Why Are Records Real? I posted a video on YouTube a few years ago that explains exactly how sound is recorded onto stereo records. I get comments from folks who ask questions about that video all the time. Most say they dont get how the audio information is “read” from the groove. I tell them that it is not “read” but truly “reproduced” when the record is played. CDs are “read” and the data extracted from them is interpreted by a digital synthesizer that closely emulates the sound that was interpreted by the quantizer when the original analog audio was sampled. Notice that there are all those words that hint at inaccuracy or guessing in that last sentence: Interpreted; emulates; sampled, synthesize(r). This sort of encoding is precisely why you can “rip” a CD into a WAV file and then burn same file to another CD. Its not audio but numerical data youre moving around. Once the audio is sampled its not audio anymore; its just a long string of code and you must have a relatively sphosticated computer to make sense of it or you can do nothing with it at all. You might have already picked up on the fact that youre not getting the whole picture when you listen to digital audio no matter how high the resolution. All the words used in describing the recoding process tip you off. The resulting playback audio is an interpretation of the real thing and not the real thing itself. However, digital audio can be quite convincing, just as a digital picture of Van Goghs “Starry Night” can evoke the mood the artist was trying to capture, digital can give us a hint at what was going on when the music was record. Does the digital pic compare to buying a plane ticket to Paris and standing in front of the original painting in the Louvre? No, but we dont expect it to, now do we? The same should be expected from digital audio... It is not and never has been perfect even though it was billed as such when we all went out and bought our first CD player. When you really get down to it, audio recording devices, analog, or digital, really dont record sound at all. They record time. Theyre a form of clock. Imagine you had a record lathe of your own and you put a blank disk on the platter, lowered the stylus onto it and cut a groove on it for 15 minutes exactly at 33 & 1/3 RPM. What you would get is a record of that time and if you played that disk on a turntable at the original speed, it would spin for exactly 15 minutes before the stylus would drop into the run out groove. Its an hour glass of sorts. Same would go for a tape moving from one reel to another at a fixed speed or even a digital file with time code but no audio in it. Were not even talking about capturing audio yet and you can already see a big technical challenge in this endeavor because both “clocks” used to record and playback any medium at alter time have to be in synch and very accurate or were going to get a misrepresentation of the original. With analog, both tape and disc, the result of a mismatch will result in changes in perceived pitch and a shortening or lengthening of time played. Digital suffers from the same problem but instead of pitch changes the two clocks not being in exact synch will cause “jitter” in the synthesized audio. Jitter causes all sorts of strange sounding distortion like grittiness, harshness and a generally metallic sound. Mich of the time what denotes a really good piece of playback gear is how accurate its clock is, whether that be a spinning turntable or digital time keeper in a CD player. The actual method used to represent the sonic vibrations that are sound becomes secondary in consideration once you understand the concept of the record/playback system being a kind of clock. So what about the record? What is it really? Well, its NOT sound. Not at all. It cant make any sound of its own; it is inert. We are all at least generally familiar with the basics of disk recording, stylus cuts a groove into a master disk while it vibrates in synch with a signal fed to the cutter head. The squiggles, hills and dales left behind in the groove represent the motion of that stylus. That master disk is plated and those plates become stampers, still holding those impressions from the cutter head, and they stamp out copies that we can play at home. The record just holds a record of of what the cutter stylus did in a certain amount of time. We need a clock to recreate it. The details tend to get very complex but the general concept of the whole phonographic system is actually very simple. So simple that you can reproduce ineligible audio from a modern LP or 45 with nothing more than a sewing needle and a good sized Styrofoam cup! You can try it for yourself and see but dont use a record you care anything about because the steel needle will damage the groove. Its this very simplicity that makes the phonograph such a fascinating device. Thomas Edison introduced the first working phonograph in 1877. There has been 137 years of research and development applied to the technology we still marvel at, even in todays world of iPods and surround sound. So, why is it still around? I mean, really? When you think about it, everything else has changed and digital everything is the norm these days. Well, I think its because we have yet to come up with anything better. Sure, you can go out and get yourself a great big analog tape recorder with 14 inch reels of half inch tape running at 30 inches per second and get better quality audio than what you get from an LP but you better have a lot of cash to spend and the ability to maintain such a beast! Even if you do have one of these machines, where are you going to get tapes to play? You can always record yourself singing in the shower but that would get old after a while... No, there are billions of records out there and they can be found for cheap unless youre getting a new audiophile pressing or happen to be hankering for an original Blue Note jazz LP from the 1950s. They get pricey. Best to leave the half inch analog tapes to the guys who use them to cut records. Thats what they are really good for and I believe that you get a lot closer to that tape when you listen to a well cut record than when you hear it from digital anything. Records are not perfect; they never have been but they do a better job of conveying the spirit of the music than any other medium. Even a sliighjtly worn record with audible surface noise will get you closer to reality than a squeaky clean digital stream. Heres what I think is the reason why: All your cartridge really is is a type of microphone that converts the physical vibration of the little chunk of diamond at the end of the stylus that runs through the groove on your record. Those vibrations are a reproduction in the truest sense of the word of the audio fed to the cutter head. It is a performance in and of itself. Theres no reading or interpreting or synthesizing or emulating. It just is. As long as your clock is in synch and your stylus keeps in contact with the groove walls at all times, youre hearing the real thing. Long live the phonograph!
Posted on: Fri, 19 Sep 2014 19:19:37 +0000
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