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Old 2nd September 2011, 11:57 PM   #21
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terry, im basing this on results of other ideas i checked out... it seems the key is making the laser beam as small as the tip of a stylus through a lense, parts to do this seem to be readily available and i can probably use the same type of lasers i used for my pickup... theyre cheap little things and come in a variety of colors, im not sure color will make much of a difference.. but it would be curious to try a couple laser colors and see if it does since they operate at different wavelengths

stylus isnt really the major issue.. i guess making a stylus to read the music is the easy part.. making a laser stylus that actually tracks the groove is different... as the record turns the stylus rides in the groove until the record is done... but without physical contact how will the laser move to stay with the groove? do all records have the same groove spacing? if not it would be very, very difficult to make this work.. but if they do you could simply use a gear ratio with the main motor to move the laser across the surface of the record at a rate according to the speed of the rotation, which for my project would be 33 1/3

another way i guess would be to have another laser or photodiode programmed to read the location of a groove, and somehow follow it... i dunno, this is definitely the hard part
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Old 3rd September 2011, 03:39 AM   #22
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The dust could also make trouble to laser .In the past there were some attempts to make a laser pick up,but I do not know the results.
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Old 3rd September 2011, 05:22 AM   #23
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seems the least light touching the record besides that of the laser, the less noise you will receive as there would only be light from the laser reaching the photo-diode... so i wonder if you could remove noise by getting a matching laser and diode that worked in a very, very uncommon spectrum of light... or possibly one that bounces a radio wave off of the surface of the record which wouldnt have any feedback from light.. though cell phones would probably screw it up
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Old 3rd September 2011, 05:39 AM   #24
TerryO is offline TerryO  United States
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Quote:
Originally Posted by AnimusDivinus View Post
terry, im basing this on results of other ideas i checked out... it seems the key is making the laser beam as small as the tip of a stylus through a lense, parts to do this seem to be readily available and i can probably use the same type of lasers i used for my pickup... theyre cheap little things and come in a variety of colors, im not sure color will make much of a difference.. but it would be curious to try a couple laser colors and see if it does since they operate at different wavelengths

stylus isnt really the major issue.. i guess making a stylus to read the music is the easy part.. making a laser stylus that actually tracks the groove is different... as the record turns the stylus rides in the groove until the record is done... but without physical contact how will the laser move to stay with the groove? do all records have the same groove spacing? if not it would be very, very difficult to make this work.. but if they do you could simply use a gear ratio with the main motor to move the laser across the surface of the record at a rate according to the speed of the rotation, which for my project would be 33 1/3

another way i guess would be to have another laser or photodiode programmed to read the location of a groove, and somehow follow it... i dunno, this is definitely the hard part
Following the groove "is" the hard part.
To answer the question about groove spacing: They aren't evenly spaced as the cartridge traces side to side movement to create the sound. Really loud passages have wider swings than quiet passages and the spacing is adjusted accordingly.

Best Regards,
TerryO
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Old 3rd September 2011, 11:04 AM   #25
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Quote:
Originally Posted by AnimusDivinus View Post

stylus isnt really the major issue.. i guess making a stylus to read the music is the easy part.. making a laser stylus that actually tracks the groove is different... as the record turns the stylus rides in the groove until the record is done... but without physical contact how will the laser move to stay with the groove? do all records have the same groove spacing? if not it would be very, very difficult to make this work.. but if they do you could simply use a gear ratio with the main motor to move the laser across the surface of the record at a rate according to the speed of the rotation, which for my project would be 33 1/3

another way i guess would be to have another laser or photodiode programmed to read the location of a groove, and somehow follow it... i dunno, this is definitely the hard part
You really need to educate yourself in the science of record making, so you have a understanding of just whats involed in making a record. To put it bluntly, it might actually be easier to make a DIY CD or DVD player than make a laser turntable. A company many years ago tried to do this and after many years and 20 million dollars spent was finally able to bring a product to market. You can buy one for the tidy sum of 10000 dollars.

Laser turntable - Wikipedia, the free encyclopedia
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Old 3rd September 2011, 01:43 PM   #26
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I should ad to my post that if your looking to minimize record wear there are readily available techniques to do this. Get a cartridge with a fineline stylus, align the cartridge on the tonearm properly, set the tone arm to the proper tracking weight, properly adjust the vertical tracking angle, clean the stylus, and most importantly keep your records clean. Record wear comes from playing dirty records with a worn, improperly aligned stylus. If you eliminate the dirt and keep a good stylus your records will last decades, and take 100's of play with almost no wear. That's why you really need to take the time to go on site like Vinyl Engine or others and read. You will find you don't need fancy lasers, just good proper execution of the available conventional record technology's and techniques to get the most enjoyment out of your records.
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Old 3rd September 2011, 06:33 PM   #27
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is there any way to back up a record into a computer without losing the quality of the sound?... i know records are analog with a perfectly smooth soundwave, where digital audio is stepped, but are digital to analog converters good enough to perhaps take a 96,000hz 24 bit stereo lossless audio file and convert it back into an analog signal worthy of perhaps cutting a new record in the future should mine ever wear and be hard to find?
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Old 4th September 2011, 12:13 AM   #28
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anyway.. back to the origional question... i have a few different ways i know to make the tonearm.. is my best bet to buy a complete cartridge? if so.. whats a good cartridge for playing new records?... and about what sort of power will i need in a motor for spinning the table, and what sort of electronics am i looking at needing for the table?..

is it better to have a motor that can automatically turn at 33 1/3, 45, and 78 RPMs?.. or maybe a variable dial i can use to fine tune the RPMs like a potentiometer with a strobe light to aid in fine tuning the speed?
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Old 4th September 2011, 01:22 AM   #29
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apparently i dont need any fancy strobe device.. just a strobe disc in which case i can burn the proper marks into the sides of a wooden platter, or just buy a platter somewhere that has them... or print the disc out on paper

what i think ill do is have a single motor hooked up to the platter via a belt, of course, and then very simply wire that motor into a 3 way switch, and each setting on the switch will be wired to a potentiometer to control the motor... so if the switch is set to position 1, the power is routed through potentiometer one which will be set to 33 1/3 RPM... pot 2 would be used for 45, and pot 3 for 78s... or i can just use each individual pot to pre-set the speeds i want

maybe ill just have a small perfboard set up for all of that.. and have screw driver adjusted pots under a panel on top i can pop off and use a screwdriver to fine tune each one to the three speeds, then replace the cover because if they were knobs on top it would just be too likely for me to accidently bump one and mess up the timing... then i could wire up a small 60hz LED strobe circuit board i could permanently mount inside the turntable with an on/off switch

that all solves the motor and timing... im really liking the idea of making the tonearm out of a piece of carbon fiber tubing i can get really inexpensive

found a circuitry "kit" for a phono pre-amp to use on turntables, thatll give me the amplification ill need

ill make a platter out of red oak which i can route a bit of a recess into to set a cork mat.. under the cork mat however, im going to print off the strobe sheet for 60hz 33 1/3, 45, and 78 RPMs onto a transfer sheet... transfer the ink onto the platter below, and then clear coat the wooden platter before laying the cork mat on... then i can just lift up the mat for the strobe markers

that being said.. i think i pretty much figured out what i want to do for the diy turntable... did i miss anything?

Last edited by AnimusDivinus; 4th September 2011 at 01:34 AM.
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Old 4th September 2011, 01:32 AM   #30
TerryO is offline TerryO  United States
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Quote:
Originally Posted by AnimusDivinus View Post
is there any way to back up a record into a computer without losing the quality of the sound?... i know records are analog with a perfectly smooth soundwave, where digital audio is stepped, but are digital to analog converters good enough to perhaps take a 96,000hz 24 bit stereo lossless audio file and convert it back into an analog signal worthy of perhaps cutting a new record in the future should mine ever wear and be hard to find?
The quality of the best digital gear is getting pretty close, if our Club's A/B comparisons a few months back is any indication. I'm not convinced it's better, but it is getting pretty hard to distinquish between an analog LP and the same LP that has been thru a ADC/DAC process. If kept in the digital domain like a music server, you're probably going to do well. However, burn it onto a CD and it won't be nearly as good.

We're not quite there yet, but it's coming!

Best Regards,
TerryO
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