Comparing Compact Discs (CDs) to vinyl or gramophone records is the musical equivalent of comparing digital photography with film photography. CDs and vinyl records are both audio storage and playback formats based on rotating discs, from different times in music history. The CD audio is digitally encoded and read by a laser, while analog vinyl audio is physically read by a needle.
The digital music format of CDs (and increasingly MP3s) is the dominant choice today for professionals and consumers alike. From a technical standpoint, CD audio is far superior to vinyl, but there’s always a certain niche of people who prefer the analog method and claim something is lost from the conversion of sound into digital data. Not surprisingly, this niche is expanding as old-fashioned vinyl records are experiencing renaissance among modern music enthusiasts, recording artists and audiophiles alike.
From a technical standpoint, digital CD audio quality is clearly superior to vinyl. CDs have a better signal-to-noise ratio (i.e. there is less interference from hissing, turntable rumble, etc.), better stereo channel separation, and have no variation in playback speed. The arguments against digital audio come from the fact that no matter how precise the sampling (~44,000 times per second is standard), the breaking down of music into binary data can never match the smooth and continuous nature of analog vinyl. Just like a million little square pixels can never make a perfect curve in a picture if you look closely enough.
Vinyl, undeniably prone to physical interference and noise, has a growing reputation for a warmer, more life-like sound. The technical arguments for this usually center on the inherent jaggedness of digital sampling, despite the fact that high sample rates combined with anti-aliasing (smoothing of the edges) technically negates this argument. However, the subjective claim of an overall “better” sound certainly remains among many enthusiasts and professional musicians.
Digital Music as Source for Vinyl
Writing for the Wall Street Journal, Neil Shah reported in his article Why Vinyl’s Boom is Over that
“Old LPs were cut from analog tapes–that’s why they sound so high quality. But the majority of today’s new and re-issued vinyl albums–around 80% or more, several experts estimate–start from digital files, even lower-quality CDs. These digital files are often loud and harsh-sounding, optimized for ear-buds, not living rooms. So the new vinyl LP is sometimes inferior to what a consumer hears on a CD.
Major labels claim they use original analog masters. They may have the time and budget to issue LPs from analog tapes but smaller labels often cut corners when they can’t afford the engineering and record-pressing expenses of using tape.”
Fragility and Lifespan
CDs experience no physical degradation from repeated playings, as the laser read mechanism does not physically wear down the surface. CDs are less sensitive to temperature, humidity and rough handling than vinyl, but are still susceptible to scratches and extreme temperatures or conditions. Stamped discs do not lose quality over time, but the CD-R and CD-RW formats used in-home by consumers can slowly degrade over several years.
Vinyl discs do begin to degrade in quality through repeated playings, as the read mechanism is a need that operates through physical friction with the disc. Vinyl is also more sensitive to heat, humidity, scratches and dust. A collection of vinyl records must be stored in a controlled environment to prevent degradation.
The advent of CD-R and CD-RW formats, which, rather than being factory-stamped, use photosensitive dyes to allow for writing by capable disc drives, has opened the door for anyone with a modern computer to create their own CDs at a very cheap cost. Digital audio can be shared easily and instantly, which has led to a major decentralization of the entire music business. Now amateurs can digitally record music, create CDs, and sell the music directly.
The process of printing vinyl discs and recording high-quality analog audio remains largely in the hands of experts, as the required equipment is expensive.
Take a look at the graph below. Original sound is analog by definition. A digital recording takes snapshots of the analog signal at a certain rate (for CDs it is 44,100 times per second) and measures each snapshot with a certain accuracy (for CDs it is 16-bit, which means the value must be one of 65,536 possible values).
This means that, by definition, a digital recording is not capturing the complete sound wave. It is approximating it with a series of steps. Some sounds that have very quick transitions, such as a drum beat or a trumpet’s tone, will be distorted because they change too quickly for the sample rate.
your home stereo the CD or DVD player takes this digital recording and converts it to an analog signal, which is fed to your amplifier. The amplifier then raises the voltage of the signal to a level powerful enough to drive your speaker.
A vinyl record has a groove carved into it that mirrors the original sound’s waveform. This means that no information is lost. The output of a record player is analog. It can be fed directly to your amplifier with no conversion.
This means that the waveforms from a vinyl recording can be much more accurate, and that can be heard in the richness of the sound. But there is a downside, any specks of dust or damage to the disc can be heard as noise or static. During quiet spots in songs this noise may be heard over the music. Digital recordings don’t degrade over time, and if the digital recording contains silence, then there will be no noise.
From the graph you can see that CD quality audio does not do a very good job of replicating the original signal. The main ways to improve the quality of a digital recording are to increase the sampling rate and to increase the accuracy of the sampling.
The recording industry has a new standard for DVD audio discs that will greatly improve the sound quality. The table below lists the sampling rate and the accuracy for CD recordings, and the maximum sampling rate and accuracy for DVD recordings. DVDs can hold 74 minutes of music at their highest quality level. CDs can also hold 74 minutes of music. By lowering either the sampling rate or the accuracy, DVDs can hold more music. For instance a DVD can hold almost 7 hours of CD quality audio.
CD Audio = 44.1 kHz
DVD Audio = 192 kHz
Samples per second
CD Audio = 44,100
DVD Audio = 192,000
CD Audio = 16-bit
DVD Audio = 24-bit
Number of Possible Output Levels
CD Audio = 65,536
DVD Audio = 16,777,216
DVD audio discs and players are rare right now, but they will become more common, and the difference in sound quality should be noticeable. To take advantage of higher quality DVD audio discs, however, you will need a DVD player with a 192kHz/24-bit digital to analog converter. Most DVD players only have a 96kHz/24-bit digital to analog converter. So if you are planning to take full advantage of DVD audio be sure to look for a 192kHz/24-bit DAC.