would smaller, slower, 80 minute records be possible? - diyAudio
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Old 1st September 2011, 08:37 PM   #1
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Default would smaller, slower, 80 minute records be possible?

im just curious if in this day in age if it would be at all possible to make a lower RPM, smaller disc capable of holding as much music as a CD?... imagine a 4.7 or 5 inch record that would play at something like 12-13rpms capable of holding 80-90 minutes of music.. if the sound could come out right you could pretty much sell analog records in CD cases... im just curious if this is even possible, certainly it has been tried but im not familiar with such results

maybe ill try it myself... it wouldnt be difficult to build a cutting device for testing purpose, ive built CNC machines for carving wood and aluminum and this is insanely less complicated since its basically a gear ratio to determine the rate the cutting head moves across the surface, and how fast the record spins and the cutting head itself is basically a stronger stylus with music being piped into it causing it to resonate at the frequency of the music... might have to test this out someday and see if it works.. im not confident it will work, but im curious to see just what happens

one thing to note is there have been phonograph records 7 inches in diameter that turned at a very, very slow RPM, and held 4 hours of speaking which leads me to believe with technologies we have now that 90 minutes of music wouldnt be out of the question...

downside it it would probably very quiet, so of course, amplification will be neccessary

if this did work... or not, i had the idea of having a cartridge move across the surface of the record by way of a rail suspended over it.. a belt could be used to automatically move the head to a given location, and possibly a very, very tiny transmitter could be placed somewhere near the center of the record itself that could relay track information to the motor so that someone could select a track by number, and with information from the record the cartridge could automatically move into position to start at that track...

so in all, giving analog records the convenience and features of a compact disc, but with the analog sound quality of a record

anyone have anything to comment on this idea?
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Old 1st September 2011, 08:46 PM   #2
kevinkr is offline kevinkr  United States
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There's a lot of physics involved - figure out how short the wavelength of a 20kHz sine wave recorded on disk at 12rpm and you will probably find that there is no stylus small enough to play it. Imagine the problems we already have reproducing good quality high amplitude HF on the inner grooves of a record. On the other end bass would have to be even more severely attenuated to keep from overcutting from one groove into the adjacent ones which would affect SNR, dynamic range and rrequency response. The current disk size, playing speed and playable area are all very carefully thought out compromises based on the limitations imposed by physics, materials and cost.

In addition real analog electrical engineering is dead even if it were possible to do so given the limitations imposed by physics.
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Old 1st September 2011, 08:50 PM   #3
SY is offline SY  United States
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Actually, they used to do this for "Talking Books." They ran at about 16rpm and gave doubled playing time. Bandwidth was quite limited, as was dynamic range. If you slow down a record, you unavoidably compromise quality.
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Old 1st September 2011, 09:04 PM   #4
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it would still be interesting to see what happens with it at a slower RPM.. you could probably play music but the slow RPMs would make it really, really quiet, so it would need built in amplification
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Old 1st September 2011, 10:03 PM   #5
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the cartridge could automatically move into position to start at that track...
I recall there being turntables with that capability. Whether it's limited to the ELP I don't remember.
It's worth keeping in mind that if manufacturers could make virtually the same product with significantly less raw materials, they would be strongly motivated to do it.
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Old 1st September 2011, 10:15 PM   #6
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There's another example of this other than SY's. One of the records I inherited is a 10" LP, i.e. on a 33/78 TT you would set the automatic cueing to 10" as for a 78 and the speed to 33 RPM.
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Old 1st September 2011, 10:45 PM   #7
DF96 is offline DF96  England
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With modern heavily processed/compressed 'music' the awful sound from a slow disc with narrow grooves and significant HF distortion might not be too noticeable. It would be too slow for decent HF, and insufficient groove space for decent LF. Fine for speech, but not serious for music.
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Old 2nd September 2011, 12:15 AM   #8
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Originally Posted by leadbelly View Post
There's another example of this other than SY's. One of the records I inherited is a 10" LP, i.e. on a 33/78 TT you would set the automatic cueing to 10" as for a 78 and the speed to 33 RPM.
Ah, youth!

They used to call those ones 'EP's - they were pretty common, actually.

And, if your family had a really 'modern' record changer, it would sense the record diameter and drop (pretty much!) the tonearm in the right general area.

......aka 'the bad old days' of audio.

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Old 2nd September 2011, 03:32 PM   #9
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Originally Posted by VictoriaGuy View Post
Ah, youth!

They used to call those ones 'EP's - they were pretty common, actually.

And, if your family had a really 'modern' record changer, it would sense the record diameter and drop (pretty much!) the tonearm in the right general area.

......aka 'the bad old days' of audio.

I always thought "EPs" were extended playing time 7 inch 45s. 10 inch 33 RPM LPs were common in the early 50s, I have several.
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Old 2nd September 2011, 03:56 PM   #10
kevinkr is offline kevinkr  United States
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Originally Posted by leadbelly View Post
There's another example of this other than SY's. One of the records I inherited is a 10" LP, i.e. on a 33/78 TT you would set the automatic cueing to 10" as for a 78 and the speed to 33 RPM.
I have a few of those records, mostly from the UK. Mine are pressed on thinner vinyl and don't sound all that stellar..
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