LAB REPORT: MICHELL PRISMA (Vintage)

摘要

The Prisma's various rumble spectra [see Graph 1, below] are instructive because they reveal a series of structural modes -most obvious on the through-bearing trace (black) - at 62Hz, 70Hz, 81 Hz and 85Hz. The main 62Hz drone is some 25dB above the vinyl noise floor and a good 10dB higher than the hum components at 50Hz and 150Hz. It may well exert some subjective impact. The modes are sufficient to appear directly on the flutter spectrum of the deck, albeit at a low level, as is clear from the 'clumps' at approximately ±60Hz either side of the main driving tone on the W&F plot [see Graph 2, below].