This results in a square waveform representing that impulse across the time of the single sample as shown in the image above. A system where that single impulse point is held over the sample duration. ![]() Suppose we start with the most basic DAC, one that does NOT offer an anti-imaging filter. Nor would single impulses like this sound any good anyhow! We can model it in a computer of course just like in electrical systems we can show true square waves even though in nature, ideal square waves of vertical slope do not exist either. We do not get instantaneous transitions like this that suddenly start and stop the air waves in real life physical systems. Realize that a " Dirac impulse" (the idealized single point spike) is not inherent in natural sounds. For a typical 8x oversampling DAC, that 44.1kHz is upsampled to 44.1 x 8 = 352.8kHz or 8 intermediate samples are calculated for every single point. When I measure an "impulse response", basically what I'm asking the DAC to reproduce (typically with a 16/44.1 signal), is that sudden sharp transition of exactly one sample in duration, asking the device to interpolate all the individual samples around that discontinuity with the filter function programmed into it. How this interpolation happens is a result of the function being applied which in an audio editor is represented by the line drawing we see. When we look at images of this data with an audio editor where the "points" are conveniently connected for us, we are actually seeing the calculated interpolation as applied by the software. I think it's useful to see it as a number sequence of discreet sample points rather than some kind of waveform image as a start. Numerically it looks like this (+32767 being the largest signed number for 16-bits, and -32768 the smallest): It's a sharp transition or transient where from a baseline of 0, it instantaneously goes up to full amplitude. MEASUREMENTS: "Pulse Response" - 5kHz & 10kHz.Ĭonsider for a moment what an "impulse" is in the digital world. MEASUREMENTS: Digital Filters and Impulse Response. Folks might want to have a look at previous articles on this: Since 2013, I had been exploring this phenomenon and trying to figure out for myself just how much of a problem this is from the perspective of magnitude of audible effect. Isn't it unbelievable how awful digital audio is?!īefore freaking out, let's think this through. Most horribly of course is that "pre-ringing" before the main waveform itself (what kind of Hellspawn is an "echo" before the sound itself?!!!). Terrible! That nice little clean digital "impulse" with defined onset and offset has become mangled into this "time-smeared" mess with all kinds of "unnatural" ringing. Stereophile poster makes it seem as if ringing is the apodeictic bane ofīeautiful question! Like other audiophiles, I've heard that the "dreaded ringing" (like the "dreaded jitter"), over the years has been on the minds of audiophiles as a nemesis which must be slaughtered! Typically, we see images like this in magazines which are of course extremely frightening to look at: Most of us have been enjoying digital audio for decades now. I likewise imagine that both such things are doable, inasmuch as (pre-/post-)ringing effects and to eliminate ringing in the audible of the audio world take great care to minimize Have access to), how audible are ringing effects? Or, rather, how COMMONĪre they? I kind of imagine that the Meitners, Lavrys, Levinsons, (which I've got to assume most of the folks posting on My question is less about MY having heard ringing than about theĪUDIBILITY of ringing - pre, post, or otherwise. Said: "Aha! Eureka! Thar be ringing!" Because - outside of maybe aīlurring during transients? - I have no idea what it sounds like. because I probably have - but I will say that I've never explicitly I won't say that I've never heard ringing Over-sampling and various filter techniques have tried to deal with it, ![]() This has been the bane of digital playback for 30 years, and Important than the elimination of the damaging pre-ringing distortion. Personally think that MQA has some noble goals, in terms of getting asĬlose to the original master as possible, but I think that is far less In any case, I read the following (tonight) on the Stereophile forums: If you ever do decide to get to/address it, that'd be great. Since I've been fretting over it afresh, I thought I'd just post it Wanted to ask you a question, too, but I don't know how the bleep to to I have to thank you for doing what you do. A couple weeks ago, Whackamus posed this interesting comment and question which I thought would be a good topic to discuss and explore in greater detail and with some examples/samples:
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |