If you're going through all the effort to design a PCB have you thought about driving the I2S input digitally? I skimmed through the AD85050 datasheet and it has internal DSP functionality which would have been already tuned for the drivers and box by Marshall. The reason powered boxes sound decent despite their relatively cheap hardware is because of the extensive processing they have in the background to compensate for any hardware defiencies.
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.
I have this speaker and cannot believe how annoying the smart features are. I'll be talking on the phone in my apartment and the speaker will think I'm trying to prompt it.
"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.
This looks an EE‘s approach who hasn’t had a lot of exposure to speaker design. You need to consider Thiele/Small parameters of the chassis, enclosure volume, baffle design and a million other factors to design a proper crossover. You can’t just ltspice your crossover and call it a day. VituixCad would be a more appropriate solution.
And then you actually have to measure!
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.
mysteria ·5 days ago
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.
Show replies
gavinuhran ·5 days ago
"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.
Show replies
tlhunter ·5 days ago
Show replies
05 ·5 days ago
[0] https://github.com/hn/linkplay-a31
MrBuddyCasino ·5 days ago
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.
Show replies