Comment by torginus | Hacker News Reader

Comment by torginus | Hacker News Reader

My educated guess would be no - excepting specialist applications like super high frequency signal processing, or very high power levels. If we look at trends, as computers got faster, more and more analog signal processing circuitry got replaced by digital equivalents, with some analog frontend that does downmixing and initial filtering as a frontend for the ADC.

For example, transistor-driven class A and AB amps that used to be analog amplifiers were replaced by class D amps - essentially a pulse-width modulated signal controlled by a switch-mode FET with a filter bank on the back end. This allowed the creation of very compact and power efficient audio equipment - like the portable Bluetooth speakers we have today.

Likewise, all other traditionally analog stuff, like power supplies, signal processing, motor control got a major boost from improving digital technology to the point I can't really imagine analog making a comeback if not for some niche reason.

I generally agree (love my class D amp).

Low power is another niche where analog can be best. Did you know that even current smartphone designs include electromechanical (really) filters for radio signals? SAW filters convert electrical oscillations to mechanical ones and back.

AFAIK hearing aids also rely on analog stages in some pretty clever ways to save energy.

Not to start a tube vs. solid-state flamewar, but I thought class D were awesome too — until I swapped out the class D in my office for a tube amp.

When some audiophile type talks about "listening fatigue" (and the lack of it from tube amplifiers) I get what they're describing now.

(This is the "Darling" tube amp I built for maybe $200: https://imgur.com/PBKOQMk)

I’ve always heard the preference for tubes[a] comes from them having a “warmer” sound. Could that warmer sound be alleviating the “listening fatigue”?

[a]: by non-audiophiles

And to cut a little more audiophile fuzziness out, I’d say I’d associate warmer with high cut and boosted upper mids. Which sounds like it would alleviate fatigue to some degree, perhaps be perceived as louder at a given spl.

Tangentially, I built a little transmission line speaker, see Woden Designs Baby Labs pdf, I built the redeye, IIRC, the one that used the cheapest driver. The little 3 inch driver really rolls off above 10k, I’m missing a whole octave of the highest frequencies, and I’ve spent some time around planers and table saws and electric guitars, don’t have the best ears, but side by side with other speakers you notice. But anyway, the point is you notice, but it really doesn’t sound bad to lose a little high end. Something is missing, but it’s not ugly to listen to in the way some other speaker defects are.

By "warmer" sound, it is meant that, even if the tube amplifiers normally produce greater distortions than many of the more modern amplifiers, for some reason this kind of distortions sounds more pleasant than other kinds of distortions.

If some amplifiers would be ideal, producing no distortions, they could not be distinguished in any way, regardless what devices have been used to implement them. The modern Class-D amplifiers can behave almost ideally when amplifying low-frequency signals, but for the signals with frequencies close to the upper limit of the audio range their behavior becomes much less ideal.

While I have pleasant memories about a tube amplifier that I have used many years ago, I have never made comparative tests with other amplifiers, so I could not say whether it was better or worse regarding "listening fatigue".

Even when comparative tests are done in an identical setup, by swapping a tube amplifier with another amplifier, it is extremely difficult to disentangle which audio differences are caused by using tubes as the amplifying devices, which are caused by the audio transformers included in most tube amplifiers and which are caused by the interaction between the amplifier outputs and the loudspeakers, which can be very different between different kinds of amplifiers, due to their different relationship between output impedance and signal frequency.

"Warm" sound is rolloff of the highs by the amplifying equipment.

I hate to even bring more audiophilespeak into the thread, but I have heard the distortion (harmonics) are "even" in tube amplifier architectures, "odd" in solid-state. (I don't even know what that means though, or in any event why that would be.)

Did you buy a kit or follow a guide? I’m interested in making one.

I followed a guide. Kind of.

I started here: https://www.oocities.org/timessquare/1965/darling.html

After building a couple of point-to-point Darlings I created a PCB version to make building it much simpler and repeatable.

There used to be other Darling PCB's on eBay but I don't see them anymore. I should probably get my own PCB back in "production"....

There are plenty of tube amp kits on aliexpress, but I can't vouch for them. Maybe you can look around here for ideas/recommendations: https://diyaudioprojects.com/Forum/viewforum.php?f=9

Thank you so much!

I think you have the power situation backwards.

Analog still has not left power supplies. The dynamics are just too fast for low-power digital. So the solution for a long time has been mixed analog and digital.

At higher power, there's usually a hierarchical control scheme with an all-digital supervisor at the top. Analog isn't required at that level because the dynamics are slower, and digital has the extra benefit of more control options that analog can't do.

As the dynamics get faster, there's an even greater need for analog. You start needing increasingly expensive op amps. But op amps trade speed for convenience. So the fix is even more analog, but the integrated type. At that point, you might as well throw in more digital features.

Which is why I think we'll just see even more mixed-signal options at the lowest levels. Different ways of leveraging analog speed and low power under an increasingly sophisticated digital manager.

I don’t think that’s the case at all?

If you look at any modern voltage regulator it switches in the megahertz range with variable pulse width and interval. This is all controlled in the digital domain (lower end ones do use analog control loops, but higher end do not).

Above the megahertz level switcher everything else is just capacitors providing low impedance at frequencies into the high hundreds of megahertz (and at gigahertz it’s on-die capacitance).

‘too fast for digital’ makes no sense when talking about control loops, digital is faster.

Is it not? Show me one counter-example.

There are many parts of a control loop. An analog comparator is faster and lower power than an ADC + digital comparator, for example.

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