LutetiumSophi Kravitz so... welcome Jørgen! Let's start!
I am located in Denmark (æøå) Copenhagen - eengineer at startup Merus Audio we do the most advanced class D amplifiers 2x40W and 2x70W with analgo or digitla input
Yann Guidon / YGDES Do they use multiple voltge to save power ?
At nigth time i am tinkering on embedde device and can see that technologi will start to disrupt the way we use to designe audio systems. But let me get back to that later.
Jørgen Kragh Jakobsen Posted a link by my colleage Rien - You mite need the username and password to get to it - let me knowYann Guidon / YGDES Ah I remembered reading something about this approach a few years ago :-) You pack enormous power in really tiny spaces so you must avoid dissipating anything :-)
Sophi Kravitz how does that work?
Jørgen Kragh Jakobsen Yes in normal class A and AB you have at least 25% in you device rest goes to speakers
Jørgen Kragh Jakobsen in class D you are down to 5% loss in device
and not a big problem before you start to play party level - normal pcb coolign is ok
What frequency does it use ? are there crazy clock techniques ?
Also for EMC we have some trick to do usign 5 level swithcihg
:-)
we do 300k, 600k or 1200khz
depenting on input level - and how you setup the amplifier profile
Jørgen Kragh Jakobsen Save power and do bether THD
Yes externel filtes is mainly for EMC requiments
cuuuuute !
lol
Jørgen Kragh JakobsenThis amp can do around 2x40w cont. from a shitty supply
Jørgen Kragh Jakobsen
Analog or digital input
Lucas Coelho Cavalheiro has joined this room.
Yann Guidon / YGDES Oh that would be a perfect fit for restarting my project #Whygeephone :-D
anfractuosity How much does a board like that cost out of interest?
Jørgen Kragh Jakobsen But let get to mika's question
rpstevens What do you think of Gainclone chip amplifiers? I built one a few years ago, seems to work OK.
What is the frequency range?
Gainclone is old stuff - move on to class
Frequency range is flat upto 20K
http://www.merus-audio.com/images/pdf/extranet_download/MA12070P%20Product%20Datasheet.pdf
Please check the spec in datasheet
back to Mika
You ar not the first to have problem with stagepass or old amp/audio system in general
Get hold of schemaics of the amp/mixer
Yann Guidon / YGDES Are there features in this chip to alter/process/equalize the sound ?
and try to follow the audio path. You need to look for bad caps used or blocking DC between stage in design
I just started looking at the datasheet, it says low power aplications, but voltage is 18v, how many amps?
or look for noise on supply lines - You need a scope
And for Orkhan - every body missing bass ...
yes try do some calculation on input impeaence vs coupling cap - that is now place you could loose base
bass
any information about availability and pricing of small modules ?
other places in the speaker and speaker enclouser. You need large volume and good acustic designe to do good bass
I know I asked this before but since more people are here, is there anyone near miami with scraps they are willingly giving
Our devices is fore high volume prodution - low cost . But I would love to do an exclusive outlet to the fellow hackers.
What would be the typical application?
Jørgen Kragh Jakobsen We are selling direct to OEM and brands.
Battery powered BT/WIfi speakers
I have another application idea :-P
Jairo Hi all, I'm from Burgos (Spain) I'm building a Class-D amplifier for the final degree proyect
I have arduino library's for setting up our ampliers - not complicated.
Yann Guidon / YGDES oh, does that mean that the amplifier is not a standalone chip ?
Edgar What inputs does it have? Does it support i2s?
Neil Cherry There's a node-red like interface for the Teensy (ARM?)
and for carol : yes we use lots of pie
Carol Willing Is the library open source?
Library will open source yes
@Carol Willing think so
Carol Willing cool
Neil Cherry oops (orry)
Jørgen Kragh Jakobsen We use Pies for burn in testing - One pie baking 8 amplifers for one month
Jørgen Kragh Jakobsen to do acclerated life time test at max temp -
Not eating over at you home
Each amplifier has a one month burn in. Wow
Lucas Coelho Cavalheiro Sorry if this is already stated somewhere, but has that demo board passed EMI test in FCC or CE?
Jørgen Kragh Jakobsen we have 3 x 42" racks with 100 amplifiers buring for one month
Edgar can it be configure other ways? like 2 x 40w, 1 x 80w, 4 x 20w?
Carol Willing That's great. I like the max temp test . Good QA.
Jørgen Kragh Jakobsen Yes you set amp up in 4 x single ended, 2x btl or 1x pbtl
Yann Guidon / YGDES niiiice
Jørgen Kragh Jakobsen EMI / EMC passing is end product related
very coupled to how you wire up you speakers ....
I'm aware, but if you demo board passes, it's a good indication that the chip itself operates well withing those specs
Jørgen Kragh Jakobsen and here is our 5 level your friend
Jørgen Kragh Jakobsen Yes your are rigthLucas Coelho Cavalheiro I'm just asking because that could be a selling point for your chip meaning that as long as you make a decent system integration, it will work nice and pass the certification
and we do EMI / EMC testing on modules as well - all good
Lucas Coelho Cavalheiro Just like those small RF modules that you can easily integrate in your product =)
Nice!
houghts on when 5 level is preferable to 3 level? Applications?
Lucas Coelho Cavalheiro And by the way, the burn-in test is an awesome reasurance for anyone instersted in using it professionally. Thumbs up!
I'm an amateur Electronics Buff and still learning the basics. I'm presently trying to design my own Audio Preamp - ADC Device. Based on the TI INA2137 Audio Differential Line Receiver. I want to make a Mic Pre-Amp and USB interface for Computers. I plan on using the MSP430 Prototyping Boards, that I already have. I have 3 and two of them have the Anaren Wireless Modules on them. I would like to build two different, setups. One Wireless. And one Wired, Sending Audio into the Computer, via USB. To send the Audio into a Computer, for Recording. If this will work. I also bought, LM1085IT-ADJ/NOPB-3A Fixed Adjustable Output Linear Regulator and LM3525M-L/NOPB-Single Port USB Power Switch and Over-current Protection. In case I need to build the whole Circuit from scratch. I don't know if I need to add Resistors to the Circuit or not. Since the INA2137 has some built in. I've spent several weeks. Researching Circuit Designs, for this Chip. But, have only found two, general Designs. On other Web Sites. This one I think, would work best for me. Audio line receiver impedance balancing using a 2nd diff amp, (see hand drawing on this page, http://www.eetimes.com/document.asp?doc_id=1280384&page_number=2). Does anyone have any experience, Designing Circuits with these Chips, that you could share with me?
Thanks,
Don
Yes digital input is I2S - we take 4 audio streams in - and has only volume pr ch and some limiter function on chip
Additionnal audio processing is normal done in DSP
What would be the minimum voltage? I saw the 250mw ratings for idle, but could it be made into a Pi HAT to do like a portale streaming jukebox?
But time has change and as micro processers is getting faster and get some DSP like instructions
there is no need add a DSP to the party - if you are just to do some bass enhacemnt and speaker EQ
yes, some lifting wavelets work
Lucas Coelho Cavalheiro Jorgen, what would you say that was the most challenging feature or part in the design of the chip that you think you guys are doing better than the competition in the market?My friend ower at ESP32 forum BuddyCasino ported SprieTM's mp3 decoder from the es8266 to esp32
Carol Willing :-)
I have a question regarding class D, which as I understand (perhaps incorrectly) uses mosfet switching and PWM. I'm interested in how duty cycle of the switching affects (or doesn't affect) the amp's ability to maintain frequency response across the spectrum. It seems like it can't be completely independent, and also should affect signal to noise ratio... or is it simply that the mosfet switching frequency is so fast that it does not get into the audio spectrum (because, Nyquist)?
Jørgen Kragh Jakobsen I made it stereo and added some DSP - and the ESP32 has still misp to be used.
I think we have a very nice platform to go to very interesting audio applications
tarting point woud be Paul Stoffregens Teensy DSP library
lucus : that is our 3 level output stage - and BLT to get 5 level. Dynamic change of modulation base on input level. Nobody does thatLucas Coelho Cavalheiro says:12:59 PM
Nice! I'll look into that to understand a bit more! Thanks!Jørgen Kragh Jakobsen says:12:59 PM
Larsen: Yes switching freq is way above audio - and we have feedback to do very low THDJørgen Kragh Jakobsen says:1:00 PM
For you nerds here is a very deep insight to all the fancy stuff we do on circuit level / ic integration level
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7707461
Lutetium :)
Carol Willing Awesome! Thx.
Lutetium and please feel free to add more questions here: https://docs.google.com/spreadsheets/d/1xLtoZIUYbqK-UQTdQrp0KaO9QCe_xmDW0N5nyYAN8IY/edit#gid=0
Sophi Kravitz hanks Jørgen!!
RRcoderthanks very interesting chat.
Kenji Larsen Thanks Jørgen! how high does the mosfet switching frequency get? I think you must be making some optimizations since faster state switching means more power consumption...
Jørgen Kragh Jakobsen Please just reach out for me - if you have any audio / class d related question - I am all ways around here
Carol Willing thanks Jørgen for the extra nerd info and a fun chat.
anfractuosity that paper looks nifty, will have a skim of that, not that i'll be able to understand it though, but it's cool to see companies publishing things like that
Orkhan AmirAslan Thanks, Jørgen. It was very informative
Thanks Hackaday too.
That IEEE paper is awesome, I'll love to play with one of these modules !
Larsen - Fast switching gives all kind of trobles - we slow down the speed of mos fet - if not we will do large voltage spikes (inductive load and upto 10 amp and bonding wires ) Dead chips
Right - hence my interest in how you solve this? Does this also imply that when an audio amp is processing a higher frequency tone or signal, that the mosfet frequency must similarly be higher, and consume more power? Like, will a Class D playing a constant lower note consume less than when playing a higher note?
I will do what ever I can to set up and outlet. If any one has good connection to Seeed / Sparkfun or Adafruit I will be more then happy to co - build a module
Free samples? Hehe Just kidding... Thank Jorgen and Hackaday! =D
Or is the mosfet frequency high enough to be maintained constant regardless of the input signal frequency?
Larsen: Switing frequency not trelated to audio frequency
Or do you throttle it to save power if you do have a lower frequency input?
but plaing bass requires more energy the playing high frequency content
OK, you keep it independent then
Kenji Larsen Oh interesting about base
Jørgen Kragh Jakobsen We change power modes ( switch freqncy ) base on input level -
Kenji Larsen meaning amplitude?
Jørgen Kragh Jakobsen that is how mutch energy need to be supplied ot load
Jørgen Kragh Jakobsen to load (speaker)
Jørgen Kragh Jakobsen yes amplitude
makes a lot of sense. That must dominate the power, of course. I focus too much on the semiconductor properties... Thanks so much, very informative!
Does the EMI/output filter alter THD and stability of the feedback loop ? Is there a "sense" input directly to the loudspeaker coil ?
I will take a break - Thanks for all you interesset - Thanks Sophy - Lets lake some noize later...
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