https://hermitaudio.github.io/index.htmlWelcome to the Terje Sandstrøm Audio Technology site For several years I worked on the design of audio equipment for very high fidelity use, primarily for Electrocompaniet. As I no longer work actively in that field, I’ve put as much of what I know onto this site for anyone to look at. This site covers the audio technology I worked on, the history of the early Electrocompaniet period from 1975 to 1980 and their “Otala” 25W amplifier, plus schematics, troubleshooting guides, theory articles, my M.Sc thesis on weak non-linearities, and other audio-design work.Hugoen-ushttps://hermitaudio.github.io/history/index.htmlMon, 01 Jan 0001 00:00:00 +0000https://hermitaudio.github.io/history/index.htmlHistory The story of the early Electrocompaniet period (1975-1980) and the “Otala” 25W amplifier: the people involved, the press coverage, the brochures. Ported from Legacy/: the Otala story, the people involved, protection networks, the Audio Critic test, marketing brochures, and Norsk Radiofabrikk. Not ported: photo.htm (a generic FrontPage sample-photo placeholder with no real content) and news.htm (a changelog of the old website itself, not Electrocompaniet history).https://hermitaudio.github.io/schematics/index.htmlMon, 01 Jan 0001 00:00:00 +0000https://hermitaudio.github.io/schematics/index.htmlSchematics & Troubleshooting Circuit schematics and troubleshooting guides for the Electrocompaniet amplifiers and preamplifiers, from the original 1973 Otala design through the EC production schematics, the 1982 preamplifier, and the later NRF/Special Version modifications. Ported from Legacy/: evolution of the schematics, original 1973 schematics, the real EC schematics, 1982 preamplifier schematics, transformers, wiring & mechanical assembly, troubleshooting the amplifier, troubleshooting the preamplifier, the NRF modifications, calculations on the 25W amp, and the regulated 25W power amplifier.https://hermitaudio.github.io/theory/index.htmlMon, 01 Jan 0001 00:00:00 +0000https://hermitaudio.github.io/theory/index.htmlTheory The theory of the Otala amplifiers, and thus the basis for the Electrocompaniet amplifiers, has been detailed in many papers, mostly by Matti Otala, but also by several others. At Electrocompaniet these theories were extended, and a theoretical framework for our amplifiers was established. The following pages give you an insight into both the original theories by Dr. Matti Otala, and also the theories built up in the first years of Electrocompaniet. Some of the thoughts are solely mine, however — don’t assume that Electrocompaniet of today will vouch for all I say here :-)https://hermitaudio.github.io/thesis/index.htmlMon, 01 Jan 0001 00:00:00 +0000https://hermitaudio.github.io/thesis/index.htmlM.Sc Thesis — Weak Nonlinearities University of Oslo, 1985 The thesis itself will be uploaded once it’s converted, preferably to English, and at least from printed form — it was written on a long-forgotten computer and I’m no longer able to read the diskettes. (Update since the old site: a scanned copy of the printed thesis exists and will be added here.)https://hermitaudio.github.io/audio-design/index.htmlMon, 01 Jan 0001 00:00:00 +0000https://hermitaudio.github.io/audio-design/index.htmlAudio Design Miscellaneous audio-design work not tied directly to the Electrocompaniet history: the school amplifier project, cooling-fin calculations, the AES paper on AB distortion, later prototypes, and other designs. Ported from Legacy/: the School Amplifier, the ultimate cooling fins, the AES paper on AB distortion, the May ‘78 preamplifier, later designs (the 1982 preamplifier and power amplifier prototypes), other designs (including the “Krinken” preamplifier for NRK), and the Perfect 25W Amplifier design notes.https://hermitaudio.github.io/about/index.htmlMon, 01 Jan 0001 00:00:00 +0000https://hermitaudio.github.io/about/index.htmlAbout Independent consultant and former Visual Studio ALM MVP. Former audio designer at Electrocompaniet. Born 15 September 1956 in Oslo, Norway Spouse Ann-Louise Children Uno, born 24 Nov. 1983; Isabel, born 3 Oct. 1996 Occupation Independent software programming consultant at Hermit AS Open Source NUnit Core Team Lead Education Cand. Scient in Physics (Master’s degree) from the University of Oslo Location Hvalstad, a place in Asker 20 km south-west of Oslo, Norway Awards Microsoft Visual Studio Development Techniques MVP, 2009-2024 Blog Hermit Contact I do answer questions on audio and early Electrocompaniet amplifiers. Send me a private message on Facebook or Twitter.