Monday, February 12, 2024

"Clarity II" - LJM Class AB power amp












 

This was a slow burn build. I had completed the amp section but no PS. After completing two commission jobs I could finally complete the amp. The compact enclosure for the amp was built around two heatsinks I had had for years and the enclosure for the PS the same. Caps standing out of the top of the PS I was given years ago and are Nippon Chemi-com. Total capacitance is not large but is well snubbed and the amp is quiet.

Two fast diodes provide rectification and four 3.3uf polies snub the bigger caps which are 3900uf each. Tranni is 160VA so the amp is capable of 80Wpc. The LJM Class AB modules used are rate 120W and are all bipolars. I like the sound of bipolar transistors and these modules contain nothing else and are very inexpensive. 

A local metals provider cut the plates for the amp to my specs and after a lot of drilling and tapping came together well. Three large gold plated brass cones balance the amp and add to the looks and improves the sound. An umbilical cord connects PS and amp using a large XLR connection. DC offset for these modules does not require adjustment and is extremely low.

The sound is super clear, detailed and expansive. Bass extends just beyond 30Hz the limit of my speakers. Regardless of type of music played it comes through, clear and uncluttered. After hours of listening the amp is still cold. I believe the amp would have no problems driving low efficiency difficult speakers. Very pleased with both the looks and the sound. 

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