What does a vinyl record groove look like?


I have been scouring the internet in an effort to better understand how vinyl is cut and what the groove actually looks like, and therefore tracks like. This is what I think I have learned. A record cutter is a 90 degree V-shaped chisel that undulates back and forth and up and down and in so doing cuts vertical tracks into the sides of the groove it cuts. Bass notes are large undulations (relatively speaking) with midrange and treble undulations riding on top of them and along with them. According to Neil, who might chime in here, the cutter is tilted back 1 degree like a chisel might be, in order to peel up the vinyl that it removes as it cuts. Am I right when I say the cuts in the 90 degree sides of the groove are then 1 degree of vertical (as you look at a groove from the side)? What confuses me is I keep reading articles that talk about 22 degree, or 24 degree, or something like that, cutting angles. What is this all about? My whole purpose here is to completely understand how a groove really looks so I can better understand how a stylus can best track that groove. Not to mention it is flat out amazing to me that all that information can be cut into the groove of a chunk of vinyl in the first place.
240zracer
Am I right when I say the cuts in the 90 degree sides of the groove are then 1 degree of vertical (as you look at a groove from the side)?
Correct, subject to a few refinements:
- different record producers used slightly different angles over the years
- variations from one cutting lathe to the next
- variations from one cutting stylus to the next
- variations from one machine setup person/operator to the next, etc.

What confuses me is I keep reading articles that talk about 22 degree, or 24 degree, or something like that, cutting angles. What is this all about?
The 1 degree angle Neil mentioned and which you have visualized correctly, refers of course to the angle of the edges of the cutting stylus itself (compared to straight vertical). Of course to play a record back most accurately requires that the contact edges of the playback stylus be at the same angle. This ~1 degree angle (cutting or contact edges of styli compared to vertical) is called the Stylus Rake Angle - SRA for short.

That 22/24/etc. degree angle you heard about is the angle of the cantilever when viewed from the side, relative to the horizontal plane of the record. Technically it's the angle between two intersecting lines:
a) the horizontal plane of the record and,
b) a line drawn from the point of the stylus through the pivot point of the cantilever inside the cartridge suspension.

This is called (mysteriously) the Vertical Tracking Angle - VTA for short.

[quote]My whole purpose here is to completely understand how a groove really looks so I can better understand how a stylus can best track that groove.
That is a VERY useful mental exercise. Learning to think like a stylus trying to trace a modulated groove is most helpful. It will save you all kinds of time and trouble when setting up or adjusting your rig (or anyone else's rig for that matter).

The more you listen to vinyl and make adjustments, the more you hear and understand - especially if you work at it. Your ability to hear when something is will improve. Your ability to understand what to adjust, in which direction and by how much is an ear/brain skill. You can develop and improve this skill with practice and reflection.

Go to Vinyl Asylum and read the FAQ's. Most of what's there is correct and all of it is interesting. Jon Risch's article, "VTA once and for all" is especially helpful for understanding the questions you've posed here.

[quote]Not to mention it is flat out amazing to me that all that information can be cut into the groove of a chunk of vinyl in the first place.
Me too!

Don't forget to enjoy the music. That's what it's all about!
Doug
Inner groovewall = L channel
Outer groovewall = R channel

Very important to know for fine-tuning antiskate, for example.
Just a point of clarification:
Only the metal master is 'cut', the actual vinyl lp's are stamped from the metal masters.
This is pretty cool

Go to my system and you can see what a record groove looks like with a needle in it.

Mark
Mark! That is an amazing picture! Probably the best example of a picture being worth a thousand words I have ever seen. Thanks, Doug, I knew I was missing something. I am having a big problem with a defective cartridge right now but I am one of those guys who is right on the verge of some really good analog sound.