AUDIO CONNECTION

Instrument Direct input & Parallel Link connection
As with all audio gear, always ensure audio system levels are turned down or equipment turned off before making connections. This will avoid plug-in or turn-on transients from damaging more sensitive components such as tweeters.

There are 2 channels on the SDI-2, each featuring an XLR- ¼“TRS combo jack INPUT, a TS ¼“ parallel LINK output and a balanced XLR OUTPUT.

Connect your source instrument or audio device to the input and the balanced XLR output to the mixing console. The LINK connector output provides the means for connecting the signal to an instrument amplifier or personal monitor system. Unbalanced cables are much more susceptible to noise than their balanced counterparts. Keeping unbalanced cables under 8 meters (25 feet) in length is good practice while balanced cables can easily extend to 100 meters (300 feet). The balanced output of the SDI-2 is mic level, meaning that it should be connected to the mic input of a mixing console or mic preamp.

INPUT PAD ATTENUATION

The most common use of the direct input is with guitar pick-ups, keyboards or audio devices like CD players, computers etc. The optimal setting for this is most likely with the pad switch set to 0dB, although with some high-output pick-ups the performance of the direct input may be improved if the pad switch is set to -20dB to prevent possible clipping of the input signal.

The instrument is connected to the XLR-¼“Combo jack socket using a TS jack plug, and a parallel link feed taken from the LINK TRS jack socket to the instrument amplifier.

The direct input can also be fed either from a line-level output from the head-amp (pad set to -20dB) or from the head-amp speaker output ( pad set to -40dB).

The PAD setting applies to both inputs.

ELIMINATING HUM AND BUZZ AND THE GROUND LOOP

The SDI-2 is equipped with output isolation transformers to eliminate hum and buzz caused by stray DC voltage and ground loops.

Computers, CD players and other consumer equipment can be noisy – this is particularly true when incorporating audio with a projector – so isolation transformers can be very useful when combating system noise.

The independent Ground Lift switches on the outputs takes this one step further by lifting pin-1 on the XLR. Computers are often the source for noise problems in audio systems, so greater care is certainly needed to keep things quiet.

．Dual-channel, high-impedance, direct inputs for an electronic musical instrument or line-level audio source from a music player or computer.
．¼“ TS LINK socket. A parallel-wired connector which feeds the direct input signal to another destination such as instrument amplifier.
．Selectable, 3-step attenuator acting on the high-impedance (hi-Z) direct input signal.
．Dual-channel XLR with transformer-isolated, balanced, low-impedance (low-Z) output.
．Ground lift switch acting on pin-1 of the balanced output.

	SDI-2
Circuit design
Input connectors	2 Unbalanced combo jack ( Pin-2 hot, Pin3&1 ground )
Link connectors	2 Unbalanced phone jack
Input pad switch	0dB / -20dB / -40dB
Input DC impedance	0.82KΩ / 40KΩ / 44KΩ
Max. input level before clipping	+26dBv
Output device	2 XLR w/balance transformer isolated
Output DC impedance	1.08KΩ nominal, Transformer balance
Output level	+26dBv
Frequency Response	20Hz to 20KHz +0.2 / 0 dB
Dynamic range	>109dB
S/N ratio~ un-weight 20Hz to 20KHz	-131.8dB
T.H.D~ 1KHz, 0dBv output	< 0.0002%
Ground/Lift switch	Lift pin-1 on XLR outputs, separate
Construction	1.6/1.2mm steel cabinet & chassis
Surface finished	Durable powder coating
Dimension(WxDxH)	124 x 78 x 46mm
Weight	0.5Kg
Shipping weight	0.6kg
Packing per carton	20pcs/13Kgs
Shipping dimension per carton	350 x 310 x 207mm