Grimm Audio UC1 User manual

Please read this manual before operating the
unit.
The Grimm Audio UC1 is a high quality Mastering and
Mixing Universal Converter oering very broad digital
application functionality. This ‘quick guide’ covers the
specic functionality for use in an Audiophile System.
Please read this manual before operating the unit.
HiFi DAC quick start guide

Quick Start Guide UC1-HiFi © Grimm Audio
2
Table of Contents
1. Introduction 3
2. Signal Connections 6
3. Operation 8
4. Menus 10
5. Source Routing & Settings Examples 17
Table of Contents

3
1. Introduction
The Grimm Audio UC1 is a high quality Mastering and
Mixing Universal Converter oering very broad digital
application functionality. This manual, however, covers
the specic functionality for use in an Audiophile
System.
Please read this manual before using the UC1 to
understand its operation and make optimal use of its
versatility as a high audiophile quality DAC / HPA / PRE.
Applications Overview
Let’s have a look at how to use the various inputs and
outputs in this context.
DAC - The Primary Function
USB Connection :
The “rear” USB input [ Input 6 ] as well as the “front” USB
input, aka the “i-put” are connected to your digital source,
be this a Server, a Streamer or a Computer.
AES3 S/PDIF Connection :
Two rear AES3 inputs can be connected to a digital source
that has AES output, be this a Server or a Streamer.
The AES3 input can also connect a CD Transport via an
AES > Coax adapter cable. Note that some high end CD
Transports oer Master/Slave clock connection, such as
the C.E.C. TL2N. The UC1’s superior clock output can in
this case can act as the Master when connected to the
clock input of the Transport. The UC1’s clock quality
equals that of Grimm Audio’s CC1 and CC2 master clocks.
When the UC1 is used as a standalone audiophile DAC
and / or a monitor controller, the clock settings need to
selected accordingly in the UC1’s “F2” function menu.
PRE - Monitor Function
XLR Analog Loudspeaker Connection :
The UC1 oers 3 analog XLR outputs. One of these output
pairs, preferably “Ana Out 3|4”, can connect directly to a
pair of active loudspeakers via their respective XLR inputs.
(Continued)
1. Introduction
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Quick Start Guide UC1-HiFi © Grimm Audio
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A secondary loudspeaker system can connected to a
dedicated XLR output pair [ “2nd Out” ] that runs in parallel
to the Headphone output situated on the front panel.
Digital RJ45 Loudspeaker Connection :
This dedicated connection connects directly to a pair of
Grimm LS1 or PMC loudspeakers via their respective
inputs.
In the menu you select to which Output the Loudspeaker
system is connected. Although not typical in the Hi
Universe, please note that the UC1 oers several
interesting Pro Audio monitor settings such as “Mono”,
“Side”, and “Stereo Swap”.
PRE - Gain & Control Functions
Gain / Volume / Mute / Polarity & Settings :
As the UC1 is a Pro Audio component, Gain - which can be
increased or decreased via the volume dial knob - is
expressed in positive or negative “dB deviation” from a
reference loudness level nominally called “0dB”. This level
is by convention expressed in “db SPL”. This level
corresponds to an SPL of 79db in a small recording room.
To adjust the UC1 to the HiFi usage convention, reset the
default -8dB setting under the P2 function to -18db which
eectively equals an output level of 0VU. The DAC’s output
clips at +18db (5Vpp), so the gain would cover a range of
-18dB > +18dB.
Please note that the Volume and Mute functions are
available for all input / output signal paths, but in the
absence of a basic remote, these need to be adjusted
manually. News : A remote control 3.5 mm socket on the
back panel is for future use and is not yet enabled.
This is not really an issue as in almost all cases the UC1 as
a standalone DAC will be connected to modern HiFi
ampliers with “remote”. “Mute” is selected in “F1”.
The signal’s Polarity can be inverted in “P2”, but note that
this function is only available for Headphone Out signals
traversing the “Foldback Route”, which, if used, needs to
be activated in “F1”.
Furthermore, the ‘Foldback’ function is limited to two
output paths, notably to Headphone and 2nd Out .
(Continued)
1. Introduction

Quick Start Guide UC1-HiFi © Grimm Audio
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PRE - Headphone Function
6.35mm / 1/4” Jack Connection :
The UC1 oers a 6.3mm headphone output with gain
control. The acoustic sensitivity of headphones on the
market varies by as much as 30 dB. Consumer ear buds
are more or less standardized on a sensitivity of
approximately -14 dBu (~0.15V) for 100 dBA. Some
professional 600 Ohm headphones however may need as
much as 15 dBu (~4.4V) to reach 100 dBA. This example is
of an HP with a sensitivity of 85dB/mw. The UC1 is
targeted at the professional audio market and therefore
oers enough gain to drive these types of demanding
headphones. The majority of HiFi audio headphones are
far less demanding and, as such, the UC1 will
drive these with ease.
The Headphone output circuit runs through the Foldback
route of UC1. As such, the Mute and Polarity Inversion
functions are available. HP output volume can be
controlled via the dial knob directly next to the output
jack. Switching between HP and Loudspeaker monitoring
can be done by briey depressing the main dial at the far
right of the front panel.
PRE - Analog In
XLR Connection :
This input was intended for recording analog signals for
mixing / mastering purposes. It does not serve as a typical
analog input to which rst gain is applied before
being“passed-through” to the UC1’s analog outputs.
In eect, any Analog signal input would be converted by
the A/D chip circuit to digital … and then reconverted back
to analog by the D/A chip circuit.
This may be useful only if the UC1 is connected to a pair of
active loudspeakers, and where it is not connected to a
Preamplier > Amplier > Loudspeaker system chain.
In extremis, It would be imaginable that if one wanted to
connect a Turntable with a dedicated Line stage with
integrated Phono to this analog input via RCA > XLR cable
adapters, one could in fact do so. The SQ output post A/
D/A conversion would be “acceptable”. This would also
apply to the connection of a Reel-to-Reel tape machine.
1. Introduction

6
2 A. Signal Connections - Front Panel
2. Signal Connections
Display
Head-Fi
Headphone
Controls
VOL / MUTE
POLARITY
Analog In
eg. MP3 Player
Controls
VOL / MUTE
Note : Z=1Mohm
USB In #2
Server/Laptop
Controls
VOL / MUTE
POLARITY
Main Controls
Settings
F = Functions
P = Preferences
Main Controls
Settings
Source
Volume
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2 B. Signal Connections - Back Panel
2. Signal Connections
USB In #1
Server/Laptop
Controls
VOL / MUTE
From
Grimm MU1
AES>AES Cable
CD Transport
AES>RCA Cable
To
Amplier 3
XLR Cable
Output CTL
VOL / MUTE
POLARITY
To
Amplier 2
or Active Speaker
XLR Cable
Output CTL
VOL / MUTE
To
Amplier 1
XLR Cable
Output CTL
VOL / MUTE
Clock Out
CD Transport
Example
CEC TL2N
Quick Start Guide UC1-HiFi © Grimm Audio

Quick Start Guide UC1-HiFi © Grimm Audio
Buttons and display
Most functions of the UC1 are adjusted via the main dial
and the two control buttons on its left side. Additionally
there are knobs for the phones output gain and the jack
input gain.
The main dial can be turned and pushed. In normal
operation, turning changes the gain of all monitor paths
(main, 2nd and phones) and pushing mutes the
speakers while engaging the headphones output on the
front. When press-holding the main dial, the current
monitor source (indicated top left of the display) starts
Main screen, USB 1/2 selected
3. Operation
blinking. Keep pressing the main dial while turning it to
change the monitor source. All inputs and outputs can
be selected. Their name is shown in the display and
their channels are highlighted in the meter. When
releasing the dial the indicated source stays selected.
Alternatively, release the dial when the blinking starts.
Then turn to select a source and press to conrm.
The large number in the display indicates the current
monitor gain level in dB’s. The monitor outputs oer 8
dB of clean gain above ‘0’ on the display. In other words:
a full scale signal will only reach full scale on a monitor
output if the monitor gain is set to +8 dB. This may
seem odd, but the idea is that the ‘0’ indication of the
display is your reference playback level to which you
always return after a louder of softer playback. This is
common practice in mastering. The ‘0’ level is usually
aligned with an SPL of 79dBC when playing a SMPTE
reference noise signal on a single channel. The Grimm
LS1 is factory aligned to that, you may adjust the gain of
your 3rd party amplier to achieve the same result - or
to select another acoustic SPL that suits you as
reference playback level. In case you feel the need to
(Continued)

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3. Operation
adjust the ‘0’ level of the UC1, you can change it in menu
P2 (see chapter 6. Menus).
Note that the monitor gain can be set to display values
up to +18, which means that there is 10 dB of positive
gain available in the UC1 to audition very soft noises.
Note that any signal above -10 dBFS will in that case clip
– please use this extra gain with caution!
The volume control is in 0.5 dB steps above -17 dB and
1 dB below it. If you have a Grimm Audio LS1 or PMC
digitally controlled loudspeaker connected to the
proprietary cat 5 output on the back, the volume control
Main screen, Digital 1/2 selected, in phones mode
takes place in the DSP of the loudspeaker. In all other
cases the volume control is in the DSP of the UC1. At
volume setting ‘+8’ the data to the digital output and build-
in DACs is put through transparently. At other levels the
digital gain control is properly dithered at 24 bits.
Optionally, volume control of the main out can be disabled
in the menu. In that case the indicated monitor gain only
applies to the 2nd out and phones.
The knob to the right of the phones jack can be used to
align the headphones’ acoustic level with that of your main
monitor system. The idea is to switch between speakers
and phones (removing your headphones when listening to
the speakers) and adjust this control until speakers and
phones sound equally loud to you. From then on just use
the main dial for changing your monitor gain and leave the
phones control at its calibrated level.
In the bottom left corner of the display the clock status of
the UC1 is indicated. The clock source can be set manually.
Please refer to the menu chapter for instructions.
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Quick Start Guide UC1-HiFi © Grimm Audio
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4. Menus
The UC1 has many functions, preferences and system
setup items that can be controlled from the menu. To
enter the menu, press the top button with ‘menu’ next
to it on the display. You will see a screen with 6 tabs,
labeled F1 and F2 for Functions, P1, P2 and P3 for
Preferences and S1 for System info. We walk you
through all these settings in the pages below. To move
to the next tab, press the top button ‘next tab’. To exit
the menu, press the bottom button ‘exit’. Note that the
exit button is disabled when an option is selected and
its arrow is blinking. Turn the main dial to select a
function, press to change it, then turn to browse the
options and press again to conrm your choice.
F1 menu
Whenever you enter the menu, the F1 page will be
available rst. This page gives access to monitor
functions that are often used.
• Monitor source. You can select all inputs and outputs
here by pressing the main dial briey (the arrow starts
blinking) and then turning the dial. When you reach the
last source, the order wraps and the rst source
appears again. To conrm a choice, press the dial again
(the arrow stops blinking). This item does the same as
press-hold the main button and then turn. The result is
immediately visible in the left top corner of the display,
and the selected source becomes audible.
Grimm LS1 customers, please note that the UC1 cannot
select the analog and digital inputs of the LS1 as a
source. In case you need to access these, please use the
(Continued)
F1 menu.
4. Menus