What is "Analog Warmth"?

If you have heard the term "Analog Warmth" and wondered what it really means, this will hopefully clear up some of the confusion.

It's gone from obscurity to having an almost mystical status, mostly because of the rise of digital recording systems as the main method for studio recording, and a noticable lack of "warmth" in those recordings when compared to the era when analogue tape was the main format for recording music/audio.

The Vinyl revival has certainly been the main impetus behind the return to analog music formats from the past. It's never gone away, with a devoted fan base that spans every generation, in 2020 sales of albums on vinyl outsold CDs for the first time since the 1990s, sales of music on cassettes are also seeing remarkable year-on-year increases.

It's hardly surprising that the cassette is making a comeback as well. There are a growing number of people of all ages reaching out for a cassette tape rather than a playlist, they do this for a wide variety of reasons:

Tangibility | The tape and vinyl record have something that no software, no matter how cleverly it is designed, can give the listener the experience of holding the music in their hands, toching, smelling, reading the liner notes, watching the disk or tape spin around...

crate of records

... these are just some of the things that appeal to the analog listener. There are other reasons, sonic quality, despite the rumours spread by low quality players and ratty old tapes from the 80s, or new cassettes being made with ghastly 30+ year old tape inside them, the sound quality of a new high quality cassette is in most respects, far higher than many common digital formats, such as 128K mp3.

Allow me to explain: In ancient the past (the 1970s), before digital recording and playback was common outside of the most expensive recording studios, all music was recorded in analog, on to tape, and then made into the vinyl records and cassette tapes which were sold in stores.

The reel to reel recorders used in studios were capable of incredibly high fidelity recording quality, with ultra low signal/noise ratios and stunning dynamic range which could replicate music almost perfectly.

Even the early magnetic tape formulas of the 1950s & 1960s provided approximately 65,000,000 (65 million) magnetic particles per second on a 1/4" tape running at 15ips (inches per second) speed, the individual oxide particles (or groups of them) are arranged in either a North or South orientation, the particle count is just part of the "warmth" with the particles stacking randomly to give a "super binary" recording, which far exceeds the highest bit depth of today's best digital recorders, which at best are capable of slightly over 4,600,000 bits switching every second, so as you can see, even the 1950s magnetic tapes had a higher "sample rate" than 2020 digital recordings, and modern professional tapes such as RTM's SM900 have over 80,000,000 per second on 1/4" at 15ips.

reel to reel tapes

Then along came digital recording which massively increased the possibilities for mixing the music, opening up new sound and removing many of the limitations that working with tape imposed, which enabled artists to use the studio in new ways, it also flowed through to the production end of the music industry, where records on CD could be produced faster and for much less cost, which appealed to the major record labels who had seen the profits to be made by ditching analog for the shiney new laser disk wonder that was compact disk, the future seemed bright for all.

Brilliant! Well, yes and no. The developers of digital audio were trying to sell their shiney new toy, and they made all kind of claims about the "perfect sound" and how it would make the old formats obsolete, which it mostly did, the CD came along and sales of vinyl records soon plummeted, along with cassettes and other formats, the CD was here and here to stay, nobody was going to go back to using Edison’s technology, Grandparents listened to that, we had lasers.

RIAA Sales Chart

To achieve their shiny digital audio sound and make it work within the limitations of mid-late 1970s computer processing capabilities, they had to fit all the information to reproduce audible sounds into what we regard now to be a small amount of data.

The system used to create a digital audio file is called: ‘pulsed code modulation’ file or ‘p.c.m’ , the technical standard they chose allows for up to 74 minutes of digital sound. A sample rate of 44.1Khz, or 44,100 samples per second. A transfer rate of 150 kilobytes per second, also known as "single-speed" or 1X. Can contain up to 99 tracks. Know as the 'Red book audio standard' it is also referred to as CD-DA (Compact Disc-Digital Audio). Introduced by Sony and Philips in 1980, the Red Book standard was simply designed to be a universal medium for distributing digitized music. The Red Book CD was to become the template for which all other "book standards" were created.

The first edition of the Red Book was released in 1980 by Philips and Sony, it was adopted by the Digital Audio Disc Committee and ratified by the International Electrotechnical Commission (IEC) as an International standard in 1987.

Providing a greater high frequency response than analog was the focus for engineers at the time, the general public had been brought up to desire better treble, and digital audio was going to be the silver bullet that gave us that "crisp, clean sound", but at what cost?

The cost was not so apparent at first, the World had never heard such detailed high frequencies without all the background hiss of the tape or crackle of the vinyl, it was shiny and new and oh so 80s cool, and the World embraced CDs as the new format, "vinyl is dead" they said, but people couldn't help notice that their dead vinyl just seemed to sound better.... "warmer".

Warmth was a term that now applied to the sound of analog audio, it was still a term full of conjecture, and even some hatred by certain audiophiles and engineers of the time, how dare they bandy about the phrase "analog warmth" as if it had some scientific merit?

Anecdotes can often have some basis in truth, soon enough scientific curiosity took hold and provided answers to the question of whether or not "analog warmth" was a phenomenon or simply a popular myth, and indeed that there was some truth to the concept that analog audio was warmer. Not that the answer was by any means definitve, it was more to do with larger and larger numbers listeners starting to notice what digital audio lacked rather than any fault of the familiar flaws with analog audio definition.

woman wearing headphones staring out of a window

The limitations of the digital audio bandwidth and sample/bit rate made the engineers decide to devote more bits of each byte of information to the higher frequencies (treble) in proportion to the lower frequencies (bass) in order to achieve what to the 1970s ear was a more "natural" sound, with less emphasis on the lower frequencies which analog sytems tended to over-emphasise at the time.

However, we were flying space shuttles and watching television and movies recorded on the new video tape machines that had arrived in our homes, so why should music be stuck on these clunky old formats when we had LASERS?

I'm sure that the laser aspect had a great deal to do with how the general public perceived compact disk, it made it seem futuristic, unlike dragging a needle across a piece of rotating plastic, lasers were space age, and super cool, so they must be better right?

Well they are better for all sorts of stuff that a needle and vinyl records will never be, but when it comes to reproducing a more faithful sound, the scratchy old needle and disk still had something over the new laser toy, it didn't discriminate against the warm bass frequencies, nor make the high frequencies too harsh, unlike digital audio.

Basically, a digital recording system samples sounds in many tiny snippets of time, much like a video camera takes multiple still frames each second; this eliminates a whole bunch of information that is happening in the moments that fall between samples, whilst it's not much on paper, it is a whole lot when it comes to reproducing the soundwaves for our analog ears, that is where the elusive "analog warmth" is to be fealt, it's the way that magnetic particles on tape capture the whole sound, not just a series of samples.

While this may be fine for video, where it only has to slightly exceed our visual system’s “frame rate” to give a perfectly acceptable moving image with no sign of flickering, that is why when moving pictures were first invented, it was quickly realised that a frame rate of 25/sec was sufficient to give the viewer a natural flow of time and motion, albeit within the limitations of the early technology; hand cranked cameras with black and white film.

The same analogy cannot be said for sound and the human auditory system, which, in comparison to the eye’s 25/sec (or 25 Hertz) frame rate, is more sensitive by almost 1000 times the "frame rate" of the eye.

It can (when we are young) perceive frequencies from 20 Hz to 20,000 Hz with staggering sensitivity, from a vibration that is less than the orbital frequency of the electron surrounding a hydrogen atom in amplitude (volume), to the other end of it’s threshold at around 120dBSPL (decibels/sound pressure level) which is the point where it becomes painful to most people, these are jet engine, or rock concert volume levels, which can quickly cause hearing damage.

So… we now know that the human ear can perceive a broad range of frequencies within a broad dynamic range, and that even though the digital sample rate is 44,100 Hz, more than double the theoretical frequency limit of the auditory system, it does not accurately represent the sound waves because the information about what happens in between the sampled moments is missing, giving the sound waves a staggered appearance when examined in detail, this is the “jagged edge effect”, rather like driving on wheels with thousands of flat spots compared to the analog wave which is continuous and smooth like a perfectly round wheel rolling, it has the comfortable feeling of something natural: “analog warmth”.

To give even greater fidelity, many studio tape recorders can run at twice that speed, a remarkable 30ips, and a very few can record at 60ips, this gives stunning results, and is the favoured tape speed for classical/jazz recording, where the goal is to reproduce the sound of the finest musicians and instruments in a concert hall or venue with no distortion or alteration of the original sound. Rock and popular music often favours recording at 15ips for the slightly "grittier" quality of that speed, with a hotter (higher voltage) signal sent to the tape recording head.

Whilst there's a plethora of other factors that can contribute to the "warmth" of a recording, things like the individual recording studio acoustics, microphones, instruments, and the musicians themselves, all flow together to give each recording it's individual characteristics, and then there's the listener's experience, which can vary hugely depending upon the playback machine, the speakers, room acoustics... all of these things can colour the sound, however, digital has the same drawbacks, so when comparing the two, listeners invariably favour the analog sound regardless of the listening environment.

Analog Natives.

Long Live Analog!