Unika PRO Series User manual

PRO 248
USER MANUAL
Index
GENERAL PRECAUTION BEFORE USE
PRODUCT OVERVIEW
CAUTION
PARAMETER TEST CONDITIONS
FEATURES
APPEARANCE PARTS & FUNCTIONS
ISO TRANSFORMER SCHEMATIC
PULSE TRANSFORMER SCHEMATIC
INPUT PAD ATTENUATION
POWER SUPPLY
ELIMINATING GROUND LOOP NOISE
CONNECTION GUIDE
SPECIFICATIONS
6F, No.168, Xin-Hu 2nd Rd.
Nei-Hu District, Taipei City. 11494.
Taiwan, R.O.C.
[phone]
[phone]
[email protected]
UNiKA Electronic Co., Ltd.
www.unikapro.com
PRO SERIES AUDIO INTERFACE
DESIGN & MADE IN TAIWAN
DUAL ACTIVE DIRECT BOX

UNiKA PRO 248 User Manual
1
GENERAL PRECAUTION BEFORE USE
PRODUCT OVERVIEW
Thank you for purchasing the UNiKA PRO SERIES AUDIO INTERFACE. Before using,
please read this manual carefully and pay attention to every detail that you must pay
attention to. If you use a mixer to connect to this interface, please turn off the mixer
power and +48V phantom power before connecting, and then turn on the power and
phantom power after inserting the signal cables. For passive models, please do not
turn on the phantom power to avoid leakage or damage the equipment.
If using a model with a volume knob, turn the volume knob to the minimum. During
use, please do not plug or unplug the wires arbitrarily to avoid signal loss. Please
refer to the following instructions for the soldering method of the plugs to ensure the
expected level and keep the signal smooth.
If you need further installation or operation guidance, please directly contact UNiKA's
dealer or distributor, or write to the following mail address for help:
[email protected]
PRO 248 is an active dual-channel DI box. Unlike traditional DI, PRO 248 uses +48V
phantom power instead of the traditional 9V dry cell battery, so users can use it on the
mixer or external phantom power supply. Power is supplied to PRO 248, the power
supply circuit and the output signal line are shared, and no additional power cord is
required. The +48V indicators are set on the upper cover. The +48V circuit specially
selects the British OEP PT-4 pulse transformer.
PRO 248 has a pair of built-in UNiKA-PROTM EI30A10E 1+1:1+1 isolation transformers,
which has a special copper foil layer and a dedicated ground layer, which allows
this device to restore high signal/noise ratio and dynamic sound, and can avoid
unnecessary leakage caused by radio frequency interference, ground interference and
potential difference. PRO 248 is especially suitable for electronic musical instruments,
recording studios and xed installation projects by using mixers.
The PRO 248 uses two TRS sockets on the input, and two TRS through out are
convenient for musician to pass the direct signal to the instrument amplifier. In
addition, it is equipped with a 0/-20dB attenuation switch and LED indicator, which is
suitable for various types of audio signals with high and low impedance. The output
terminal is also equipped with a GND/LIFT button to quickly eliminate ground noise.

2
UNiKA PRO 248 User Manual
CAUTION
FEATURES
This product has undergone rigorous inspection before leaving the factory. If
customers encounter failures during use, please contact your local dealer or distributor
for replacement or repairing, do not disassemble the case or replace parts by yourself,
which will invalidate the warranty.
For details, please refer to the warranty regulations in the enclosed warranty card, and
ll in the details, and get a valid stamp or signature of the dealer or distributor.
• Power by external +48V phantom power
• Built-in UNiKA-PROTM EI30A10E isolation transformer
• Use British OEP PT-4 1:1 audio pulse transformer in phantom power circuit
• +48V status indicator on the upper cover
• The input socket uses a pair of TRS jacks
• Use a pair of TRS jacks as through out terminal
• At 0dB input, the set load impedance is 260KΩ, which can clearly show the high
frequency overtones , harmonic and graininess of electric guitars or electric bass
• 50Ω ultra-low impedance output, suitable for various types of mixers and
pre-amp equipment
• There is 0dB/-20dB input signal attenuation switch with status indicator
• The output is equipped with a GND/LIFT switch
PARAMETER TEST CONDITIONS
In the development and manufacturing process, Audio Precision's 2700 series and 500
series are used to test and verify electrical characteristics.

UNiKA PRO 248 User Manual
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①CH-1 signal output: XLR terminal, isolated
balanced output of the transformer, need
to turn on +48V phantom power supply for
PRO 248 proper working after connecting to
the mixer.
②Output grounding/floating switch: when
the switch is not pressed,the first pin
(PIN-1) of XLR is grounded. PIN-1 will be
disconnected from ground after pressing.
This button should depend on the system.
Used in the situation, in order to isolate the
ground loop noise or leakage.
③CH-2 signal output: XLR terminal, Isolated
balanced output of the transformer, need
to turn on +48V phantom power supply for
PRO 248 proper working after connecting to
the mixer.
④ +48V phantom power indicator: When
CH-1 or CH-2 receive +48V phantom power,
the indicator will be shinning the blue color.
⑤CH-1/CH-2 Signal input: A pair of 6.35mm
TRS sockets, can input balanced or
unbalanced LINE signal.
⑥PAD input attenuation switch: Provide 0/-
20dB two options, when inputting signals of
various impedances and levels.
It can be attenuated by 20dB to avoid
overload or clipping.
⑦Attenuation active indicator: When the
PAD attenuation switch is pressed (-20dB),
the indicator light will be shinning the yellow
color.
⑧ CH-1/CH-2 signal through out: Convenient
for musicians musical instrument speakers
or other DI and peripheral equipment.
① ② ④
APPEARANCE PARTS & FUNCTIONS
⑤ ⑥⑦ ⑧
③

4
UNiKA PRO 248 User Manual
ISO TRANSFORMER SCHEMATIC
1 5
10 6
Screen Secondary
Cooper foil/
Core
Secondary
Primary
Primary
PULSE TRANSFORMER SCHEMATIC
UNiKA-PROTM EI30A10E
OEP PT-4
3 layers of thermo setting
adhesive polyester tape
between windings
1
2
4
5
6
7
8
9
3
10

UNiKA PRO 248 User Manual
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The most widely used DI box is to connect electronic
musical instruments, sound source of A/V equipment
and computers, convert their output signals into
balanced signals and then extend the transmission
distance.
The most ideal state is to set the attenuator to 0dB
position (button up) for musical instrument. For some other type of signals, you can press
the button to make the signal is attenuated by 20dB to avoid clipping caused by signal
overload.
When the button is pressed, the PAD indicator on the right will light up.
This attenuator acts on the input terminals of CH-1 and CH-2 at the same time.
INPUT PAD ATTENUATION
The built-in channel independent balanced isolation
transformer has solved the potential difference leakage
problem. When the system causes a ground loop due
to poor wiring, the noise can be eliminated through the
GND/LIFT button.
The GND/LIFT button determines whether pin 1 of the
output XLR is grounded, grounded when it bounces,
and disconnected from ground when pressed.
ELIMINATING GROUND LOOP NOISE
POWER SUPPLY
PRO 248 is an active DI box and requires +48V
phantom power. It can work normally when it is
powered, but no additional power supply is required.
Just use balanced wires to connect the device to the
mixer’s input channel, and turn on the +48V power
switch of the mixer, similar to connect a condenser
microphone to the mixer.
When the +48V power supply is suppling properly, the
+48V ACTIVE indicator light on the upper cover will
light up.
Before connecting the device, do not turn on
the +48V switch of the mixer.

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UNiKA PRO 248 User Manual
CONNECTION GUIDE
Connect the balanced wire
from ISO OUT to the mixer,
the mixer needs to turn on
+48V phantom power
1-Shield pin
2-Hot pin
3-Cold pin
The unbalanced connection, pin-2 is hot, pin-3 is shield paralleled with pin-1.
Output from
musical instrument
to INPUT
Output via THRU OUT
to musical instrument
ampliers
12
3
1
3
2
XLR-Female connector XLR-Male output jack
TS Unbalance plugTRS Balance plug
Tip-Signal Hot
Ring-Signal Cold
Sleeve-Shield
Tip-Signal
Sleeve-Shield

UNiKA PRO 248 User Manual
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SPECIFICATIONS
PRO 248
Circuit principle Active low-noise op-amp with Transformer
balance output
Input connector 2 x TRS
Thru connector 2 x TRS
Input pad switch/indicator 0/-20dB push button with LED
Power supply +48V Phantom power through output
connector with LED indicator on top cover
Output connector 2 x Male XLR through ISO Transformer
Output GND/LIFT switch Shared push button
Input impedance 260KΩ / 0dB, 50KΩ/-20dB
Output impedance 50Ω
Max. input level before clipping +10dB
Max Output level +10dB
Frequency response 20Hz-20KHz, +0.05/-0.5dB
S/N ratio @20Hz~20KHz un-weight >95dB
T.H.D. @1KHz 0dBV output <0.02%
Transformer Ratio 1:1+1:1
Chassis 1.6mm/1.2mm steel cabinet and chassis
Surface nished Durable complex painting
Dimension (W x D x H) 78 x 124 x 46 mm
Weight 0.55kg
Shipping weight 0.65kg
Packing per carton 20pc/14kg
Shipping dimension per carton 350 X 310 X 207 mm
(Specications are subject to change without notice.)

1. Equipment
EU DECLARATION OF
CONFORMITY
Product name Dual active direct box
Model PRO-248
EAN Code 4711064410198
2. Manufacturer
Manufacturer UNiKA Electronic Co.,Ltd.
Address 6F, No.168, Xinhu 2nd Roadn, Nei-Hu, Taipei, Taiwan
EMI:
EN 55032:2015 IEC 61000-4-3:2006+A1:2007+A2:2010
EN 61000-3-3:2014 IEC 61000-4-42012
EN 61000-3-3:2013 IEC 61000-4-5:2014+A1:2017
EMS: IEC 61000-4-6:2013/CORE1:2015
EN 55035:2017 IEC 61000-4-8:2009
IEC 61000-4-2:2008 IEC 61000-4-11:2-4+A1:2017
7. Where applicable, the above equipment will be tested and revision of existent certicate by WH
Technology Corp. (TAF Accreditatio Number:2954) for compliance With EMC requirements
set forth in the EUROPEAN COUNCIL DIRECTIVE 2014/30/EU and the technical standards
mentioned above. The results of testing in this report apply only to the product/system, which
was tested. Other similar equipment will not necessarily produce the same results due to
production tolerance.
8. The technical le is available from the manufacturer at the address above
Signed for and on behalf of: UNiKA Electronic Co.,Ltd.
Place of issue: Taipei
Date of issue: May 03th, 2021
Name: Yung-Ho Hsu
Position: Marketing & Product director Signature:
3. This declaration of conformity is issued under the sole responsibility of the manufacturer.
4. Object of the declaration, Product: Direct box for musical instrument and A/V device.
5. The object of the declaration described in point 4 is in conformity with the relevant
Union harmonisation legislation 2014/30/EU The Electromagnetic Compatibility Directive
6. References to the relevant harmonised standards used, or references to the specications in
relation to which conformity is declared: