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Reproduction of timbre

Discussion in 'Sound Science' started by old tech, Apr 23, 2019.
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  1. SilentNote
    Not sure if what I’m noticing is timbre / tone or something else. But some IEMs have odd sounding tenor drum hits or cymbals that just aren’t quite right sounding. It’s even more obvious when compared to the ER4SR, not that I need the ER4 to notice it in the first place.

    Am I just noticing something else or this is more common in IEMs?
  2. gregorio
    1. Yes, you are right in saying that but it's important to qualify that statement because it's not just the frequency response of reproduction equipment that's responsible for "timbre" but also the frequency of the sound waves that enter your ears and then the frequency response of your ears themselves. For example, if we playback some sound/instrument through speakers then the furniture, walls, etc., will create reflections which will arrive at your ears later than the direct sound from the speakers. Those reflections will interact with each other and the direct sound, resulting in a significantly different "frequency response" entering your ears. "Timbre" is a musical term and therefore describes perception rather than purely audio properties. Exactly the same "frequency response" can be perceived as a different "timbre". For example, playing back exactly the same frequency content at a significantly higher or lower level can/will change the "timbre" because your ears respond to frequency differently at different loudness levels (as demonstrated by equal loudness contours).

    2. Typically but not "inevitably", depending on:
    A. What exactly do you mean by "bass boost", what frequency range does this cover? And ...
    B. What frequency range does the sound/instrument cover? And ...
    C. How (if at all) will this affect your perception.

    For example, if A and B are the same then boosting the bass will not alter the frequency response; the harmonics will be the same, the relative balance between them will be the same and so the timbre will be the same, unless you raise the bass sufficiently to affect the perception of bass freqs (according to the loudness contours). A kick drum is an interesting choice because although they always produce significant content above 1kHz, you virtually never hear what a kick drum produces on commercial recordings (or at live gigs), they are virtually always processed and typically massively so (even well beyond the point of being unrecognisable!). The answer to your question is therefore "probably", but not "inevitably".

    Not really, in fact a very large timing error probably wouldn't affect the timbre of musical instruments as a very large timing error (in excess of roughly 50-150 milli-secs) would be perceived as separate events rather than as a single event with it's timbre altered. However, relatively small timing errors (for example, 1 milli-second or so) can affect the timbre of musical instruments, significantly so.

    SilentNote likes this.
  3. SilentNote
    Excellent, this answers my question. Thank you!
  4. bigshot
    One millisecond is a tiny frame of time, but it's a hefty timing error. You're not likely to find timing error in the millisecond range in most home audio equipment. That's a significant phase shift.
  5. gregorio
    Yes you are, I gave such an example in point #1 of my previous post.

  6. bigshot
    The room? I'm not talking about that. That's a given and that is an important part of the sound. You wouldn't want to eliminate that completely. I was talking about electronic equipment.
  7. Glmoneydawg
    Right!!...the room is a constant....we have to embrace it.At the recording end i want to hear it...at the listening end i want to make the most of it.
  8. bigshot
    Yeah, you just want to minimize bad effects of the room, not eliminate it completely.
  9. gregorio
    1. We're talking about timing error/s that can/will affect timbre and that includes the room/s.

    2. Agreed, up to a point! And that "point" is the point at which the room affects the timbre of the reproduced instruments/sound.
    2a. Ideally you would want to completely eliminate the room effects that alter the timbre of the instruments/sound, which is why acoustic treatment exists. You obviously don't want standing waves/room modes or cancellations/comb filtering altering the timbre of the reproduced sound.

    3. I was talking about the sound that reaches your ears and how you are likely to perceive it, which is what defines "timbre". And let's not forget that these timing errors occur at both ends of the chain, the recording being played back already contains timing errors. For example, two mics placed 34cm (about 1'1") apart will result in almost exactly our 1 milli-sec timing error.

    1. Not really. "The room" is an almost infinite number of constants, it's only "a constant" at one particular position in the room and with one signal. For example, just moving an inch or two from that one position will give us a different frequency response ("constant"), commonly enough of a difference to be potentially audible and, we don't just play one signal but a whole variety of different signals (songs/tracks/recordings), each of which can/will affect the room response depending on what frequencies it contains and therefore what room modes and other effects are excited.
    1a. Some of it we want to embrace, we obviously don't want to embrace standing waves, comb filtering or anything else that will affect timbre.

    2. "At the recording end" the room is not a constant, it's several different constants mixed together. I can't think of any commercial music recording scenarios where we record with just one mic in one position, we typically record with different several different mics in several different positions and as soon as we use more than 1 mic we introduce timing errors which can/will affect the timbre, sometimes very severely! Of course though, this can be altered (though not "cured") during the mix process and as that's what the engineers/artists heard and approved, we would ideally want to reproduce those errors (and resultant timbre).
    2a. Agreed, but obviously you're not going to "make the most of it" if your listening room is changing it.

  10. bigshot
    OK. I was saying that you aren't liable to find timing errors of the millisecond range in home audio electronics. We just talked past each other there.
  11. old tech
    Isn't time of an audio signal the same thing as its frequency?
  12. bigshot
    They're related. but a timing error can cause group delay and frequency cancellation, in addition to wow and flutter. It isn't really much of an issue with digital audio.
    Last edited: Jul 23, 2019
  13. Daniel Johnston
    The way I understand "timbre matching" with multichannel (which I did with my home theater), is due to the drivers. I went all Klipsch Reference (RF7 II, RC64 II, R3800W II surrounds). They all have the horn loaded tweeters and cerametallic woofers. I didn't want to mix different kinds of tweeters and woofer cone materials. Speakers definitely have a sound signature. Martin Logans sound completely different than Paradigms even matched for "price tier". The Klipsch horn tweeter has a different timbre than the B&W diamond tweeter. Both reproduce signals accurately but sound different.

    Now could you match different speakers from different manufacturers using different driver materials and styles? Probably, but it's going to take some wicked EQ to accomplish. Even then, I would wager you could hear differences between the speakers. YMMV
  14. old tech
    Sure, but that wouldn't show up in the measurement of frequency response?

    For example, some claim that jitter and timing errors can be an issue with DACs (and of course this leads to all sorts of marketing claims to support their $$$$ DACs), but how do those claims sit with, for example, a CD which measures linear in frequency response at +/- 0.5 db?
  15. bigshot
    It would technically be distortion, wouldn't it? Distortion can affect frequency, amplitude and time all at once.

    Yes. That is what I've done in my own multichannel system. You can balance response with any kind of speaker. But there's more to it than just response... there's dispersion patterns too. What works well in the mains may not work as well in the rears. I have both directional and broad dispersion in different places for different purposes. If the response is balanced, the dispersion is what you're hearing as being different from speaker to speaker.
    Last edited: Jul 23, 2019
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