ESI U108 PRE User manual

Professional 24-bit USB Audio Interface
User’s Guide

ESI - Copyright © 2018
Revision 1, May 2018
www.esi-audio.com

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INDEX
1. Introduction .................................................................................................................................. 4
1.1 Features ................................................................................................................................................................ 4
2. Installation .................................................................................................................................... 6
2.1 System Recommendation ..................................................................................................................................... 6
2.2 Hardware Installation ........................................................................................................................................... 6
2.3 Driver & Software Installation ............................................................................................................................. 6
2.3.1 Installation under Windows .............................................................................................................................. 6
2.3.2 Installation under macOS .................................................................................................................................. 8
3. Control Panel ................................................................................................................................ 9
3.1 Latency settings ................................................................................................................................................. 10
4. Specifications .............................................................................................................................. 11
5. General Information .................................................................................................................. 12

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1. Introduction
U108 PRE is a special USB 2.0 Hi-Speed audio recording interface providing a solution for a very
basic requirement: connecting a lot of professional microphones for simultaneous multichannel
recording at one time.
U108 PRE provides a total of 10 high quality professional microphone preamps. Two XLR
connectors are on the front panel, the others on the rear panel of the device. For all separate
preamps, +48V phantom power can be enabled when needed and the input level can be adjusted
separately for each channel. The input level is also displayed via LEDs on the front panel. Of course
you can use all input channels simultaneously. In addition, there are two alternatively usable Hi-Z
instrument inputs for electric guitars. For playback, 8 independent line outputs and a separate mix
output (via the integrated monitor mixer) are provided.
U108 PRE provides drivers that work with very low latency - with support for WDM, ASIO 2.0 and
CoreAudio, based on our EWDM- and DirectWIRE-Technology. That means that the unit can be
used wih all common applications on both Mac and PC. With the bundled software you can start
using it right away and simply start working out of the box.
U108 PRE is the perfect solution for multichannel recording when using a multiple number of
microphones.
1.1 Features
The front panel of the U108 PRE hardware has these main features:
1. microphone and Hi-Z instrument input channel 1 with XLR/TRS combo connector, use this
connector to connect a dynamic or condenser microphone or an electric guitar. Next to it is the
Hi-Z switch that enables this input for usage with an electric guitar when pressed. When not
pressed, the input works as a microphone input. With the gain knob you can control the input
level which is indicated with the LEDs above it. The +48V switch enables phantom power if
required for a condenser microphone. Please note that for microphones you should use XLR
connection while a guitar needs to use a TRS connection.
2. microphone and Hi-Z instrument input channel 2 with XLR/TRS combo connector, use this
connector to connect a dynamic or condenser microphone or an electric guitar Next to it is the
Hi-Z switch that enables this input for usage with an electric guitar when pressed. When not
pressed, the input works as a microphone input. With the gain knob you can control the input
level which is indicated with the LEDs above it. The +48V switch enables phantom power if
required for a condenser microphone. Please note that for microphones you should use XLR
connection while a guitar needs to use a TRS connection.
3. switch for +48V phantom power for channels 3 to 6, use this switch to enable phantom
power if required for a condenser microphone for inputs 3 to 6.

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4. switch for +48V phantom power for channels 7 to 10, use this switch to enable phantom
power if required for a condenser microphone for inputs 7 to 10.
5. gain knobs for microphone inputs 3 to 10, allows you to control the input level which is
indicated with the LEDs above it.
6. MONO switch, allows you to create a mix down for the input channels to a dual stereo signal
(i.e. input channel 1 goes to channel 2 and input channel 2 goes to channel 1 for instance), for
the monitor mix.
7. LEDs for phantom power, show the status of the phantom power for each input. There is one
LED each for input 1, for input 2, for inputs 3-6 and for inputs 7 to 10.
8. monitoring mixer, these two gain knobs allow you to control the integrated monitoring mixer
of U108 PRE. The first knob controls the volume of the input channels, the second the volume
of the output channels. The mixed signal is available via the headphone output (when selected)
and the mix output on the backside of the unit.
9. headphone output with 1/4" TRS connector and headphone signal selection switch, use this
to connect a pair of headphones and control the volume / gain of it with the knob next to it. The
switch allows you to select if the main signal from output channel 1/2 (switch is off) or from
the mix output of the integrated monitoring mixer (switch is on) will be used.
10. power switch / LED, allows you to switch U108 PRE on and off. When on, the LED next to it
shows the status.
The rear panel of U108 PRE has these main features:
11. If required, this connects your unit to a standard laptop lock connector, preventing it from
being stolen.
12. 12V DC power connector, connects to the included DC power supply. U108 PRE requires this
power supply to operate.
13. USB connection port, connects to your computer with the supplied USB cable.
14. mix output, provides balanced / unbalanced 1/4" TRS connectors for the stereo master mix
signal from the integrated monitoring mixer of U108 PRE. This connects typically to your
studio monitors if you choose to use the integrated mixer.
15. line outputs channel 1 to 8, these balanced / unbalanced 1/4" TRS connectors provide each
independent analog output signal of U108 PRE. If you do not use the integrated mixer, you
would typically connect output 1/2 to your studio monitors.
16. microphone input channels 3 to 10 with XLR connector, use these connectors to connect
dynamic or condenser microphones.

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2. Installation
2.1 System Recommendation
U108 PRE is not simply a standard digital audio interface, but a high-resolution device capable of
advanced processing of audio content. Even though U108 PRE is built to have low-CPU resource
dependability, system specifications play a key part in the U108 PREs performance. Systems with
more advanced components are generally recommended.
Minimum System Requirements
PC
- Windows Windows 7 / 8 / 8.1 or 10 (32- and 64-bit) operating system
- 1 available USB 2.0 port
Mac
- Mac OS X 10.8 or higher, or current version of macOS
- 1 available USB 2.0 port
2.2 Hardware Installation
U108 PRE is directly connected to an available USB port of your computer. In order to make sure
the unit works, you need to use the included electric power supply that connects your mains power
outlet to the 12V DC connector on the backside of U108 PRE. Once this connection is made,
simply install the hardware by plugging it into your computer with the supplied USB cable.
USB port of a computer
2.3 Driver & Software Installation
After the connection of U108 PRE, the operating system automatically detects it as a new hardware
device. However, you need to install our driver in order to use it.
We strongly recommend to download the latest driver from www.esi-audio.com before installing
U108 PRE on your computer. The driver on our website can always be more recent compared to the
driver on the included Installation DVD.
2.3.1 Installation under Windows
This text explains how to install U108 PRE under Windows 10. If you use Windows 7, Windows 8
or Windows 8.1, the steps are basically the same. Connect U108 PRE before you install the driver,
but turn it off first.
To start the installation, launch the setup program, which is an .exe file that is inside a recent driver
download from our website or in the Windows XX folder (XX refers to the Windows version) of the

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included Installation DVD, by double clicking on it. When launching the installer, Windows might
display a security message. Make sure to allow the installation. After that, the following dialog on
the left will appear. Click Next and then the dialog on the right will appear:
Now click Install. Files are now being copied. After some time an additional dialog will appear:
Confirm this by clicking Next. Again some files are being copied and typically you will be
prompted with a Windows Security message like this:
Confirm it by clicking Install. After a while the installation then will be completed and the
following dialog will appear:

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Once you see the window on the left, click Finish. In many cases, the window on the right appears
then. We strongly suggest to select Yes, restart the computer now and then click Finish.
You can connect U108 PRE to your computer anytime if not done yet and switch it on. Windows
will automatically setup the system so you can use the device.
To confirm the completion of the installation after rebooting the system, please check if the orange
color ESI icon is displayed in the taskbar notification area as shown below.
If you can see it, the driver installation has been completed successfully.
2.3.2 Installation under macOS
To use U108 PRE under macOS, you need to install the driver from the included Installation DVD
from the macOS folder or from newer driver download from our website, which is recommended.
The driver and control panel gets installed by double clicking on the .dmg file and then in the
window that opens again double clicking on the installer. After that follow the instructions on your
screen. At the end of the installation, we recommend to reboot your system.
If the installer does not launch via a double click, click on it with the right mouse button (or hold
the ctrl-key on your keyboard while clicking with the left mouse button) and then choose Open and
then Open again.
Controlling some of the basic options of U108 PRE under macOS can also be done via the Audio
MIDI Setup utility from macOS (from the folder Applications > Utilities).

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3. Control Panel
This chapter describes the U108 PRE Control Panel and it's functions.
Under Windows, to open the control panel double click on the ESI icon in the task notification area.
Under macOS, there is an icon in the Applications folder. The following Control Panel dialog will
appear:
The panel has the following functions and sections:
INPUTS
The main part of the INPUTS section contains signal level meters for each and every physical input
channel.
Under it, the current SAMPLERATE is displayed.
OUTPUTS
The main parts of the OUTPUTS section contains volume control sliders and signal level meters
for each playback channel. Under each channel is a button that allows you to mute playback for that
channel (M). With the LINK button you can choose if you want to control the left and right
playback channels simultaneously.
Under OUTPUT LEVEL you can switch between +4dBu to set the output level of each individual
line output pair optimized for balanced audio signals to +4dBu studio standard level or -10dBV to
set the output level optimized for unbalanced audio signals to -10dBV consumer/HiFi standard
level.

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3.1 Latency settings
Under Windows via Config > Latency in the Control Panel it is possible to change the latency
setting (also called “buffer size”) for the driver of U108 PRE. A smaller latency is the result of a
smaller buffer size and value. Depending on the typical application (e.g. for playback of software
synthesizers) a smaller latency is an advantage. At the same time, the best latency setting indirectly
depends on the performance of your system. For recording applications, a typical latency buffer size
between 4 and 8ms is standard, a value displayed typically inside your audio application. Note that
the latency has to be setup before launching the audio application using U108 PRE.
Under macOS, the latency is depending on the audio application and usually setup there inside the
settings of that software.

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4. Specifications
Key Features
- 10 input / 8 output 24-bit / 96kHz USB 2.0 Hi-Speed Audio
Interface
- 10 input channels and 8 output channels available for
simultaneous usage
- 10 professional microphone preamps with +48V phantom power
support
- 2 Hi-Z high performance instrument inputs with 1/4" connector
- 10 microphone inputs with XLT connectors
- 8 line outputs with balanced 1/4" TRS connectors
- headphone output with 1/4" stereo phone connector
- separate stereo mix output as master / monitoring output
- integrated monitoring mixer controlled on front panel
- powered by included DC (12V) power supply
- dimensions roughly 45.0cm x 14.5cm x 4.5cm
Audio Specifications
- supports up to 24-bit / 96kHz
- A/D Converter:
- 107dB (@ -60dBFS A-Weighted)
- 20Hz to 20kHz, +/- 0.02dB frequency response
- D/A Converter:
- 112dB (@ -60dBFS A-Weighted)
- 20Hz to 20kHz, +/- 0.02dB frequency response
Compatibility
- supports Windows 7, Windows 8.1 and Windows 10 with ASIO 2.0,
MME, WDM and DirectSound (incl. EWDM /DirectWIRE)
- supports Mac OS X (10.8 and above) and macOS via CoreAudio USB
audio driver

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5. General Information
Trademarks
ESI, U108 and U108 PRE are trademarks of ESI Audiotechnik GmbH. Windows is a trademark of
Microsoft Corporation. Other product and brand names are trademarks or registered trademarks of
their respective companies.
The FCC and CE Regulation Warning
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two
conditions : (1) this device may not cause harmful interference, and (2) this device must accept any
interference received, including interference that may cause undesired operation. Caution : Any
changes or modifications in construction of this device with are not expressly approved by the party
responsible for compliance, could void the user's authority to operate equipment.
Note: This equipment has been tested and found to comply with the limits for a Class A digital
device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference when the equipment is operated in a commercial
environment. This equipment generates, uses, and can radiate radio frequency energy and, if not
installed and used in accordance with the instruction manual, may cause harmful interference to
radio communications. Operation of this equipment in a residential area is likely to cause harmful
interference in which case the user will be required to correct the interference at his own expense. If
necessary, consult an experienced radio/television technician for additional suggestions.
Correspondence
For technical support inquiries, contact your nearest dealer, local distributor or ESI support online at
www.esi-audio.com. Please also check our extensive Knowledge Base with Frequently Asked
Questions, installation videos and technical details about our products in the support section of our
website.
Disclaimer
All features and specifications subject to change without notice.
Parts of this manual are continually being updated. Please check our web site www.esi-audio.com
occasionally for the most recent update information.