After the euphoria over receiving my new Sony Minidisc bundle had partially subsided, I noticed that the portable unit, the MZ-E40, has a rather weak output. Measurements showed that it can only manage 80mV rms output and only about 74dB SPL output from the phones. This is when recording at average level with 8dB of headroom. In contrast, an orchestra can deliver more than 95dB SPL and they aren't considered headbangers. I tried all sorts of solutions, but in the end realized that the only solution yielding the headroom and quality worthy of the marvelous minidisc is to build a headphone amp from scratch.

Build your own LC Meter and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils. LC Meter can measure inductances starting from 10nH - 1000nH, 1uH - 1000uH, 1mH - 100mH and capacitances from 0.1pF up to 900nF. The circuit includes an auto ranging and "Zero Out" function to make sure the readings are as accurate as possible ... [more]