Audio Restoration 101 - One method of De-noising using DC8

This is my "preferred" method of noise reduction:
1. Choose your turnover frequency response.
2. Low and High pass filter the audio (I use a 10kHz low pass consistent with the theoretical recorded frequency range of 78s).
3. Multiple Continuous Noise Filters (different FFT sizes from 2048, 1024 and 512 or 256).

By performing the noise reduction in multiple steps you can avoid generating digital artifacts that may otherwise result. The idea is that you use the 1st more "specific" run of the CNF to partly separate the noise from the music content. The 2nd run aims to further the noise separation and reduce the noise to a more reasonable level (you can attenuate more than the 6dB I have here). Then the last run is to set the desired residual noise with lesser effect on the ambiance/timbre of the recording than the other larger FFT sizes.

It takes a bit of fiddling to get used to, but give it a go. It produces a very different effect from doing a single CNF pass with a noise attenuation of 18dB or more.