Quote:
Originally Posted by
analogsurviver 
jaddie - enjoy reading your posts, nice to read pro experience with lacquer cutting.
One question - how much attention did you personally and on "general level in industry" pay to the correct azimuth of the cutting stylus ? Is that adjustable at all or it is at the mercy of each sample of recording stylus? I ask this because even test LPs from the same manufacturer but different time periods ( making the use of the same cutting stylus unlikely due to wear, even if cutter chain was the same ) differ slightly in azimuth - just as it does with phono cartridges, although to a much lesser degree.
There are adjustments for all physical alignments on the head and stylus, and yes, azimuth is there. There are optical methods used to adjust the stylus position, but what you have to realize is this is one of those things that you can obsess about all day, but when it comes down to it, the precision to which the cutter stylus is aligned far exceeds the precision to which a turntable is usually aligned. The fact that you've taken the trouble to play test records that show up az issues (you're probably looking at channel separation, right?) is very unusual, and yes, that would show up misalignments like that. But it's actually sort of a hyper sensitive test. In practice, you can't actually hear small changes in channel separation once they're up where they belong. What's odd about your observation is that test records weren't exactly made in the mass-quantity of a popular release. I would think there would be very little need to cut a fresh lacquer. You can get about 1000 pressings out of a stamper, and 8 to 10 stampers out of a mother, and about the same number of mothers out of a father, so all together they should have gotten something like 10,000 records before a new master would be needed, and if they did the 3 step process, something like 100,000 if memory servers. That's a lot of boring test records! But possible they underestimated, and did the two-step process, got their 10,000 copies, then the record went platinum and the had to cut new masters.
Anyway... though I haven't surveyed labs to that detail, I would expect that once the stylus is aligned to a certain precision, they stop worrying about it. Every change in the head and stylus would dictate a realignment, which the responsible labs would have done, to the best of their ability. But their reference is an optical process used to determine a physical position. They couldn't use a playback cartridge to confirm it because that cartridge and stylus has the same alignment problem, so there are limits to how precise this adjustment can be.
As to industry or my personal practice in lathe alignment, full disclosure, I was not responsible for any lathe maintenance. I was a client of the lab, not an employee. Yes, I'm an engineer, but for those projects was hired to a rather odd position, that of technical supervision. I was one of the engineers who designed and built the studio where the projects were recorded, and assisted during the sessions, then the record company hired me to track and supervise the projects technically all the way to production of the final releases, which were both vinyl and CD. My solution to precision lathe calibration, and in fact, the entire analog mastering chain, was to work with the best lab I could find, interview them thoroughly, and then trust their team to make sure the gear was in peak condition. Then I supervised the actual mastering sessions, observed and confirmed the operation of everything (contributed very little!) and left with the reference lacquers under my arm. I didn't supervise the process at the making of the metal parts or the process pressing plant, but again, hired the best I could find, and then beat them all up over bad test pressings anyway. The process past cutting the lacquer is really difficult, and full of problems. We went through several different vinyls, one bad mother/stamper combo, etc. At least half a dozen test pressings before we got a good one. But right up to cutting the lacquers, it's pretty well in control. Side note, by contrast, the CD version came back perfect the first time.
And now, to put this "on topic"... our piano sound on those records was superb. The Steinway D never sounded better. Whew.
Edited by jaddie - 1/2/13 at 10:21am
