I measured the vinyl roar on one clean record at about -40 dB in the low bass, but I want to do that measurement again more carefully—I recently bought a new test record through which I have not plowed furrows yet. (That project follows my current project of getting my CDs ripped.) I can’t hear it when -40 dB is masked by ambient noise, but that’s at fairly low listening levels. I can hear through it even it’s audible. My preamp’s phono section is known for a quiet background, and it is that when the arm is up, so I know what’s causing it.
Usually what has me looking for CD versions of vinyl LPs is some semblance of restored dynamics. The cutting engineer (what we used to call the mastering engineer) has to make choices to fit stuff in the dynamic range of a vinyl LP, and often it seems that remastering is just transferring what’s on the final tape mix to digital without that extra step. Maybe they do a bit of judicious noise reduction to reduce tape hiss. But it’s mostly the dynamics I’m looking for on a “remastered for digital” CD.
But a lot of my LPs sound really good without that and the music material masks the roar. If the dynamics are preserved, there will usually be some distorted peaks on those high-production-volume 70’s LPs, but that just matches the distortion in my left ear.
Rick “agreeing, in case it isn’t obvious” Denney
-40dB is about right for LF noise, which makes rumble measurements difficult. I don't know how some reviewers get rumble figures of -60dB or more from an LP. Using a rumble bridge avoids the LP itself, but there are few of those about.
LP cutting and mastering are separate although closely related activities.
In the Good Old Days, when LPs were released all round they world, Major labels like CBS and EMI would have the LPs pressed locally, both for cost and logistical reasons. However, it was important that all LPs were nominally the same wherever pressed, so the original master tape was cut by the original cutting/mastering engineer. Cutting an LP from a flat, finished stereo master tape involved lots of decisions including things like HF limiting, reduced separation in the bass and often dynamic EQ and compression, all designed to get the best out of vinyl's limitations. These decisions were committed to tape, and a
Disk
Cutting
Master created, which converted the flat stereo master into a tape that could be copied and sent round the world to pressing plants for them to cut locally. As all the difficult decisions were incorporated in the DCM, all the local plant had to do was to cut a flat copy of the tape with no further changes. Assuming the local plant was well set up and maintained, this would theoretically result in a pressing that was indistinguishable from one pressed in the original CBS, EMI or whatever plant. Of course the reality was sometimes different, but at least that's how it should have worked. Listening to a DCM tape was rather different, and generally nothing like as good as the original final master, as it needed the limitations and changes made by the LP manufacturing process.
One aside, is that DCMs should only ever have been used for cutting an LP, but in the early days of CDs, quite a few got used, out of ignorance or carelessness, for producing CDs. The result was fairly predicable, that with a completely flat reproduction method such as CD, all the adjustments necessary for vinyl were audible, and unpleasantly so. I had a couple of DCM copies on tape many years ago, and they certainly sounded odd when played at home.
S.
