DAPAudio Palladium P-400, Product Manual

9

Input Attenuates

The two input attenuator controls, located at the front panel, adjust gain for their respective amplifier
channels in stereo mode. With attenuate fully clockwise at 0 dB, professional power amplifiers have the
rated power (when the rated input is 0,775V) In bridged mode, only channel A’s attenuate controls the
power level, while channel B’s does not function.

Protection Features

Every amplifier incorporates several circuits to protect themselves and the speakers under virtually any
situation. Dap Audio has attempted to make the amplifier as “foolproof” as possible by making it impervious
to short and open circuits, DC Voltage and overheating.

When a problem occurs, that causes a channel to go into a protection mode, the PROTECT for that channel
will glow. DC voltage on the output, excessive subsonic frequencies, or thermal overloads will cause the
channel’s output relay to disconnect the speaker load, until the problem is corrected or the amplifier cools
down.

The internal fan(s) will keep the amplifier operating well within its intended temperature range under all
normal conditions.

When a channel’s heat sink temperature reaches 90 ºC, which may indicate an obstructed air supply,
clogged air filter, etc, the channel will disconnect its load. Normal operation will resume automatically once it
cools to 80 ºC. During this time, the channel’s PROTECT LED will light.

Short Circuit

If an output is shorted, the protection circuit will be more sensitive, than in the normal protection situation
and will protect the channel’s output transistors from the current stress. The channel’s PROTECT LED will
light. If the short circuit remains, the channel will eventually thermally protect itself by disconnecting the load.

DC Voltage Protection

If an amplifier channel detects DC voltage at its output, its output will immediately open to prevent speaker
damage. The channel’s PROTECT LED will light.

Subsonic Frequencies

All amplifiers have a built-in subsonic frequency protection circuit, cornered at 10Hz, for each channel.
An additional feature is a special high frequency protection technology, which enables you to automatically
disconnect speakers, when excessive high frequency energy appears at the output.

Turn-On/Turn-Off-Protection

At power up, the speakers are disconnected. The power supplies charge for about 2-3 seconds and
stabilize, and then the speakers are connected. When power is removed, speaker loop is synchronized with
the turn off signal, therefore no thumps or pops are heard.

Speaker-Protection

All amplifiers automatically protect speakers from DC voltage, subsonic signals and excessive high
frequency signal, but users should be aware of the application limits of their speakers.
Be aware that the amplifiers power does not exceed the speaker’s power capabilities.