The black art of disc cutting has always intrigued me and I always had great admiration for my colleagues in Decca who had mastered this skill and demonstrated it with precision.
Pre 1950 virtually all recorded material was cut directly to wax discs. Radio stations used 16” transcription discs which operated at 33.3rpm and had capacity for 15 minutes of material on each side. While at Decca I had the privilege of transferring the entire collection of Bing Crosby’s radio recordings from such discs. These programmes had been sponsored by Kraft, Chesterfield Cigarettes and Philco Radio and had been broadcast in America throughout the 1940s and 50s. However, due to problems with copyright, we were unable to release any of the restored material at the time which was unfortunate because the shows included a host of top names of that era, Al Jolson, Anne Shelton, Bob Hope, Andrew Sisters to name just a few.
Once magnetic tape was adopted in recording and radio studios around the world the need to cut direct to disc was soon abandoned. All recordings were made to tape with the advantage of editing, re-recording, multi-tracking and greater versatility.
The disc cutter came into his own when the finished master tapes were passed to him for transfer to disc. Developments in the 1950s meant that wax discs were replaced by lacquer-coated metal blanks. The lacquer was a cellulose nitrate coating soft enough to be easily engraved by the cutter yet hard enough to permit a number of direct plays. This ruggedness meant that during the cutting operation the engineer could monitor the quality of the cut by switching between the signal applied to the disc and the audio actually cut onto the disc. The picture below shows Decca disc cutting engineer Harry Fisher using a Neumann cutting lathe to produce a master lacquer disc. Harry had a great fondness for music from the 1940s and 50s and was therefore always assigned the tasks of cutting the material I worked on. Every cutting engineer would leave his insignia in the run out groove of the discs they cut, we termed it the “dash number” Harry’s was always W, Trevor Fletcher, who cut all the Decca singles was C. Their insignia was always preceded by the lacquer reference number. For example if a disc was the first cut from the master tape the dash number would be -1W. Sometimes the master discs were damaged in the processing operation at the pressing plant. A second or third disc would then need to be cut; these would be -2W or -3W and so on.
Decca Disc Cutting Room
In the photo you can see Harry inspecting the quality of the groove using a x40 microscope. To the right of the picture (just out of shot) is a rack carrying the high powered amplifiers necessary to energise the cutting styli. These amplifiers were generally operating in the order of 600w per channel, this amount of power generated heat on the coil cutting head of 200 degrees Celsius. This was cooled using helium gas. The stylus itself was heated which allowed a smooth cut in the lacquer therefore reducing surface noise.
Other points of interest in this photo: firstly the Decca made console in the middle of the shot. Every cutting room and tape duplication room had a similar sized console with standard equipment; Decca designed and made equalization units, limiters, test tone generator, quadrant faders and remote control switching units. Also seen in this shot is the triangular shaped meter panel. All monitoring at Decca was performed with PPM meters working to a reference point of + 4dBm, peak recording level was usually +8dBm. For comparison purposes a pair of VU meters were also on this panel. On the rear of the console you can see the patch field. To the left of the console and built into a white cabinet is a Garrard 301 turntable for the playback and quality check of new pressings as seen on the table. Outside of the shot is a Philips Pro’ 51 tape machine. These machines were standard in most of the rooms by the early 1970s. The Pro’ 51s used in these cutting rooms were especially modified by our engineers to include an extra playback head. This head was situated before the main bank of heads and allowed an early audio signal to be sent to the lathe for groove adjustment depending on modulation variations.
My grateful thanks to Wes Stillwagon who administers the excellent Mantovani web site: www.hallowquest.com/ and who kindly allowed me to reproduce this photograph.
