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More Distortion? Yes Please!

Posted 3rd June 2011 at 04:58 PM by Pano

Can High Fidelity include audible distortion?

From the ultimate heights of fidelity we should hear a perfect reproduction of the recorded signal all the way from source to speakers right? Perhaps that depends on your idea of fidelity. Where does your fidelity lie? What are you being faithful to? To the recorded waveform, or something else? Could your idea of fidelity be that you want the final result to be faithful to the direct sound of the music? Is your goal a faithful reproduction of the music, or of the recorded signal? The two are certainly not mutually exclusive, but can often be at odds.

Low distortion is the second of the two founding pillars of HiFi - frequency response being the first. Any distortion alters the signal, therefore it must be wrong. Or so says conventional thinking. To be highly faithful to the signal, we must alter it as little as possible, granted the possible exception of overall level or volume. But what if our goal is not the most faithful reproduction of the signal itself, but of the original sound? How much does distortion matter in that case?

For years on this forum I and others have talked about inaudible distortion. There are numerous studies going back to the 1930s that show certain forms of distortion are inaudible, by ear you simply can't tell them from a pure sine wave. You may be able to measure them, but you can not hear them so they simply don't matter to the ear. There are other forms of distortion that can be heard even in tiny amounts and they do matter. Many tube amps and speakers produce large amounts of inaudible distortion, many solid state devices produce significant levels of audible, and often objectionable, distortion. Of course both types of distortion are present in tubes, speakers and solid state, so it's not an either/or situation. HiFi life isn't that simple. Euphonic distortions, harshness, warmth, cold, lifelike, accurate, etc. We've all heard these.

Now follow me out of the box and onto a shaky limb for a few moments. What if audible distortion actually helps audio reproduction? Could certain distortions bring our perception of reproduced sound closer to what we hear live? We know that electric guitar players love distortion and that sound engineers often use it live or in recordings to achieve the sound they want, but what about in reproduced music? Could audibly distorted playback be closer to the "real thing" than a purer version? I don't mean simply "sounds better to me" but actually more faithful to the original sounds.

Let me frame the question in a different way. Can you imagine a case in which a distorted signal can give a more realistic, more accurate perception of the original than an undistorted version? Or a case where perfectly undistorted signal does not give the most accurate perception? You may be shaking your head "No." You are invited to grab your mouse and keyboard and do a little research on the "Globe Effect." It's not Shakespeare, it's optics. And although it is optics and not acoustics, it may just open your mind a bit to the possibility that perfect is not always correct.

I'll be back after you've done your reading and thinking.

"Please sir, I want some more." said little Oliver Twist.
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Comments

  1. Old Comment
    Sorry the end of my last post reads a little more coarsely than I intended!
    permalink
    Posted 6th June 2011 at 05:52 PM by CopperTop CopperTop is offline
  2. Old Comment
    Pano's Avatar
    No worries!

    I like your analogy about viewing the Mon Lisa thru scratching or wavy glass because that is exactly what we are doing! A recording ain't the real thing, it is seen thru a glass, darkly. The recording and reproduction chain is far from perfect.
    permalink
    Posted 6th June 2011 at 08:28 PM by Pano Pano is offline
  3. Old Comment
    wintermute's Avatar
    One of the things that I see mentioned every now and then is that an amp with relatively high second harmonic distortion sounds more musical than one without. I've also read that suppression of odd order harmonics also helps. Is it possible that the recording process misses some of the even order harmonics that are present in the real live event, so when played back through say a tube amp these are re-introduced, or "enhanced" perhaps back to a closer level to that of the original?

    Very simplistic view of things I know, and I suspect it would be higher order harmonics that would be lost. I guess though that a microphone like a speaker (for playback) only has a finite ability to record what is there. the more complex the signal the harder it will be for it to capture it faithfully. And therin lies the rub, is it possible to make a microphone, and recording electronics, that can do as go a job of recording as the ear can listening? Even if you could how could you ever prove it! The recording may be perfect, but without a perfect reproduction system it could not be tested in a DBT with the real thing

    Tony.
    permalink
    Posted 6th June 2011 at 10:07 PM by wintermute wintermute is online now
    Updated 6th June 2011 at 10:13 PM by wintermute
  4. Old Comment
    Pano's Avatar
    Ah Tony - you're getting ahead of me. That was going to be a big part of the next post.

    It's very much along the lines of what I've been thinking. So much of the audio gear I've been able to hear, study and measure tends to suppress the even harmonics and favor the odd. Adding back in a little even order may help to "even" things out. In music production there is rarely a problem of things being too warm, quite the contrary. The refrain "Make it Warm" is even a running gag among mastering engineers. Some of the is just taste, to be sure, but not all of it. When I hear live, unamplified music it sounds much warmer and smoother than the recorded variety.

    That is not the whole problem, but may be a big part of it.
    permalink
    Posted 7th June 2011 at 12:09 AM by Pano Pano is offline
  5. Old Comment
    Radugazon's Avatar
    Do you only think of harmonic distorsion (H2X mainly) or do you think also of spatial /temporal distorsion ??? It's a huge field...
    permalink
    Posted 7th June 2011 at 01:56 PM by Radugazon Radugazon is offline
  6. Old Comment
    I totally disagree that 2nd harmonic makes it sound musical. 2nd harmonic is generally a byproduct of single-ended gain stages. But it is not what makes it musical. It is the single-ended stage itself. Simplicity is what gives it the characteristic musical sound.

    Besides, just measuring distortion is meaningless. Our ears are fairly tolerant of harmonic distortion anyway. What doesn't sound real is temporal distortion, as Radugazon highlighted above.
    permalink
    Posted 10th June 2011 at 05:22 AM by ra7 ra7 is offline
  7. Old Comment
    Pano's Avatar
    Quote:
    Originally Posted by Radugazon View Comment
    ....do you think also of spatial /temporal distorsion ?
    Yes, there is more too it than just harmonic or inharmonic distortion. In room response and how the speaker sprays the sound around the room, to name just two.
    permalink
    Posted 18th June 2011 at 06:57 PM by Pano Pano is offline
  8. Old Comment
    Pano's Avatar
    RA7. I like single ended amps for their purity of sound, not for coloration. Not all are great, of course. And there is more to it than just distortion. But many do have a good "harmonic fingerprint" and can maintain it thru most frequencies and power levels. It's important to know that.

    Measuring distortion is FAR from meaningless, it can often tell us a lot about the subject qualities of an audio device. Just citing THD figures taken at a fixed level and frequency don't relate much at all to what we hear, I'll agree with that.
    permalink
    Posted 18th June 2011 at 07:03 PM by Pano Pano is offline
  9. Old Comment
    Great blog & great thread started by Wintermute - these areas need to be teased out as they are fundamental to our understanding of this hobby.

    Here are my thoughts - could it be the case that we have some form of distortion along almost all stages in the audio reproduction process, ending finally in an instrument that itself distorts the sound ie the ear. Maybe by introducing some colouration, we are actually masking other, more annoying distortions in the reproduced signal?

    Continuing the analogy with visual perception, it strikes me that we are at the stage in audio where art was before perspective was discovered. At the moment we seem to be trying to get each & every colour & tone as accurately rendered as possible without the more holistic view of what we are trying to portray. We even could stretch the analogy & say that digital audio is like Pointilism movement in art but then this is beginning to sound crazy.

    Anyway, that's not to say that reducing or eliminating distortion in each stage is not a worthwhile & necessary goal but not at the expense of the final goal of a natural portrayal of the original event. Who knows maybe we are being completely unrealistic in our expectations that this portrayal can be successfully achieved with 2 speakers? Maybe we need cubism :)
    permalink
    Posted 24th June 2011 at 10:28 PM by jkeny jkeny is offline
    Updated 24th June 2011 at 10:32 PM by jkeny
  10. Old Comment
    Pano's Avatar
    Quote:
    Originally Posted by jkeny View Comment
    Who knows maybe we are being completely unrealistic in our expectations that this portrayal can be successfully achieved with 2 speakers?
    No. It can be done. I've heard it on a few systems and they were consistent. Nothing too exotic, but of high quality to be sure. Jean Hiraga's Altec A5 system comes quickly to mind.
    permalink
    Posted 25th June 2011 at 02:54 AM by Pano Pano is offline
  11. Old Comment
    chris661's Avatar
    Is it possible that:
    1) - there's an Uncanny valley - Wikipedia, the free encyclopedia in audio.
    2) - additional distortion takes us away from the valley, thus enhancing our enjoyment of music.
    permalink
    Posted 18th August 2011 at 09:57 AM by chris661 chris661 is offline
 
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