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In Reply to: Re: It's in the grooves posted by Robert C. Lang on January 2, 2007 at 20:07:19:
Before we go much further, I must point out I'm not trying to pick a fight here, and as you well know I like SA-CD a lot and I have stated in the past vinyl is my least favourite format for many reasons.*** The beauty of SACD is that any player can track the most dynamic recordings out there ***
Conversely, I could argue that all digital formats have a hard ceiling in terms of maximum amplitude that can be captured, whereas analog on the other hand has no artificial upper limit.
Think of it this way, you can never record a digital signal higher than 0dBFS, by definition. If you do, the signal clips.
Whereas there's no artificial limit in terms of how "hot" you can cut a signal on LP. Theoretically, if you master at a slow enough cutting speed, and your stylus is up to it, you can record a groove containing a signal hotter than a notional "0dBFS". This is not just theory, it actually happens in real life. I did mention that I record my LPs with about 12dB headroom. That headroom is necessary, because I regularly encounter signals hotter than the notional 2V maximum (for line levels coming out of my phono stage). It depends on the recording, and the pressing. But it's not uncommon.
*** the loud passages will always consume more vinyl space (wider passages) than the quiet passages. ***
As I've mentioned before, this is not necessarily the case. The loud passage can consume exactly the same space as the quiet passages.
It seems from your post you think the groove spacing must be increased for loud passages relative to the quiet ones, but this is not so. It is good practice to widen the groove spacing for difficult (i.e. loud and dynamic) passages, but it doesn't have to be so. In fact, you don't need to vary the groove spacing at all as long as it's wide enough to accommodate the hottest peak. As I mentioned before, based on my experience, there's little or no correlation between groove spacing and actual signal amplitude. In fact, the LP I own with the widest groove spacing happens to be a very quiet LP, it's because each side only contains about 8 minutes or so, so the cutting engineer decided to cut the record with very widely spaced grooves to fill out the side.
If you want to argue differently based on two specific records in your collection, that's fine. I'm just saying that's not my experience for most of my record collection.
Follow Ups:
Mastering lathe cutting pitch does NOT effect the level of the recorded signal. It's the other way around. The level of the recorded signal controls the cutting pitch. The cutting system pre-delay simply tells the lathe what pitch must be set one revolution ahead for the upcoming signal. That's how more than 15 minutes of playing time can be achieved on a 12" LP. Prior to Vari-Pitch, all cutting was done at a constant pitch setting with no accomodation for levels.I hate to burst a bubble here, but the vast majority of modern (mid-80s to present) disk cutting systems use a pcm digital delay to feed the cutter head, regardless of the recording source. In the case of analog tape, the direct tape machine output feeds the pre-delay control signal to control the cutting pitch. A pcm digital delay of the same signal feeds the cutter head. Exceptions would be where the system is set up with an analog pre-delay tape head prior to the main tape machine PB head. That's the way it was done prior to the advent of high-quality pcm digital delays. I'd like to think that ace mastering engineers such as Steve Hoffman would be using the all-analog method rather than a pcm delay in the chain. I've been out of the loop in LP mastering awhile so I don't really know.
Best Regards,
HowdyAt MikeL's house on his Rockport Sirius III with single sided half speed mastered 45... discs I thought (just a few times) I could hear a pre-echo, telegraphing or a shadow of what was coming a revolution later, since I don't believe it was a failing of the TT or the disc, I wounder if it was a change in the recording pitch when a change in dynamics was approaching. Does this sound possible or is it something more mundane?
What you're hearing is likely "pre-echo." That can occur as a mastering defect if the cutting pitch wasn't expanded enough. Normally, at the beginning of each track the pitch is supposed to be overly coarse (lots of land between the grooves) to minimize pre-echo. Pre-echo can also occur as a pressing defect, particularily if the vinyl press is set up with too much pressing pressure on the "biscuit" of vinyl.You could also be experiencing "print-through" from the original analog tape if that was the source for the recording in question. You'll hear print-through a lot on older analog tapes with no noise reduction or that were recorded too "hot" to tape. Frequently, just being stored for a long time - and perhaps with too tight of a tape wind - the print-through occurs.
Best Regards,
HowdyDSD has 6dB of soft clip at the top not hard like PCM, so in fact you can go to +6dB in DSD. Just like analog you want to avoid if possible since there is some loss of signal quality when you use it. I'm told it sounds like tape saturation.
In my experience, it doesn't sound as benign or 'euphonic' as tape saturation - I refer to it as 'scar tissue' as it's obvious (and difficult to remove) once it's there. Short peaks are fine, but any longer and "ouch!"As usual, thanks for all of your helpful posts, particularly the recent SACD MCh discussion - I wish more people could/would hear it done well!
Best,
However, in practice, +3dB is not very useful, since on analog tape you can easily achieve +10-15dB without too much ill effects (provided the peaks are fairly irregular, otherwise the tape will over-saturate).I've been doing a lot of field recording lately, and I certainly miss the headroom you get on tape! No matter how carefully I set the recording levels, I always get some clips. And I don't want to set the levels too low, otherwise the recording as a whole sounds rather murky.
With a supposed 70 Dbs, heck even a claim of 90 Dbs of possible range, why do you insist in over saturating the tape, thus causing other possible ill effects to the sound?
Deliberately over-saturating drums for example creates a very nice thud. You've probably heard that thud in countless 80s pop albums!These days it's possible to digitally simulate the effect of tape saturation, but that thud sound is no longer "fashionable". The so called "New York" style popular in the late 90s and early 00s instead is created by hypercompressing the drums and mixing the result together with the original uncompressed version. Creates a different kind of "thud" - more edge to it.
HowdyNot that I hold the Wikipedia to be the best reference, it at least is widely available: "...Unlike CD, which sets the 0dB level right at the theoretical PCM signal limit, and doesn't take into account oversampling, SACD sets the 0 dB level at 6 dB below the theoretical full-scale DSD signal, and prohibits peaks above +3 dB..." http://en.wikipedia.org/wiki/Super_Audio_CD
Also here's a post from Graemme in on a conversation you (and Christine) were a part of: http://www.audioasylum.com/forums/hirez/messages/182566.html
Both say something I should have been more explicit about, tho there is some head room, it's really just 3dB not 6dB as I implied because using the last 3dB is illegal according to the spec.
Graemme weighed in other times: http://db.audioasylum.com/cgi/search.mpl?searchtext=db&author=Graemme&forum=hirez
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