as ad inistrator
7. Confir "Continue Installation" when warned that the
co puter requires a reboot after install.
8. Click Restart
After installation of the software connect the INT202 to
the co puter. Make sure to plug in the Firewire cable in
the proper orientation! If the connector is plugged in
reversed the INT202 can be distroyed because of the bus
power on the Firewire bus.
The power LED at the INT202 ay be lit. If this is the
case then the INT202 is powered fro bus power on the
Firewire bus. If the LED is not lit then an appropriate
external power supply (available fro Weiss) has to be
connected to the INT202 and the power switch at the
INT202 has to be switched to “on”.
The INT202 should now be recognized auto atically. In
Windows tell the installation window that you do not
want to check the Microsoft website for drivers and then
let the drivers be installed auto atically. Ignore
warnings concerning “Windows Logo Test” and continue
the installation until co pleted. You will be asked to
install drivers for "Weiss Engineering Ltd. --Firewire Unit-
-" and "Weiss Firewire IO MIDI". There will be two passes
of installation, which is nor al.
Software etup
The connected INT202 device can be controlled through
the “Weiss Firewire I/O” Control Panel.
Window :
The control panel can be accessed by clicking on the
“Weiss Firewire IO” icon on the desktop.
Device Settings / General: The device settings should be
pretty self explanatory.
Device Settings / Fir ware Loader: Allows to upload new
fir ware to the INT202. Not used for nor al operation.
Global Settings / Bus:
Master: Is the device which is sync aster on the virtual
bus in case ultiple devices (“INT202s”) are connected.
Sync Source: The clock to which the INT202 should sync
to. Usually this is the INT202’s internal clock generator.

OPERATING INSTRUCTIONS FOR THE INT202 FIREWIRE INTERFACE
Page 20 Date: 03/10
Sampling Rate: The sa pling rate of the device when
internally clocked.
Buffer Size: Larger buffer sizes increase robustness
against dropouts, lower buffer sizes provide low latency.
Operation Mode: deter ines the stability of the syste .
Try other odes if there are clicks in the usic.
Global Settings / WDM: Enables the WDM driver.
Global Settings / DPC: Deter ines your co puters
perfor ance and reco ends a operation ode.
Global Settings / Syste : So e utilities to deter ine the
chipset in your co puter and to get infor ation on the
sup-ported chipset. Required for debugging if prob-le s
with the Firewire connection are encoun-tered.
Global Settings / Info: Infor ation about the driver
version.
Mac OSX:
Configure the INT202 via the “Audio MIDI Setup”
(Applications > Utilities) and the “WeissFirewire Control
Panel” (Applications).
Device Settings / General: The device settings should be
pretty self explana-tory.
Device Settings / Fir ware Loader: Allows to upload new
fir ware to the INT202. Not used for nor al operation.
Global Settings / Bus:
Master: Is the device which is sync aster on the virtual
bus in case ultiple devices (“INT202s”) are connected.
Sync Source: The clock to which the INT202 should sync
to. Usually this is the INT202’s internal clock generator.
Sampling Rate: The sa pling rate of the device when
internally clocked.
Operation Mode: deter ines the stability of the syste .
Try other odes if there are clicks in the usic.
Global Settings / Info: Infor ation about the driver
version.