[Reader-list] audio restoration

[budhaditya chattopadhyay]

Hi all

It's monsoon, a nice time to work indoor. I am currently working with the restoration process of the transferred recordings from 78 RPM 10 inches discs of Bishnupur Gharana recordings. I did the transfers using one DUAL and a PHILIPS 533 turntable. The main concern at the time of play-back was the speed and the signal chain. For speed control I kept the turntable on rotation without load for one day and with load for one day checking the speed in alternate hours. Tried to avoid transmission loss at the signal chain with better pairs of cables. Used balanced I/O connectors at the line levels. 
I transferred the audio materials to a Digital Audio Workstation with a Creative Audigy Platinum Professional sound card. This sound card is easy to use and enough to handle a limited dynamic range of shellacs. I recorded the tracks on NUENDO, and using Adobe Audition 2 for cleaning the surface noise. Here is a trick, I take out the noise with a medium sized FFT and put it in reverse against the original track. It is certainly eating up the original noise content of the disc surface to a decent level. Hereafter, I’m using an optimum level of equalization in NUENDO. But the processed sounds are renamed and kept separate from transferred originals as meta-data in pool. 

Each disc was cleaned of its surface dust before play back. For that I used solution of Labtone Detergent in de-ionized H2O. Bought one polyester velvet to use as a cleaning cloth--the pile is soft but gets into the grooves effectively without scratching. Labtone is a balanced detergent, rinses off totally (in de-ionized water, off course) so there is no residue to worry about. The discrete droplets of water left on the surface can be quickly dried with 100% cotton wipes. Shellacs are to be exposed to moisture the absolute minimum of time, if at all.

More on the discography and thanksgivings to the private collectors
in my next posting..

Enjoy monsoon.

Budhaditya 


  
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