Novice Question

[jlach9]

How exactly does a person or the machine convert an mp3 track to grooves?

[petermontg]

are you asking hoe the groove works or hoe the cutterhead works?

[jlach9]

How does the cutterhead know what to cut?

[opcode66]

Wow that is a huge can of worms. I will post a reply when I have time to write it...

[piaptk]

The very short answer is that the cutter head vibrates the needle as the mp3 is being played through it, like a speaker vibrates when you play loud music through it. These vibrations leave a distinct signature in the grooves that can be reproduced by the playback needle.

For more:
http://www.ehow.com/how-does_4596014_vinyl-record-work.html

[subkontrabob]

Hi,

these books can be downloaded for free, and should answer most of the questions:

http://www.tubebooks.org/Books/read_recording.pdf

http://www.tubebooks.org/Books/Atwood/Sunier%201960%20The%20Story%20of%20Stereo.pdf

EDIT: you should probably start by exploring the concept of analog electrical signals (the MP3 has to be converted to an analog signal before you can listen to it or cut it to disk)

(if you don't understand that, search wikipedia for digital to analog conversion and read the article about mp3...)

best regards,

Robert

[Aussie0zborn]

Hmmmm.... jlach9, welcome to the forum.

MP3 is the worst thing that has happened to the art of sound recording. You need to get out more, throw away your portable MP3 player, delete all your MP3 files and start buying vinyl records.

Let's assume nobody is cutting records from MP3 files out of preference. Discs are cut from high quality sources such as analogue tape, DAT, CD, digital files, etc. MP3 is not a professional format and let's hope it never becomes one.

[fraggle]

Aussie is right mate:)

[opcode66]

As was stated by everyone you don't want to turn an MP3 into a vinyl record. I'm going to assume you said MP3 because you are a child of the new digital age and refer to all digital music as MP3's. I'm sure you are aware of Wave or AAC or any number of other digital formats that are not compressed. So, no need to go further with that.

Music is simply the culmination of my sound waves coming together to make a summed waveform. Waves have two components: frequency and amplitude. The frequency determines if the wave sounds low (bass) or high (treble). The amplitude is the intensity or volume of the wave. In the digital world, these characteristics are captured in a serious of samples. All digital sounds are is a series of samples that when played one after another approximate a real wave. But in actuality, they are simply points that form a wave. That is the difference between analog and digital. Analog sound is generated as a smoothish wave form. Digital is a wave produced by a number of points. The distance between each point is made so small that it is hard for the human ear to tell the difference. The more points per second, the better the sound. CD audio is 44.1 kHz, which means 44,100 samples per second. Or, 44,100 points to graph that would form a wave for one second of audio. Most Digital Audio Workstation (DAW) software allows you to select what sample rate you want to use 44.1, 48, 96, 128 are common values. I use 96 for most everything I do.

The other aspect to digitized sound is the precision of each sample taken. So, for one second at 44.1 you have 44,100 samples. Each sample has a particular accuracy which is another setting that you can usually select in a DAW. Typical settings are 8 bit (old sampler sound), 16 bit (cd quality), 24 bit, or 32 bit. I generally always use 24 bit. So, at CD quality each sample is 16 bits which means that you can store values 0 through 65,535. At 24 bit, the samples for the same piece of audio would simply be more accurate. This would be like measuring something with a ruler that was only precise to an 8th of an inch and then using a ruler that was accurate to a 16th of an inch. You would get a better measurement with the more precise ruler. It is the same for the accuracy in the digital world.

So, now you know what the data is in the digitized music file and how it relates to the real world of sound waves. The final bit is to explain how those get translated on to the blank discs by a vinyl lathe. The concept is very much like how a speaker works. An audio amplifier takes a nominal signal and makes it very intense. The intense signal is then capable of driving the electromagnetic coil inside a speaker which then makes the cone (paper part) of the speaker start to oscillate. The movement of the speaker cone pushes air. The pushing of the air simulates the original sound wave that was recorded to make the audio you are playing. If you can understand this concept then you already know how a cutterhead on a vinyl lathe works.

A cutterhead is driven by a cutting amplifier. Old cutterheads were mono and only translated one stream of audio (waves). Newer heads were stereo. You probably have only heard mono audio on you cell phone... But, once upon a time, sound systems were all mono. So, a modern stereo record has two streams of audio that are multiplexed into one groove. That one groove on playback is decoded into two streams of audio and then can be played via a standard audio amplifier and speaker.

How does a cutterhead work? Well, that is really what you are asking. Think of the speaker analogy but instead of driving a cone of paper you are driving a shaft. Two of these piston like shafts being driven by two electromagnetic coils is a simplified way of thinking about a cutterhead. The two pistons come together to form a Y shape. The pistons are at 45 degree angles. So, when the piston on one side pushes it forms a wave on one side of the groove. And the same happens for the other side of the groove by the other piston. When audio is in phase the waves follow each other. When out of phase there is cancelation and the stylus tends to move up and down more than side to side. There is a great visual of this all on Souri's site http://www.vinylrecorder.com/stereo.html. Please check it out because it does a better job of explaining this than I can through words.

Once a groove is cut into a record it can be played back via a pickup. The pickup takes mechanical energy and translates it into electrical energy. Thus the movement of the playback stylus get converted into an electrical signal which is then preamped and amplified in order to be played back on a speaker system. The sound waves then actually end up as linear waves in the cut grooves. The perceived volume of the material is determined by the amplitude of those waves. So a louder wave will make the playback stylus move a lot compared to the same wave played at a lower volume. The speed or velocity of the playback stylus is generally measured in cm/second and that accounts for the volume of a wave on vinyl.

Please read books. The ones mentioned should help. Also check out the AES book DISK RECORDING VOL.1: GROOVE GEOMETRY AND THE RECORDING PROCESS. You can purchase this book for $40 at http://www.aes.org/publications/anthologies/

Hope this helps. Please ask more questions if you are still unclear about the mechanics of cutting. There are a number of good people here who are happy to help.

[jlach9]

Thanks for all of the replies. Being 22, I suppose I am a kid of the digital age. I do however own more vinyl than mp3s. I can't seem to get the ipod to work correctly. It resets itself every time I go to put more music on and I lose everything. I just used mp3 as an example.

I'm wanting to open a record store in the first brick and mortar Biscuits + Groovy (I have two food trailers now, they're huge in Austin) and wanted to offer "Vinyl Services" as well for all the indie bands here in Austin. I've been looking for a lathe to purchase, and just wanted to understand how it works a little more clearly.


Thanks again for all of the replies.

[piaptk]

Thanks for all of the replies. Being 22, I suppose I am a kid of the digital age. I do however own more vinyl than mp3s. I can't seem to get the ipod to work correctly. It resets itself every time I go to put more music on and I lose everything. I just used mp3 as an example.

I'm wanting to open a record store in the first brick and mortar Biscuits + Groovy (I have two food trailers now, they're huge in Austin) and wanted to offer "Vinyl Services" as well for all the indie bands here in Austin. I've been looking for a lathe to purchase, and just wanted to understand how it works a little more clearly.


Thanks again for all of the replies.

You could talk to John and Patrick from the Austin band Salesman. They just bought a couple lathes from me (and they lurk around here a bit), and would probably be happy to help you out. Before you decide to jump into cutting as a service, be sure to read a lot on this board, and especially this recent thread:
https://lathetrolls.com/viewtopic.php?t=2342&mforum=lathetrolls
As you will see from that thread, the "vinyl services" is not much of a money maker, nor is it a walk in the park... it's not like burning a cd... there is a ton of mechanical adjustment and straight up luck involved. And the equipment is fickle, fragile, and expensive.

[opcode66]

And, you can't cut something unless you done soemthing with it to master it. That involves yet more gear and the know how that you only get from years of experience working with audio. Quite a lot to just jump into. But, possible.

What kind of budget do you have?