3 ms·

I have always noted this when listening to music on my M1 MBP. "There is NO way my tweeters aren't about to explode!" I recall how quickly the speakers in my Mi

I have always noted this when listening to music on my M1 MBP. "There is NO way my tweeters aren't about to explode!" I recall how quickly the speakers in my Microsoft surface laptop self-destructed... In my experience, the #1 prerequisite to driving a speaker this aggressively without destroying it is having a clean source of power. Hard distortion and clipping are what break voice coils in direct, physical terms. Thermals can be tolerated over brief durations. I have found (in larger scale pro audio) that the amplifier topology can have a major impact on the amount of real power you can put into a loudspeaker. One of the most popular is Class D because it requires virtually no magnetics (i.e. no toroidal transformers). The tradeoff is that it needs to have a lot of safety nannies at the extremes and will have to attenuate aggressive program material. You almost always have to put a full-time DSP on these amplifiers. Compare this to Class A,A/B, G or H topologies which can be pushed well-beyond rated supply amperage for brief durations (i.e. your lights will dim slightly, rather than the amp/DSP limiting its power draw). You can drive these with any kind of signal you please, filtered with nannies or otherwise. These topologies are where I go when I want to be able to reach to DC on a loudspeaker and am willing to replace the drivers if I bump a knob the wrong way.

tcrenshaw 4y ago
Most, if not all, of the class D amps at the large scale pro audio level have that DSP built into the amplifier itself. More and more speaker manufacturers are also selling their own amplifiers (not necessarily made in house) with limiting that takes specific drivers into consideration, along with FIR correction for the whole box. I've also used a few that you can tell exactly what kind of power you're hooked up to (120v @ 25 amp perhaps) and it will draw just up to that limit and stop. Neat stuff
- bob1029 4y ago
  > More and more speaker manufacturers are also selling their own amplifiers (not necessarily made in house) Indeed. I've had horrible luck with reliability of these products (i.e. loudspeakers with integrated class-D amplifiers). I would strongly recommend going for external amplification wherever possible, especially if you are running cabinetry that weighs more than 100lbs.
amelius 4y ago
We're talking about laptop speakers here, where power consumption is important.
- bob1029 4y ago
  In a laptop's energy budget, power spent driving the loudspeakers is probably one of the last concerns. If you integrate the actual power consumed over the playback duration of typical program material, you would find figures that are essentially irrelevant compared to the cost of running the backlight or WiFi radios.
  - dzhiurgis 4y ago
    Screenshot says 1W or so. My laptop uses about 10W on light scrolling.
  - pjc50 4y ago
    I saw a nice demo recently of the use of chargepump power control to stop the backlight dimming if the audio got too loud, a microcosm of the "PA so loud your lights dim" situation. (no, I've not been able to find it to show hn)
  - kkielhofner 4y ago
    While you're probably right technically speaking laptops compete heavily on battery life. I wouldn't be surprised at all if (like mobile devices) they're at the point of optimizing relatively minuscule points of power draw. Like most things once you start looking at dozens of factors that are 0.5% wins each you end up with a substantial improvement that in the case of battery powered productivity devices is significant from a sales standpoint.
mjb 4y ago
If your lights are dimming, you've wrecked your THD+N by feeding your amp AC for the period the power supply filtering caps are empty. (It's even worse than AC, transiently, because of the effect of trying to refill the caps while driving the amp). Also, the tweeter killing effect is because of the harmonic effects of clipping, so if you're hitting the rail voltages with any topology you're going to have a bad time.
- bob1029 4y ago
  You are implying that there are 2 discrete states: fully charged and fully discharged. In reality, this is an infinite spectrum. You will know when the capacitors are actually empty. When you flip on a 2-4kW pro audio amp, you can hear the electromagnetic forces for about a second. If you have a UPS on the same circuit, it will likely trip. That is empty. During normal use, there is no such thing as empty.

tcrenshaw 4y ago

Most, if not all, of the class D amps at the large scale pro audio level have that DSP built into the amplifier itself. More and more speaker manufacturers are also selling their own amplifiers (not necessarily made in house) with limiting that takes specific drivers into consideration, along with FIR correction for the whole box. I've also used a few that you can tell exactly what kind of power you're hooked up to (120v @ 25 amp perhaps) and it will draw just up to that limit and stop. Neat stuff

bob1029 4y ago
> More and more speaker manufacturers are also selling their own amplifiers (not necessarily made in house) Indeed. I've had horrible luck with reliability of these products (i.e. loudspeakers with integrated class-D amplifiers). I would strongly recommend going for external amplification wherever possible, especially if you are running cabinetry that weighs more than 100lbs.

amelius 4y ago

We're talking about laptop speakers here, where power consumption is important.

bob1029 4y ago
In a laptop's energy budget, power spent driving the loudspeakers is probably one of the last concerns. If you integrate the actual power consumed over the playback duration of typical program material, you would find figures that are essentially irrelevant compared to the cost of running the backlight or WiFi radios.
- dzhiurgis 4y ago
  Screenshot says 1W or so. My laptop uses about 10W on light scrolling.
- pjc50 4y ago
  I saw a nice demo recently of the use of chargepump power control to stop the backlight dimming if the audio got too loud, a microcosm of the "PA so loud your lights dim" situation. (no, I've not been able to find it to show hn)
- kkielhofner 4y ago
  While you're probably right technically speaking laptops compete heavily on battery life. I wouldn't be surprised at all if (like mobile devices) they're at the point of optimizing relatively minuscule points of power draw. Like most things once you start looking at dozens of factors that are 0.5% wins each you end up with a substantial improvement that in the case of battery powered productivity devices is significant from a sales standpoint.

mjb 4y ago

If your lights are dimming, you've wrecked your THD+N by feeding your amp AC for the period the power supply filtering caps are empty. (It's even worse than AC, transiently, because of the effect of trying to refill the caps while driving the amp). Also, the tweeter killing effect is because of the harmonic effects of clipping, so if you're hitting the rail voltages with any topology you're going to have a bad time.

bob1029 4y ago
You are implying that there are 2 discrete states: fully charged and fully discharged. In reality, this is an infinite spectrum. You will know when the capacitors are actually empty. When you flip on a 2-4kW pro audio amp, you can hear the electromagnetic forces for about a second. If you have a UPS on the same circuit, it will likely trip. That is empty. During normal use, there is no such thing as empty.