https://stream.echo6.co/videos/watch/f337cb65-45c1-4f0b-a4a2-b95934639a97 Dave reverse engineers the XuanZu X2-U808 Hi-Fi Headphone Amplifier to see if the valves actually do anything. What is the circuit topology? E180F (6J9) pentode valve datasheet: http://frank.pocnet.net/sheets/009/e/E180F.pdf Doug Ford's Microphone design series: https://www.youtube.com/playlist?list=PLvOlSehNtuHv98KUcud260yJBRQngBKiw Reverse Engineering How-To video: https://www.youtube.com/watch?v=lJVrTV_BeGg Forum: http://www.eevblog.com/forum/blog/eevblog-837-reverse-engineering-a-valve-headphone-amplifier/ EEVblog Main Web Site: http://www.eevblog.com The 2nd EEVblog Channel: http://www.youtube.com/EEVblog2 Support the EEVblog through Patreon! http://www.patreon.com/eevblog EEVblog Amazon Store (Dave gets a cut): http://astore.amazon.com/eevblogstore-20 T-Shirts: http://teespring.com/stores/eevblog Donations: http://www.eevblog.com/donations/ Projects: http://www.eevblog.com/projects/ Electronics Info Wiki: http://www.eevblog.com/wiki/ 💗 Likecoin – Coins for Likes: https://likecoin.pro/@eevblog/dil9/hcq3 Tue, 12 May 2026 13:29:27 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://stream.echo6.co https://stream.echo6.co/client/assets/images/icons/icon-512x512.png https://stream.echo6.co/videos/watch/f337cb65-45c1-4f0b-a4a2-b95934639a97 All rights reserved, unless otherwise specified in the terms specified at https://stream.echo6.co/about and potential licenses granted by each content's rightholder.