A Custom Audio Test Set (vintage 1969) from the NOS

In the post-war years, the Nederlandse Radio Unie – which later became the Nederlandse Omroep Stichting or NOS [Netherlands Broadcasting Foundation] – was a pioneer in making very high quality audio recordings, and in broadcasting those recordings without any loss of quality. Their attitude was that they were the source of the audio, and any form of distortion was unacceptable. This article aims to show that NRU/NOS electronic engineers were serious about the business of keeping that horrid ‘D’ as low as possible.