• Slowly...

    Shrad • 05/18/2017 at 22:29 • 0 comments

    Slowly progressing as raising children consumes a complete time and more...

    Prototype input stage with PAM8304 basic ebay board and homemade 35:5 transformer... experimental results show an unloaded voltage gain of 40 which is nice as a 5V swing will generate a 200V output, perfect for driving any phase splitter as soon as I have the miliamp or so to do it

    Completing board tomorrow :)

  • Slowly getting further...

    Shrad • 04/25/2016 at 15:29 • 0 comments

    small news is better than no news, I scored a little 40W push-pull valve amp on a local second hand site for 50€ and will use it as an intro to debugging valve amplifiers with the help of a book from publitronic (modern valve amplifier design) to gain better knowledge of how it works

    once I have a better hand at it I'll make a small push-pull of EL36 like the one at http://www.guitargear.net.au/discussion/index.php?topic=34435.0 and try to drive it with the PAM module

    once this is OK I'll adapt the PFC stage of a DELL server PSU

    the current process is to trace a 1kHz sinus along the signal path of the 40W amplifier and find the source of an anormal clipping at the input stage

  • First fiddling with the concept...

    Shrad • 03/24/2016 at 16:10 • 0 comments

    Just received today a PAM8403 based 3W class D filterless amplifier which works at 200~300kHz

    A crude test with audio in, 5VSB transformer at output gave a swing of 240V at the oscilloscope... looks promising

    I'll have to set up a small valve amp SE stage to proof the project viability, and check optimization at the PAM8403 output stage :)