Okto Research DAC8 PRO User manual

DAC8 PRO
The nicest 8-channel D/A converter
Owner’s manual

2 | DAC8 PRO Owner’s Manual
Contents
Technical speci ications ............................................................................................................................. 3
Mechanical drawings ................................................................................................................................. 5
Back panel overview .................................................................................................................................. 6
Package contents ....................................................................................................................................... 6
Digital connections ..................................................................................................................................... 7
USB ............................................................................................................................................................. 7
Host drivers ....................................................................................................................................... 7
AES/EBU .................................................................................................................................................... 9
Analog Connections ................................................................................................................................ 10
Main outputs ......................................................................................................................................... 10
Headphone output .............................................................................................................................. 10
Input modes ................................................................................................................................................ 11
Pure USB .................................................................................................................................................. 11
USB / AES ................................................................................................................................................ 11
Pure AES .................................................................................................................................................. 11
Controls ....................................................................................................................................................... 12
Rotary control unctionality ......................................................................................................... 12
Remote control unctionality ....................................................................................................... 12
User inter ace and menu system .......................................................................................................... 13
Main screen – le t display ............................................................................................................ 13
Main screen – right display ......................................................................................................... 13
Main menu....................................................................................................................................... 14
Volume submenu .......................................................................................................................... 14
Routing submenu .......................................................................................................................... 15
System submenu ............................................................................................................................ 15
Displays submenu .......................................................................................................................... 16
Filters submenu .............................................................................................................................. 16
Status submenu .............................................................................................................................. 17
Warranty ..................................................................................................................................................... 18
Manual revisions ....................................................................................................................................... 18

3 | DAC8 PRO Owner’s Manual
Technical speci ications
Digital connectivity
•USB
o8 output and 8 input channels
oasynchronous, UAC 2.0 compliant
oplayback data ormats
PCM, up to 192kHz / 32-bit
native DSD, 64x / 128x
DSD over PCM (DoP), 64x
orecording data ormat
PCM, up to 192kHz / 32-bit
•AES/EBU
o4 AES/EBU inputs (SPDIF compatible)
up to 192 kHz / 24-bit
resampling- ree (i.e. requiring a single signal source)
unique USB/AES input mode ensures a bit-per ect data low rom
AES/EBU to USB, allowing or a real-time signal processing or
simultaneous recording & playback with no resampling applied
o1 AES/EBU output
ixed to playback channels 1 and 2 (o USB or AES/EBU, depending on
the selected input)
Analog connectivity
•Main outputs (back side)
o8 x Neutrik gold-plated XLR connector
oOutput level: 4.1 V RMS di erential ull-scale
ooutput impedance: 200 Ohms
•Headphone output ( ront side)
o6.3 mm (1/4”) TRS connector
oOutput level: 4.1 V RMS ull-scale
o120 mA linear output current
oixed to output channels 1 and 2
ooutput impedance <100 mOhm

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Analog per ormance
•0.000032 % / -130 dB THD (Total Harmonic Distortion) ull-scale, 1kHz
•0.00011 % / -119 dB THD+N (Total Harmonic Distortion + Noise) or 119 dB SINAD
ull-scale, 1kHz
•125 dB dynamic range
•0.000224 % / -113 dB THD+N @ 100 mW into 32 Ohms headphone output
Menu unctions
•Individual volume or each o the 8 output channels (relative to the master volume)
•Routing matrix (any input channel to a speci ic output channel)
•Upper volume limit
•Remote control learning
•Choice between 7 PCM reconstruction FIR ilters
•Con igurable display timer to dim or turn o the displays
•Con igurable auto on / auto o with non-zero audio data detection
Other eatures
•Trigger output
o5 V voltage level
oshort-circuit proo with 15 mA maximum current
opulse or continuous
•Full control with either rotary or remote control
•Rack-mountable with optional 2U, 19” rack mounting brackets
Dimensions
•448 mm x 183 mm x 50 mm, excluding user-removable eet
•Weight: 4.5 kg (10 lbs)
Power
•Mains voltage: 120 V AC or 230 V AC (depending on the country o order)
•Power rating: 15 W

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Mechanical drawings

6 | DAC8 PRO Owner’s Manual
Back panel overview
Package contents
•DAC8 PRO (silver or black depending on your choice, 120 V or 230 V version
depending on the country o order)
•USB cable (black, 2 m)
•Apple Remote (optional)
•Rack mounting brackets (optional)

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Digital connections
USB
Host drivers
On Mac OS and Linux, no driver is needed thanks to the USB Audio Class 2.0 standard used
by the unit, and the DAC8 PRO will be recognized as an 8-channel playback device and an
8-channel recording device. The only action required by the user is to select the DAC8 PRO
in your operating system’s audio control panel.
This also applies to Windows 10 and newer, however, it is strongly recommended to use
ASIO to bypass the Windows sound mixer and allow or an exclusive access to the device
and a bit-per ect data transport. Please contact us i you are interested in using the DAC8
PRO with older Windows operating systems.
To enable ASIO playback, please download the latest version o ASIO4ALL driver rom
asio4all.org and ollow the installation steps.
A ter the installation is complete, you will be able to see “ASIO4ALL v2” as an output device
option in any ASIO capable playback so tware. The ollowing picture displays the output
device setting in JRiver:

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Our recommendation: not all Windows applications are capable o ASIO output ( or
example a Spoti y desktop app or the Chrome browser). However, you are still able to
achieve an ASIO playback with “ASIO Bridge / Hi – Fi Cable” by VB-Audio, that is available
as a donationware on vb-audio.com/Cable/. A ter being installed, the ASIO Bridge will
appear as a new audio output audio device and needs to be selected as de ault:

9 | DAC8 PRO Owner’s Manual
The actual ASIO output o the ASIO Bridge needs to be selected in the application’s control
panel (that can be accessed a ter clicking the icon on Windows taskbar) by clicking on “ASIO
Device” text string:
Please consider donating to the creators o both ASIO4ALL and ASIO Bridge i you like their
work.
Warning: The USB input o the DAC8 PRO may not work correctly (or at all) when connected
to a USB hub. It will also not work i connected to a USB 1.0 port. Be sure to use a native
USB 2.0, USB 3.0 or USB 3.1 port o your computer.
AES/EBU
The DAC8 PRO o ers 4 AES/EBU inputs that are ree o resampling. That allows or a bit-
per ect playback by the DAC8 PRO as well as recording at the USB host side, but it also
requires the inputs to be mutually synchronized and carry signals with matching sampling
rates.
Additionally, i only one input is used, it needs to be the input 1. I 2 o them are used, they
need to be the inputs 1 and 2. There is no requirement or inputs 3 and 4.
The AES/EBU inputs will also accept a signal with the lower SPDIF voltage levels and while
the requirement or termination impedance is di erent or the two standards, the SPDIF
signal will generally be received correctly i the cables are not too long to cause signi icant
re lections resulting in data corruption.

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Analog Connections
Main outputs
The main analog outputs provide an extremely accurate analog representation o the digital
signal received by the DAC8 PRO’s selected input.
The ull-scale voltage level is 4.1 V RMS and the output impedance is 200 Ohm di erentially.
The outputs are protected against long-term short circuit.
The volume control is always applied to the analog outputs. To bypass it, simply set it to
0 dB. Additionally, per-channel volume relative to the master volume can be applied i a
non-zero value is selected in the Volume menu.
Warning: we discourage rom using balanced-to-unbalanced cables and converters. Doing
so will result in a vastly decreased analog per ormance and may be also cause o ground-
loop induced hum issues. Unbalanced signal paths (e.g. widespread RCA) are unsuitable or
device-to-device connections i high signal per ormance is desired, since they do not o er
a separate path or equalizing ground loop currents that will naturally occur in a real-world
environment.
Headphone output
The headphone analog output, available on the ront panel via a 6.3 mm (1/4”) TRS
connector, provides 4.1 V RMS ull-scale voltage level, up to 120 mA linear current and less
than 100 mOhm output impedance. It is suited or majority o headphones and earphones,
ranging rom 16 Ohm IEMs to a large 600 Ohm headphones with open construction.

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Input modes
Because the DAC8 PRO is an asynchronous device in regard to its USB input, it sets the pace
o the rate in which samples are coming rom the USB host when the USB playback is active.
On the other hand, AES/EBU connections require a synchronous operation o the receiving
device with the transmitting device as they have no receiver-to-transmitter eedback path
and the clock signal is encoded in the data stream instead. The three input modes o the
DAC8 PRO were designed to make the two standards work together and o er the most
unctionality.
Pure USB
Pure USB input mode does make use o the DAC8 PRO’s low-phase noise oscillators as the
master clock or XMOS processor acilitating the USB data transport and processing. In the
Pure USB mode, AES/EBU output is operational and transmits channels 1 and 2 o the USB
audio data.
USB / AES
USB / AES is a unique mode o operation that does use the master clock recovered rom
the 1st AES/EBU to set the pace o the audio data trans er rom the USB host. This means
that the data recovered by the AES/EBU inputs are transported in a bit-per ect manner to a
USB host via the 8 USB input channels, allowing them to be recorded or processed and sent
back to the USB output channels to be replayed by the DAC8 PRO.
Because the UAC2 audio device is unable to change the USB host current sampling
requency, the DAC8 PRO will display a warning message i the sampling requency o the
received AES/EBU signal does not match the one selected by the USB host. It is up to the
user to make the sample rate o the AES/EBU transmitting device match the sample rate o
the UAC2 driver o the USB host.
Pure AES
Pure AES mode does not need a USB connection or operation. It does use the recovered
AES/EBU clock or processing the received audio data and DAC8 PRO’s internal, low-phase
noise oscillators or the D/A conversion. The DAC8 PRO’s jitter eliminator is active to ensure
the highest-per ormance possible.

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Short press: turn on, mute
Long press: turn o
(or three subsequent presses in case o some
remotes that don’t use the NEC protocol)
Enter menu, exit menu
Enter menu, select, con irm
Controls
DAC8 PRO can be ully controlled with either a rotary control including a push-on switch or
an IR remote in an intuitive way. Additionally, any IR remote can be used thanks to the
learning unction. I you ordered an Apple Remote together with your DAC8 PRO, it will
come paired with the unit.
Rotary control unctionality
Device state
Off Main screen Menu Menu,
selected
Input
Left/right
turn
- Volume
control
Navigation Modi y
Push Turn on Enter menu Select Con irm
Long push Turn on Turn o Back Con irm
Remote control unctionality
Volume- / Menu down
Volume+ / Menu up
Input change / Menu back

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dB
max
User inter ace and menu system
Main screen – le t display
•Play / pause icon: indicates incoming data
•Input mode indicator: shows selected input mode
•Audio data in ormation: shows sampling requency, bit depth and data ormat (i
applicable to the selected input mode and incoming data type)
Main screen – right display
•Volume: current master volume in dB relative to the nominal ull-scale output
•Mute icon: appears i mute is enabled using remote control or in the menu system
•Min / max indicator: only appears i the volume reaches upper limit (set in the Menu
> Volume > Lim) or minimum value (-99 dB)
-
32
Pure USB
96kHz 24bit PCM

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Main menu
The main menu appears on the le t display when the knob is pressed or a Menu or Enter
button is pressed on the remote control.
Volume submenu
•Mute: mutes all the analog outputs (de ault: o )
•Limit: sets the maximum allowed volume
o0 to -50 dB (de ault: 0 dB)
•CH1 to CH8 volume: an additional, per-channel volume relative to the master
volume displayed on the main screen
Mute
Limit 0 dB
CH1 volume 0 dB
...
CH8 volume 0 dB
Volume
Routing
System
Displays
Filters
Status

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Routing submenu
•Out1-8 source: selects the source channel or the respective analog output
System submenu
•Input: selects signal input. Please re er to the “Input modes” or details
oPure USB (de ault)
oUSB/AES
oPure AES
•Trigger: sets trigger output as continuous or 10 ms pulse on turn on and o
ocont. (de ault)
opulse
•Auto ON: turn on the unit on incoming signal
•Auto OFF: turn o the unit a ter certain period with no signal present
onever
o10 min
o30 min
o2 hrs (de ault)
•Learn remote: learn commands rom any IR remote
•Load de aults: load actory de aults
Input Pure USB
Auto ON
Auto OFF 2hrs
Trigger cont.
Learn remote
Load de aults
Out1 source: CH1
Out2 source: CH2
...
Out8 source: CH8

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Displays submenu
•Brightness: sets display brightness in 6 steps (de ault: 6)
•Timer: sets a timer to dim or turn o the displays
oo (de ault)
o10 s
o60 s
o5 min
•A ter timer: sets display action a ter the selected timer value expires
oo
odim (de ault)
•Menu return: sets the time or an automatic return rom the menu to the main screen
oo (de ault)
o10 s
o60 s
o5 min
Filters submenu
•FIR ilter
oFRLP ( ast roll-o , linear phase)
oSRLP (slow roll-o , linear phase
oFRMP ( ast roll-o , minimum phase) (de ault)
oSRMP (slow roll-o , minimum phase)
oAFRLP (apodizing, ast roll-o , linear phase)
oHFRMP (hybrid, ast roll-o , minimum phase)
Brightness 6
Timer o
A ter timer dim
Menu return 60s
PCM ilter FRMP
DSD ilter auto

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oBW (brickwall ilter)
•DSD ilter – sets the cut-o requency o the low-pass ilter or DSD playback
oauto (de ault)
o50 kHz
o60 kHz
o70 kHz
Status submenu
•Serial number – shows the serial number that is burned in the OTP (one-time-
programmable) memory. The reading will not be a ected by irmware updates.
•FW version – shows the current version o the device irmware
•Temperature – reading o the temperature at the DAC8 module
• Uptime – shows the elapsed time since the unit was powered on
Serial number 8
FW version 1
Temperature 35°C
Uptime 1:22:33

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Warranty
The DAC8 PRO is designed or a maximum reliability and each unit is tested extensively
be ore it is shipped. However, i a spontaneous mal unction occurs, the product is covered
with a 2-year warranty. Please be aware that any damage caused by abusive operation is
not covered.
To ensure your satis action, we also o er a 30-day return policy. In case o a return, the
customer pays the cost o the shipping back to us and the re unded amount does not
include the cost o the previous shipping rom us to the customer. The returned product
and accessories must be complete, clean and ree o scratches and other damage.
When receiving the product, customer is required to care ully check the package or
damage and i some is present, require the delivery person to document the damage and
write a report. This report, together with photographs, then needs to be e-mailed to us as
soon as possible. I these steps are not taken, the transportation damage will not be covered
by the warranty.
Okto Research
U Druhe baterie 785/15
16200 Prague
Czech Republic
in [email protected]
www.oktoresearch.com
Manual revisions
Rev. 1.1
Improved drawings
Rev. 1.0
Initial
release
ASIO is a trademark o Steinberg Media Technologies GmbH.