635
Overcome (sh.itjust.works)
submitted 8 months ago by to c/programmer_humor@programming.dev
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[–] 6 points 8 months ago (5 children)

Once someone tried to tell me that the wrong cable impedance to the speakers affected sound. Asked him what is the wavelength at audio frequencies, conversation died.

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  • [–] 5 points 8 months ago (4 children)

    If they were passive speakers being powered through the cables and an amplifier wouldn't the additional impedance of the cable result in a (probably imperceptible) reduction on volume? I agree it wouldn't effect the waveform, and thus, the quality of the sound though.

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  • [–] 4 points 8 months ago (2 children)

    Resistance can reduce the volume. E.g. if your wires are too thin for the current you want to send over them. The guy was talking about impedance.

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  • [–] 6 points 8 months ago (1 child)

    Impedence is the combination of resistance (ordinary resistance to current) and reactance which is resistance specific to alternating current which comes from the capacitors and coils in the equipment. Even a squiggly circuit trace can create reactance. So, impedence is resistance.

    Whatch this short for a clear explanation:

    https://youtube.com/shorts/tanon58nW1o

    From what I've read, and from talking to a guy who own a music studio near me, impedance mismatch is a real thing in audio equipment. At best, it'll lower the sound level causing you to have to crank up the volume, which just puts more strain on your equipment. Worse, it can cause crackling from waveform peaking. At the very worst, it can damage equipment.

    Brushing it off just because the guy doesn't know the wavelength of audio signals is a dick move. No wonder he stopped talking to you. I bet you, yourself, know a lot of things, a lot of true things, that you can't explain to the utmost detail.

    "You say quarks are combined with the strong force to make protons, huh? Well, what's the binding force between an up and down quark? Oh, you don't know? Curious."

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  • [–] 3 points 8 months ago

    Impedance mismatch between two pieces of equipment (amplifier and speaker, in this case) is a thing, and depending on how the amplifier is built can be a problem. But for the piece of wire connecting them to behave like a transmission line it needs to be a significant fraction of the wavelength of the signal, which at audio frequency is quite a lot, so unless you have your amplifier on the other side of town it is totally irrelevant. The guy was blabbing nonsense. We didn't talk about quarks.

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  • [–] 1 point 8 months ago

    Yeah, if the cable impedance is small enough that you can still get the volume you need it doesn't matter

    The comment above is informed by radio electronics - in 1980s Australia had TV on low enough frequency that we used balanced wires (two parallel conductors, like speaker wires) for best interference rejection, with opposite voltage in each conductor and interfering signal will affect both conductor equally and opposite, cancelling the interfering signal (we also needed a "balun" on the antenna to match between the balanced wires and the unbalanced antenna)

    Now every antenna you see on roofs and wifi devices connect with coax cables and connectors which are impedance matched to the antennas because impedance really really matters at microwave frequencies, those cables need shielding as they can't reject interference in the way balanced cables can

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