MItAC update

- reading and note-taking continuing on vinyl physics, a few interesting facts that may have direct consequence to our study

• cutters use carriage that moves radially across vinyl, whereas playback turntables typically rotate from a pivot. Thus such turntables suffer from unavoidable pitch/azimuth errors
• RIAA reproduction EQ curve (the inverse of the RIAA lathe cutter curve) does not account for the typical 50kHz rolloff in most lathes. Optical methods could allow properly compensating reproduction curve, as well as compensate for non-standard EQ curves used prior to standardization
• curvature of playback stylus greatly determines amplitude of certain frequencies i.e. elliptical stylus fits into tightly packed modulations better and allows for more displacement, thus explaining better response to higher frequency. Optical method completely avoids this and is now only limited by groove space requirements and capabilities of cutter
• tracing distortion (caused by differences in linear travel speed of stylus across record width) is unavoidable, and results in different frequency performance in inner and outer grooves. Outer modulations perform better at higher frequencies since modulations are stretched out, which is the same principle as improving sound quality via increasing rpm. Again optical method completely avoids this in theory

- updated Wiki to include vinyl physics links found on the internet. Draft status
- EndNote database started to incorporate large body of work in Journal of AES on phonographs