Defect in groove. Anybody else seen this?

[mossboss]

So It is not on the lacquer when it leaves you????

[concretecowboy71]

I cannot say that for sure.

Even though I examine each lacquer before it goes out, finding a single spot that you don't know you are looking for is pretty difficult.

My feeling is that they are there, but were not seen until they caused a skip and then it is easier to pinpoint the spot on the lacquer.

[jjgolden]

Thanks for the photo.
Such a tough thing to pinpoint.

With regards to the Drop chip theory:
The only real way I can think of to check/prove this would be to watch the stylus as it's cutting over the entire side. If there's a temporary drop or balling up of the chip that's long enough for you to actually see, take note of what diameter you're at, then scroll back and inspect the grove in that area after the cut. I believe it's plausible for a chip wad/string to ball up around the stylus then be pulled from the inner disc side of the stylus then off the lacquer and into the suction tube.

With regards to the wire theory:
In the photo the untrimmed area of the wires are too long, but you'd notice if they were falling down onto the lacquer before you cut. So I don't think that could be the cause unless they were sticking out and down.
I've always trimmed then short.
It's also good to have a bit of slack in the wires between the terminal and the stylus. Can't really tell from the photo though.

Mossboss, is it possible for there to be a short if those wire ends are touching? (See his photo) Nothing to do with the weird groove anomaly though.

Lacquer cutting forensics!!

JJG

[mossboss]

My wild theory/guess was a very high frequency spike coming down one channel shooting the head side ways and back on its path
If you study the extraneous cut it seems to be deep at the point where it starts from than it almost disappears to nothing like a gentle lift off the stylus from the lacquer
The last photos with the reticle showing indicates that it is not that long
That is why the questions on my last post as if this is the case that would be embossed rather than cut having been cut with the back of the stylus
I will most likely discount the drop chip and the wire theory as it does not show as that, it looks more like a cut rather than a scratch
The reason for the wild theory is the cut rather than the scratch look of it
Stan Ricker proposed some time back that an SX 74 would cut up to around the 100 odd KHZ mark as he had a lacquer with superficial "engraving" on its surface from a tape that was biased at around that frequency
There is a post on this somewhere on the net
Kevin Gray also confirmed right here that he has also seen that type of superficial cut on the surface of a lacquer
I have never seen it
Did a search for it just than but did not come with it I am sure is there but in that little search I come across this little gem
Steve Hoffman
09-25-2003, 04:36 PM
There is something about Rudy Van Gelder master tapes from the late 1950's and early 1960's that freaks out Neumann cutting lathes. There is a very high frequency oscillation in those tapes that loves to burn up cutter heads and cutting amps.

I was cutting LUSH LIFE today with Kevin and I couldn't believe how crazy the equipment was getting. We slowed down the master tape and FOUND IT! A pesky tone, embedded in the Van Gelder tapes that is around 20,000 cycles. ONLY on the cymbals, or when the cymbals hit. I have no idea why this happens, but we speculate that it was some kind of RVG studio RCA limiter reaction to the crash sound; much worse than limiter splatter.

As Kevin and I were pulling out (just his) hair over this, we were talking about the Neumann cutting system he has. Get a load of this:

It is a Neumann SX-74, built in West Berlin, Germany in very late 1973. It was shipped new to Whitney Recording Studios in Glendale in 1974 and was sold to LRS (Location Recording Service) in 1976 where it stayed until 1999 when Kevin Gray bought it For AcousTech Mastering in Camarillo.

Kevin estimates that (conservatively) he has cut 40,000 sides with this unit since 1978. An amazing amount of vinyl!

Now, here is the blow-mind part: The unit cuts flat from 2 hz to 27,000 cycles! Imagine that. :love: :love: :love:

So, in the 1950's and '60's, the Van Gelder stuff was cut with Scully/Westrex systems that started rolling off around 12k. No one had any problem cutting these tapes. With the advent of the Neumann system (which had to be able to cut an RCA CD-4 quadraphonic carrier tone on the disc with no problem) things got bad, quickly.

I remember when I cut the original DCC LUSH LIFE LP with Stan Ricker we were both dumbfounded at the wacky things the tape was doing to the machinery. Today brought it all back.

Oh, we finally "got it", but it was tough!

Love that Neumann SX-74 though!

Argh The joys of cutting
I love it warts and all
Cheers

[dietrich10]

I still believe it is caused by using the flip side of a lacquer and marks left by the platter are the mystery lines

[concretecowboy71]

I just cannot buy into that idea. The marks are too much the same. They have the same characteristics.

What really sinks it for me is the fact that they always start right on the edge of one groove and move towards another groove. A scratch in the lacquer would probably cross THROUGH a groove and possibly more than one.

Compare all three pictures. Even the angle that the flaw comes off the main groove is the same.

I knew I would take some flak for not trimming my wires, but I figured I would post the picture anyway. This is the first time I have left them untrimmed, I thought I might need more slack and then never cut them.

[jjgolden]

Yea, I thought so too.
All 3 pics exhibit the same angle and originate from the same area of the groove wall. In order for the head/stylus to create that while cutting, the stylus would need to be in 2 places at once.
I would think a high frequency spike would cause a barely visible modulation probably seen as a white line @ 20+K, and not a wide 10+mil excursion like the once we see in the 3 pics
I would hope the circuit breakers would pop before something too crazy got down the line.

Dietrich: In some of the pics it does look like something was on the lacquer, as the defect looks to be "cut through",, but it happening 3 times at random diameters and very similar geometry makes it less likely.
Also, something that significant on the platter would cause the lacquer to give a once around ripple or a, "this disc is not flat" look that would be very noticeable before cutting.

I didn't mean to incriminate about the long wires, just an observation:>)


Keep us posted Concrete!
Having fun with this one :>)
JJG

[markrob]

Hi,

I agree with JJG, that it would not be likely for a 20Khz+ signal to cause 10 mils of stylus deflection as a baseband source. The forces required to make that happen would be astronomical. But if the ultrasonic signal was in effect demodulated due to non-linearity in the analog signal path, you would see that as a lower frequency spike (the detected envelope of the high frequency pulse). This type of thing happens when you are able to recieve AM broadcasts on your audio equipment. If there weren't non-linearities in the signal path, you would not hear the station.

Not sure this is what is going on here, but just a thought.

Mark

[dietrich10]

I agree it seems to 'exact' placement of the one issue(line off) to be lines from flip side of a used lacquer side

It does look just like the same 'lines' when i do tests cuts on a flip of a blown.

Could chip build up on the stylus ever be at fault?

[mossboss]

This is to consistent to be caused by a heater wire The angle is almost the same in every photo We are scratching for an answer so everything is on I suppose
Keep them coming guys We may get there
Cheers

[Infrasonic Sound]

Have you asked the plant for the lacquers back for inspection? Were all of these job done at the same plant?

[concretecowboy71]

Nope. Most of the jobs are plated at mastercraft. The last photo was plated at united.