Speakers are typically around 4-8 ohm. With long cables, it is easy to get several ohms of resistance, meaning a significant part of the current is going to end up heating the cable instead of producing sound. Not only it is a waste, but impedance is frequency-dependent, so sound quality will be affected. It is not audiophile bullshit, you can hear it clearly. What you need are the thickest and shortest cables that you can reasonable use. For very long distances, active speakers are preferable, or a high voltage (typically 100V) line and transformers.
Interference doesn't matter. You are putting lots of power in these wires, enough to move the speaker membranes, then move the air, then move your eardrums. Compared to that, what you get from external sources is negligible. If you hear humming, that's a ground loop, and your speaker wires are not at fault.
Now CAT5 cable could make great subwoofer cables. I don't know, but it kind of makes sense. Subwoofer cables are low current, and therefore more likely to pickup parasites. They also tend to be longer than typical interconnects. So shielding and twisting may help.
Yah. Take an 8 ohm speaker, which might vary from 5 to 20 ohms, but is relatively close to 8 ohms for much of its range.
At 5 ohms, your voltage is attenuated by 5% -- this is -0.45dB. Re: the "heating the cable" waste, you're losing .45 dB of sound output to heat.
At 20 ohms, your voltage is attenuated by almost nothing (.05 dB).
In any room, and with any real driver and amplifier you're going to have far bigger concerns for flatness of response than this .4 dB variation.
Bigger concerns are--- having something stranded and chonkier with big thick insulation is good for robustness and strain relief instead of trying to abuse network cables (even stranded) for the job. You can get thicker, nicer wire for this purpose than network cable for less money.
It's a bit humorous to think audiophiles might be spending thousands of dollars on speaker cables to listen stuff that could have passed through literally $5 cables in the studio.
If induced noise is a problem in such a setup, the actual improvement to be made would be to use twisted pair or shielded cable, rather than bare parallel wires. This helps eliminate differential-mode noise due to near-field EMI which parallel wires are susceptible to.
One would think so...
https://toshiba.semicon-storage.com/us/semiconductor/knowled...
Where the triangle isn't perfectly linear. If any RF gets into the output, it can be converted to audio frequencies by the nonlinearity and amplified. The open loop gain of the amplifier component can increase the magnitude of signals like this by tens of decibels.
Nah-- it's about high frequency noise getting in via the speaker lead, and coupling to the negative feedback of the amplifier stage, and getting rectified and amplified.
Yes, most interference is via line level inputs, but it can easily be via the "output" as well.
I dispute that. Source: I could hear at a previous apartment where I used to live that something was off when I was listening to music. It was subtle, but it was there. It drove me mad until I realized that by lifting the speakers cable off the floor the interference was gone.
I don't care about the science in this case. I just don't for I've witnessed it myself (well, heard it really). I've tested my theory (lifting the cable of the ground) and repeated the experiment. It is a fact (for you it may just be a comment on the Internet, but for me it is factual).
Putting the cables on little wooden pieces I made got rid of the interference (at least I couldn't hear it anymore).
That was happening on a "budget" (less than $1 K) setup (including a DAC). Very clean source: bitperfect rips of my CD collection.
Quiet room. The added noise was noticeable and was perturbing the listening.
Swapped for better shielded cables and the hiss/hum went away and it was dead silent when it was supposed to be.
But it was also only noticeable on the satellite speakers that had 50ft+ cable runs. It was inaudible on those short <6ft runs.
The extreme case is when you can receive radio signals on the speaker wire that are rectified and amplified by the amplifier; but you can get wonkiness short of that.
This is why you find things like this in design manuals. These are focused on offset errors in instrumentation amplifiers hooked to long cables (but intermodulation is an equal or larger concern in applications that care about frequencies above DC):
"In addition to filtering the input and power pins, amplifier outputs also need to be protected from EMI/RFI, especially if they must drive long lengths of cable, which act as antennas. RF signals received on an output line can couple back into the amplifier input where it is rectified, and appears again on the output as an offset shift."
https://www.analog.com/media/en/training-seminars/tutorials/...
Microchip says the same thing: "Amplifier outputs also need to be protected from EMI/RFI, especially if they must drive long lengths of cable, which act as antennas. RF signals received on an output line couple back into the amplifier input where they are rectified and appear again on the output as an offset shift."
https://ww1.microchip.com/downloads/en/appnotes/00001767a.pd...
https://www.physicsforums.com/threads/how-does-an-amplifier-... post #4
Note that I'm not really saying you need anything special on speaker cables, other than common sense: don't separate the pair for as much of the run as possible, and make sure the terminations at the end are not total garbage. If you have strong RF sources nearby, like when I had a 50W HF transmitter in my apartment, you may need to add RF chokes/ferrites on the amplifier end of speaker cables to reduce interference (I did).
Indeed, the ARRL (American Radio Relay League, an amateur radio association) describes that adjusting speaker cables is a frequent way to cure interference for neighbors of people with high power transmitters:
"Speaker wires are often 8 to 16 feet long. When you put two of them together, you make an efficient receiving antenna. Try bundling the speaker wires to reduce their effectiveness as an antenna. This procedure has been known to eliminate the interference all by itself."
"A: For a detailed explanation, you can refer to the ARRL Handbook's section on controlling RFI, and the section of the ARRL web site on EMI/RFI Products and Other Resources. You can build two of them, one for each speaker output. Wrap ten to fifteen turns of speaker wire onto an FT-140-43 ferrite core. Use an FT-240-43 if the speaker wires are large, and use "73" material for interference from 80 or 160-meter signals. Alternately, type "31" material is an excellent general purpose choice for HF. Install them right at the amplifier. If the system uses amplified speakers, you should install one at each speaker, too."
Asking me to figure out what you're arguing based on a 17 minute video is not reasonable. I skimmed the video and took my best guess of what you're advocating. (It's not a representative or useful test; yes, it's harder to measure RF on a cable when it's plugged into an amplifier, but that doesn't tell you that RF on cables can't be rectified and amplified by the amplifier). You can use your words yourself.
In any case, the people who have asserted that RFI can get into ampifiers from speaker wires and cause problems are correct.
Your assertion "this is not an issue for anyone" contradicts the direct experience of lots and lots of people who have lived close to large RF sources and had RFI problems in audio fixed by adjusting speaker wires, such that it's the first step for engineers and radio amateurs working with angry neighbors.
Buying more expensive cables isn't generally the cure and is snake oil. Indeed, shielding itself can add enough capacitive loading to actually reduce speaker high frequency response.
But having to put in an RF choke on speaker wire to prevent RFI from having negative audible effects is common. And using a little bit of care to keep as much of the cables paired as possible, keeping runs as short as reasonably possible, and making reasonably good terminations is good insurance against it being a problem for you.
I've given plenty of high quality evidence, while you've given a long video of someone making a measurement that is meaningless to what I'm asserting.
The ARRL wouldn't have to help neighbors of amateurs put chokes on speaker wires if this couldn't happen.
Most of us have the experience of having a cellphone close to speaker wiring and hearing LOUD buzzes and clicks. It was a bigger problem in the AMPS days (with higher output power), and more often the interference gets into the amplifier by signal lines than it does by getting in through power lines and speaker wires, but it can certainly go in the output (or power) as well. Have you never experienced this?
I still remember the first time I experienced this. I was 12, returning from a road trip with my (older) sister and her significant other's family, where we had handheld CBs. The hifi inside the house was demodulating and amplifying our CB signals; they could be clearly heard when we used the CB from the driveway. 5 meters of speaker cable was a good antenna for a 10 meter wavelength RF signal; a poorly filtered amplifier stage was demodulating and amplifying the signal.
https://www.reddit.com/r/audio/comments/rfmfkq/home_audio_sp...