Owner`s manual

A DEEPER LOOK: BALANCED OR UNBALANCED?

When cables are very long (e.g., over 6 meters/20 feet), the cable itself can

act as an "antenna" and pick up radio frequency noise, AC hum, or other types

of noises. To avoid these problems, many recording studios and live sound

installers use balanced lines. The average application may not require balanced

lines, but committing balanced connectors between the mixer and your A1000.4

will cause less ground loops and hum in the system. Balanced lines carry

signals, each one out of phase with respect to the other. To be converted back

into a single, unbalanced line, both balanced lines feed a differential amplifier

input that responds to the difference in levels between signals. In this way, the

out-of-phase signals are recombined into an unbalanced signal, but interference

induced into the cable will not be out of phase. Since the difference between

these signals is zero, the differential amplifier will reject the interference

completely.

two

4. OPERATION

1. Connect two pairs of PA cabinets or studio monitors to the output of your

A1000.4. make sure that your A1000.4 is switched off and that the volume

controls are turned down all the way.

2. Connect your A1000.4 to a mixer, a preamplifier or another source making

sure that the gain and volume controls on the mixer are turned down.

3. Connect some source such as microphones, keyboards or CD player into your

Mixer or preamplifier and start to make some noise.

4. Adjust the output level of your mixer or preamplifier at a proper level. A very

low output level will generate unwanted noise.

At this point, gradually turn up the volumes in your A1000.4 making sure that

the limit LEDs only flash occasionally.

OPERATION ADVICES:

4.1 TEMPERATURE CONSIDERATION IN RACK MOUNTING:

Notice

You can mount your A1000.4 in only 1.5U with the special optional brackets.

Although your A1000.4 generates almost no heat at all, you must secure proper

ventilation inside the rack to avoid overheating.

A sustained high-temperature operation will adversely affect the sound quality,

and the amplifier may shut itself off for as long as the excessive temperature

conditions exist.