• Item: Low profile 100W Class D amp  
  • Type: retro-thermionic “Image”  
  • Posted: 8 February 2020  
  • Builder: mwhouston  
  • Country: Australia  
  • Comments: 0  


"Image" started off as a low profile 150W Class D amp but though it sounded very good I could not remove a very low level buzz. I changed the amp to a 25W chip amp but that played no music regardless of all voltages being correct and no cct. errors.

Wanting to make my own Devailet right from the start I found a very inexpensive, extremely compact 100W Class D module using some newer Class D chips - TDA7498. The amp will produce 80W into 8ohms and works from the original PS I built in this chassis. A 36V single rail well filtered (19,000uf) PS supplies dead quiet current to this power amp. As with most of my builds the amp includes a RFI/EMI power filter and a ferrite choke on the power cord. Part of the supply filtering is a 10uf poly and two 0.1uf polies. These are to provide a better mid and high frequency signal path and reduce bridge (35A) and filter cap noise.

The amp looks super smart in its ash black stippled 1U 19" rack mount enclosure with handles. It sits on rubber feet and has quality gold plated RCAs and solid brass three way binding post. A retro-thermionic amber "ON" LED and power switch are upfront for easy access. The amp in operation is dead quiet has excellent bass extension and sounds balanced over the rest of the frequency range. It sounds much bigger than its 100W rating and appears to drive all my speakers very well. Even after hours of use it is cold to the touch above the heatsink. Very pleased with he compact build and overall sound.


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