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Comment by rzzzt | Hacker News Reader

This is a DAC. The low-pass filter is an integrator in disguise.

I think a 1st order RC filter is simple enough that you could argue that "you don't need a DAC" and is what I expected.

But when I opened up the post and saw a 2nd order (probably) Sallen-key (or is this a MFB? I always get my topologies confused...) with a full-bore OpAmp and capacitors up the wazoo... erm... yeah, they're basically hand-building a DAC at this point.

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A lot of stuff is wishy-washy definitions anyway. What's the difference from an analog-comparator and a ADC anyway? An analog-comparator is just a 1-bit ADC after all.

So a lot of "what is a DAC" exactly is up to opinion around the edges. But if you've got op-amps and signal conditioning, you're getting pretty darn close to "proper DAC" except you know, not as good (ie: cheap, fast, or simple) as a proper professional solution.

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EDIT: Reread blogpost. It looks like the RC-filter is in fact, being used. The Espressif docs __suggest__ the OpAmp based 2nd-order filter, but the blogpost is strictly with the simple 1st order RC-filter.

So yeah, I'd say that RC-filter is "not a DAC", due to being too simple. (It functions as a DAC in this case, but we got to draw the line somewhere).

It's how every sigma-delta DAC works, basically. Less snappy headline though.

Yes. Sharp had a line of minidisc players back in the day with a 1.8 MHz ”1-bit” technology. https://global.sharp/products/1bit_system/tech_sub.html#:~:t....

Aparently very high quality audio.

https://www.reddit.com/r/minidisc/s/OTHQJwSt92

They used ΔΣ as their logo.

That's how SACD works too: 1-bit 2.8MHz DSD.

"We don't need dedicated hardware that's marketed as a DAC on the ESP-32-S3"?

This was so obvious before even clicking, I couldn't imagine that level of trolling on HN, I had to click in to see what they were actually doing.

Nope, that's what they're actually doing. Congrats, you've built a very simple external DAC.

Low-effort clickbait? Or an innocent misunderstanding by someone who thinks DACs have to be expensive?

> Low-effort clickbait? Or an innocent misunderstanding by someone who thinks DACs have to be expensive?

Probably the latter. Things like Arduino and cheap ESP modules from china have made electronics vastly more accessible than they were previously. Given that, it makes sense that somebody wouldn't really understand _how_ a DAC works but would understand what one does, what it's used for and that the datasheet for $currentModule says there is none present.

I have no problem with the article, wouldn't say that it's clickbait either. Just saw a DAC >:)

The ready availability of Arduinos and similar technology has brought a lot of people into that scene who are not aware of what all is available to them, what all the bits and bobs are, and what you can bash together with a few resistors and capacitors hooked up correctly.

People like me. I think I can call myself tolerably good at programming, but I can easily tell I'm much more newb at EE and I can really only operate with things that have clearly defined outputs that match up to some other input. Where you may see trivial conversions you could bash together in your sleep, I see an output that doesn't match the input and don't immediately know where to go with that.

In my case, I'm able to follow the post just fine, but if I had to put that circuit together from scratch from first principles I'd be looking at weeks of learning more about EE. And as a result, as I am blundering about an unfamiliar landscape in some personal projects I've got going on, I appreciate posts like this.

That’d be some mighty selective baiting leading to a disappointingly feeble number of clicks. Unless the population of Arduino+audio nerds is secretly massive, which I’m pretty sure is not the case.

In think they just mean "on-chip/integrated DAC peripheral" when they say DAC (which is what a lot of hobbyists/non EE folk think of from the term). The article's just trying to say you don't need one for an audio use case and can use a discreet RC.

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