If you use such a system, you will need to post filter your recordings, in a way opposite to what the RIAA equalization changed. The above two examples are excerpts from Edward M. Favor's 'Theodore', recorded around 1905. The record is loud and clear, but does have a normal amount of surface noise and wear. The spectrums shown above are each from this same record, showing the same slice of time, about one second. Time is represented from left to right, and frequency is displayed from the bottom, to the top.
Color shows how intense the energy of a given frequency is, at a given time.
Black represents no energy, while yellow indicates the greatest energy. This record's meaningful signal is mostly between 250-3000 Hz. Most of the color displayed should be below the 5000 level, as seen at the right, in the spectrum graphs. Color seen above this level, will indicate noise. The light weight, modern cartridge requires a large amount of amplification, and is very sensitive to every inflection in the surface of the record.