The Big Mystery: Analog Tape - why does it sound so good?

Discussion in 'Audio Hardware' started by Holy Zoo, Nov 2, 2003.

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  1. Holy Zoo

    Holy Zoo Gort (Retired) :-) Thread Starter

    Location:
    Santa Cruz
    We all love that analog tape sound. But why? Just what is that magical quality? And how would you describe it? Warm, lush, smooth? Personally, I like "yummy". :)

    Then there's the technical level: *Why* does it sound so good, compared to so many digitally mixed/mastered albums?

    In my constant thirst for knowledge, I found the following by poking around on the web. I'm curious if anyone here has any thoughts on "The Big Mystery"


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    [...]typical for professional analog tape machines, but they don't sound anything like 800 times as distorted (as you've obviously noticed).

    A high quality tube mic pre might run about .5%, roughly half that amount (although a few, like the Millenia are exceptions and have much less). So tubes and analog tapes generally produce much more distortion than modern solid state electronics do. However, both kinds of distortion/coloration when found in well designed pieces (like an Ampex ATR-100 series tape machine or a Fairchild 670 limiter) have a euphonious, pleasing nature and don't really *sound* distorted in the usual sense of the word. These devices manage to sound "hi fi" to the ear in spite of what their measurements imply.

    This is the main reason why I think signals coming out of these things often sound better than when they went in. The result sounds like "color" and "liveliness" were added but IMHO it's mainly subtle distortion. Also, part of the distortion in both tubes and analog tape (as well as transformers) is time based - a "slewing" that can have a pleasant smoothing effect.

    With digital tape machines the measurable THD is *much* less but that doesn't begin to explain the reason why they don't sound as good. Many factors (poor phase coherence in particular) contribute to the problem. There's also brickwall filtering (empirically above the "audible" range) side effects, clock/jitter issues, sample/bit rate issues and on and on, none of which are factors in analog devices.

    I'm not sure anyone fully understands why digital devices that pass 20hz-20khz sine waves flat as a ruler don't have as clear sounding a top end as analog devices that extend well beyond the "limits" of human hearing, but they do. It's a mystery still and maybe some day we'll have a definitive explanation.

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    "Harmonic distortion" is what we're talking about really, which is pretty much your garden variety distortion. THD means Total Harmonic Distortion and is expressed as a percentage of the signal added by a particular device. The amount and type of THD added has a major effect on the sound. As someone else mentioned here, analog tape and tubes produce more "musical" sounding (even order, musically related) harmonics and digital and solid-state devices produce more "unmusical" (odd order, musically discordant) ones.

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    For one thing analogue distortion consists of integer multiples of the desired frequencies: harmonics. Digital distortion consists of non-harmonic aliasing. Since the distortion products of digital devices have no relation to the desired signal, even miniscule amounts sound like unnatural crap. Also, a great analogue machine exhibits response out to 30K or better. While we cannot hear that high, we can hear how those frequencies modulate what we can hear. With tubes, the difference is also in the distortion products. Yes,tubes create more distortion than transistors and ICs. However, solid-state devices distort in odd harmonics, while tubes produce even multiples. Even harmonics just plain sound less obnoxious (and the second harmonic tends to emphasize the fundamental).


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  2. Grant

    Grant Life is a rock, but the radio rolled me!

    In so many words, HZ, it's the pleasent type of distortion analog tape adds to the sound. That and compression.
     
  3. Holy Zoo

    Holy Zoo Gort (Retired) :-) Thread Starter

    Location:
    Santa Cruz
    Ahem - gee, thanks Grant. ;) I already knew that.

    I want to know *WHAT* is going on, at the electrical or magnetic level. Tube distortion I understand somewhat, having taken a few (too many) EE courses in college. But I don't quite follow what's happening with tape - is the sound colo(u)ration caused be the alignment of the magnetic particles when recording? Or is it something else? I'm curious if this has been studied.

    Traditionally engineers strive to create something perfectly neutral - to eliminate all distortion. So I don't know if the euphonic distortion added by magnetic tape reecording has been studied much as being "good" as opposed to being studied as being "bad" and reducing all coloration to zero.

    jeff
     
  4. Holy Zoo

    Holy Zoo Gort (Retired) :-) Thread Starter

    Location:
    Santa Cruz
    In regards to compression: how is it compressing things? Is it a linear compression? Or does it compress the highs in a certain way without affecting the bass?
     
  5. Steve Hoffman

    Steve Hoffman Your host Your Host

    Compression? Distortion? On analog tape? Only in the hands of someone inept.
     
  6. Holy Zoo

    Holy Zoo Gort (Retired) :-) Thread Starter

    Location:
    Santa Cruz
    I think we're working with the true definition of the word "distort", which at it's core simply means to alter from it's original form.

    Steve, are you saying that you feel that analog tape has no "sound" - makes no change whatsoever to the audio signal?
     
  7. Grant

    Grant Life is a rock, but the radio rolled me!


    Steve, how about electronics? That's where you're headed, right HZ?

    Cause Steve, If I didn't know any better, I could almost swear that your work sounds almost, uh, "digital", in terms of pure clarity, but still has that warm sound.

    I'm getting outta here. I think i'm out of my element.
     
  8. Uncle Al

    Uncle Al Senior Member

    Location:
    Long Island, NY
    Analog = continuous
    Digital = sampled, algorithms fill in the blanks.

    Technical measurements tell me the later is more accurate - yet I still haunt garage sales to purchase used vinyl for the former. A bit of crackle is preferable to me then the "blanks" I shouldn't notice.

    Guess I need some digital ears.
     
  9. Holy Zoo

    Holy Zoo Gort (Retired) :-) Thread Starter

    Location:
    Santa Cruz
    Yeah, but Steve's able to get that analog sound from the tape onto CD.

    I suspect that digital's not at fault, but rather analog tape adds something.

    If you mix to analog tape then master to CD - you can have great results.

    Conversely, mixing to digital seems to often (not always!) produce cold sounding results.
     
  10. JoelDF

    JoelDF Senior Member

    Location:
    Prairieville, LA
    So, is it really the "tape" itself?

    Or, is it the "tubed equipment" that the recorded sound is being sent through and then recorded to tape?

    How often does digitally recorded music filter through tubed consoles during recording sessions? I'm not asking about analog recorded music that is then digitally mixed. Or, is it that all studios with digital recorders are completely solid state?

    Joel
     
  11. VU Master

    VU Master Senior Member

    maybe it's not the tape

    maybe it's more about recording (miking/tracking) technique than recording media.

    I'm not so sure that magnetic tape, with its inherant noise, delivers any magic.
     
  12. Holy Zoo

    Holy Zoo Gort (Retired) :-) Thread Starter

    Location:
    Santa Cruz
    Re: maybe it's not the tape

    I've been recording some of my "cold" sounding CDs to tape recently, and then back to cd. The "after" is sounding better than the before. Well, to my ears. :)

    I don't know what's changed though, the tonality seems mostly unchanged, but the "tape processed" result sounds fuller. (I wish I had Steve's ears and experience so that I could describe this with the correct terminology). Again, "yummy" is the closest word that comes to mind. It's like you can grab the notes out of the air and eat them.
     
  13. Casino

    Casino Senior Member

    Location:
    BossTown
    Re: Re: maybe it's not the tape

    I've had the same experience. Weird, ain't it? Cold CD 's can sound better when transferred - and LP transfers we do at home can sound better than the commercial CD's of the same album where the engineers supposedly used the "master" tapes.
     
  14. -=Rudy=-

    -=Rudy=- ♪♫♪♫♫♪♪♫♪♪ Staff

    Location:
    US
    Maybe it's the natural "dithering" that analog tape adds? (The very faint addition of noise.)

    Maybe it's the higher "sampling rate" of millions of tiny particles of ferric oxide, vs. cast in stone digital bits?

    Think I'll go join Grant... ;)
     
  15. Casino

    Casino Senior Member

    Location:
    BossTown
    I'm witcha, Rudy. But we've still gotta go back to digital bits also - we ultimately have to do that to make the CD-R's. And they CAN sound significantly better than commercially-available product.
     
  16. Taurus

    Taurus Senior Member

    Location:
    Houston, Texas
    My little theory on why digital can sound worse than analog is because digital is so good at capturing almost everything that the mic hears AND any recording mistakes or subpar support equipment noises. This then all gets recorded & then played back on the consumer's end.

    And I'm not sure who wrote that article above, but while I believe the thing about digital having some ugly distortions, the fact that their level is so dang low makes them--to me--an irrelevant problem.

    My personal belief is that the music carrier (CD, master tape, whatever) should be as neutral as possible so that the musician or engineer can be assured that whatever he puts on it is not adversely affected and the end user will hear exactly what the music's creators intended.

    [T]
     
  17. ybe

    ybe The Lawnmower Man

    That's it, IMO. Analog tape (or an LP) stores more information (has more resolution) than digital.
     
  18. Doug Hess Jr.

    Doug Hess Jr. Senior Member

    Location:
    Belpre, Ohio
    I agree with the earlier assessments about continuous versus sampling. It's like looking at a lithograph of a painting compared to the real painting. The painting has continuous, solid paint colors while the eye has to blend the up to 6 layers of colored dot printed on the copy to see the right colors in your head. The real painting always looks better. The same with real typesetting versus 300 dpi laser printing.

    Since our senses "sample" as it were for us to experience things, I believe we enjoy having the added information to pick from rather than sampling a sample-- like encoding and decoding and then encoding an MP3 file so many times you get errors due to a lack of data.

    Our eyes "sample" at 60 "frames" a second and our hearing is from the vibrations of the bones and hair folicols in our ears with the electro-chemical "sampling" by the brain to interpret it into sound.

    That brings me back to continous "analog" visual and auditory stimuli would be more pleasant than digital.

    Just my opinion.
     
  19. Bob Lovely

    Bob Lovely Super Gort In Memoriam

    Friends,

    As many of you know, I am a Reel Tape recording hobbyist. When properly recorded, I prefer the sound of Reel Tape over CD's even when the tracks recorded on Reel Tape are taken from CD's. I cannot explain why the sound is more compelling - simply that it is. Additionally, I re-master tracks from CD and then record them on Reel tape as a creative endeavor. The changes in sound to my ears are subtle but, highly desirable.

    I do not possess the technical knowledge to explain the 'why' but I can share that tracks recorded on Reel Tape do have a certain additional Analog warmth when recorded on Reel Tape from CD's. The key is to use very high quality tape and record tracks properly. I record tracks with the very highest transients at +3 VU. On high output tape, this avoids additional tape compression. I never, ever use NR.

    Bob:)
     
  20. -=Rudy=-

    -=Rudy=- ♪♫♪♫♫♪♪♫♪♪ Staff

    Location:
    US
    I was actually making a point that even analog tape was a type of "sampling", if you consider each tiny magnetized particle a "bit" and the sampling rate being the rate at which these bits move past the tape heads. Sort of an abstract idea, I know, but at a microscopic level the number of particles is very high and, hence, is very smooth on the output.

    :D
     
  21. Holy Zoo

    Holy Zoo Gort (Retired) :-) Thread Starter

    Location:
    Santa Cruz
    I agree about the "continuous" concept. But, it doesn't explain the phenomenon of CD->Analog->CDR sounding better than the original CD.

    Maybe Taurus's theory makes more sense? That digital captures everything, warts and all, whereas tape is removing some of the "glare", warming things up? Then, when going from analog to digital, since digital can capture everything it captures the "stuff" that analog tape "added" (or removed?).
     
  22. Grant

    Grant Life is a rock, but the radio rolled me!

    Exactly. Distortion in the purest sense.
     
  23. Steve Hoffman

    Steve Hoffman Your host Your Host

    It all depends on your ORIGINAL source. If it sounds wonderful to begin with, dubbing it to a non-pro tape analog deck will render it soft and flabby. If it sounds cold, dubbing it to a non-pro deck will warm it up.
     
  24. Bob Lovely

    Bob Lovely Super Gort In Memoriam

    Jeff,

    To my ears, making comparisons between Analog and Digital recording from a 'process' perspective is quite challenging because the processes are so different. Certainly, when I record in each domain, the rules of the game are different, the challenges different. The recordist working in either domain must think differently when recording in each domain, respectively. Honestly, there are 'tricks' to making great sounding recordings in each domain but rarely are those tricks identical...

    Bob:)
     
  25. Grant

    Grant Life is a rock, but the radio rolled me!

    Bob, you have a pro deck, don't you?
     
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