Replacing and amp and „smart“ crap is easy if there is an analogue crossover you can reverse-engineer, if it was just some DSP things get difficult quickly (unless its just a single broadband chassis, but even then…).
And no, you can’t use pre-built „standard“ crossovers or some calculator on a website either.
But other than that, nice that he saved some hardware.
To get around this, Google put in the TI TAS5825M smart audio amp. By measuring the speaker parameters through V/I measurement and a model, it drives the speaker in a closed loop way with far more power than it would actually be able to handle nornally to compensate for the resistance from the enclosure air pressure, and throttles to maintain the coil at a safe temperature. The chip also does DSP to compress the audio signal, cutting the peaks off the bass as needed when the volume is turned up so volume is maintained at the cost of bass.
One way to explore could be to just feed I2S audio from an I2S ADC i.e. PCM1808 to the digital input of the amplifier. The processing is internal to the amp so theoretically you won't lose the tuning. However this may turn out to be a relatively annoying reverse engineering project with fine magnet wire involved.
Note: I2S is different from I2C - the amp will likely have both. You will likely need to keep the original system around to program the amp over I2C (or capture the transaction and replay it) - otherwise you will likely get no audio.
The "raw" audio performance of this device (just an amplifier connected directly to the internal speaker and dsp on the computer) is impressive, kicking out bass down to 40Hz. It will, however, not last long like that. Reports online are that these blow speakers easily even when used with the default amplifier.
I would recommend that if 3.5mm input is desired, to replace them altogether with the IK Multimedia iLoud Micro Monitors. These have sound quality just as good as the Google at similar size, with the same DSP tricks, but have regular inputs and no smart features.
You're right that iLoud Micros sound similar, they're 3x the price (The Nest Audios were sold at $50/each on sale). Definitely worth it, I just like tinkering with things.
I'm sure that's true, but how important is that really for a set of crappy plastic speakers?
You don't even need a lot of "lab equipment dollars", measuring the basics can be done with ~100€ calibrated USB mic. As a rule of thumb, you cannot develop a good speaker without measuring, unless you have advanced modelling tools and experience to use them correctly, in which case the measurements will mostly match the simulations.
Says who? You should really acquaint yourself with current research, starting with Toole's infamous "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms".
Anyone who has read about or experienced instruments and music halls that were made before the commodification of electricity?
My point was more along the lines of „a layman reading this might draw the conclusion that this is the proper way to solve this problem, because the text is written with an engineering mindset and demonstrates a certain degree of sophistication“, and I wanted to caution people that this is not the case.
Turns out you can, they just did and are happy with the results.
Which means most people can’t tell the difference. This is mildly upsetting to the people who can.
The biggest electrolytic caps in this circuit cost $3.29 each in qty 1, but they're fancy "audio-grade" Nichicon caps; a standard-grade capacitor of that size would cost you $1.68 if you want a Japanese brand, or as little as $0.36 if you can settle for a Chinese brand.
It’s insanely cheap. 5 years ago when I was last regularly getting PCBs built it would cost 10x that. And it would be a really manual process - loads of emails back and forth. PCBway have managed to automate basically the whole process.
But I can't knock a man for having a hobby. Clearly they're optimizing for fun and nerd cred, not cost.
"SORRY. YOUR DEVICE IS NOT CONNECTED TO THE INTERNET. PLEASE CHECK YOUR BLUETOOTH SETTINGS AND TRY AGAIN." (at max volume!)
It's unbelievable. I'm not an EE, but would love to know how I can disable these incredible unsmart features.
If you go that route you don't really need much EE knowledge.
(This is also only if you already have this box and want to reuse it. Otherwise I would just go to your next neighborhood garage sale and pick up some good speakers for $10)
If you want to understand the whole thing in depth, then yes, I guess so. However, at the end it just links to the already made project published at MIT license that you can simply replicate with barely any knowledge. It's an equivalent of self-compiling a software project after checking out its repo, which sure, may seem overwhelming if you never did that before, but ultimately it boils down to some reading comprehension and step following exercise.
I would not assign this to someone as their first electronics project. They would have to order all the components and get the PCB etched themselves. There's a fair bit of soldering, and a usable soldering iron is not cheap. And there's no undo button in hardware: if you solder something in backwards and pop it, you get pay for a new component and wait for it to ship to you.
The hardest part will be ordering the components, or more specifically verifying that you got them right, as the KiCad project does not include a BOM. Other than that, it's as easy as it gets. Entry-level workshop stuff, about as complex as ArduTouch. People who never held a soldering iron in their life successfully learn on this kind of boards.
(and if you're willing to spare a few more bucks you could even get it assembled by a PCB fab and just receive ready-made boards in your mailbox - the prices aren't prohibitive there either)
...with the risk that you may get "THE BLUETOOTH DEVICE IS READY TO PAIR" instead, although others have figured out how to replace the prompt sounds on some series such as the JieLi SoCs.
And now I wish HN had spoiler tags and a culture of using them along with trigger warnings...
Now we have the answer.
I am an EE, so let me tell you.
Use a hammer.
You are eligible for a voucher to get a discount when you upgrade to a newer model."
Sonos at least reversed their decision to disable the devices when they sunset S1. They just made them incompatible with their current system but allowed people to download the old apps.
Unfortunately, devices that were already marked for trade-in before they made the decision are still completely bricked.
I contacted Yamaha, the answer was “it still works, we never promised it would be forever free” PoS
Now it just acts as a dumb screen for my Apple TV box.
It behaves like a monitor. I never see the TV UI unless I ask for it.
The "smart" part is what makes TVs cheaper, since that's what opens the door to a higher CLV. People willing to put their money where their mouth is can still buy dumb displays: https://www.bhphotovideo.com/c/browse/Multimedia-Displays-Di...
I have a cheap FireTV which cannot be made to behave this way. If you disconnect it from the internet, it will still require you to interact with the (slow-ass clunky) OS in order to select a different input.
Your best case scenario with some of these smart TV's is the ones which run Android to replace the launcher. Possibly, this gets reset periodically, meaning you have to keep doing it.
Apparently there's a few Fire devices which can be flashed with LineageOS - I might try researching that and see if it is doable. A FireTV stick with LineageOS would be the best case scenario.
As the AD85050 has a stereo I2S input there's a possibility for the actual crossover to be either done on the amp chip itself (with the same signal driving both channels) or done on the Amlogic SOC. The latter would be ugly as you would need another DSP chip on your board to do the crossover functionality, or perhaps you could program the AD85050 via I2C to add the appropiate low and high pass filters.
A two channel A/D converter would work on the front end, as you could drive both channels with a single analog input to get a stereo I2S out with duplicate channels to drive the amp. A USB input would be much messier if you want true stereo using two speakers unless you plan on doing routing on the software side. With SPDIF you probably could get away with splitting the signal and using a SPDIF to I2S converter chip in each speaker, but you would still need some way to separate out the left and right channels. The AD85050 has mixing functionality via I2C which may help with that.
And of course, all this might be more work than desigining an amp in the first place, and it really depends if you want to explore the analog or digital side of things.
Replacing the DSP with a simpler amplifier may allow to get more detailed sound from the drivers and the box themselves and may create a more pleasant listening experience.
From what I have seen, the drivers seem pretty full-size for that box, and any disturbing sound characteristic can be tuned with a simple equalizer. A more dynamic approach might create audibly weird sound profile if done wrong.
Modern DSPs are magic, but I still prefer an audio pipeline where things show their deficiencies and not hide things real-time.
I will not argue that that could be one ingredient, but a couple of months ago I did a toy for my kids, I bought decent speakers, placed them in a cheap plastic box, and was absolutely amazed bybthe sound quality. The amplifier is a sub 1 dollar class D bought in a Raspberry Pi shop. No processing at all. If the box is sturdy and sealed, and the speaker is good, is incredible what you can do.
I just want to note that software is built with collaboration of Bang & Olufsen. Both hardware and software oozes quality.
[0]: https://www.hifiberry.com/shop/boards/dealing-with-blocked-p...
The speakers: https://www.reichelt.de/de/de/shop/produkt/breitbandlautspre...
Box: https://www.reichelt.de/de/de/shop/produkt/gehaeuse_serie_op...
Design of a friend, final product looks like this: https://hackaday.io/project/198249-untonie-antony
As always the speakers are the crucial part and having decent speakers will make a big difference. What a DSP can do is correct bad speakers to some degree. A typical cheap computer speaker has a muddy midrange, can't reproduce past 13 kHz or so, and has little bass due to the small driver. With DSP the manufacturer would typically low pass the amp input, smooth out the nonlinear frequency response, lift the bass a bit, and apply compression and limiting to increase perceived volume and protect the system. The results are still constrained by physics but the manufacturer is in this case able to save money on the drivers and box while getting similar sound quality.
https://www.amazon.com/Introduction-Loudspeaker-Design-John-...
https://www.youtube.com/watch?v=-eeC1XyZxYs
This is hardly surprising; cabinet design matters for every kind of loudspeaker. Note also that electric guitars can produce a wide range of frequencies, especially once you add distortion. Distortion generates additional tones both higher and lower in frequency than those already present.
I've already figured out the control signals and have designed a new daugterboard with an ESP32 to drive the I2S output. I just need to figure out how to downmix the audio to mono and to DSP the L/R channels into tweeter/bass outputs, or to find some code already out there that does this. Any help/pointers here would be appreciated!
Pretty neat for any former car audio heads.
The much simpler explanation is that it has hollowed out mids because it's a Marshall.
Practically every guitar amp's "netural" settings are scooped to an extent, though. People like that sound and it's "traditional". Even when people play direct into a mixing desk, I find that they almost always scoop the mids a bit, it's simply what you associate with electric guitar.
There is no escape from this.
Thanks for the Kali tip. They are a little more expensive in Europe, but still a possibility.
I guess re DIY I'm looking for that mythical thing where it is still cheaper to do something yourself rather than buy it!
Click on the magnifying glass with an "A" to get to the advanced search to be able to filter by price.
Its amazing what a brand name does to ones ears, all of a sudden a small plastic box with SBC Bluetooth codec sounds great.