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K5181 • Classic 250W Class D Audio Amplifier Kit


Cat. Page 199

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  • $69.95
  • 4+ $62.95
  • Price per each
  • Includes GST


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Last updated 25-10-14 10:04:41

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Loudspeaker Protector Kit to suit K5181


  • $19.95
  • 4+ $17.95
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(Silicon Chip Magazine Nov 12) This high specced power amplifier operates in Class 'D' as opposed to earlier amplifiers which run in the more conventional Class 'AB' or Class 'A'. The new Class 'D' amplifier offers the extremely low distortion figures of a Class 'A' whilst still having the efficiency of a standard class'AB' amplifier. This simple to build kit with its 250W into 4Ω output will make an ideal subwoofer or front floorstanding speaker driver in a home cinema setup.

Important Note For Kit Buyers:
This product is supplied in component form and requires soldering, drilling, and assembly. We recommend users are familiar with at least basic electronic principles and have the ability to solder.


  • High efficiency
  • high power
  • Low distortion and noise
  • Bridging option for driving 8Ω loads with two modules
  • Over-current protection
  • Over-temperature protection
  • Under-voltage switch-off
  • Over-voltage switch-off
  • DC offset protection
  • Fault indicator
  • Amplifier running indicator
  • Optional speaker protector module

Why buy an Altronics Kit?
Altronics kits are premium do-it-yourself projects designed to be assembled with ease. However, basic electronics knowledge and soldering skills are essential to construct our kits. A difficulty rating is provided to help determine if your ability is sufficient to build the kit project. Please note, once assembly has been commenced we are unable to honor any warranty claims. Please see the full details here.


  • Total harmonic distortion and noise: Typically <0.01%
  • Power output: Up to 150W into 8Ω and 250W into 4Ω power supply dependent
  • Power output, bridged, 8Ω only: 450-500W power supply dependent
  • Efficiency: Typically 90% at full power for 8Ω and 83% for 4Ω
  • Signal-to-noise ratio: 103dB with respect to full power
  • Input sensitivity: 2V RMS@4Ω, 2.2V RMS@8Ω
  • Frequency response: 10Hz - 20kHz +/-1dB
  • Power requirements: +/-40 - 60Vdc, 50-55V nominal
  • Over-temperature cut-out: 75C
  • Under-voltage threshold: +40V
  • Over-voltage threshold: +75V
  • DC offset protection threshold: > +/-4Vdc
  • Over-current threshold: 29A
  • Idling (no signal) frequency: 500kHz adjustable
  • MOSFET dead time: 45ns

*Specifications are subject to change without notice.

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  • Hi there, What is the power supply required for this unit? Cheers Global PC
    Global PC

    Power supply, transformer, rectifier etc are not included. However the kit instructions (page 14) do give some extra detail on suitable parts to buy. For example, the K 5168 power supply kit is suitable for use as a power supply, along with a 35-0-35 transformer (such as M 5535) and a bridge rectifier (Z 0091.)