[HN Gopher] De-smarting the Marshall Uxbridge Bluetooth speaker
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De-smarting the Marshall Uxbridge Bluetooth speaker
Author : fanf2
Score : 201 points
Date : 2025-01-11 15:42 UTC (7 hours ago)
(HTM) web link (tomscii.sig7.se)
(TXT) w3m dump (tomscii.sig7.se)
| MrBuddyCasino wrote:
| 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.
| ipsum2 wrote:
| You seem to be very knowledgeable about this subject. I have
| some Google Nest Audio speakers that sound fantastic, but have
| the same problems as bluetooth speakers, and lack a 3.5mm input
| jack to convert into normal speakers. Do you have any
| recommendations on how to do this, for someone with minimal
| audio knowledge and some basic EE?
| liminalsunset wrote:
| The Google Nest Audio speakers are kind of a special case.
| They only sound good because they use a sealed, extremely
| rigid cast aluminum sealed enclosure with a high excursion
| driver. The performance of these speakers with a regular
| crossover and amp will be poor, due to the low efficiency of
| the enclosure/small driver.
|
| 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.
| ipsum2 wrote:
| Thanks for the comprehensive answer, I'll look into the I2S
| audio solution.
|
| 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.
| encom wrote:
| >You can't just ltspice your crossover and call it a day.
|
| I'm sure that's true, but how important is that _really_ for a
| set of crappy plastic speakers?
| MrBuddyCasino wrote:
| At the end of the day, if you're happy and it sounds ok:
| thats fine, most people can't tell the difference anyway or
| they get used to however it sounds. But it will inevitably
| leave a lot of potential performance on the table.
| AstroNoise58 wrote:
| Do not underestimate audio circuit tuning based on listening
| tests. Good ears and patience can substitute a lot of lab
| equipment dollars, especially for a hobbyist.
| MrBuddyCasino wrote:
| I would say its the precise inverse: very few people can do
| it well by ear, and it takes a lot of practise and
| experimentation. At the most basic, try matching the volume
| level of a subwoofer to the main speakers - even this is
| already very hard to do by ear, for reasons of human auditory
| perception and psychoacoustics.
|
| You don't even need a lot of "lab equipment dollars",
| measuring the basics can be done with ~100EUR 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.
| AyyEye wrote:
| The best acoustic devices in the world have been made and
| tuned by hand for thousands of years. "you cannot develop a
| good speaker without measuring, [modelling, or
| simulations]." Is fundamentally untrue despite what the
| cybernetic totalists may want to believe.
| BoingBoomTschak wrote:
| >The best acoustic devices in the world have been made
| and tuned by hand for thousands of years.
|
| 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".
| Blackthorn wrote:
| Yeah but there's a pretty important caveat here. The person
| who's actually doing the listening is the only person's
| opinion who matters about the quality. This is very much of
| a case of "if it sounds good it is good" That's why you're
| doing here because that is literally the only person who
| needs to be satisfied with this arrangement.
| seba_dos1 wrote:
| > You can't just ltspice your crossover and call it a day
|
| Turns out you can, they just did and are happy with the
| results.
| Mathnerd314 wrote:
| I'm curious about price - sure, the speakers were free ($240
| value), but I don't think printing up a PCB is cheap, and those
| are some pretty big capacitors.
| stavros wrote:
| A PCB like that would cost around $1 each, if you got 10 or so,
| so it's not expensive at all. I don't know how much assembly
| costs, but I'd be surprised if the total was over $20.
| jdietrich wrote:
| JLCPCB have changed the game. Five 2-layer PCBs of up to
| 100x100mm cost just $3.50 including global shipping. Things get
| more expensive if you stray from their standard specs, but
| you're still looking at just a few dollars per board.
|
| https://jlcpcb.com/
|
| 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.
| f1shy wrote:
| And you can even order all or the SMD components soldered for
| less money that you can buy solder and other consumables for
| soldering never mind the time.
| leoedin wrote:
| I recently got 20 reasonably complex 4 layer gold plated
| pcbs assembled for about $10 a piece by JLCPCB. Maybe 20
| items on the BOM, 50 parts total.
|
| 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.
| beala wrote:
| I think the biggest cost is labor. Dumpster diving for speakers
| and then spending dozens of hours in high skilled labor to
| replace the insides is actually hilarious. I wonder how much
| he'd charge a client for a project this size? Probably many
| thousands of dollars.
|
| But I can't knock a man for having a hobby. Clearly they're
| optimizing for fun and nerd cred, not cost.
| gavinuhran wrote:
| 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.
| emidoots wrote:
| Return that crap and buy something like Audio Pro speakers
| instead
| seba_dos1 wrote:
| There's an article that tells you that. I believe it's linked
| somewhere above this comment.
| bonzini wrote:
| The article removes all the smart features (not just the
| annoying ones) and requires pretty serious knowledge of
| analog electronics. Probably it doesn't fit the bill for the
| parent comment.
| dheera wrote:
| I mean, it's a speaker in a box, so you could also just
| snip the speaker wires, ditch the circuit board, solder
| some extension wires, and plug it into an external audio
| amplifier box of your choice.
|
| 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)
| seba_dos1 wrote:
| > and requires pretty serious knowledge of analog
| electronics
|
| 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.
| Blackthorn wrote:
| Jim Marshall is rolling over in his grave at what happened to
| this company.
| mgaunard wrote:
| what exactly is the problem with smart speakers? Most people just
| want to stream Spotify
| netsharc wrote:
| "We are delighted to announce an update to our smart speaker
| line: we are sunsetting the online services for this model.
| Your devices will be disabled in March 2025. They will no
| longer work, and please bring them to an electronics recycling
| center near you.
|
| You are eligible for a voucher to get a discount when you
| upgrade to a newer model."
| mynameisvlad wrote:
| This is pretty much word for word what has already happened
| at least once.
|
| 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.
| lelandfe wrote:
| "Sustainability is non-negotiable!" was my favorite
| platitude from their website at that time. As Sonos
| needlessly condemned 6 year old speakers to the landfill.
| exe34 wrote:
| corporations are functionally psychopaths. they will say
| whatever you need to hear to spend money and they will do
| whatever it takes to maximise profit, even when it goes
| contrary to what they have said.
| f1shy wrote:
| I bought a Yamaha CD-N301, came with a web radio, where you
| could setup a user, and make an index of URIs with
| webradios. After that you could select the station from a
| menu in the front. 3 months after purchase, the service
| started costing 3 dollars per month. I only use the CD
| function now.
|
| I contacted Yamaha, the answer was "it still works, we
| never promised it would be forever free" PoS
| ipsum2 wrote:
| It's mentioned in the article, but briefly 1) latency (300ms+)
| and 2) random voices at max volume while you're trying to
| listen to music.
| recursive wrote:
| I also want to play my own music or play video games or movies.
| Bluetooth latency is not suitable for any of these
| applications.
| tlhunter wrote:
| Lately I've been wondering if there's a way to do this to Smart
| TVs. Personally, I like the name "stupify" better ;)
| rotifer wrote:
| A year or so ago I bought a Hisense 65U88KM, which comes with
| Google TV. During the setup procedure it asked me if I wanted
| to enable the "smart" features, such as Google TV, the camera
| and microphone, or connect it to a network. I said no to all of
| them, and that was that.
|
| Now it just acts as a dumb screen for my Apple TV box.
| Astronaut3315 wrote:
| I did the same with a Sony A80L, which also runs Google TV. I
| even uninstalled the bundled streaming apps for good measure,
| although I never see the home screen.
|
| It behaves like a monitor. I never see the TV UI unless I ask
| for it.
| dexterdog wrote:
| I find that most of those reset to some nonsense
| occasionally or whenever the power goes out. I make sure
| they have no internet connectuon, but I usually have to dig
| up the remote to get back to hdmi1 so my device interface
| will come back up. I accept the annoyance because I
| accepted the discount that they give to have all of the
| spyware crap on there that I am blocking. I wish they could
| sell something cheaper that is just a display, buy product
| managers will be product managers.
| mysteria wrote:
| 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.
| bayindirh wrote:
| Marshall speakers, from my experience, has a brand sound
| signature, and that tuning is not very optimal for every genre
| of music.
|
| 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.
| f1shy wrote:
| > 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.
|
| 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.
| acchow wrote:
| I'm interested in which speaker and amp those were. Also, the
| plastic box :)
| bayindirh wrote:
| Not the OP, but if you have a little budget, HifiBerry's
| AMP2 [0] sounds great. After my dad gave his Hi-Fi stack to
| me (due to having no space at home), I built a small system
| with this and connected to a set of passive 2.1 Kenwood Hi-
| Fi speakers for him. They sound _amazing_ , plus HiFiBerry
| OS is superb for connectivity.
|
| 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...
| f1shy wrote:
| The amp: https://www.reichelt.de/de/de/shop/produkt/entwick
| lerboards_...
|
| The speakers: https://www.reichelt.de/de/de/shop/produkt/br
| eitbandlautspre...
|
| Box: https://www.reichelt.de/de/de/shop/produkt/gehaeuse_se
| rie_op...
|
| Design of a friend, final product looks like this:
| https://hackaday.io/project/198249-untonie-antony
| mysteria wrote:
| Most cheap amp ICs perform well when they're outputting less
| than a watt, with distortion barely audible. Try connecting
| the same amp board to your main HiFi system if you have one
| and do some listening tests against the original HiFi amp.
| Then turn it up and it's a completely different story.
|
| 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.
| f1shy wrote:
| Yes, of course is not hifi. Not in any dreams, but for the
| price, being 2 orders of magnitude less money, impressive.
| Also in comparison with old little radios, much much much
| better.
| Blackthorn wrote:
| It's been shown that, at least for guitar speakers, the box
| they're in doesn't matter at all. The entirety of the sound
| quality or lack thereof is in speaker itself. Of course that
| is only one speaker , no crossover to worry about.
| AstroNoise58 wrote:
| I assume you mean AD85050 (rather than AD8255). And yes, the
| last paragraph before "Going all-in" is about the idea of
| driving the I2S. But the I2C config sent to the ESMT chip would
| have had to be reverse-engineered as well...
| mysteria wrote:
| Fixed, thanks. Somehow the title of the datasheet pdf is
| AD8255 despite the chip being an AD85050.
| zxcvgm wrote:
| I have the same thoughts about the approach, and I'm actually
| working (on the back burner) a similar thing. It's a harman
| kardon "smart" speaker with a similar design where the brains
| are on a separate daughterboard and that's now fried.
|
| 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!
| j45 wrote:
| There's no shortage of projects on YouTube where people are 3d
| printing their own speakers, including arranging electronics.
|
| Pretty neat for any former car audio heads.
| 05 wrote:
| There's a project to load OpenWRT onto LinkPlay A31 [0], might be
| easier than basically replacing the insides..
|
| [0] https://github.com/hn/linkplay-a31
| kazinator wrote:
| > _I liked it even though the sound reminded me of the "disco
| smile" (hollowed out mids), but I chalked that up to overly
| consumer-friendly default EQ settings._
|
| The much simpler explanation is that it has hollowed out mids
| because it's a Marshall.
| szundi wrote:
| Article suggests that complicated tools are annoying and not
| right to be that complicated. But one can argue, that if such
| complexity is actually needed to tackle tasks (like the
| multiplatform compilation of the Linux Kernel for example), then
| it is pretty obvious that in the optimal case the learning curve
| is at least in a linear relationship with the complexity. If
| given complexity is high enough to surpass the related learning
| time threshold of the given person then he/she/whatever is going
| to be annoyed for sure.
|
| There is no escape from this.
| munchler wrote:
| For those (like me) who are unfamiliar with this device: It looks
| like a Marshall amp, but is a 9" tall Bluetooth speaker.
| jimnotgym wrote:
| Tangential question, I have a nice audiophile so and no speakers
| at the moment. I want some speakers for $low that have decent
| performance. I can build boxes (used to be a carpenter), but need
| a design and what look like expensive drivers and crossovers. Is
| DIY speaker construction actually a cheaper way of getting a top
| notch hifi, or should I just buy second hand?
| Blackthorn wrote:
| What do you consider low price? For sheer quality, it's pretty
| damn hard to beat the price of Kali studio monitors.
| jimnotgym wrote:
| I'm really thinking of 'low enough that my wife doesn't kill
| me', which is a variable amount!
|
| 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!
| alright2565 wrote:
| This website is a good starting point:
| https://www.audiosciencereview.com/forum/index.php?pages/Rev...
|
| Click on the magnifying glass with an "A" to get to the
| advanced search to be able to filter by price.
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