6 ms·

Interference isn't a problem in speaker cables because it is an amplified signal, so any added noise is too little to be audible.

LoganDark 3y ago
> any added noise is too little to be audible One would think so...
- searealist 3y ago
  https://youtu.be/TVCmPrDthlE https://youtu.be/TVCmPrDthlE
  - LoganDark 3y ago
    Whether it's "too little to be audible" depends on how sensitive your speaker driver is and what the noise floor of the room is.
    - searealist 3y ago
      In the video I linked, he was unable to induce any noise into the speaker wires greater than -130db at 60hz. The threshold for human hearing in absolutely ideal circumstances is about -115db. Anything less than that is provably inaudible for all frequencies, and for 60hz the threshold is much higher than -115db. The noise floor of the room only raises that further. For perspective, the very best state of the art DACs can only keep noise levels to -123db and just a few years ago the number was significantly worse.
      - mlyle 3y ago
        The design of an amplifier stage often looks like this: https://toshiba.semicon-storage.com/us/semiconductor/knowledge/faq/linear_opamp/why-is-feedback-used-in-op-amps.html 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.
        searealist 3y ago
        And yet in real consumer hardware this is never an issue. Do you just like wasting people’s time?
        LoganDark 3y ago
        If noise gets into the pre-amplified signal then it won't matter which wire you use to connect the speakers. This is why ground loops are bad.
        mlyle 3y ago
        > If noise gets into the pre-amplified signal 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.
- kevin_thibedeau 3y ago
  Class-D amplifiers pump out a signal literally buried in noise. You can't hear it because it's all shifted beyond human hearing and filtered by the speakers.
  - LoganDark 3y ago
    Class-D amplifiers are basically PWM run through some capacitors as a low-pass filter. The speakers are not what do the filtering, it's the capacitors.
TacticalCoder 3y ago
> Interference isn't a problem in speaker cables because it is an amplified signal, so any added noise is too little to be audible. 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.
- searealist 3y ago
  If there was interference then you would _always_ hear it, not just when playing music. In fact, it would be significantly easier to hear it when not playing music.
  - kenhwang 3y ago
    Yes, it's annoying and only very noticeable when the speakers were supposed to be silent, but weren't and hissed and hummed instead. 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.
    - searealist 3y ago
      Can you please link the cables you purchased?
  - mlyle 3y ago
    Weird things can happen. If you pick up RF on the speaker wire, it can make the output stage of the amplifier nonlinear in weird ways. 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.
aidenn0 3y ago
Interference will not generate significant current in the cables, but for a sufficiently long run, it can generate measurable voltages at your amplifier output. Depending on the power stage, this can cause your amplifier to react to the interference (e.g. if there is high-impedance negative feedback). With just the correct setup, a poorly designed power stage, and a long enough speaker cable run, you can pull in an AM station.
- searealist 3y ago
  If you have a reference showing audible noise resulting from interference on a speaker cable running from an amplifier to a passive speaker then please share it.
  - rsaxvc 3y ago
    This happens near loads of broadcast AM stations. https://www.reddit.com/r/audio/comments/rfmfkq/home_audio_speaker_cables_picking_up_radio/ https://www.reddit.com/r/audio/comments/rfmfkq/home_audio_sp...
    - searealist 3y ago
      Everyone in that thread says it's not the cables.
- searealist 3y ago
  See also https://www.youtube.com/watch?v=gL4O_Do2PuQ https://www.youtube.com/watch?v=gL4O_Do2PuQ

LoganDark 3y ago

> any added noise is too little to be audible One would think so...

searealist 3y ago
https://youtu.be/TVCmPrDthlE https://youtu.be/TVCmPrDthlE
- LoganDark 3y ago
  Whether it's "too little to be audible" depends on how sensitive your speaker driver is and what the noise floor of the room is.
  - searealist 3y ago
    In the video I linked, he was unable to induce any noise into the speaker wires greater than -130db at 60hz. The threshold for human hearing in absolutely ideal circumstances is about -115db. Anything less than that is provably inaudible for all frequencies, and for 60hz the threshold is much higher than -115db. The noise floor of the room only raises that further. For perspective, the very best state of the art DACs can only keep noise levels to -123db and just a few years ago the number was significantly worse.
    - mlyle 3y ago
      The design of an amplifier stage often looks like this: https://toshiba.semicon-storage.com/us/semiconductor/knowledge/faq/linear_opamp/why-is-feedback-used-in-op-amps.html 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.
      - searealist 3y ago
        And yet in real consumer hardware this is never an issue. Do you just like wasting people’s time?
      - LoganDark 3y ago
        If noise gets into the pre-amplified signal then it won't matter which wire you use to connect the speakers. This is why ground loops are bad.
        mlyle 3y ago
        > If noise gets into the pre-amplified signal 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.
kevin_thibedeau 3y ago
Class-D amplifiers pump out a signal literally buried in noise. You can't hear it because it's all shifted beyond human hearing and filtered by the speakers.
- LoganDark 3y ago
  Class-D amplifiers are basically PWM run through some capacitors as a low-pass filter. The speakers are not what do the filtering, it's the capacitors.

TacticalCoder 3y ago

> Interference isn't a problem in speaker cables because it is an amplified signal, so any added noise is too little to be audible. 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.

searealist 3y ago
If there was interference then you would _always_ hear it, not just when playing music. In fact, it would be significantly easier to hear it when not playing music.
- kenhwang 3y ago
  Yes, it's annoying and only very noticeable when the speakers were supposed to be silent, but weren't and hissed and hummed instead. 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.
  - searealist 3y ago
    Can you please link the cables you purchased?
- mlyle 3y ago
  Weird things can happen. If you pick up RF on the speaker wire, it can make the output stage of the amplifier nonlinear in weird ways. 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.

aidenn0 3y ago

Interference will not generate significant current in the cables, but for a sufficiently long run, it can generate measurable voltages at your amplifier output. Depending on the power stage, this can cause your amplifier to react to the interference (e.g. if there is high-impedance negative feedback). With just the correct setup, a poorly designed power stage, and a long enough speaker cable run, you can pull in an AM station.

searealist 3y ago
If you have a reference showing audible noise resulting from interference on a speaker cable running from an amplifier to a passive speaker then please share it.
- rsaxvc 3y ago
  This happens near loads of broadcast AM stations. https://www.reddit.com/r/audio/comments/rfmfkq/home_audio_speaker_cables_picking_up_radio/ https://www.reddit.com/r/audio/comments/rfmfkq/home_audio_sp...
  - searealist 3y ago
    Everyone in that thread says it's not the cables.
searealist 3y ago
See also https://www.youtube.com/watch?v=gL4O_Do2PuQ https://www.youtube.com/watch?v=gL4O_Do2PuQ