I returned to DIY electronics in 2009 after a 20 year pause by building a few kits to get in shape. This blog is for me to keep track of my progress.
Aikido headphone amplifier
Posted 11th June 2017 at 04:16 AM by alexcp
I built a headphone amplifier using John Broskie's Aikido All-in-One PCB with Tube Rectifier. The PCB is well made and easy to build, and I am satisfied with how it sounds.
One comment is that R9, R10, and R13 (see the attached schematic) affect the distortion introduced by the circuit. By changing R13, I was able to cut the distortion by as much as 90%, from 0.2% @1kHz 1Vrms output down to 0.02%. My optimum was R13=90ohm with B+ at 310V (using the recommended Hammond 270EX power transformer) and all other values as in the attached schematic.
One comment is that R9, R10, and R13 (see the attached schematic) affect the distortion introduced by the circuit. By changing R13, I was able to cut the distortion by as much as 90%, from 0.2% @1kHz 1Vrms output down to 0.02%. My optimum was R13=90ohm with B+ at 310V (using the recommended Hammond 270EX power transformer) and all other values as in the attached schematic.
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