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FRONT PANEL DIAGRAM 

 

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1.

 

POWER SWITCH –

 Turns the amplifier on/off. 

2.

 

POWER LED – 

Illuminates when the amplifier is on.  

3.

 

LED METERS – 

Indicates the audio signal level. 

This LED will light up when the signal at the output is at least -

20 dB.

 

4.

 

CLIP –

 The red "Clip" light indicates the signal is distorting or "clipping," which occurs when the volume 

exceeds the amplifier's maximum output. 

This LED will flash when distortion reaches a level of 0.5%. 

Consistent clipping can damage your amplifier and speakers. If the signal is regularly clipping, reduce the 
volume of the amplifier. If it is lit about half the time, the amplifier channel's thermal protection will cause 
the channel to shut down within a few minutes.   

5.

 

PROT – 

The red "Prot" light indicates the output for that channel has turned off to protect your amplifier and 

speakers, which can be damaged by excessive volume resulting in clipping.  If the meters' red lights are 
illuminating, decrease the levels of your CHANNEL GAIN knobs.   

6.

 

CHANNEL GAIN – 

This knob controls the channel's output signal. 

7.

 

COOLING VENTS –

 These vents help to cool the internal parts of the amplifier when in use.  Do not block 

these vents, and keep the vents clean at all times. 

 

SPEAKER CONNECTION 

 

 

SHORT CIRCUIT PROTECTION 

Output short circuit protection protects the output devices of the amplifier from short circuits and 
stressful loads.  If your speaker lines short, the amplifier automatically detects this problem and 
discontinues operation for that channel.  (If one channel's short circuit protection is activated, the other 
channel will continue to operate normally.)  During short circuit protection, the "Clip" and "Protect" 
LEDs will light simultaneously, and all output from that channel will stop.   
 
Short Circuit Protection can often be traced back to the signal output line (i.e., the speaker line). 
Check the line from the output terminal of the amplifier to the speaker. If this line is still good, check 
the internal speaker connections and components.  (A short circuit can often be traced to a bad cable or a bad 
speaker component and is rarely traced to the amplifier itself.) 
 

Bare Wire Connections: 

When connecting your speakers to the amplifier using bare wires, follow these steps: 
1.

 

Unscrew the red and black caps of the binding posts. (Be sure not to completely remove or unscrew the red 
and black caps.) 

2.

 

Strip back the wire insulation 1/2" (13mm). 

3.

 

Insert the bare wire into the hole exposed under the binding post cap.   

4.

 

After inserting the wire, screw the binding post cap down on the wire.  

 

Spade Connector: 

When connecting your speakers to the amplifier using spade connectors, follow these steps: 
1.

 

Unscrew the red and black caps of the binding posts. (Be sure not to completely remove or unscrew the red 
and black caps.) 

2.

 

Insert the spade connectors into the binding posts. 

3.

 

Tighten the caps down on the spade connectors. 

 

Banana Connectors: 

When connecting your speakers to the amplifier using banana connectors, follow these steps: 
1.

 

Be sure that the red and black caps of the binding posts are tightened completely.  

2.

 

Insert the banana connectors into the caps of the binding posts. Be sure that the connectors are inserted 
securely.  

WARNING!:

  

 

Do 

not

 make any connections when any device is powered on. 

 

Do 

not

 allow the wires from terminals to come in contact with each 

other. 

 

Do 

not

 connect either positive (red) output to chassis ground.

Summary of Contents for APX1500

Page 1: ...APX1500 QUICKSTART GUIDE ENGLISH ...

Page 2: ...ll faders and gain knobs are set to zero 6 Connect all sound sources outputs to amplifier inputs as indicated in the diagram 7 Connect the amplifier outputs to speakers 8 Plug all devices into an appropriate power source 9 Switch everything on in the following order Sound sources i e microphones turntables CD players etc Mixer Amplifier Speakers 10 When turning powering down turn everything off in...

Page 3: ...signal will be output from the CH 2 output connector Parallel Mono Mode In this mode CH 1 input signal will be output from the output connectors of both channels Bridged Mode In this mode CH 1 input signal will be output from the bridge mono output connector 5 CHANNEL OUTPUTS Connect your speakers input jacks to these outputs For the binding posts red is the positive signal and black is the negati...

Page 4: ...ue to operate normally During short circuit protection the Clip and Protect LEDs will light simultaneously and all output from that channel will stop Short Circuit Protection can often be traced back to the signal output line i e the speaker line Check the line from the output terminal of the amplifier to the speaker If this line is still good check the internal speaker connections and components ...

Page 5: ...d the channel 2 input signal will be output from the channel 2 output connectors STEREO PUSH PUSH OPERATION IN PARALLEL MODE In this mode the channel 1 input signal will be output from the output connectors of both channels The channel 2 input jack is not used the channel 1 and 2 volumes can be adjusted independently Use the Parallel Mode when you want to drive two speakers with only one input sig...

Page 6: ...r speaker before operation BRIDGED PUSH PUSH RACKMOUNTING TIPS It is a good idea to mount this in the bottom of a rack frame Supporting the back of the unit may be necessary for portable or road use The APX1500 mounts into a standard 19u rackmount ALTO amplifiers are well shielded however mounting low level electronics some distance away from power amplifiers is common practice to reduce the possi...

Page 7: ...0 3 dB VOLTAGE GAIN 32 dB DISTORTION SMPTE 1M 0 5 S N ratio 110 dB Inrush Current at initial switch on 8 24A Inrush Current after power supply interruption 9 30A GENERAL SPECIFICATIONS PROTECTIONS ON OFF muting DC fault load grounding relay Internal fault fuses CONTROLS Front AC switch CONTROLS Rear Low pass filter mode selector SIGNAL INDICATORS 2 green LED CLIP 2 red LED POWER INDICATORS 1 Blue ...

Page 8: ...www altoprofessional com MANUAL VERSION 1 2 ...

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