• Item: Pass inspired F5  
  • Type: retro-thermionic - "Essence"  
  • Posted: 25 July 2021  
  • Builder: mwhouston  
  • Country: Australia  
  • Comments: 0  

Class A power amp

Being very impressed with my earlier F5 build (see previous post) I made a second but this time spent a lot more on a better, cleaner, more robust power supply. Same Jim's Audio amp boards but now with Mundorf MLytic audio grade filter caps. The caps are larger providing a total of 88,000uf of filtering. Again the filter caps are snubbed to ensure a dead quiet PS and an extremely pure midrange and treble. Only twisted pairs of Cat5 solid core wire used throughout for all hookups. No shielded wire for the signal path.

To bolster the PS even more a 300VAC transformer was used. Bigger caps and bigger tranni made for a tight fit in, once more, a compact pro enclosure. The enclosures got lost in transit and when finally arrived the front panel was scratched and gouged. To hide what I couldn't sand out a hammertone copper finish was applied. This has a nice textured finish and looks excellent.

All the audio and sonic qualities of the previous build were even more enhanced in this build. Hearing deeper into acoustic instruments and texture in voice were far more evident. 25W in my system is more than enough and this build has impressed me so much I am making two more with the intention of keeping one and selling the other. Such a simple design and inexpensive to build, I have to have one for myself.


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