The road to true digital speakers very long

[7beauties]

I was thinking about how modern TV evolved from analog RF to digital HD so successfully, yet we don't have digital speakers. Then I lit a cigarette which got me to thinking about piezoelectric lighters; squeezing the crystal causes it to produce the spark to ignite the butane. Then I remembered that inversely induction of current causes the piezoelectric crystal to move. I excitedly wrote an email to an engineer friend of mine and asked him why can't a membrane with millions of piezo-pixels not be able to become the world's first truly digital speaker. My friend gave me a link where I read about very similar ideas, some going back many years ago. Apparently Sony and a few others have made prototypes but the result doesn't justify the expense and engineering hurdles. For a while I was excited.

 

[ImcLoud]

smoking is not good for you... Health wise.

 

[avliner]

Maybe it's technically possible, but I don't believe we'll see that happening in a 100 years time, though.

AFAIK, sound coming from a speaker will always be analogue and that's the sole reason for all digital rigs being equipped with an onboard DAC, but as the says goes... never say never

 

[JohnA]

AFAIK (and I could be wrong), you will still have to convert the 0's and 1's from a digital source into some analog form for our senses (hearing) to interpret the sound, unless you had a digital jack right into your head.

 

[AcuDefTechGuy]

AFAIK (and I could be wrong), you will still have to convert the 0's and 1's from a digital source into some analog form for our senses (hearing) to interpret the sound, unless you had a digital jack right into your head.

No kidding. We are humans, not bad robots.

The sound is analog waveforms/ sound waves traveling through air and reaching our ears and interpreted by our brains as sound.

We ain't no bad robots.

 

[JohnA]

No kidding. We are humans, not bad robots.

We ain't no bad robots.

 

[jonnythan]

Sound waves are analog.

 

[JerryLove]

Lightwaves are analog too.

Digital TV isn't quite as digital as you may think. It it was, then all TVs would look the same. They don't because of how that digital information is converted.

But video can be digital because the nature of our reproduction is discrete. It's not moving (it's 60- still frames in rapid succession), it's not accurate (R+G+B isn't full-spectrum white; see CRI on LEDs for a discussion of the issues), and we don't care about the transitions (they blur together).

Even if we could think of audio as still positions (which we sort-of do with class D amplifiers): it's 20,000+ states per second and transition rates to matter.

Imagine (unrealistic as it would be 1/60th Hz) that you have an audio wave that goes from XMin to XMax once per minute. It matters whether that driver takes 60seconds to transvers or waits 30 seconds than moves instantly. (in video: we want the fastest transitions possible; because we are interested in the stills. In audio it's the transition itself that interests us.

Notice, for example, that you can have a still picture but not a still sound.

 

[Irvrobinson]

There are many examples of the old technology, like moving coil speakers, staying around far longer than anyone expected due to the combination of huge R&D investment, technical breakthroughs, and being good enough. Hard disk drives, gasoline automobile engines, coal electrical generation plants, the Compact Disc...

 

[Steve81]

Notice, for example, that you can have a still picture but not a still sound.

I'm not sure that's a fair comparison. A still picture on a TV screen is no different than playing 60Hz sine waves on a loudspeaker. You're simply repeating the same light waves and sound waves over and over again.

 

[slipperybidness]

Maybe it's technically possible, but I don't believe we'll see that happening in a 100 years time, though.

AFAIK, sound coming from a speaker will always be analogue and that's the sole reason for all digital rigs being equipped with an onboard DAC, but as the says goes... never say never

Exactly, you can't have a truly "digital" speaker. Digital, by definition, is "on" or "off" (0 or 1). Not continuously variable as a speaker (analog transducer) must be.

 

[slipperybidness]

Lightwaves are analog too.

Light waves could be thought of as digital AND analog. It's called the dual particle/ wave theory of light. You can measure the wave properties of light and you could consider that as an analog signal (constructive/destructive interference). However, light is also transmitted as discreet packets of photons (quantum or digital nature of light).

Wave

 

[JerryLove]

I'm not sure that's a fair comparison. A still picture on a TV screen is no different than playing 60Hz sine waves on a loudspeaker. You're simply repeating the same light waves and sound waves over and over again.

I understand that perspective, and even considered it: but the difference here is that an audio system must drive a repeating wave. A video component does not (the wave is the result of light passing through a colored LCD).

And that assume specific video technology. What about an e-paper example? The screen can be "shut off" and the picture is still there. Ditto a printed photo.

You cannot do those things with sound. Video can be viewed as discreet in ways that sound cannot.

 

[Steve81]

I understand that perspective, and even considered it: but the difference here is that an audio system must drive a repeating wave. A video component does not (the wave is the result of light passing through a colored LCD).

I'm not sure I follow here. The television has to drive repeating waves, else you just get a black screen.

And that assume specific video technology. What about an e-paper example? The screen can be "shut off" and the picture is still there. Ditto a printed photo.

A physical picture can still be there, as it is an object. But without a light source to bounce light off the picture, what good is it to your eyes? Further, if you take a still picture into a room with a strobe light that varies color, you're not going to see the same thing as if you take it into a room with a regular lamp.

You cannot do those things with sound. Video can be viewed as discreet in ways that sound cannot.

Depends on how we want to think about it in the end. From a perceptual and practical standpoint, you're probably correct. I just like to be difficult

 

[jonnythan]

There can be no "true digital" speaker. There's no "true digital" TV either. Ultimately the signal has to be converted to analog for final output.

"Digital TV" refers to signal processing and transmission. We went from analog transmission and processing to digital transmission and processing.

We made that jump with sound quite a while ago. We have all-digital music, transmitted over digital cables, processed digitally in receivers, and finally converted to analog for final output. Just like TV.

 

[JerryLove]

I'm not sure I follow here. The television has to drive repeating waves, else you just get a black screen.

The waves are not stored (say) a BD, as they are on a CD.

The entire video system does not think in waves. It thinks in discrete bits.

I could make a TV display entirely out of lightbulbs (it would be a big display, but I could). If you assert that the TV has to "drive repeating waves", then you must make the same assertion over a lightswitch; at which point we've become so broad in our meaning as to have completely changed topics.

I can write a pixel. 255,255,255 (hex FFFFFF). There. It's a white pixel.
Write a static sound.

You can't discuss sound without discussing the time domain. You can discuss video that way.

On an academic level somewhere you are right; but for all practical purposes here you are wrong.

Otherwise: tell me how to build a speaker of (auditory) lightbulbs.

(though light and sound have a lot in common: the way we see and the way we hear are quite different)

A physical picture can still be there, as it is an object. But without a light source to bounce light off the picture, what good is it to your eyes? Further, if you take a still picture into a room with a strobe light that varies color, you're not going to see the same thing as if you take it into a room with a regular lamp.

So you agree with me that pictures and sound are very different? Good.

Depends on how we want to think about it in the end. From a perceptual and practical standpoint, you're probably correct. I just like to be difficult

Good job

 

[JerryLove]

There can be no "true digital" speaker. There's no "true digital" TV either. Ultimately the signal has to be converted to analog for final output.

I think you are equivocating "digital". A proper definition is : using discrete (discontinuous) values.

If I view a lightbulb as either on or off: it's digital. If I view it as infinitely varying levels of brightness; it's analog.

We made that jump with sound quite a while ago. We have all-digital music, transmitted over digital cables, processed digitally in receivers, and finally converted to analog for final output. Just like TV.

The digital data is transferred through what is being called an analog medium.

If the light going down the fiber cable is "digital light", then so is the light coming out of the TV.

Digital has values of finite, quantifiable precision. Analog does not.

Sound cares about the infinite transitional points in a wave.

 

[jonnythan]

And light is quantized. Ultimately the whole world is digital. Any signal is inherently analog, as it's a physical construct. Whether it's voltage on a PCB trace or light in a fiber cable, the signal itself is analog. But it encodes digital information.

That's besides the point though. A fiber cable carries digital information the same way an HDMI cables. The processing is all done in binary. Everything in a modern stereo, from CD to receiver, including all processing, is done in the digital domain. It's only converted to analog at the very end to move a driver.

Same as a TV. Everything is done in the digital domain until you actually create the light. That's a digital to analog process, the same as in a receiver for sound.

The point is that we're at the same point for TV that we are for sound. You can't have a "true digital speaker" any more than you can have a "true digital LCD backlight." It's a D/A process.

 

[Adam]

You can't discuss sound without discussing the time domain. You can discuss video that way.

You can discuss either without discussing the time domain - but I believe that you'd be wrong in both cases.

A 500 Hz sine wave is going to sound (at least to me) "static." It won't be changing as far as I can tell, but as you say, it isn't static. Likewise, a 500 THz signal will also appear to be static to my eyes as orange, but it isn't static.

It's entirely possible, or perhaps likely, that I'm missing the point - but I think that there's some confusion in the light bulb example. The fact that a light bulb can be turned on or off (which you equate to digital) is an artifact that such a device was created to convert electricity to light, and that electricity is applied via a switch. I could use the same thinking to claim that sound is digital because I can turn an electric horn on and off by toggling a switch - it either generates sound or it doesn't.

 

[Steve81]

The waves are not stored (say) a BD, as they are on a CD...I can write a pixel. 255,255,255 (hex FFFFFF). There. It's a white pixel. Write a static sound.

Naturally. Because a videos that we see are just a bunch of still images (thanks to how easily we can fool our eyes), it is possible to digitize it in a way that simply isn't feasible for audio. OTOH, while you've written a pixel, it still isn't static unless you code it into each and every frame of the video.

I could make a TV display entirely out of lightbulbs (it would be a big display, but I could). If you assert that the TV has to "drive repeating waves", then you must make the same assertion over a lightswitch; at which point we've become so broad in our meaning as to have completely changed topics.

That absolutely is my assertion. A lamp is the light equivalent of having a speaker play a 60Hz tone repeatedly. And yes, as I've acknowledged, we're leaving the realm of practicality at this point.

You can't discuss sound without discussing the time domain. You can discuss video that way.

You can discuss a picture that way, but not a video. I mean, even if you were to say frame 228234 as opposed to talking about a specific time stamp, it still relates to the time domain given a specific frame rate.

Otherwise: tell me how to build a speaker of (auditory) lightbulbs.

I suppose in my own little mind that it is my contention that a regular loudspeaker as we know it is a variable wavelength audio light bulb, controlled by the alternating signal fed to it by an amplifer.

Good job

Think of it this way: conversations that make you think will help your brain ward off dementia as you age. So really, I'm doing you a favor