Myst DAC 1866 OCU User manual

DAC 1866 OCU
Operating Instructions

DAC 1866 OCU is a Hi-Fi digital-to-analogue audio
converter. In accordance with Russian state standard
specification 24388-88, its output amplifier belongs
to zero (highest) complexity group. The device
is based on precision 16-bit R2R DAC from
Analog Devices — AD1866.
Specifications:
Frequency response 10—20 000 Hz
THD 4,6 dB
Signal/noise ratio 93 dB
Harmonic distortion 0,005 %
Stereo crosstalk −60 dB
Minimal impendance 8 Ω
Mains voltage 220 V +10 %
Digital inputs:
optical S/PDIF;
coaxial S/PDIF;
USB 1.0.
Analogue inputs:
linear (max voltage 2V RMS);
headphone output (max voltage 5V RMS).
1

Technical features of the DAC 1866 OCU
DAC 1866 OCU has an active filter with cutoff frequency
40kHz which can be turned off (about turning off the filter
see P.6). Power supply is external and has it's own ON/OFF
switch. Analogue and digital parts of the unit has separate
powering. Digital outputs has galvanic isolation from the main
scheme. Linear and headphone outputs are protected from
electric damage by power delay when turned on. Headphones
are plugged with a reliable Neutric connector.
In order to preserve the maximum speed and precision of
attacks in sound the Bessel's filter of the 4th order is used.
Multibit R-2R DAC was chosen to obtain maximum clarity and
precision in transitional characteristics of the sound. Unlike
the widely used delta-sigma DACs, multibit DAC is capable of
producing fast attacks in a single step, while delta-sigmas use
multiple steps which leads to blurred and distorder attacks.
Besides, multibit DACs are capable of more detailed and
faithful presentation of high frequencies.
2

Front panel:
1 — ON/OFF switch;
2 — power indicator;
3 — headphone input;
4 — input selector;
5 — volume control.
3

Rear panel:
1 — coaxial S/PDIF output;
2 — optical S/PDIF output;
3 — linear output;
4 — USB connection;
5 — power supply.
4
COAX LINE OUT USB
POWER
OPT
LR

Installation
1. Plug the power adapter in the appropriate jack.
2. Plug your sound source inputs (several input
connections can be plugged in simultaneously).
3. Attach headphones to a front panel jack and/or
audio receiving device to the linear output.
4. Plug your power cord into 220 V wall socket.
5. Turn on the power supply, light indicator on the
power supply should turn on.
6. Turn on the ON/OFF switch on the front panel of
main unit, the light indicator on the front panel
should be on.
7. Choose appropriate input with input selector.
8. Set up desired volume level using volume control.
5

Turning off the filter
DAC 1866 OCU has an active filter with cutoff frequency 40kHz
which can be turned off if nessesary. The filter is turned off and
on by setting jumper position according to the scheme below.
6
When jumpers are positioned on the right
the filter is turned off.
The filter is on when all jumpers are
on the left position —
closer to the "FLT ON" marking.
Front panel
Rear panel
«FLT ON»

Attachment
Graphical presentation of DAC 1866 OCU characteristics
7
AFC (SOLARTRON INSTRUMENTS 1201 FFT SPECTRUM ANALYZER)*
Меандр(?) 100 Hz (at the left) and 10 kHz (Tektronix TDS1012)
* Instruments used in these measurements are indicated by asterisk.