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Can Digital Audio Ever Be Indistinguishable From Analog?

As digital-audio resolutions increase from 44.1kHz/16 bits to 96kHz/24 bits to perhaps even 384kHz/32 bits, I wonder if there's a point at which digital becomes indistinguishable from analog. After all, the human hearing system is not infinite in its discrimination, so there must be a digital resolution beyond which we can't hear the effect of increasing it further. If that's the case, is digital audio at that resolution indistinguishable from top-notch analog, or is there some quality that will always allow us to identify it as digital?

Those who prefer the sound of analog will probably vote that digital will always be distinguishable from high-quality analog, no matter how high the resolution is, and I'd really like to know why you believe that. What is it about digital audio that will always allow humans—at least those with trained ears—to identify it as digital?

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Can Digital Audio Ever Be Indistinguishable From Analog?
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notabadname's picture

What we are hearing is of course never digital, but simply our analog speakers being driven by surges of voltage to elicit movement from the soundwave-producing speakers. By their physical nature, a speaker ends up creating an increasingly smoother analog "curve" from what ever source it is receiving as long as the sample rate is high enough in the case of digital. A speaker can not physically move in a "digital" fashion. So at some point, the sample rate will create enough points across the sound being created that the speaker will move across the same "anti aliased" curve as if it were being driven by an analog source. Mathematically, there is certainly a sample rate that will send the same analog current coursing through the speaker wire to drive the speakers identically to the way they would be driven by an analog source.

And isn't it a mute point if most recordings are being recorded digitally now anyway?

saint0's picture

My music collection consists of 400 LPs, over 3000 CDs and a few MP3 files from iTunes and High Res files from HDTracks. CD or 44.1/16 playback through a good quality DAC (e.g. 192Hz/24b) and HiFi system is good enough for me.

I got a Meridian Sooloos recently, and is in the process of ripping my CDs in FLAC for the Sooloos and in 320kbps AAC for iTunes and my mobile devices. I hardly touched the CD player & the turntable since I got the Sooloos. The CDs are going to the garage once they're digitized. I'll keep my LPs for now, but have no plans to add more.

I also updated my main system, replaced my separates with Devialet D-Premier integrated DAC/AMP. It's a novel class-A/digital hybrid amp, so even the phono input is digitized by a 192Hz/24b ADC. The sound quality of LP playback with the Devialet is actually better than my old pure analog system even though it's converted to digital. I have some albums in all 3 LP, CD and 96/24 formats, and the sound quality of the digital sources are better and cleaner (lower noise floor) than LPs IMO; while the difference between 96/24 and 44.1/16 sources are very subtle or hardly noticeable with the Devialet (couple of reviewers of the Devialet had the same comment). Actually, some of the "High Res" files from HDTracks sounded worse than CDs with elevated background noise and hiss (probably due to old master tapes or poor processing), so I'm not sure if it's worth spending the extra $$$ for 96/24 files. I'll stick with CDs until there are other comparable digital download options.

While some may think digital is imperfect, having my entire music collection accessible via a remote touch panel or iPhone/iPad APP and distributed to 6 audio zones in the house, or having 200 albums on my iPhone while I'm traveling is priceless. Vinyl is a new novelty for the young MP3 crowd, but they'll soon discover it's mechanical limitations and the storage and maintenance hassles. I suspect physical media will disappear as soon as the greedy studios fully embrace the brave new digital age; it'll save a lot of plastic and trees, and reduce the carbon footprint of the music industry.

saint0's picture

We all know the min. sampling rate needed is 2x the BW, so 44.1 sample/sec is sufficient to capture the information for a 20KHz BW. You can theoretically recreate a perfect 20KHz sine wave from 44.1 sample/sec source. The nasty sound quality from earlier CDs are due to poor digital mastering and the digital to analog conversion & filtering issues. The DAC & analog filtering issues are very well understood these days, and good quality 192Hz/24b DACs are widely available at fairly reasonable cost. There are "audiophile" $20K to $50+ CD players around, so it's kind of an endorsement for the CD medium.

The number of bits affects the dynamic range. Again, can we actually hear the difference between 16b vs. 24b of dynamic range? Unfortunately, many popular recording's dynamic range is compressed these days, so the extra bits have no effect.

I'm not sure how many people have their hearing checked regularly? Our hearing degrades as we age, usually with more and more high frequency roll off. It can be a shocker. So, all the $$$ we spent to get perfectly flat response can be kind of meaningless. It may also be the reason why some "audiophile" system & loudspeakers have ear piercing tweeters; and why people are willing to pay a premium for more bass, as we can actually still "feel" it even as we age; but that's another subject...

I concur with "notabadname"; your loudspeaker and room response are the major factors that affect the sound quality of your system.

cbono's picture

it's not high enough

Scott Wilkinson's picture
How high would digital audio resolution need to be in order to be indistinguishable from analog?
RAllen's picture

Let's not get back into voodoo hi-fi. The higher sampling rates give a sound that is only distinguishable from analog because the noise floor is so much lower. You can imagine that you hear the digital differences but I'm not sure the human ear can distinguish these infinitesimal differences. I love my old records as much anyone, but the argument is essentially over now that sampling rates have gone up and filtering/DAC technology is so improved.

samuels's picture

At this stage of the game it do not matter that much to me if digital audio will ever sound like analog. And that is not a bad thing. Each have pluses and negatives. For me digital audio have far less negatives than a very costly analog turntable system. Since I've never listen to a 100k plus turntable setup I can only make this judgement call using my humble 15k system as a ref. I still very much enjoy listening to LPs on a Music Hall mmf 2.2 tt and Ortofon Red cartridge. My lp collection dates from 1965 to 1986. Haven't gotten one since and likely never will. (Red book cds make up the least part of my music collection. Thank goodness.) But I love just as much watching and listening to Chris Botti Live on blu ray, George Benson on 96/24 Monstermusic dvd, or the Mahler series in sacd with Michael Tilson Thomas conducting the San Franciso Symphony. For me those three formats come closer to the real thing than my turntable system ever will. I'm enjoying my music more now than the turntable days of the past. Digital audio can be just as smooth and grain free as analog with careful system matching components and the care put into the recording process. Digital audio being indistinguishable from analog audio is just another moot point.

uavtmsorosk's picture

Why do people want digital to sound like analog ? I much prefer digital . Got rid of my analog rig 7 years ago and don't miss it or want another .

gaslight's picture

There is a upper frequency limit on LPs. This is especially apparent as the stylus reaches the innermost grooves. At this point, the wave pitch is smaller than the stylus radius, and conequently the stylus cannot track frequencies higher than 10 khz. Moreover, as stylii and records wear, it tends to decrease frequency response.

lawsonjl's picture

I'm a digital junky with a state-of-the-art digital home theater system (the only non-HDMI cable in my system is the analog cable from my turntable). I have modern records(current releases)that I compare to the CD recordings every chance I get. I tend to find the same 3 things when comparing analog recordings to uncompressed digital recordings. 1. The noise level of the analog recording is much more noticeable and effects the sound of the recording, some people call this "warmth." 2. The frequency response of the uncompressed digital source is much better then the analog. 3. The sound field is much wider and taller with uncompressed digital and sounds are more easily localized. I personally think a well done uncompressed CD (or 96kz 24bit audio file) is higher quality then any analog source currently available. This doesn't mean that I don't like listening to my LP's, they do provide a unique sound and a different listening experience. That isn't a bad thing. Digital is the cleaner, purer source and doesn't give the sound a special character because of the medium. That being said I completely hate compressed music. Lossy compression strips away any of the fine detail that was present in the music and ruins any potential the digital recording ever had.

JustinGN's picture

It wholly depends on if we can find a way to sample and store analog content in a lossless digital format. The problem is that the analog waveform isn't fundamentally understood by computers - analog audio has a (theoretically) infinite sample rate, while computers will always have some sort of gap between samples. For analog masters with analog mixes, this is a problem that we still can't necessarily overcome with technology, not entirely. However, as more and more new music is recorded and mastered in an entirely digital domain, it'll be impossible to recover this lost information to the point of full, 100% accurate reproduction of the recording or performance.

That is the problem with digital mastering - it's a destructive process for the time being, and I don't think many record companies or audio engineers fully grasp that concept. Even if we were to sample 64-bits at 705.6kHz, there's still missing information in the signal during its transition from analog to digital domains. Even the renowned SACD is inevitably missing information from the original analog performance, though at that point it's more semantics than anything.

Alas, without a record, cassette, or other analog audio player (lost my job before I could purchase a Rega RP1 to get going), I can't honestly render a judgement as to which I prefer. I certainly enjoy high-resolution digital content from the likes of HDTracks and B&W's Society of Sound, but my current equipment makes the differences between 24/96 and 24/192 difficult to distinguish, and that's the other problem - until quality, top-shelf equipment becomes mass produced or affordable again, there's no reason to invest in better recording or mastering technologies. The lowest common denominator is the MP3, iTunes, and Amazon, so that's what companies are catering to.

At the end of the day though, I think the entire argument is sort of a moot point. Other adjustments to audio (eliminating Dynamic Range Compression, for instance) can have a much higher impact on music quality than a better sampling rate or improved vinyl pressing. Even then, people will listen to what they enjoy, regardless of things like bitrate, sampling, or analog/digital domains. Until and unless we can educate people about the differences in the above samples, audibly demonstrate what they're missing by choosing (presumably) inferior technologies, then this argument will persist in audiophile circles, and everyone else outside said circles won't know or care about it. A shame, but c'est la vie.

I guess what I was trying to say is that yes, digital will always be distinguishable from analog on a technical level. So long as it's distinguishable on a technical level, regardless of sample rates, then someone will claim they're able to hear it. With current technology however, I wager that amongst seasoned audiophiles, digital will be distinguishable from analog in many (but not all) cases. Which sounds superior is more up to the equipment used and the listener preference, than the format itself.

And ultimately, that's what makes being an audiophile so much fun.

uavwilldao's picture

I concur with RAllen, notabadname, saint0, and perhaps others:

Analog is primarily distinguishable via its higher noise floor (and to a lesser extent, other anomalies, such as possible feedback from subs, with turntables, lower possible dynamic range especially at the low end, at volume, also with turntables, etc.)...and, fixing any possible speaker-room interactions will have far more noticible effects on sound quality than the "mere" differences between analog versus digital sources; or, source players, for that matter, above a relatively "good" threshold. Also, room-deadening to hinder deleterious effects from HVAC units, outside traffic, etc., probably has a more beneficial effect than one might imagine: given the inherent noise floor of your (presumably "average") listening space, can you even discern minute differences between or among analog and digital sources?

My two cents.

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