Record Player Physics

[OutdoorInnovator]

Hi, I have a project for my Dynamics and Vibrations class and I wanted to do it on the vibrations of a record player. Does anyone know what equations would be most relevant? I know this is a very general question but the project is large so I'm still figuring it out! Any thoughts are super appreciated.

 

[berkeman]

Welcome to PF.

What have you found in your research so far? What would be some of the sources of vibrations, and what-all could contribute to resonances? What would different vibrational modes do in terms of distorting the audio pickup/playback signal?

 

[OutdoorInnovator]

Welcome to PF.

What have you found in your research so far? What would be some of the sources of vibrations, and what-all could contribute to resonances? What would different vibrational modes do in terms of distorting the audio pickup/playback signal?

I've found that the needle moves along the ridges which causes it to move up and down and move a magnet attached to the cantilever to vibrate between 2 coils to convert the mechincal energy to electrical energy

 

[berkeman]

Sure, but how is that audio information encoded in those grooves? Up/down or sideways or a combination? How is stereo information encoded in a single groove with a single pickup needle?

And what are the most common vibration noise sources in such a mechanical system?

 

[OutdoorInnovator]

its a combination but I believe up and down for non-stereo systems

 

[berkeman]

What have you found in your research so far? What would be some of the sources of vibrations, and what-all could contribute to resonances? What would different vibrational modes do in terms of distorting the audio pickup/playback signal?

And what are the most common vibration noise sources in such a mechanical system?

 

[gmax137]

Hi @OutdoorInnovator , and welcome to PF!
You may want to check out information from the phono cartridge manufacturers, i can think of Ortofon, Shure, Grado off the top of my head. I haven't looked, but they may have tech info on their websites.

I'm not sure of your academic level. You might find Fourier analysis interesting, this is a way of breaking complex waveforms (like music) into sums of simple sine waves.

 

[256bits]

I have a project for my Dynamics and Vibrations class

Since Dynamics and Vibration, you should look up mass-spring-damper system, and mechanical-electrical transducers.

The cartridge pickup is a mechanical system that vibrates, with the attached coil connected to an electrical system that can amplify the signal. Or the 'needle' can be directly connected to a horn to produce sound waves.

Apparently, this is a simplified model. ( an electrical representation of the mass-spring-damper )
https://en.wikibooks.org/wiki/Engineering_Acoustics/Phonograph_Sound_Reproduction