I have some CDs of music by the great conductor Arturo Toscanoni…these were recorded by the NBC symphony orchestra, in the time period 1952-56, by the RCA label. These are great…possibly some of the finest renditions of Rossini ever made…however, they are old, and the sound quality seems a bit degraded.
The wind instruments come in great (flute, clarinet, bassoons), but the brasses seem a bit flat. Also, the dybnamic range isn’t quite as good as in a modern recording…overall the effect is also flat.
However, the microphones used were quite sensitive…I could actually hear a amn coughing in the background.
My question for you sound guys: presumably RCA enginners used the best technology available at the time…would that be a multi-track taperecorder? Also, it appears to be in steroe-were stereo recordings done that early?
All in all, these are stillsome great pieces of music…and, the background noiselevel is pretty low(no60-cyclehum apparent to me).
Would these recordings have been dolby-processed?
Anybody knowif earlier performances by Toscanini arre availableon CD?
You gotta whole lotta questions wrapped up into one!
Multi-track recorder: could possibly be, as Les Paul created the first one in the early fifties. However, per this site the first multi-track recorder (2 tracks) didn’t come out until 1954, so it’s unlikely.
It seems that Dolby Noise Reduction was not created until the mid sixties, so it certainly wasn’t a part of the orginal mastering process (what happens after the recording and mixdown, but before duplication).
As for stereo - Stereo didn’t become a widely used format until 1965 (advent of the Stereo 8) - People had been experimenting for decades, but between the lack of public format and the lack of recording technology (see above), I find it extremely unlikely that this was recorded in stereo.
60 cycle hum is not what is usually referred to by “Background noise”. 60 cycle is a specific byproduct of poor grounding, and would indicate a total moron of an engineer was involved. Noise is related to equipment quality and of technique - when mic’ ing you try to use as “hot” a signal as possible without overdriving your hardware - more sound = less noise - and the poorer the quality of hardware, the more noise is introduced by the circuitry itself.
If the recording is remarkably devoid even of this type of noise, it owns to the room, the mic, and the mic placement more than anything else. Unless you’re talking about true background noise, like people shuffling feet, adjusting chairs, cars going by outside, hot dog vendors doing buisness in the aisles - the solutions to which should be extremely obvious and have little to do with recording engineering.
So what you are most likely listening to is the product of some carefully placed, good quality mics (mic technology had already come quite a way), and some excellent musicianship. That’s back in the day when you coulding piece together performances measure by measure. . .
Finally, An Overly Pedantic Nitpick: Of course these are still great pieces of music - that has nothing to do with the recording, or even the performers! What is “still great” is the capture of a performance, considering the technology of the day. 
This post is based on my general knowledge of the biz and a bit of web surfing - call it an educated guess.
As I mentioned, the microphones used were pretty good…if Iturn up the volume, I can hear the man coughing! I also understand that old recordings acn be digitally cleaned up-how do you remove extraneous noise from such a recording.
Also, if two tracks were made (from spaced microphones), can a 'stereo"type remastering be done?
Some very well respected makes and models would have been available then - a lot of studios will have a Neumann U87 in their armoury. These mics were certainly around (albeit in a vacuum tube rather than modern-electronic variety) since 1949, and are very highly thought of - in fact a lot of people swear that the older ones are better, although probably slightly noisier than their modern counterparts.
You certainly can clean up old recordings. In the early days of digital this was an expensive option utilising dedicated hardware, but these days a lot of pc/mac-based wave editing packages have plugins which will generally remove the worst artifacts. As with a lot of this technology there are generally a number of parameters the user can tinker with, and the trick is to remove just enough without noticably altering the underlying recording. Too much and you throw the baby out with the bathwater. There are also plugins for eq’ing and artificially widening the stereo perspective.
I’m not quite sure what you’re asking here. If you recorded onto a 2-track (i.e. stereo) machine in the first place using a pair of mics then both your tracks are - of course - perfectly in synch. If you have two separate recordings (say one recorded in the left hand side of the hall, one on the right) you’ll never get them to stay in synch. Even if you transfer them to a wave editor (and hence can move the start position of one of them so that they start exactly at the same time) the machines used to play the recordings into the pc won’t stay locked at the sample level. Sorry if I’ve misunderstood what you were getting at…
They could always do the old “reprocessed for stereo” trick where everything below a cutoff frequency went to one channel and everything above it to the other. It’d sound lousy but you’d have two different channels.
Seriously, one reason for the lack of brightness on the CDs could be because 1952-56 was very early in the life of magnetic recording as a professional recording medium. Tape technology itself was only about fifteen years old. Early tape didn’t have the dynamic range of modern tape and it was subject to a lot of hiss. I suspect that the original tapes were put through some form of noise reduction when the CDs were made (not much, including Dolby, was available when the originals were recorded) and the brightness baby was thrown out with the hissing bathwater.