There is a great deal of enthusiasm and strong belief from my customers about the superior sound that analog vinyl records deliver over digital recordings as presented via your standard CD. Worse yet is the sound quality of digital downloads such as the default iTunes format. I often hear audiophiles in my shop and at LPs shows all in agreement about the superior sound of vinyl records. Stay with me on this as I state the facts…
According to settled science, no human being can distinguish the difference between a digital soundwave with a high enough sample rate and an analog soundwave, but some of us remain unconvinced. “Sure Joe, but I tell you that vinyl presents a “warm” characteristic that can’t be matched by digital recordings”, says my anonymous vinyl head patron. You have to understand that from a psycho-acoustic perspective what you are describing is harmonic distortion which is also present in other analog mediums such as tape.
That classic “Vinyl” sound is influenced by how music is originally recorded (analog tape versus digital hard drive) and how the original recording is then carved into the media (the mastering), the characteristics of the medium itself (vinyl) and finally the playback mechanism (turntable, stylus, cartridge, electronics, amp, speakers, etc.).
The meaning of “vinyl sound” is often approached subjectively. Different people have different ideas of what a sound has to have and/or lack to be considered “vinyl sound”. To answer this question objectively, we can take a look at measurable characteristics and dynamics of the medium. There are two issues here that are hard to separate: analog recording and vinyl as a medium. There are many basic misunderstandings of how digital sampling and psycho-acoustics work in what is delivered as the final media.
When people refer to “vinyl sound”, they are most likely referring to one or a combination of the characteristics as follows. The importance of each characteristic in the “vinyl sound” definition is the subjective part.
Low frequencies (bass): Low frequencies panned between the left and right channels can knock around the needle, so you’ll find low frequencies to be monophonic. Even with centered low frequencies, the record can skip with excessive low end. Because of this, excessive low end is not a feature often found in vinyl.
High frequencies (treble): High frequencies and sibilance can cause distortion because the stylus cannot properly track them in the disc’s grooves. Because of this, highs might need to be tamed down (reduced, compressed, flattened) for vinyl playback.
Wow and flutter: Wow and flutter are a change in frequency of an analog device and are the result of mechanical imperfections, with wow being a slower rate form of flutter. For LP records, the quality of the turntable will have a large effect on the level of wow and flutter. A good turntable will have wow and flutter values of less than 0.05%, which is the speed variation from the mean value.
Inner and outer portions sound different: The distance around the inside of a 12-inch record is about half the distance than around the outside, as the distance around each revolution decreases, the high frequencies become harder for a playback stylus to read. As a result, the inner tracks will sound duller than the outer tracks. The high frequencies simply can’t be reproduced the same as if they were cut on the outside of the disc.
Surface noise: Pops, clicks, crackles – for some part of the enjoyment of listening to vinyl. You’ll find them even on high-end setups. Sometimes the bane of our store because of the desire for a perfectly clean “audiophile” copy. How and the hell do I know if the person I got the LP from cut their stash of the cover and laid the record down on top of those stems after playing side 1.
Dynamic range: Vinyl microgroove phonograph records typically yield 55-65 dB, though the first play of the higher-fidelity outer rings can achieve a dynamic range of 70 dB. For comparison, 16-bit PCM (CD quality) has a theoretical dynamic range of about 96 dB.
RIAA curve: The Recording Industry Association of America (RIAA) equalization curve allows engineers to overcome certain limitations and maximize the amount of full-frequency music they can get onto a record. The EQ curve is applied as the music is cut into the master lacquer. When a record is played back, the inverse of this EQ curve is applied by the phono preamp so that the listener hears the music as it was intended.
Because low frequencies require larger grooves and more space on a disc than high frequencies, the EQ curve gradually rolls off the bass by 6 dB per octave starting at 1 kHz so that by 20 Hz, the level has been reduced 20 dB. Without the RIAA bass cut, only about 5 minutes of low-frequency information could be stored per 12-inch side. In addition, the RIAA curve boosts the frequencies above 1 kHz to increase the signal-to-noise ratio in the high end. The maximum increase is about 20 dB around 20 kHz.
Unless linear-phase filters are used, phase changes will be induced both times the curve is applied (once in reverse), so both the mastering engineer and your turntable are injecting their character into the sound. How audible the change is depends on the filters used, some high-end systems aim for as little change as possible.
So what is a better medium for listening to music?
Current digital recording technology using 24-bit, 192 kHz sampling can capture more information that we can hear so that was why the original CR Red Book specification adopted the 20Hz-20kHz. More settled science: The human hearing range spans 20Hz to 20kHz, period. Though you can record more than that range, you just can’t hear it. It is possible you can “feel” sounds outside that range but almost all stereo gear a consumer would buy cannot play that range back beyond the established 20Hz-20kHz threshold, if that.
Unfortunately, all the high end we’re now used to experience from our digital recordings is aggravated by the RIAA curve. When they came up with this system, there wasn’t much going on above 8 and 10 kHz. The benefit of the high end we hear today is often perceived as being “cold”, hence not “warm”
As for vinyl itself, there are specific frequency response characteristics that the RIAA imposed on the microphone – tape deck/mixing board – vinyl pressing – stylus – amplifier – speaker signal chain back in the day. The so-called “RIAA curve” was one: it specified that the signal going on to vinyl would have serious roll-off in the bass register so that the needle would not jump out of the groove during playback. The missing bass gets put back in when you set your amp to the “phono” setting. It stands to reason that this type of response curve, especially when replayed on modern equipment, would sound different than the theoretically flat response curve enabled by the CD player (which, not being electro-mechanical, doesn’t care how “big” the virtual grooves are).
One way to artificially achieve that “warm, analog” sound from your digital recording is to crank the bass a few notches and roll off the treble. Better yet, get a DAC (digital-to-Analog Converter) device that simulates the response curve of vinyl.
Still no answer to which medium is better. As for almost all of us fellow “vinyl heads”, just grab yourself a drink, put that LP on the turntable and enjoy reading that LP cover for the hundredth time and let the music take you someplace else. Crackle and pop, that just reminds me to make some popcorn when I get up to flip the LP and enjoy the second side, while enjoying my second cold brew. Play it again, Jimi!