I would either recommend reading either my instructable http://www.instructables.com/id/Make-a-Playable-La...or Amanda Ghassaei's instructable http://www.instructables.com/id/Laser-Cut-Record/for this step.I have also uploaded the .PDFs for "The Mexican Hat Dance" for 78 RPM ...
In most grocery stores, there's a section of shelving dedicated to tortillas, usually categorized near the meat section.
Most of them will be cooked and either corn or flour.
Corn is a bit too lumpy for this purpose cooked or uncooked.
I found that the cooked tortillas tended to shred a bit when the outer cooked layer peels away from the inner less-cooked core.
Also, the cooked flour tortillas have uneven lumps as well from the cooking process.
I settled with uncooked flour tortillas made by Canasta which is found in most groceries. They are very soft, however, so try to get the ones that are as flat as possible near the bottom. The kind that are made without lard seem to keep the best at room temperature as well.
Unfortunately, Canasta seem to be the only brand of uncooked tortilla available in most groceries. They come in roughly 9" sizes.
The tracks on the outer edge of a record sound better because they are less compressed than those closer to the center. Therefore, the tortilla should be as large as possible. I could only get the tortilla to consistently make 7" records, the same as a 45.
I have heard that Costco sells Porkyland uncooked tortillas in 12" size. But I was only able to find them in the frozen section. The temperature difference may cause unwanted condensation when thawing out. In addition, they are not recommended to be stored at room temperature.
You can use any audio editing program for this. I am using Audacity.
First you need to make sure your file is stereo. If it is in mono, you can duplicate the tracks and merge them into a stereo track.
Project rate should be 44100Hz.
Trim your track to around 30-40 seconds.
Then select Effect > Equalization. Under Select Curve, choose RIAA. Hit Invert and OK.
Your track will now sound very tinny.
If you 've ever taken a regular vinyl record and played it without turning on the speakers, you can heard the needle of the record player vibrating. The song however is very tinny as well.
The RIAA equalization standard was developed so that the needle wouldn't move so much and damage the groove walls when attempting to track bass frequencies. The record itself plays with boosted treble and dampened bass, hence "tinny".
Record players and pre-amplifiers automatically apply the RIAA equalization standard so that playback will sound with boosted bass and lessened treble, reducing the "tinniness" and restoring the recording to its original sound.
Applying an inverted RIAA curve will imitate how records are made and will help the laser cutter avoid vibrating too much.
Export the stereo file as a .wav and you should be done for this step.
Step 3: Generating the Cut Files
I would either recommend reading either my instructable
From amandaghassaei's instructable: "Sampling rate is the amount of samples per second in a song. Usually the sampling rate is 44.1kHz (or 44,100 samples a second). When the sampling rate drops below about 40kHz the higher frequencies of a song start losing their detail, but depending on the song you can go down to 20 or even 10kHz sampling rate without too much of a problem." Ideally, 78 rpm should be able to provide a higher possible sampling rate with better sound.
At 78 RPM (78.26 rpm for 60Hz countries, 78.92 for 50Hz countries)
revolutions per second = (revolutions per minute)/(seconds per minute)
revolutions per second = 78.26/60 = 1.30
inches per revolution = 2*pi*(radius of needle)max inches per revolution = 2*pi*5.75 =~ 36
minimum inches per revolution = 2*pi*2.35 =~ 15
sampling frequency = (resolution per inch)*(inches per revolution)*(revolutions per second)
maximum sampling frequency at 78 rpm = 1200*36*1.30 =~ 56200 = 56.2kHz
minimum sampling frequency at 78 rpm = 1200*15*1.30 =~ 23400 = 23.4kHz
At 45 RPM
max sampling frequency at 45 rpm = 1200*36*0.75 =~ 32400 = 32.4kHz
min sampling frequency at 45 rpm = 1200*15*0.75 =~ 13500 = 13.5kHz
At 33 RPM (inaudible in sample tests)
max sampling frequency at 33 rpm = 1200*36*0.5 =~ 21600 = 21.6kHz
min sampling frequency at 33 rpm = 1200*15*0.5 =~ 9000 = 9kHz
Inherently sounds better since more data is passing by the needle per second.
More grooves are needed to play the same length of song / Longer cut times, more files
More grooves have to get closer to the center, leading to inner groove distortion
Need a turntable that can play at 78 RPM
Soundwaves are compressed together allowing for more grooves to fit on one side / Shorter cut times, fewer files
Most grooves can be arranged nearer to the edge.
More record players are able to play at 45 RPM (33 RPM is nearly inaudible)
Inherently sounds worse or inaudible since the sound waves are compressed past the point the laser is accurately able to resolve them onto the surface of the tortilla.
With a 7" record, you can only fit around 30-40 seconds of audio before the grooves start to run together as the tortilla shrinks from moisture loss.
If I could find 12" uncooked flour tortillas that keep at room temperature, I could make better sounding records. However, larger tortillas are damaged more easily when still uncooked and may not lie flat.
Step 6: Further Thoughts
This was a proof of concept to see if I could make an actual working tortilla record. I ran off a couple of other songs for no particular reason except that they were vaguely tortilla-related or were reminiscent of Mexico.
"Yakko's World" - Animaniacs - 78 RPM
Uses the same melody as "The Mexican Hat Dance". The first 30 seconds of the song are the North and South American countries. Vocals are there, but hard to distinguish without subtitles.
"Macarena" - Los del Río - 45 RPM
Latin dance music with strong rhythm. Can be heard distinctly at 45 RPM especially the, "Hey, Macarena"but would probably sound better at 78RPM.
"Putting on the Ritz" - Taco - 78 RPM
Famously syncopated song re-imagined by a curiously food-named artist. Heavy use of synthesizers blurs out the words.
Ideal songs to put on a tortilla
Words spoken distinctly
Would this be suitable for a restaurant or a commercial ventures?
At the very least, the laser cutter would have to be purchased new even hope to be certified as food-safe.
The tortillas are edible, but taste rather burnt where the laser has to work harder to slice apart the edges. Of course, cooking them removes the possibility of playing them.
All in all, around 30 minutes of cutting time for a 30 second snippet of a song on a tortilla.