Altec Lansing 6125A, 4200A manual Distorted Sound, Hum or Buzz Noise, Dimensions

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Operating Manual 6125A and 4200A Multi-Channel Power Amplifier

11.2Distorted Sound

1.) Clip LED is flashing regularly

Amplifier is being overdriven. Turn down the in- put level control, or reduce the output level from the sig- nal source.

2.) Clip LED is not flashing at all

Amplifier input signal may be exceeding input headroom, which is greater than +12dBu, or 3.4V rms (measured using continuous 1kHz sine wave). Incoming signal level higher than +12.8 dBu will cause distortion in the amplifier. Turning down the input level controls will not eliminate distortion if the input headroom is exceeded. Turn down the output level of the device driving the am- plifier instead.

Additionally, an input signal may already be dis- torted before it gets to the amp. Check to see if a piece of equipment in the signal chain before the amp is clipping. For best performance, the amplifier should be operated with input levels fully CW. Also check for damaged speaker drivers that could cause distorted sound.

11.3Hum or Buzz Noise

Be sure that the power cord’s 3-prong plug is con- nected to a properly earth-grounded outlet. Lifting the grounding third prong may not improve hum or buzz and can create a potential shock hazard.

Hum is usually caused by ground currents flow- ing between different pieces of equipment. Ground cur- rents can be minimized by using a single point AC ground for the sound system, and by using balanced connections with quality cable throughout the audio path.

Buzz, as well as certain audible high frequency tones, can be caused by environmental emissions such as lighting dimmers, neon lights, or computer equipment. Use balanced connections, and try moving the amplifier, wir- ing, lighting, or other equipment to different locations to isolate the source of the noise.

Sections 3.3, 5.3, 7.1, and 7.2 further discuss is- sues related to grounding and noise problems.

12.DIMENSIONS

16.9" (430)

13.5" (344)

2.25"

(57.2)

13.2" (335)

1.25"

(31.8)

18.5" (470)

 

 

 

 

 

 

 

 

 

 

 

 

5.19" (132)

 

4.75" (121)

 

 

2.25"

 

 

 

 

 

 

 

 

(57.2)

19" (483)

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Contents 6125A 4200A Table of Contents Risk of Electric Shock Do not Open Unpacking AC Power RequirementsIntroduction Voltage RequirementsCable Requirements RACK-MOUNTING RequirementsFront Panel Features Input Ground Switch Rear Panel FeaturesInput Connectors 50Hz Low Cut SwitchStereo/Mono Switch Input Level ControlsSELF-PROTECTION Features AC InletSpecific conditions resulting in a fault are as follows Typical ApplicationsSix Channel Setup dual stereo Bridged Mono Setup No Audio Output Troubleshooting TipsDesign Theory Hum or Buzz Noise DimensionsDistorted Sound 6125A 4200A SpecificationsWarranty Information 6125A4200A6125A-0