Can *YOU* blow a PC speaker using only a Linux kernel driver? • Hacker News Board

Re: Can YOU blow a PC speaker using only a Linux kernel driver?

#31

Post by nitrogen » Fri, Jun 18, 2021, 10:06 PM UTC

bob1029 wrote: post #18

jolmg wrote: post #12

Earlier quoted context omitted.

The audio mixer is dependent on the speakers, not the other way around. The speakers should be able to handle anything the mixer is able to throw at it. If they aren't, that's fault on the speakers' part.

I think this is a grey area depending on your setup and listening preferences. I have ~2kW of RMS amplification available to my floorstanding loudspeakers and subwoofer. There is a lot of DSP/EQ protection in between my HTPC and the mechanical drivers in the speakers. Despite all of this, I have had incidents where the software glitches out and plays the un-decoded DTS/DD stream. If you have your volume set at or nea…

To add to this, depending on the amplifier design you might get better linearity (less harmonic distortion) by significantly overprovisioning power.

Re: Can YOU blow a PC speaker using only a Linux kernel driver?

#32

Post by throwaway789657 » Fri, Jun 18, 2021, 10:20 PM UTC

walshemj wrote: post #29

throwaway789657 wrote: post #28

Earlier quoted context omitted.

In no other high-end consumer product would that unreliability be tolerated. Why would you ever run your speakers at a volume that might blow them out depending on what the next bar of the song sounds like? Are you pre-screening every single bit of audio that will get played over your speakers? Otherwise, you should never run speakers at a borderline volume. This protection should be built in to the speaker. No matte…

It happens with DJ sound systems and Band PA's

So this poor reliability is just rampant in the sound industry? Unless there is some reason why such a circuit is not feasible without, e.g., decreasing sound quality. Which is the kind of thing my original question is asking about.

Re: Can YOU blow a PC speaker using only a Linux kernel driver?

#33

Post by throwaway789657 » Fri, Jun 18, 2021, 10:22 PM UTC

kube-system wrote: post #24

throwaway789657 wrote: post #10

Why don't all speakers have some circuitry that blocks any signal that could blow out the speakers? This has always seemed like an absurd state of affairs. It should not be possible to damage speakers by turning the volume too loud.

It's mostly a matter of matching the output characteristics of the amplifier to the capability of the speakers... which is what most consumer products with speakers do. Note that the OP concluded that it likely wasn't possible to blow the PC speaker.

If you have your own receiver and your own speakers--a home stereo system, not a PC speaker system--it is just a matter of turning the nob too high to blow them out. With all these wifi-connected receivers these days, I bet if your laptop is compromised, a hacker could turn up the volume and physically damage your speakers. Anyone inside your wifi can cause many thousands of dollars (or whatever your speakers cost) of physical damage. Wow!

Re: Can YOU blow a PC speaker using only a Linux kernel driver?

#34

Post by [deleted] » Fri, Jun 18, 2021, 11:41 PM UTC

bob1029 wrote: post #18

jolmg wrote: post #12

Earlier quoted context omitted.

The audio mixer is dependent on the speakers, not the other way around. The speakers should be able to handle anything the mixer is able to throw at it. If they aren't, that's fault on the speakers' part.

I think this is a grey area depending on your setup and listening preferences. I have ~2kW of RMS amplification available to my floorstanding loudspeakers and subwoofer. There is a lot of DSP/EQ protection in between my HTPC and the mechanical drivers in the speakers. Despite all of this, I have had incidents where the software glitches out and plays the un-decoded DTS/DD stream. If you have your volume set at or nea…

[deleted]

Re: Can YOU blow a PC speaker using only a Linux kernel driver?

#35

Post by unparagoned » Fri, Jun 18, 2021, 11:45 PM UTC

throwaway789657 wrote: post #32

walshemj wrote: post #29

Earlier quoted context omitted.

It happens with DJ sound systems and Band PA's

So this poor reliability is just rampant in the sound industry? Unless there is some reason why such a circuit is not feasible without, e.g., decreasing sound quality. Which is the kind of thing my original question is asking about.

It's just the way things are when it comes to speakers. What you are suggesting would be really expensive, unreliable and have all sorts of downsides. It's like asking how comes cars get stuck in traffic, why don't they just make cars fly when the roads are busy...

Re: Can YOU blow a PC speaker using only a Linux kernel driver?

#36

Post by squarefoot » Fri, Jun 18, 2021, 11:59 PM UTC

The PC speaker was driven by square waves, therefore there was no way to alter the audio volume, or change its sound. Only frequency could be altered, literally by inverting the pin status N times a second. Then it came the PWM idea, and hackers found the way to implement analog sounding audio through it (the same principle used to fade a led through a GPIO). The port became a DAC, audio levels were encoded through PWM, and the speaker inertia made for a crude but effective Nyquist-like filter. Having full hardware access to the port, the nastiest thing one could do is to keep the speaker on fixed DC by setting the port to a digital value (that is, 1 or 0) and never changing it. PWM ensures that sometimes the speaker isn't driven, which reduces the average current, and therefore the load from the driver perspective, but now we're making current flow through it continuously. Will that destroy it? I don't know, but to my knowledge it seems the only way one can abuse it, or the port that drives it. It all boils down to current limiting circuitry; if it's present, then I guess there's no way to damage either the speaker or the driving port.

Re: Can YOU blow a PC speaker using only a Linux kernel driver?

#37

Post by simonblack » Sat, Jun 19, 2021, 12:16 AM UTC

Whether or not you can blow a speaker has nothing to do with what kind of signal you are sending it but the power you send to the speaker.

In other words, whether the current going through the speaker is sufficient to either overheat the voice-coil, or to drive the speaker-cone beyond its physical limits.

These are qualities pertaining to the speaker itself, not the PC's output. The easy answer to the question is "It depends".

Re: Can YOU blow a PC speaker using only a Linux kernel driver?

#38

Post by copperfoil » Sat, Jun 19, 2021, 12:17 AM UTC

throwaway789657 wrote: post #28

londons_explore wrote: post #13

Earlier quoted context omitted.

Because knowing exactly how much signal is too much is really hard. When using the speaker, for some purposes you want absolutely max volume - that involves getting the physical parts of the speaker moving fast and far. Yet move them slightly too fast or too far or do that too often and it'll physically break. Odd effects like resonance mean two very similar looking signals can have widely different physical effects.…

In no other high-end consumer product would that unreliability be tolerated. Why would you ever run your speakers at a volume that might blow them out depending on what the next bar of the song sounds like? Are you pre-screening every single bit of audio that will get played over your speakers? Otherwise, you should never run speakers at a borderline volume. This protection should be built in to the speaker. No matte…

I may be wrong, but most studio monitor speakers have limiter circuits that prevent damage from high volumes, iirc. E.g. Adam Audio or KRK speakers. These are in $100-200 per speaker

Re: Can YOU blow a PC speaker using only a Linux kernel driver?

#39

Post by boredprograming » Sat, Jun 19, 2021, 12:27 AM UTC

simonblack wrote: post #37

Whether or not you can blow a speaker has nothing to do with what kind of signal you are sending it but the power you send to the speaker. In other words, whether the current going through the speaker is sufficient to either overheat the voice-coil, or to drive the speaker-cone beyond its physical limits. These are qualities pertaining to the speaker itself, not the PC's output. The easy answer to the question is "It…

Excursion is related to frequency. A sure way to blow most up is turn bass to the max. Some speakers have bandpass filters. Cheap ones usually don't

Re: Can YOU blow a PC speaker using only a Linux kernel driver?

#40

Post by simonblack » Sat, Jun 19, 2021, 12:28 AM UTC

copperfoil wrote: post #38

throwaway789657 wrote: post #28

Earlier quoted context omitted.

In no other high-end consumer product would that unreliability be tolerated. Why would you ever run your speakers at a volume that might blow them out depending on what the next bar of the song sounds like? Are you pre-screening every single bit of audio that will get played over your speakers? Otherwise, you should never run speakers at a borderline volume. This protection should be built in to the speaker. No matte…

I may be wrong, but most studio monitor speakers have limiter circuits that prevent damage from high volumes, iirc. E.g. Adam Audio or KRK speakers. These are in $100-200 per speaker

They have limiter circuits to prevent a very high average power going through them which would overload the speaker-cone's travel limits, or would overheat the voice-coil.

On the other hand, very high-power, short-lived 'transients' are necessary to give proper clarity and realism to the music. Most amplifiers, even very-high power ones usully idle along at about one or two watts or less, but the extra couple of hundred watts available allow lots of 'head-room' for those high-power transients so that they don't get clipped and distorted.

A high-power amp doesn't necessarily sound very much 'louder', but it sounds very much 'cleaner'.