Do you have a reference to the geometrical construct to compute the tracing error of a given stylus shape? I know it's not exactly accurate but just assuming everything is rigid and the stylus moves perfectly perpendicular.
The pre-distortion for spherical tips remains a question, someone posted a couple of months ago that it was a standard accessory on Neumann lathes and there could be numerous LP's out there cut that way.
As Scott posted (and I misunderstood), alignment accuracy can also have profound effect.
Harmonic distortion (2nd) due just to tracking angle error, for a sinewave, is approx.:
20log [ V0 tan/ Vd ]
Where:
V0 is magnitude of recorded velocity [m/s]
Vd is longitudinal velocity due to rotation [m/s]
n is tracking angle error (deg or rads)
If the test tone for Adjust+ is 5cm/s rms, and the test tone is in the centre of the 33rpm record, there is a theoretical limit of -35dB harmonic distortion if tracking alignment error is 5 deg, or -49dB if alignment error is only 1 deg.
Thus alignment error can be a great leveller of measured harmonic distortion between carts, as Scott posted.
HTH !
Thanks Lucky - I'm learning!
I continue to dissent when friends tell me that vinyl aficionados are nostalgic and like clicks, pops, distortion, etc. Aside from the enormous amount of material on them which will never be transferred to silver discs or downloadable files, there is something seductive about the sound. The limited channel separation is not merely a simple amount but has some small amount of cross-channel feed as we do sometimes for synthesizing a wider soundstage---but I don't think that that is all there is. There may be some aspects of what amounts to nonlinear filtering in the whole process, which we may not be capturing despite the otherwise-excellent analysis of the geometries etc.
Another development as part of the so-called vinyl revival is the greater care being taken with the mastering and pressing. The quality of some of the reissues is very high, even if the master tapes have deteriorated. And there are a lot of new releases, particularly pop/rock/alternative that are appearing on vinyl. There is reason to believe when the CD juggernaut was unleashed that the quality of vinyl degraded markedly, but whether this was a conscious decision on the part of some I don't know. In any event, aside from wear and tear and a good deal of tape hiss, I have some very old vinyl that is still quite enjoyable (RCA Red Seal for example). In between some records were just terrible.
The demographics are complex. There are rather young people, and older folks as well. The younger ones tend to spend their limited funds on the software, but are upgrading playback systems when and where affordable. And the market is providing for them. Also the awareness that record cleaners are essential is getting traction.
Yes for a spherical shape, but principle might be applied with a bit of license to substitute the minor radius of any stylus shape.........
Funkschau 1957, Nr.16, S.745.
Harmonic distortion = 20 log [ s2r2w2/vd4 ] [dB]
Where:
s is magnitude of stylus velocity [m/s]
r is stylus radius [m]
w is angular frequency [rads/s]
vd is groove longitudinal velocity due to rotation [m/s]
What is particularly interesting is the acute dependency on longitudinal velocity, vd - 4th power. Thus inner grooves very vulnerable. But also dependency on level2, frequency2 and stylus radius2.
Also note, it is impossible to achieve zero harmonic distortion.
For Jan's example of 1kHz at 5cm/s rms and middle of a 33rpm record, theoretical limit of harmonic distortion would be -47dB for an 18um radius stylus, versus -64dB for a 7um radius stylus. If the same test track were on an inner radius the results might only be -30dB and -46dB for 18um and 7um respectively.............
But just kick the equation around in a spreadsheet and see how sensitive tracing harmonic distortion is to frequency, level and location on the record. But always be sure to use realistic levels and frequencies, given there are trackability limits.
This is just geometric tracing distortion, and adds to tracking angle distortion as per previous posts. It's typically only significant at mid-high frequency and mid-high levels.
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Everyone brings up clicks and pops on vinyl, but the elephant in the room is how many CD's get scratched and are useless after a short time. Even data disks for our computers are so often destroyed by scratches from the dust swirling around inside our CD and DVD drives, take a look at your data disks and tell me they are immune to this. To say that digital disks don't wear out is just a plain lie, they work until they don't, at least vinyl that doesn't have a major scratch will work for years and years even if they slowly are worn out. Both physical storage methods have problems, neither is perfect. Only when we store our music on hard drives are we safe, and that comes down to the life expectancy of the hard drives, even SS drives have a limited life span. I just pulled some old drives out of a very old computer, some with a build date of 1990, SCCI IBM drives with 10,000 rpm speed still working like new. Can't say that about some of the newer SATA drives out there today.
I don't think anyone likes clicks or distortion. I sometimes think that the appeal of vinyl playback is akin to that of golf. It's the satisfaction of accomplishing a difficult task using tools ill suited to the purpose.
Agreed, some newly released vinyl I have bought recently has been superb. Well recorded, well mastered, and beautifully pressed. Round, flat, quiet.
It started much earlier than that. It was the oil shocks of the late 70's that brought flimsy garbage vinyl. The record business was eating its own young before CDs came along. I would argue that the introduction of the CD breathed new life into a business that was already in trouble.
I was lucky enough to having an amazing second hand jazz and classical record shop where I lived in the late 80s. Those poor souls who were dumping vinyl meant I could buy 3-4 records for the cost of 1CD. For me more music was a winner!
Things went mad when I spent 2 years in chicago as there was an annual music marathon where you could pick up stuff (often ex radio station) for around $1 a record.
And now, rather dangerously I am getting into old mono recordings.
Things went mad when I spent 2 years in chicago as there was an annual music marathon where you could pick up stuff (often ex radio station) for around $1 a record.
And now, rather dangerously I am getting into old mono recordings.
Agreed that ALL mediums have a limited life cycle, including CD. NOTHING lasts forever. However, I do belive properly kept and stored CDs will last a lot longer than vinyl. It's true some outstanding recorded material on LPs will never be transferred to CD, but on the other hand, readily available software enabling reasonable quality trnasfer is widely available. Also some old dog tricks are well worth the effort, such as forcing the write to CD programs to avoid high speeds, like 51x, and making them spend more time on the process. Old CDs I made using 8x and smaller speeds are as good roday as they were when I made them 12 or 14 years ago.
What I see as a more serious problem is what I feel is a decreasing quality curve on modern laser pickups. Some truly problematic CDs I keep often cannot be raed on brand new laser pickups, while my ancient Philips 721 CD player from around 1996 reads them no problemo - and that was a really dirt cheap player, originally cost DM 120 (app, €60) and could be found even on some supermarket sales.
Well, here in Portland Oregon, we have a new record pressing plant opening. There does not seem to be a lack of market for the resurgence. Lead times to get records pressed are still getting longer as supply of capacity is limited. Will this be maintained? Only time will tell that.
Talking to folks who cut "in the day", most of the predistortion methods were soon disabled in the cutters as nobody seemed to like them, even Dynagroove was eventually dropped as the required method by RCA. There will be some that were cut with the Neumann system, probably hard to tell what, those would mostly be present in the year or two after the introduction of the system.
gotta drag that rock across the ole asphalt.
Cheers
Alan
Talking to folks who cut "in the day", most of the predistortion methods were soon disabled in the cutters as nobody seemed to like them, even Dynagroove was eventually dropped as the required method by RCA. There will be some that were cut with the Neumann system, probably hard to tell what, those would mostly be present in the year or two after the introduction of the system.
gotta drag that rock across the ole asphalt.
Cheers
Alan
That's the point it's an unknown, IIRC GrooveT and Thorsten L think there are more out there than folks think.
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I don't think there were many this side of the pond......... or maybe there were and we just don't know because they worked? Tracing simulators.
Such a naff idea though, bound to end badly sometimes.
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A circuit for a change, nothing special but since many of the USB sound cards have a 2K or so input impedance on their low noise inputs I cobbled together a simple JFET buffer that runs off a single battery and has no additional coupling caps. Thanks to member mlloyd for a gift of two matched pairs of genuine 2SK147's, the best gift is one that eventually is actually used. This is to match phono cartridge to microphone pre-amp and it sounds fine after digital equalization. This is one circuit that I didn't get to for my upcoming Linear Audio article on digital equalization.
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To keep others from being mislead, I might point out that there are plenty of QUALITY phono stages out there, that bring out the very best that vinyl records can do. They are not really a transistor or two, they depend on decades of experience, and they work best with the 'best' vinyl records out there, not EVERY record ever made, or records that have been damaged or stored improperly.
Vinyl recordings have a few advantages over analog magnetic tape and digital.
First, when properly recorded and processed, they can be surprisingly realistic in reproduction of a past event.
Vinyl recordings have a few advantages over analog magnetic tape and digital.
First, when properly recorded and processed, they can be surprisingly realistic in reproduction of a past event.
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