3 ms·

This is a very good explanation of impedance in audio circuits, where it's all about sources and sinks, and less about the transmission lines in between. For R

• radiowave 4y ago
  I remember learning a great deal from the SoundOnSound article, and am now only very slightly shuddering at the fact that it was almost twenty years ago. One interesting point that neither article seem to cover (at least based on me rapidly skimming through them just now) is: how do you know whether you're in a source/sink regime or a transmission line regime? The answer tends to take the form of a "percentage rule": if the wavelength of the highest frequency that you care about is more than 'x' percent of the length of the cable, then you better start treating it like a transmission line. I've heard of values of 'x' ranging from just a few percent (for PCB tracks carrying logic signals) out to about 20% (for location sound recording for TV & movies, back when the recording would be to analogue reel to reel, and you might be reluctant to move the recording equipment up near the action.)
  • myself248 4y ago
    Kuphaldt's chapter talks about when a line is "electrically short" vs "electrically long", which is precisely what you're asking.
    • radiowave 4y ago
      Ah, it does indeed. The dangers of skimming. Thanks for the correction.
• nomel 4y ago
  Are there any good analogues for mechanical impedance?