DAPAudio Palladium P-400, User Manual

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Signal-LED  

This green LED lights, when its channel produces an output signal of about 4 Volt RMS or more (0,1V or 
more at the input, with 0dB attenuation and standard 40X voltage gain). It is useful to determine whether 
the amplifier is amplifying a signal.  

Protect LED  

When the red LED lights, indicating that the channel has overheated, the channel’s output relay is open, 
and the speaker(s) has been disconnected for any of the following reasons:  
1. The unit was just powered up and is in the turn – on delay mode 
2. The amplifier senses a DC voltage at its output. 
 

Power LED  

This indicator LED lights, when the amplifier has been turned on, AC power is available and the low-
voltage power supply and fan are operational.  

 
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.