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Proel DB1A 1 Channel Active Direct Box With Isolation Transformer

Product Code PRDB1A
Manufacturer Proel

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D.I. Boxes (Direct Injection Boxes) are part of the essential set of tools required for any professional live sound situation or any application where the audio devices feature diff erent levels, impedance and connections. Transforming audio signals from unbalanced to balanced, D.I. Boxes reduce the possibility of electrical disturbances on the line - especially over long cable runs such as from a musical instrument to the FoH mixing console. The DB series includes three diff erent models of high-performance D.I. boxes: a single channel active (DB1A), a single channel passive (DB1P) and a dual channel active (DB2A). The circuitry of each model has been designed with the maximum care, using carefully selected electronic components, such as isolation transformers (DB1A, DB1P) and low-distortion ICs. This guarantees a clean, hum-free signal transmission from the instrument to the mixing consoles, even on very long cables, without impedance matching problems. On the front panels, a wide choice of connectors is available (XLR, JACK and RCA, depending on the model), allowing easy connection from a wide range of sources, including keyboards and samplers, guitars and basses, PC audio cards and any type of music player. The ACTIVE versions can be powered by 48 V phantom power from the mixing console, by a 9 V battery or, in large applications using many DI BOXES, by an external 9 V power adapter that can be daisy-chained using the double power connector on the rear panel. The innovative mechanical design of the three models includes an aluminum shell and rubber corners, which provide maximum protection in the toughest situations. When the two rubber corners are removed, two guides are exposed, allowing the coupling of two DI units, which can then be mounted in a 19” standard rack (rack ears included). This unique feature is extremely convenient for engineers who need to use a large number of DI BOXES in the same application.

RACK mountable

MU-METAL core isolation transformer

High dynamic headroom with minimum phase and harmonic distortion

Input JACK and XLR connectors with link possibility

All the connections on the same side

-10 dB, -20 dB, -30 dB PAD


Phase reverse

Powering options: 9V battery, +48V, external AC/DC adaptor supply


Input Impedance 1M Ohm (pad at 0 dB)

  47k Ohm (pad at -20 dB)

  44k Ohm (pad at -30 dB)

Max Input Level +5 dBu (pad at 0 dB)

  +25 dBu (pad at -20 dB)

  +35 dBu (pad at -30 dB)

Connectors 2 x 1/4" jack + 1 x XLR-F (unbalanced)

Output Section  

Output Transformer Balanced

(fully isolated)

Max. Output Level into 600 Ohms or greater

  +3 dBu (for 0.1% THD at 50 Hz)

  +5 dBu (for 0.1% THD at 1k Hz)

Connector XLR-M

System Performance  

Insertion loss < 1 dB

CMR > 60 dB

Phase distortion +11° at 20 Hz, -6° at 20k Hz


(THD 20-20k Hz 0dBu)

< 0.007 %

Noise < -105 dBu unweighted 

Frequency Response 10 Hz to 100 kHz, +0dB/-1 dB 


Controls On/off, Pad -10, Pad -20

Gnd Lift, Ø inv.

Indicators On, signal, clip

Phantom Power +24 volts DC to +48 volts DC 

AC/DC adaptor +12 volts DC

Standalone/Standby 9 volt PP3 type battery

Current consumption less than 3 mA 

Dimensions (WxHxD) 215 x 50 x 125 mm

Weight 1.08 kg (2.38 lb)

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