June 17, 2015 at 1:51 pm #11673Andy BrownParticipant
This isn’t really about the thread title, that’s just to get your attention.
This is a really well done video about how audio/video media in the consumer world works. It covers vinyl, CED video discs, and CD/DVD’s.
Why the resurgence of vinyl is just a fad is a fun topic, too, but we’ve been over that several times. Although if you care to discuss that again, that’s cool but beware, the numbers unavailable in earlier discussions are now spelling out pretty clearly F-A-D.June 17, 2015 at 4:46 pm #11674missing_kskdParticipant
Totally a fad, but I suspect one that will endure for a while.
Watched that one. Great look at how things work.June 17, 2015 at 5:06 pm #11675Alfredo_TParticipant
That is the best microscopic demonstration that I have seen of a record being played. Two things that amaze me about the microscopic images are that the stylus tip appears so long with respect to the record grooves and that the contact area between the tip and the groove walls appears much larger than what ones sees in diagrams that illustrate various common stylus types.
I do find it highly ironic that the tonedeaf article blames CDs for loudness wars and the consequent limited dynamic range of contemporary pop recordings. I remember 20-25 years ago when record producers deliberately allowed levels to go all over the place and technical types predicted that broadcast loudness wars would become a thing of the past the day that a digital broadcast standard reached the marketplace.June 17, 2015 at 5:55 pm #11676missing_kskdParticipant
Yeah, the author had to do stop motion to capture it. That seems to be a lot of work.
That stylus is one made for the task. He had problems with magnetics and clearances with an ordinary cartridge.
Still, it is a great view.June 20, 2015 at 9:08 pm #11762Alfredo_TParticipant
A few years ago, I did some non-destructive optical photography of a Shibata stylus tip and of some record grooves using optical microscopes designed for semiconductor work. These are microscopes where the light source is fed through the objective lens onto the sample, rather than biology laboratory microscopes, where the light passes through the sample.
I photographed several records in various stages of wear. I was curious why worn-out records often have a highly distorted sound. I found that in in the worn out records, the groove sidewalls were gouged by the stylus. Some of these records were played with excessive stylus tracking force, as was noticeable by the wear marks near the bottoms of the grooves and the stylus gouges in the lead-in area. I also discovered that some of the clicks and pops heard on records are from little whiskers of vinyl that stick out from the tops of the sidewalls into the groove area. These bop the sides of the stylus as the record spins.
I think that, sadly, it was once a very common practice to use excessive tracking force to prevent warped records from skipping. Many of the records at used record sales and thrift stores seem to have had this misfortune. Sadly, today people are buying cheaply made turntables from manufacturers like Crosley, and these have imprecise mechanisms that are prone to damaging records.
What I could not find in my record photography expedition was the “ground-in microdust” that I once saw photographed in an advertisement for a record cleaning and stylus lubricating product. That advertisement claimed that this microdust acted like sandpaper on the stylus tip, causing excessive wear and actually digging itself into the vinyl.June 21, 2015 at 10:05 pm #11780Dan PackardKeymaster
That’s so neat to watch the stylus and record groove at a macro level. I’d like to see why many records sound more distorted (vocals usually) as the needle gets closer to the center of the spindle.
Also, I recall the quality of vinyl used affected the sound. After the oil crisis in the early 1970’s, some record companies switched to cheap recycled vinyl. MCA and Atlantic record labels were guilty of this. Maybe more whiskers in them, Alfredo. On the other hand, Warner/Elektra/Asylum records sounded great (and were so exquisitely recorded).June 21, 2015 at 11:27 pm #11783Andy BrownParticipant
“I’d like to see why many records sound more distorted (vocals usually) as the needle gets closer to the center of the spindle.”
This is caused by the reduction in the linear speed (call it groove velocity) as you get towards the inner groove. The rpm’s may be constant, but that means you are traveling less distance per rev (be it 1/33 or 1/45 min). At slower linear speed you have less frequency response as the waveform on the vinyl is getting shorter. This is sort of like playing the start of your record at 15ips on tape and slowing it down to 3 3/4 by the end of the side. Eventually high frequencies become too small to move the stylus very much if at all (not to mention high frequencies are always challenged on vinyl, the key reason for RIAA equalization). Using an elliptical stylus helps minimize this problem since the smaller the diameter of the side radius, the better the stylus can track/follow the high frequencies. However if you back-cue with elliptical you maximize groove damage. It was always a trade off. Spherical/conical do less damage on the back cue, but the diameter of the stylus was too large for it to fit between the corrugations in the groove which recorded higher frequencies.
Reducing the diameter of the stylus was not possible as it would cause the contact patch to drop too far down the groove… and the tip of the needle might then drag along the bottom. That’s the main reason elliptical styli were developed.
In analog FM broadcasting, that’s why you have pre-emphasis/de-emphasis as high frequencies are harder to modulate, transmit, propagate, receive and demodulate.
Many good sounding albums are programmed to have ‘less challenging’ tracks at the ends of sides.
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