WEISS MEDUS User manual

Weiss Engineering Ltd.
Switzerland
www.weiss-highend.com
MEDUS
OWNERS MANUAL

OWNERS MANUAL FOR WEISS MEDUS D/A CONVERTER
INTRODUCTION
D ear C stomer
Congrat lations on yo r p rchase of the MEDUS D/A Converter and welcome to the family of Weiss
eq ipment owners!
The MEDUS is the res lt of an intensive research and development process. Research was
cond cted both in analog and digital circ it design, as well as in signal processing algorithm
specification.
On the following pages I will introd ce yo to o r views on high q ality a dio processing. These
incl de f ndamental digital and analog a dio concepts and the MEDUS converter.
I wish yo a long-lasting relationship with yo r MEDUS.
Yo rs sincerely,
Daniel Weiss
President, Weiss Engineering Ltd.

OWNERS MANUAL FOR WEISS MEDUS D/A CONVERTER
TABLE OF CONTENTS
4 The MEDUS D/A Converter
4 Feat res
7 Operation
12 Technical Data
15 A short history of Weiss Engineering
16 O r mission and prod ct philosophy
17 Advanced digital and analog a dio concepts explained
17 Jitter S ppression, Clocking
19 Up-sampling, Oversampling and Sampling Rate Conversion in General
22 Reconstr ction Filters
22 Analog O tp t Stages
23 Dithering
25 Contact
26 Addend m for the FireWire option
33 Addend m for the ST Glass Fiber inp t option

OWNERS MANUAL FOR WEISS MEDUS D/A CONVERTER
THE MEDUS D/A CONVERTER
The MEDUS is a State Of The Art D/A Converter which handles PCM as well as DSD signals. Both digital and analog sections are
designed with great care for all the details which make the MEDUS a tr ly remarkable DAC.
Feat res
Inp ts:
There are three AES/EBU inp ts on XLR connectors, one on Toslink (optical), three RCA connectors, one USB connector. The
accepted sampling freq encies are 44.1, 48, 88.2, 96, 176.4 or 192 kHz. The USB inp t also accepts DSD Signals. Sampling
freq encies of 88.2kHz and higher can also be fed sing the d al wire scheme, i.e. one cable per channel.
Up-sampling:
Signals at 44.1 or 48 kHz are p-sampled in the MEDUS’ DSP chip, sing o r own st dio q ality p-sampling algorithms. Th s
the DAC chip always receives signals at a 88.2kHz minim m sampling rate.
Synchronization:
Several signal re-clocking schemes are combined for extremely high jitter atten ation, making the MEDUS virt ally imm ne to
jitter over a very wide bandwidth.
Converters:
The DAC chip p-samples the inp t signal to abo t 1.5MHz. Fo r D/A conversion channels are sed per a dio channel,
res lting in exceptional performance specifications. The I/V conversion after the DAC chip ses two of o r own discrete OP-
AMPs (the OP1-BP) per channel.

OWNERS MANUAL FOR WEISS MEDUS D/A CONVERTER
O tp ts:
O r discrete OP-AMPs are also sed in the o tp t stage, two per a dio channel for a differential o tp t. O tp t levels can be
set between –4.0dB and +27.0dB (6dB less on asymmetrical o tp ts). The level setting is done in 1dB steps via a rotary
switch at the back of the nit. Both o tp ts are set to the same level at any time. The o tp ts are symmetrical on XLR
connectors and asymmetrical on RCA connectors. No so nd degrading servo mechanisms are sed.
The Weiss OP1-BP discrete OP-AMP
Power S pply:
A powerf l non-switching power s pply is sed. All sensitive voltages have their own reg lators which are separated between
left and right channels. The res lt is an analog o tp t free of "digital noise" and channel crosstalk. The power switch activates
a semicond ctor relay which only switches on or off at zero crossings of the mains voltage. This ass res a glitch free power
switching.

OWNERS MANUAL FOR WEISS MEDUS D/A CONVERTER
Mechanical Design:
The MEDUS employs a twin metal frame. The inner chassis is made of steel and acts as a very effective shield against
electrostatic and electromagnetic radiation. The o ter frame is made of massive anodized al mini m for additional shielding,
res lting in optimal heat convection and bea tif l looks.
Front panel controls:
•Fo r switches with corresponding bl e LEDs are sed for selecting one o t of fo r inp t so rces.
•A display.
•A power switch.
Back panel elements from left to right:
•Analog o tp ts on XLR and RCA connectors with o tp t level switch.
•Digital inp ts 1 – 4 (three XLR, three RCA, one Toslink, one USB connector).
• Mains connector with f ses and voltage selector.

OWNERS MANUAL FOR WEISS MEDUS D/A CONVERTER
Operation
Unpacking and Set p of the MEDUS
Caref lly npack the MEDUS. The following items sho ld be enclosed:
•The MEDUS D/A Converter nit
•The MEDUS Remote Control nit
•This Owner’s Man al
•A Certificate of G arantee
The MEDUS sho ld be placed horizontally on a plane s rface. Avoid p tting any other eq ipment or
any other material on top of the MEDUS as not to compromise the MEDUS’ heat convection system.
Mains Connection
Before connecting the mains cable make s re the voltage selector switch on the back of the nit
(integrated into the mains connector) is set to the appropriate voltage. If this is not the case then
open the mains selector lid with a strong screwdriver. The mains pl g m st not be pl gged into the
connector for that p rpose. Now yo see a black selector dr m with appropriate voltages written in
white letters. Remove this dr m, t rn it to the appropriate voltage and reinsert it. Now firmly close
the lid again. Connect the MEDUS to the wall o tlet with the mains cable.
Driver installation
For OSX (Apple) operating systems it is not necessary to install any driver for USB. For Windows based systems a driver is
incl ded on the CD in the MEDUS man al.

OWNERS MANUAL FOR WEISS MEDUS D/A CONVERTER
Inp t So rce Connection, Selection and Synchronization
Connect so rces with sampling freq encies of 44.1, 48, 88.2, 96, 176.4 or 192kHz to the inp t
connectors at the back of the nit. Note that there are a total of fo r inp ts. The following
connectors are available:
Inp t # 1: one XLR and one RCA connector ( se either XLR or RCA at a time, i.e. yo may
connect two so rces sim ltaneo sly, b t only one so rce nit m st be switched on at a time).
Inp t # 2: The same as Inp t # 1 applies here.
Inp t # 3: one XLR and one USB connector ( se either XLR or USB at a time, i.e. yo may
connect two so rces sim ltaneo sly, b t only one so rce nit m st be switched on at a time).
Inp t # 4: one TOSLINK (optical) and one RCA connector ( se either TOSLINK or RCA at a time,
i.e. yo may connect two so rces sim ltaneo sly, b t only one so rce nit m st be switched on at
a time).
The inp t so rce p shb ttons correspond to the fo r inp ts as described above.
Inp t # 1 (left) and Inp t #2 (right) can act as an inp t for so rces s pporting the two wire
scheme, i.e. one cable per channel. The MEDUS a tomatically detects whenever s ch a so rce is
connected to inp ts #1 and #2 and switches to the appropriate conversion mode. In that mode
both LEDs of inp t #1 and #2 are lit. The two wire scheme is sed by some so rces with sampling
rates of 88.2kHz or higher.
If a valid AES/EBU or S/PDIF formatted signal is present at the selected inp t, the display indicates
the sampling rate and the word length (the n mber of active bits in a digital sample) of the inp t
signal. If the format and/or the sampling freq ency is not valid, the word “ nlocked” is shown in
the display. In that case the analog o tp ts are m ted.
The MEDUS a tomatically synchronizes to the incoming signal. If the sampling rate of the signal is
not within a range of +- 80ppm of one of the nominal sampling rates (44.1, 48, 88.2, 96, 172.4,
192kHz) then the bl e LED of the active inp t is flashing. The analog o tp ts are m ted in that
case.
The states of all settings are stored in non-volatile memory, i.e. the act al inp t selection, vol me
control etc. are retained when powering the nit off.

OWNERS MANUAL FOR WEISS MEDUS D/A CONVERTER
O tp t Level and O tp t Connection
Connect yo r preamplifier or power amplifier to the o tp t connectors of the MEDUS. Use either
the symmetrical (balanced) lines (XLR connectors) or the asymmetrical ( nbalanced) lines (RCA
connectors). Or both, if yo need to feed two amplifiers. Symmetrical is preferred, provided yo r
preamplifier s pports symmetrical connection.
The basic o tp t level is set either via the rotary switch on the back panel or via the remote control
“gain trim” switches. This level setting is done in the analog domain and is sed to set a basic level
s ch that the s bseq ent amplifier is operating at its preferred inp t level.
If yo se the remote control to change the basic o tp t level press and hold the ALT key and then
press the gain trim + or – keys to adj st the level. The display shows the maxim m o tp t level
for both XLR and RCA o tp ts in dB .
The position of the switch on the back panel does not indicate the basic o tp t level. The switch
merely acts as a rotary encoder, i.e. rotating clockwise increases the basic level and vice versa.
Use the back panel switch or the remote control to adj st the basic o tp t level to a val e which
matches yo r amplifier. If yo r amplifier has a vol me control, adj st the MEDUS o tp t s ch that
yo get a normal listening level with the amplifier’s vol me control set to abo t midway between
minim m and maxim m vol me.
Note, it is normal when after setting the basic o tp t level the MEDUS o tp t m tes again for a
short time.

OWNERS MANUAL FOR WEISS MEDUS D/A CONVERTER
Remote Control
The Remote Control allows to control the following
parameters:
-basic o tp t level with the gain trim keys as described
above
-o tp t vol me in the digital domain with 0.5dB steps
over a range of 60dB. With the 0dB setting (maxim m
level) the vol me control is bit transparent
-o tp t m te
-p-sampling filter A/B selection
-absol te polarity (0 / 180°)
-inp t n mber 1…4
-display brightness
A paper on the topic of digital level control (incl ding so nd
examples) can be fo nd here:
http://www.weiss-highend.ch/comp terplayback/Digital_Level_Control.pdf