NelsonPassAmp.qsch (18.4 KB)
Welcome to a new weekly feature on the QSPICE Forum. Each week, we’ll be posting a schematic capture you might find interesting. Please send any submissions to me at tim.mccune@qorvo.com
This simple audio amplifier schematic was done by Nelson Pass, a friend and renowned audio amplifier designer. Nelson came up with this design for beginning students to build. Our friends at diyaudio.com offer a kit with the entire BOM. https://www.diyaudio.com/community/threads/amp-camp-amp-aca.215392/ (Schematic Capture Post #001)
That’s the value Nelson Pass set in the design. R14 is used to bleed off
DC voltage through C1, preventing thumps from the addition or removal of sources and loads. One of the things students building this project would do is change the value of that and see what happens. Some more info is attached. art_amp_camp_1.pdf (1.0 MB)
Thanks for the pdf, there it’s made completely clear with a schematic that properly shows external connections. (Nice to see that the schematic in the pdf is drawn according to Mike’s rules [as published elsewhere a while ago], with, e.g., properly sized junctions.)
Did a double take on the photo of the gargantuan heat-sink: I was not expecting a Class-A design :–)
Yes, my son did that project a dozen years ago, in high school, the heat sink was the highest-cost item, aside from the enclosure. He still has them, they were fun dorm room amps.
Definitely a bad way to draw a schematic diagram…Qspice uses very small join dots, so from a screenshot of wire crossing it is not easy understanding where a connection is present and where it does not. Four wires in a cross must not connect to a point, wires must not cross and connect.
