How Vinyl Works - just for fun

I guess that's what I have a hard time believing and acknowledging. How does a groove in wax sound like a church/hall/outdoors, etc... it's a damn groove! lol. science.

When they manufacture records, they are just stamping the grooves into a piece of vinyl with a punch press. So, of course you can have a mechanical process reproduce the grooves and it still sounds like what it's supposed to.

Were you under the impression that each record was cut by playing the recording into the lathe? Only the master is done that way (thus the term "mastering"). Then that master is used to make the plates that are used to press the grooves into all the records they produce.
 
I guess that's what I have a hard time believing and acknowledging. How does a groove in wax sound like a church/hall/outdoors, etc... it's a damn groove! lol. science.

The groove on the record is the same shape as the waveform you see in the daw. Which is the path that the speaker cone travels to reproduce that sound. (Over-simplification) that is why that shape groove will always sound the same.

Imagine the resting point of the speaker is the 0 line in the middle of the daw track. Now imagine looking down on the speaker cone from the top. The cone will follow that waveform in and out.

On vinyl, that waveform is physically etched into the record. That squiggle is the path the speaker cone will take to reproduce the sound on the record.
 
Here's a quick video on how the grooves work:

https://www.youtube.com/watch?v=eJFuRnolwWk

Except, I think he is wrong with the stereo aspect. The right and left side of the groove do not make up the right and left channels. The grrove is cut so the needle moves left and right AND up and down. The left/right motion is for one channel, the up/down motion is for the other channel.

How to pack a stereo signal in one record groove

Then you have this video which shows how they press the vinyl. Kinda cool. I didn't know some of this....

https://www.youtube.com/watch?v=molqV4L23FM
 
Vertical motion is the sum channel, equivalent to the mid channel of a M-S mic array. Horizontal motion is the difference channel (like the M-S side channel). Diagonal movement is left or right channel.

When the stylus is moving only vertically the sound is the same in both speakers. When the stylus is moving only horizontally (rare) the sound comes from both speakers but the polarity is opposite, and on a surround system that signal will be directed to the rear speakers.

LPgroove.png
 
The "groove", in modern terms, is a un-equalized signal. They can't cut bass grooves full-on. When we used to sharpen our needles, there wasn't any bass to speak of. It was there on radio. My Heathkit preamp has something like three EQ curves for records ? The ceramic cartridge could do OK without out EQ - that's, typically, the needle with the flip arm.

So, the modern record is something like 3D without the 3D glasses. Even with RIAA EQ, the cannon grooves on the Telarc 1812 are kind of a marvel - with large lateral movement tossing the tonearm into the air, or, the heavier arm on a skid across a inch or two of adjacent grooves.

My Garrard Lab80 had a ceramic cartridge on it 'til 1972 when I got a Sure M-44e which is a magnetic cartridge and I then needed the RIAA EQ. Typically, a modern stylus doesn't contact much of the groove, but advanced designs are more like a pointy garden hoe - giving more contact to the groove. I've had the line contact/shibata types from Empire, AT, and Rega, and the old Rega R100 was my FAV. Get a good stylus !
 

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When they manufacture records, they are just stamping the grooves into a piece of vinyl with a punch press. So, of course you can have a mechanical process reproduce the grooves and it still sounds like what it's supposed to.

Were you under the impression that each record was cut by playing the recording into the lathe? Only the master is done that way (thus the term "mastering"). Then that master is used to make the plates that are used to press the grooves into all the records they produce.

Yup. And in those days, the process of mastering involved much more physical control, to allow the cutter assembly to use as much deviation as possible for each groove while remaining within spec and not causing the groove wall to become too thin and interfere with intermediate grooves.

Today's idea of mastering a part of creating the sound is a major evolution since then.
 
Well, records were easy when automation came to the lathe world. Plop a stack on the changer. They still spent a lot of time mastering to 2-track 7 1/2 ips and then making high-speed duplication work. Play/record your 15/16ips at 7 1/2 and see if there is a shift : )
 
Only the master was cut by the needle, or multiple masters. From the master the mass production was by pressing the vynl with a reverse image which was the only way to be accurate.
 
Another vinyl fact: Fredelity is reduced as the stylus moves from the start of the record to the center. I never realized this until I read an article about it. Since the record spins at a constant rate, the inside grooves have less audio information per rotation than the outside. Mastering engineers would purposely put the songs requiring less fidelity closer to the inside of the record and save the songs that require more fedelity for the first tracks.
 
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I wouldn't say that was SOP, though. hahah Instead of the optimal 8-10 minutes per side, they could make it the most not-hardly-fidelity to get max play time.
 
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