Author Topic: OSHW audio design for critique  (Read 11801 times)

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Offline blueskull

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OSHW audio design for critique
« on: October 01, 2015, 05:55:09 am »
!!!WARNING LARGE DESIGN!!! Project Plethora high performance audio DAC

Hi all,

There is my audio DAC design for review. This is only the digital receiver, interpolation, delta sigma modulation, power and output connector board.
The actual thermometer DAC and low noise LDO daughter board hasn't been finished yet.

This is only 1/4 of the entire design. The rest 3/4 are:
a. DAC daughter board,
b. DSP firmware,
c. FPGA firmware,
d. The most important part, the DAC ASIC. I now have a chance to do an affordable MPW run on CSMC 0.5um mixed signal process.

Detailed documentation can be found in the attached zip file (7z format with zip extension name).
+1.1, 1.2, 3.3V power plane and ground plane are left blank for better visibility.




Thanks,
Bo

Added final gerber and pcb files. Check out here.
« Last Edit: October 02, 2015, 09:15:12 am by blueskull »
 

Offline Dago

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Re: OSHW audio design for critique
« Reply #1 on: October 01, 2015, 10:30:29 am »
Tried to have a look but schematic seems to be unreadable.
« Last Edit: October 01, 2015, 10:32:08 am by Dago »
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Offline blueskull

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Re: OSHW audio design for critique
« Reply #2 on: October 01, 2015, 10:58:32 am »
Tried to have a look but schematic seems to be unreadable.

Thanks, and I know about it. My design preference is to use net labels instead of wires to connect signal bunches.

Please read the attached introduction slides as well as the net label description in the schematic file. After knowing what is doing what everything will clear up.
 

Online Andy Watson

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Re: OSHW audio design for critique
« Reply #3 on: October 01, 2015, 11:17:58 am »
My design preference is to use net labels instead of wires to connect signal bunches.
Hmmm! Let's see if I have this right. You are providing a file in a format (7z) that would require me to jump through several hoops in order to undo it on a Linux platform. Then, if I jump through those hoops, the schematic is essentially unreadable to anybody who doesn't already have the insider-knowledge of its creator.
 

Online Monkeh

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Re: OSHW audio design for critique
« Reply #4 on: October 01, 2015, 11:33:05 am »
My design preference is to use net labels instead of wires to connect signal bunches.
Hmmm! Let's see if I have this right. You are providing a file in a format (7z) that would require me to jump through several hoops in order to undo it on a Linux platform. Then, if I jump through those hoops, the schematic is essentially unreadable to anybody who doesn't already have the insider-knowledge of its creator.

Er, it's just a 7z, there's not a lot of hoop jumping there.

As far as reading it goes, however.. gah.
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #5 on: October 01, 2015, 11:36:17 am »
My design preference is to use net labels instead of wires to connect signal bunches.
Hmmm! Let's see if I have this right. You are providing a file in a format (7z) that would require me to jump through several hoops in order to undo it on a Linux platform. Then, if I jump through those hoops, the schematic is essentially unreadable to anybody who doesn't already have the insider-knowledge of its creator.

The only benefit you will get from this format and a "peoper ee101" style is you can see there are 2 spi buses, a 8bit data bus and 3 differential serial io pairs. You won't be able to tell what signal is in them anyway without reading the supplemental materials. For the file format, install a lzma backend and you will be able to open it from nautilus or whatever its counterpart in kde.
 

Online Monkeh

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Re: OSHW audio design for critique
« Reply #6 on: October 01, 2015, 11:37:31 am »
The only benefit you will get from this format and a "peoper ee101" style is you can see there are 2 spi buses, a 8bit data bus and 3 differential serial io pairs.

.. And that's the whole purpose of a schematic, to convey this information.

Which yours fails to do.

You may as well post in Chinese, because it's much the same thing.
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #7 on: October 01, 2015, 11:37:53 am »
Really, if reading a "compiled" schematic is that hard, I can prepare a hand drawn section by section version of it, but don't expect too much info without reading the intro slides.
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #8 on: October 01, 2015, 11:38:49 am »
The only benefit you will get from this format and a "peoper ee101" style is you can see there are 2 spi buses, a 8bit data bus and 3 differential serial io pairs.

.. And that's the whole purpose of a schematic, to convey this information.

Which yours fails to do.

Working on a hand drawn version. Pls wait.
 

Online Andy Watson

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Re: OSHW audio design for critique
« Reply #9 on: October 01, 2015, 11:48:28 am »
Er, it's just a 7z, there's not a lot of hoop jumping there.
It is not a format that I can readily open. The limited research that I have put into opening these files is suggesting that I will have to cobbled-together some software to undo a format that is centred on M$ technology. May it's not much of a hoop if you already have that unzipper, but it is further than I am prepared to jump.
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #10 on: October 01, 2015, 11:56:31 am »
A zip version should work. See the attachment. Since you can not open Altium files, I attached only pdf and picture files.
 

Online Monkeh

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Re: OSHW audio design for critique
« Reply #11 on: October 01, 2015, 11:57:24 am »
Er, it's just a 7z, there's not a lot of hoop jumping there.
It is not a format that I can readily open. The limited research that I have put into opening these files is suggesting that I will have to cobbled-together some software to undo a format that is centred on M$ technology. May it's not much of a hoop if you already have that unzipper, but it is further than I am prepared to jump.

${PACKAGE_MANGLER_OF_CHOICE} p7zip
7z x ${FILE}

done.

I am immensely puzzled where you get the idea it's in any way tied to Microsoft.
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #12 on: October 01, 2015, 12:02:38 pm »
Er, it's just a 7z, there's not a lot of hoop jumping there.
It is not a format that I can readily open. The limited research that I have put into opening these files is suggesting that I will have to cobbled-together some software to undo a format that is centred on M$ technology. May it's not much of a hoop if you already have that unzipper, but it is further than I am prepared to jump.

${PACKAGE_MANGLER_OF_CHOICE} p7zip
7z x ${FILE}

done.

I am immensely puzzled where you get the idea it's in any way tied to Microsoft.

Let's get back on track. There are some guys have Linux religion, and some have Windows religion. They both work and I use both. MS used to be the 4th kernel contributor b/c of their hyper-V support. Many *nix standards and concepts got ported to Windows, such as posix, c/c++ and many more. So pls stop the holy war of OSes.
 

Online Monkeh

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Re: OSHW audio design for critique
« Reply #13 on: October 01, 2015, 12:03:40 pm »
Where you see a holy war, I am merely trying to help someone. Why, exactly, I'm not sure, as I've seen what lies within the archive.
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #14 on: October 01, 2015, 12:05:02 pm »
Where you see a holy war, I am merely trying to help someone. Why, exactly, I'm not sure, as I've seen what lies within the archive.

Not saying anyone here. Just a prevention. Sometimes things get really off track when anything religious came into the picture.
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #15 on: October 01, 2015, 01:09:40 pm »
Here are the hand drawn concept diagrams.
 

Offline singapol

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Re: OSHW audio design for critique
« Reply #16 on: October 02, 2015, 05:18:47 am »
The only difference you are trying to do is that I see in usb otg.gif is a box listed as "fuel gauge".
Is this for car audio? I am sure there are similar chinese products that have this concept
maybe cheaper and less complicated to save costs.

It is amusing that you come here to ask for opinions about something like audio as you have pointed out
like cpu OSs.Talking about them is like religion and you want to avoid that.:) Still it's not strange
if you are an engineer asking in an engineering/hobbyist forum.

The question most relavant to your success is who are your target users/customers.How much are they
willing to pay for your ground breaking product this being a "high performance audio".
I like to point out a common assumption that engineers assume in audio that if it 's got sound it then passes the test and therefore ready to go to market after verifying the specifications.

The thing engineers must come to a realisation that, does designing for test instruments that replace the
human ear showing low distortion, low this and that etc. equate to what a human would find listenable
or musical? Oh I'll bet you will say this is audiophools territory. What matters is the test results measured. Can test equipment replace the human ear and for that the ear is connected to the human via brain and other  senses. Can test equipment really take all these into account?

In the end you must ask yourself who you are designing for, test equipment or human beings.Engineers must sort  this out if they are to make any significant progress towards audio as many derogatorily say it's only  20 - 20Khz. What's so difficult about it?

As an aside, there are many ways or methods to tune a musical instrument for tonality but ultimately this instrument must harmonise with the other musical instruments to create an enjoyable musical experience.

I wish you success all the same.:)

« Last Edit: October 02, 2015, 05:20:21 am by singapol »
 

Offline NiHaoMike

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Re: OSHW audio design for critique
« Reply #17 on: October 02, 2015, 05:27:06 am »
What latency does it get? I can't image a good (quality wise) upscaler having particularly good latency, but maybe it's still low enough even for gaming use.
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Offline blueskull

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Re: OSHW audio design for critique
« Reply #18 on: October 02, 2015, 05:27:36 am »
The "fuel gauge" I mentioned is a Li-ion fuel gauge. Because this design requires quite some power, and I want to make it portable (smart phone accessory), I need to get power to it without draining cell phone batteries too fast. Therefore I decided to make an battery enclosure for it to power it. I need to let the device know how much power is left in the battery, so I took leverage of the unused ID pin as a low bandwidth single direction uart pin.

For the performance part, I sincerely know that human ear is the golden standard, not test equipment. The reason I care about test result is because I can introduce distortion and flavors in DSP, but I can not do too much to reduce them. Therefore, the system hardware should be as ideal as possible, so I have more space to tweaking the DSP algorithm to make it sounds better as per human ear perceives.
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #19 on: October 02, 2015, 05:35:59 am »
What latency does it get? I can't image a good (quality wise) upscaler having particularly good latency, but maybe it's still low enough even for gaming use.

The 44.1k to 48k FIR filter uses about 256 taps, so it is 5.3ms. The 48k to 1536k FFT filter uses 1024 as block size, so the latency is 6.7ms. The 1536k to 6144k cubit interpolator introduces negligible latency. The IIR delta sigma modulator also introduces almost negligible latency. All digital buffer introduce totally less than 10ms latency. The analog filters, thanks to the high over sample rate, don't have too group delay, somehow 2ms.

So the bottom line is 24ms. Unless you are using DirectX/ASIO/Pulseaudio, the KMixer/ALSA side latency would be at least one magnitude longer.
 

Offline NiHaoMike

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Re: OSHW audio design for critique
« Reply #20 on: October 02, 2015, 05:43:51 am »
24ms sounds like a lot for gaming. Might be a good idea to add a "game mode" that switches in an upscaler with less latency at the cost of a little less quality. In comparison, most ordinary DACs have latency less than a millisecond. I'm also sure the software layers on the PC side introduce far less than the 240ms you seem to imply. 240ms would be enough to make audio useless in many games.

Also, gamers at least used to frown on USB audio. Not sure if it's still relevant.
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Offline blueskull

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Re: OSHW audio design for critique
« Reply #21 on: October 02, 2015, 05:47:03 am »
24ms sounds like a lot for gaming. Might be a good idea to add a "game mode" that switches in an upscaler with less latency at the cost of a little less quality. In comparison, most ordinary DACs have latency less than a millisecond. I'm also sure the software layers on the PC side introduce far less than the 240ms you seem to imply. 240ms would be enough to make audio useless in many games.

Also, gamers at least used to frown on USB audio. Not sure if it's still relevant.

Advice accepted. I will use USB HID protocol to implement reconfigurable filter stages.
 

Offline singapol

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Re: OSHW audio design for critique
« Reply #22 on: October 02, 2015, 05:48:31 am »
The "fuel gauge" I mentioned is a Li-ion fuel gauge. Because this design requires quite some power, and I want to make it portable (smart phone accessory), I need to get power to it without draining cell phone batteries too fast. Therefore I decided to make an battery enclosure for it to power it. I need to let the device know how much power is left in the battery, so I took leverage of the unused ID pin as a low bandwidth single direction uart pin.

For the performance part, I sincerely know that human ear is the golden standard, not test equipment. The reason I care about test result is because I can introduce distortion and flavors in DSP, but I can not do too much to reduce them. Therefore, the system hardware should be as ideal as possible, so I have more space to tweaking the DSP algorithm to make it sounds better as per human ear perceives.

Ah..."fuel gauge" is battery monitor.  :) So it's a portable audio device which I said there are already similar
chinese products already on the market.They are trying to copy the success of CHORD Electronics "HUGO
" which I have listen to before it beat a diy quad dac (4X) machine. ;D Impressive but not cheap. It uses fpga and dsp techniques which CHORD is well known for. You can read the design philoshopy of HUGO design at CHORD's website. I think you can get some idea of what the designer is aiming for.

You have right mindset about human ear as the gold standard. Yes your dsp idea is in the right direction
of which the designer of HUGO also think in similar fashion. :-+

For a fact HUGO use only 1 power supply for all circuits you have many. Is it good or your pproduct may be
bigger than HUGO but if you can beat HUGO I got nothing to say. :) You have to have low noise power supply and dsp algorithms ( the secret). ( You are like man in front of tank at Tian An Men Square. ) ;D

GOOD LUCK. :-+
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #23 on: October 02, 2015, 06:01:28 am »
The "fuel gauge" I mentioned is a Li-ion fuel gauge. Because this design requires quite some power, and I want to make it portable (smart phone accessory), I need to get power to it without draining cell phone batteries too fast. Therefore I decided to make an battery enclosure for it to power it. I need to let the device know how much power is left in the battery, so I took leverage of the unused ID pin as a low bandwidth single direction uart pin.

For the performance part, I sincerely know that human ear is the golden standard, not test equipment. The reason I care about test result is because I can introduce distortion and flavors in DSP, but I can not do too much to reduce them. Therefore, the system hardware should be as ideal as possible, so I have more space to tweaking the DSP algorithm to make it sounds better as per human ear perceives.

Ah..."fuel gauge" is battery monitor.  :) So it's a portable audio device which I said there are already similar
chinese products already on the market.They are trying to copy the success of CHORD Electronics "HUGO
" which I have listen to before it beat a diy quad dac (4X) machine. ;D Impressive but not cheap. It uses fpga and dsp techniques which CHORD is well known for. You can read the design philoshopy of HUGO design at CHORD's website. I think you can get some idea of what the designer is aiming for.

You have right mindset about human ear as the gold standard. Yes your dsp idea is in the right direction
of which the designer of HUGO also think in similar fashion. :-+

For a fact HUGO use only 1 power supply for all circuits you have many. Is it good or your pproduct may be
bigger than HUGO but if you can beat HUGO I got nothing to say. :) You have to have low noise power supply and dsp algorithms ( the secret). ( You are like man in front of tank at Tian An Men Square. ) ;D

GOOD LUCK. :-+

In the OSHW world there are no secrets. Maybe I will get profit by providing "device cloning" service, so that I can create customized "profiles" for any samples the customer provides. Or I can make money by sublicensing companies to do non-open source derived works.

DSP code will be USB stack, cubic, polyphase FIR and FFT filters that the industry used for tens of years. There will be some black magic in reducing calculating complexity, but anyway I will publish it somewhere such as IEEE some time, so there are really no magic.

For the real interesting part, how to eliminate non-linear distortion, I referred something from ES9018's patent, but took a huge detour, so it won't violate any patents. These parts (SDM, DEM and calibration) are done in FPGA. All FPGA diagrams, HDL code and test benches will be open source.

There are nothing too excited in the ASIC, and if you want, you can build it with a FPGA and a shitload of logic gates and resistors with a couple of transistors. The only reason I decided not to open source the ASIC design is because the process provider doesn't allow me to do this.

The final product is WAY smaller than HUGO. The finished assembly is estimated to be smaller than 25mm*60mm*8mm.
« Last Edit: October 02, 2015, 06:03:34 am by blueskull »
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #24 on: October 02, 2015, 09:17:18 am »
I attached the final PCB in the first post. The board renders are pretty.

The bottom side's footprint is the JTAG contacts. No parts need to be soldered there.
 

Offline singapol

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Re: OSHW audio design for critique
« Reply #25 on: October 02, 2015, 09:48:19 am »

In the OSHW world there are no secrets. Maybe I will get profit by providing "device cloning" service, so that I can create customized "profiles" for any samples the customer provides. Or I can make money by sublicensing companies to do non-open source derived works.

DSP code will be USB stack, cubic, polyphase FIR and FFT filters that the industry used for tens of years. There will be some black magic in reducing calculating complexity, but anyway I will publish it somewhere such as IEEE some time, so there are really no magic.

For the real interesting part, how to eliminate non-linear distortion, I referred something from ES9018's patent, but took a huge detour, so it won't violate any patents. These parts (SDM, DEM and calibration) are done in FPGA. All FPGA diagrams, HDL code and test benches will be open source.

There are nothing too excited in the ASIC, and if you want, you can build it with a FPGA and a shitload of logic gates and resistors with a couple of transistors. The only reason I decided not to open source the ASIC design is because the process provider doesn't allow me to do this.

The final product is WAY smaller than HUGO. The finished assembly is estimated to be smaller than 25mm*60mm*8mm.

Dear friend I think you are too idealistic about OSHW. With your talent you can do many things. I heard there are specialised companies in China that can reverse engineer any product and provide a prototype pcb in 24hrs. :o A bit far fetched?

Judging from the size of your pcb I don't think it will be a threat to HUGO but who knows. But I think your
project is the first to take on HUGO head on because you are using fpga and dsp method. The other "clones" are just using off the shelf dac and usb stuff. None of the high resolution playback thing.
That said I think you should market it yourself if it works. You deserve every yuan you make. :D

I have met the founder of CHORD Electronics briefly when he travels to asia to visit his asian distributors
regularly. He is an Englishman and engineer himself. I think he started small like everyone else and eventually grew. You also need to keep an eye on current trends in the audio field to survive. If you want to be successful work for yourself not others be your own boss. :-+
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #26 on: October 02, 2015, 09:56:44 am »
Thank you for your encouragement. Doing engineering and challenging limits is my hobby, and surely making money from them is cool. But I don't do this design as a living. My living skill is power system and power electronics engineering, and my degree is a MS-electric power system engineering, which is also a msee degree.

Talking abt pcb reverse engineering, anyway they will reverse it. Instead of letting the others making crude clones that ruin my reputation, why not open it up and sell proprietary asics and services?
 

Offline singapol

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Re: OSHW audio design for critique
« Reply #27 on: October 02, 2015, 04:26:46 pm »
Can I say all the circuits you described, power, fpga,dsp, usb and dac are on this one single pcb? What about the connectors, power, usb,signal output like RCAs, etc? What is more surprising to me is what caps
are you using for signal analog coupling? All I see are smt footprints and no throughhole components.
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #28 on: October 02, 2015, 04:32:58 pm »
Can I say all the circuits you described, power, fpga,dsp, usb and dac are on this one single pcb? What about the connectors, power, usb,signal output like RCAs, etc? What is more surprising to me is what caps
are you using for signal analog coupling? All I see are smt footprints and no throughhole components.

Analog part will be on a daughter card. For the caps, mlcc will be used. Don't be surprised, with careful design mlcc can be used. Of course, only np0 will be used in signal path, and they will only work as very frequency lpf. Otherwise it makes no sense to take so much effort to do 128-256x oversampling. Connectors will be only micro usb and two 3.5mm jacks.
 

Offline singapol

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Re: OSHW audio design for critique
« Reply #29 on: October 02, 2015, 04:45:15 pm »
Can I say all the circuits you described, power, fpga,dsp, usb and dac are on this one single pcb? What about the connectors, power, usb,signal output like RCAs, etc? What is more surprising to me is what caps
are you using for signal analog coupling? All I see are smt footprints and no throughhole components.

Analog part will be on a daughter card. For the caps, mlcc will be used. Don't be surprised, with careful design mlcc can be used. Of course, only np0 will be used in signal path, and they will only work as very frequency lpf. Otherwise it makes no sense to take so much effort to do 128-256x oversampling. Connectors will be only micro usb and two 3.5mm jacks.

Is the dac a off the shelf chip or implemented in fpga? Experience has shown mlcc caps for signal will
not sound good at least to the ears trust me, despite what instrumentation suggest. :-\
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #30 on: October 02, 2015, 04:57:27 pm »
The dac will be an asic. I got a deal from csmc and they can offer me 0.5um 2p3m mixed signal process for $2500.

For the caps, the dac board has enough space to let me implement film caps based filter, so if needed I can squeeze some space from other modules.
 

Offline singapol

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Re: OSHW audio design for critique
« Reply #31 on: October 02, 2015, 05:11:32 pm »
The dac will be an asic. I got a deal from csmc and they can offer me 0.5um 2p3m mixed signal process for $2500.

For the caps, the dac board has enough space to let me implement film caps based filter, so if needed I can squeeze some space from other modules.

Please use film caps polypropylene (mkp type like WIMA red ) at the very least if you want serious audiophiles to be interested.  ;D
 

Offline NiHaoMike

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Re: OSHW audio design for critique
« Reply #32 on: October 03, 2015, 04:48:41 am »
Be sure to validate it on a USB 3.0 port, even if the unit itself only supports USB 2.0. There's a strange compatibility issue with some USB 3.0 ports. I know the common NEC/Renesas controllers got some firmware updates to fix some issues, not sure if they might be related.
http://createdigitalmusic.com/2012/06/usb-3-0-backwards-compatible-in-theory-but-some-audio-drivers-arent-cooperating/
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Offline blueskull

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Re: OSHW audio design for critique
« Reply #33 on: October 03, 2015, 04:57:33 am »
Will do. Will starr fw oding soon.
 

Offline singapol

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Re: OSHW audio design for critique
« Reply #34 on: October 03, 2015, 06:47:41 am »
Is your asic dac same as Hugo's 32 bit? Want to be sure we compare apples with apples, looking forward
to your giant killer.  :clap:
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #35 on: October 03, 2015, 06:49:01 am »
Is your asic dac same as Hugo's 32 bit? Want to be sure we compare apples with apples, looking forward
to your giant killer.  :clap:

4 bit thermometer dac. Sigma delta modulation is done on fpga.
 

Offline singapol

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Re: OSHW audio design for critique
« Reply #36 on: October 03, 2015, 07:19:03 am »
Is your asic dac same as Hugo's 32 bit? Want to be sure we compare apples with apples, looking forward
to your giant killer.  :clap:

4 bit thermometer dac. Sigma delta modulation is done on fpga.

OK current output sigma delta dac...so I/V convertor is external via opamp which gives flexibility of opamp choice for modders.  :-+
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #37 on: October 03, 2015, 07:21:02 am »
Is your asic dac same as Hugo's 32 bit? Want to be sure we compare apples with apples, looking forward
to your giant killer.  :clap:

4 bit thermometer dac. Sigma delta modulation is done on fpga.

OK current output sigma delta dac...so I/V convertor is external via opamp which gives flexibility of opamp choice for modders.  :-+

External iv, but with current mirror, so slower speed of opamp won't create trouble. Also, there are measures to tackle down inter symbol interference.
 

Offline singapol

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Re: OSHW audio design for critique
« Reply #38 on: October 03, 2015, 07:28:33 am »



External iv, but with current mirror, so slower speed of opamp won't create trouble. Also, there are measures to tackle down inter symbol interference.

Fantastic! You are the man. :D
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #39 on: October 03, 2015, 02:52:31 pm »
New bug found. I found this bug minutes before submitting the design to OSHPark. The LVDS input from isolation transformer to FPGA was not properly biased. iCE40HX FPGA doesn't have internal LVDS biasing on pins. Using my logic analyzer and pattern generator can I observe severe glitch on my HX8K dev board if a LVDS input pair was not properly biased.
 

Offline blueskull

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Re: OSHW audio design for critique
« Reply #40 on: October 06, 2015, 03:32:57 pm »
Updated design, what's new:
1. Removed +2.5V power rail. I tested on my breakout board and I can see LVDS receiver works just fine on +3.3V. So I removed +2.5V, and this gives me nice sexy +3.3V power plane for better distributed decoupling.
2. Power traces re arranged to get uncut power rails for all power supplies under DSP and FPGA.
3. LVDS traces on primary side rerouted, parts rearranged to get a perfect match.
4. LVDS receiver biased with +1.2V, as well as a capacitor of course.
5. Fine adjusted ground planes for different domains.

There is an existing bug, which is over matched differential pair length in secondary side. This will be corrected in the next revision of the design.
This version's gerber files are sent to OSH Park and OSH Stencil for prototyping.

Attached is the latest design database.
 


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