Part 2 in a series: After decades of continual improvements in audio recording and playback technologies, the average 21st Century listener will hear most music at lower fidelity than before the millennium. How did this happen, and can anything be done about it?
In Part 1, we reviewed some of the reasons for the general decline in audio quality. Here we will explore the differences between analog and digital audio and sort out the winners and losers. Let’s start with the basics: what is the difference between analog and digital audio?
All sound waves are analog: an instrument or voice produces a disturbance that moves atoms through a medium. Here on Earth, that medium is usually air.
In an analog recording, these waves are typically picked up by a microphone that converts them into an electrical signal. Variations in the voltage of the signal are then converted into a continuous physical representation of the sound on lacquer or magnetic tape.
For digital recordings, an analog-to-digital converter (ADC) samples the signal at a specified frequency, and converts the results into bits ( a series of ones and zeroes). The bits are recorded onto a digital storage medium, usually a computer disk. Most professional studios record digital audio at 96 kHz, or 96,000 samples per second. When transferred to a CD, the rate is reduced to 44,100 samples per second.
Analog recordings are most often captured on tape. They are then transferred to another physical medium such as vinyl for distribution and storage. (They can of course be transferred to a CD, at which point they are no longer analog.) Digital recordings are usually captured on a computer disk, and stored on a CD, DVD, or in a computer file.
There’s no way around it: tapes and vinyl records have to be shipped and then carried into your home. Digital recordings can be distributed in a similar manner by CD or DVD, but can also be transferred as files around the globe at the speed of light.
Analog recordings can be played back on tape or vinyl. In a reversal of the recording process, a tonearm moves a needle along the grooves of a record, and sends the signal through analog cables to an amplifier. The amp powers speakers that disturb the air to reproduce the sound waves. It’s atoms all the way through.
Digital recordings require an extra step for playback. A digital-to-analog converter (DAC) takes the bits from the file and turns them back into an analog electrical signal. This conversion can take place at the source (e.g., CD or MP3 player), within the amplifier, or in an outboard device that sits between them. After conversion, the signal is amplified and sent through the speakers.
In practice, the analog and digital realms are almost always intermixed. Vocals may be sent through a digital signal processor (DSP) before they are recorded on an analog tape deck. Digital recordings might be mixed on an analog console and then converted back to digital for mastering.
Prior to the introduction of digital recording equipment, all recordings were “pure” analog. When compact discs (CDs) first became available, they were often labeled with a three-letter SPARS code using A (analog) and D (digital) to indicate the type of equipment used for recording, mixing, and mastering.
So theoretically, a DDD disc would be “all digital”. This system has been largely abandoned because of the confusion caused by overlapping technologies at various stages of the recording process. It’s worth noting that there was at least one quadruple D disc. The 25th Anniversary Edition of Switched on Bach* from Wendy Carlos was labeled DDDD, since the sounds were produced by a digital instrument and then digitally recorded, mixed, and mastered.
Do CDs sound better or worse than the LPs they replaced?
Yes. As should be obvious by now, there are a lot of variables going into the signal that ends up as sound waves emanating from your speakers. How well was the original recording engineered? How carefully was it mixed, mastered, and pressed? After that, there are even more obstacles to high-fidelity: how good is your your turntable or CD player? What about your amplifier and speakers?
The LP was introduced in 1948, so the art of analog recording had matured considerably by the time the CD was introduced in 1982. The digital arts were in their infancy, and CDs created a huge spike in demand for catalog titles that resulted in thousands of discs being quickly, and sometimes carelessly, mastered.
Some early CD releases sound just awful compared to their analog predecessors — I know, I bought them (many for the third time: LP, cassette, CD). There were a few cases where CDs sounded harsh because the master tapes had already been equalized for vinyl, and others where the wrong (i.e., inferior) master tape was used.1 Over time, digital techniques and equipment matured and sound quality improved dramatically.
With well-produced source material, you can get excellent sound out of either a digital or analog system. The digital system will probably be less expensive, and digital formats are more portable, less prone to degradation, and easier to distribute. The advantages of analog are harder to quantify, and advocates usually end up making emotional appeals instead of technical arguments.
Broadcasting from his basement, BadEditPro concedes that a CD “smokes” the LP in just about every specification that can be measured, but prefers LPs because of their “warmth, crispness, and depth, and reality. ..you feel like you are listening to the artist and not a representation of what the artist recorded in a recording studio.” The typical arguments are nicely summed up by the writers below:
When I get a chance to hear vinyl after long bouts with zeros and ones analog always surprises me. It just sounds better–nicer–and more, well, musical. You folks who love music and have never experienced vinyl, you literally don’t know what you’re missing. No one’s saying analog’s perfect, there are distortions, scratches, noise, and dirt that dig-o-philes never deal with. It’s just that digital seems to miss the natural warmth that analog seems to capture so well. Maybe we’re “designed” for analog and digital is just too unnatural to fully enjoy.
~ Steve Guttenberg, “Intelligent Design vs Science, analog vs digital, CD vs LP–and the winner is?“
Hey, it’s one thing to subjectively prefer vinyl’s “warmth” and “richer sound” (what others might call “muddy bass” and “rolled-off highs”) to CDs. But that subjective judgment shouldn’t be equated with better “audio quality,” which implies a more rigorous technical standard of measurement.
Everything else being equal – and admittedly, that isn’t always the case – I know of no technical criterion where vinyl is in any way superior to CD (with the possible exception of upper frequency range, but only in some special cases). This of course doesn’t suggest that all CDs sound better than all LPs, or vice versa, or that CDs are perfect – only that CDs offer a (far) greater potential for accurate sound reproduction.
~ Rich Pell, “Audio myth: Vinyl better than CD?”
It’s hard to call this fight, and the results of most listening tests seem to be inconclusive. Of course, when there is a conclusion, the losing side will claim that the test was biased, or flawed. Digital may be a winner on paper, but analog has won many a heart. And there is something appealing about natural sound waves creating analogous grooves that are used to recreate the same waves in another space and time. It’s, well…groovy.
Here’s a theory. We know that sound doesn’t exist in a vacuum. In fact, since we read MMT we know that it can’t exist because there is no medium for its transmission. Do you remember the first time you used a digital voice circuit and there was a pause in the conversation? It sounded funny, right? Like, um, dead. Maybe it’s the imperfections in analog audio reproduction: the wow, the flutter — the hiss, crackle and pop that make it sound more “real” and “warm” and “life-like” to us.
But just because analog is our friend, we don’t need to make digital our enemy. One thing’s for sure: digital is here to stay. In part 3, we’ll take a closer look at the various digital formats, do some math, and find out what high fidelity means in the 21st century.
In the meantime, check out what it takes to cut and press a vinyl record below, and get the full story here.
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1 David Gerald, “Future Tense: Digital vs. Analog“