The main advantage is better signal to noise ratio and secondarily, better frequency response (because the groove wiggles are stretched over a longer length of groove.)
The downside is that there is much less playing time per side (which is the answer to your second question.)
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I think all "pre-echo" is just due to analog mastertape print-through. And as Eldartford points out would not happen in digital recording (either tape or hard drive.)
I never EVER heard of one groove affecting an adjoining groove. Even if the vinyl did expand/contract/deform slightly in manufacture, it could not do so with any degree of correspondence to actual groove modulations. In fact, RCA Dynagroove records (which have other problems ;--) do not suffer from this alleged effect, and if any records should, it would be Dynagrooves because the whole idea was to pack the grooves tighter together.
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Shadorne, just because well over half your CD's are AAD and don't exhibit print through doesn't put print through on "thin ice" at all!
First of all, if there was any print through between bands on the master tape, that's easily eliminated when transferring the album to CD, just insert new silences between bands.
Print through in the middle of a band, during rests or long silences, can't be eliminated of course -- but is also a LOT harder to hear, except in those occasional instances when a sharp crescendo follows a few bars of silence.
And last, the vast majority of analog masters do not contain print through, which was all but eliminated by thicker mylar and metal tape formulations which provided good S/N ratios with less tape saturation.
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Eldartford, I'll say it again: Even if the vinyl did expand/contract/deform slightly in manufacture, it could NOT transfer with ANY degree of accuracy (much less an EXACT copy of) the modulations from one groove to an adjoining groove. Think about it -- it would be physically impossible! Or maybe I don't understand what you mean when you say, "It's when the master disc is cut." What "it" are you referring to?
There is a great explanation of the Dynagroove process at:
http://en.wikipedia.org/wiki/Dynagroove
After reading it, I think maybe I meant Dynaflex (another RCA disaster;--))
Close groove spacing is achieved by a computer driving the lathe which is attached to a "pre-read" head in the master tape playback machine. Not possible in direct-to-disc recording, which is why they customariuloy have less material on them.
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Shad, it's easier (maybe only even possible) to do these manipulations/corrections in the digital domain -- but then there you are...............in the digital domain!!
Which is why, once CD's were available of course, I could never understand the point of buying a "Digitally Mastered" LP?
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Eldartford -- not to belabor the point, but can you explain just how the cutting head can cut the primary groove AFTER cutting a "ghost groove" (pre-echo) 1.8 seconds beforehand. Pretty fancy physics ;--)
Or if you can, please direct me to any technical writing that explains this phenomenon. So far I'm unconvinced.
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Eldartford, if what you're saying were true, the cutter would disturb the vinyl (and VERY ACCURATELY too -- carbon-copy accurately) on both sides of the groove it's cutting. But that would only produce a post-echo (in the previous groove), because the groove in which the pre-echo is supposed to occur hasn't been CUT YET!
And if you think about it, it just can't be physically possible for a cutter to produce an accurate, duplicate, identifyable signal in an adjoining groove, across the intervening uncut vinyl.
So, I still don't buy it, but thanks for making me think about it critically; it is a bit of a brain twister;--)
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So far, no one has explained just how this "pre echo" signal could be subsequently produced by deformation of the uncut vinyl, into a groove just cut, and "superimposed" on that already-cut groove with the ACCURACY of an actual cut groove, necessary to be able to identify the resulting signal (traced by the stylus,) as not only containing some kind of an "echo", but having the fidelity necessary to identify the original music signal that gave rise to it.
As for CDs, I agree with eldartford, never heard even an AAD CD with a tape print-through signal between tracks.
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Onhwy61, yes thanks for an interesting link/article. One of the things that struck me in the description of "twinning" and groove echo, was the fact that these conditions would render the disc defective so that it would not be used for production, and would be redone. Pre-echo from tape print-through however, would find it's way onto the commercial pressings (when it was present on the mastertape that is.)
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