March 31, 2014

Karajan remastered: how did they do it?

Simon Gibson, one of the 'fab four' engineers at Abbey Road Studios, explains the process and sound philosophy.

Four Engineers at Abbey Road Studios in London have remastered Karajan's historic EMI recordings from their original analogue sources for release in this anniversary edition. Between them, Simon Gibson, Ian Jones, Andy Walter and Allan Ramsay have many years of experience remastering archive recordings for EMI and other record labels. 

The process always starts with finding all of the records and tapes in EMI's Archive in London and comparing different sources and any previous CD reissues. We consult each recording's job file, which contains notes about the recording sessions made by the engineer and producer. These sometimes explain why there are more than one set of tapes to choose from. The recordings come from 78rpm records and mono or stereo ¼ inch analogue tapes, dating between the 1940s and the 1980s. All of the tapes are in good condition and we play them on our Studer A80 1/4-inch tape machine, after careful calibration of its replay characteristics.

The decision to remaster in high resolution was made because these recordings have never been transferred in this way before. By doing so, we can achieve a quality which is much closer to the original studio sound. We transfer from analogue to the digital domain at 96KHz and 24-bit resolution using a Prism ADA-8 converter and capture the audio to our Sadie Digital Audio Workstation. If necessary, we then use CEDAR audio restoration technology to reduce and remove clicks, pops and any hiss that we feel are too intrusive. Each piece of music is edited together, with ambience added between movements where necessary.  

A few of Karajan’s recordings from the 1970s were made using 1-inch, 8-track analogue tapes and, where we have these tapes, we remaster them in preference to the 2-track stereo LP master tapes.  By making an 8 track A/D transfer at 96k 24-bit and then creating a new stereo mix, we achieve a much better sound than if we had just used the original stereo LP master tape. Listen, for example, to the Wagner operatic preludes or the Brahms Violin Concerto with Gidon Kremer — all remastered from the original 8-track tapes.

The final stage of the remastering process is to make an equalised version, using the analogue EQ of EMI's own TG12412 and 12414 tone control boxes. The finished, remastered, high-resolution audio is converted to standard CD format and sent for production.

This is the first time that these great recordings have been released in a high-resolution format, offering the listener more clarity and detail than ever before.

Simon Gibson, March 2014

The first three box sets in the Karajan Official Remastered Edition are available now.