CS8416 is the Digital audio input reciever.
http://www.cirrus.com/en/pubs/proDatasheet/CS8416_F3.pdf
http://www.cirrus.com/en/pubs/proDatasheet/CS8416_F3.pdf
Yes, you would either remove this chip or cut the traces and provide a switch so that the DAC can be connected to the SPDIF input via the CS8416 or to the USB input. The DAC input cannot run from both outputs at the same time, and the CS8416 does not have an I2S input.
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Thanks for the reply, to be honest my friend is a guy that knows a lot about electronics and was pretty sure that this is just another toy that I have in the closet (I have almost every type of USB/SPDIF/I2S converter, even some XMOS based ones, he doesn't find much difference) and he was quite surprised that this is unquestionably better in most regards. He tried it on several of the DACs he designed himself to be sure, he is a good engineer and not the "Shun Mook" audiophile that I am so this was a big compliment from him. Mine was upgraded by Raycthech though, with separate supplies, Ray is one hell of an engineer too. I wish I could help with the OSX driver but my friends that actually can are quite busy with the Lion just released... I was tempted by the OSX because I love how stable macs are but with the Exa ASIO driver things look stable enough, I might postpone buying the new mac mini and stay with W7 and Jriver for now. I will post pictures of the whole setup as soon as it is ready, most engineers here will definitely like it
I'm listening to the exaU2I right now, feeding WM8741 in "nos mode" without analog filtering. I've just recently started using J.River with realtime upsampling to 176 kHz and with Fabfilter EQ vst plugin. It sounds absolutely amazing! Really the best I've ever heard. The instuments are so clearly defined both in space and time, the timbre is just right. All the details but without the harshness.
Nice, Have you compared the NOS mode to the apodizing filters? Also are you using external power still for the EXA voltages 5v, 3.3v, 1.8V? Sharing the USB ground with the WM ? What are you using for an output stage?
Just to clarify - to share the USB ground you need to artificially introduce a shortcut between the two isolated ground plates. This is the best way to compromise the performance of the device, bring noise from the imperfections of the house power lines ant the TV cable. It will also allow you to listen to the engine of your computer.
Just to clarify - to share the USB ground you need to artificially introduce a shortcut between the two isolated ground plates. This is the best way to compromise the performance of the device, bring noise from the imperfections of the house power lines ant the TV cable. It will also allow you to listen to the engine of your computer.
Your DAC has Vdigital and Vanalog supplies, it aslo has an analog ground and a digital ground. The isolation if needed should be here between the DAC digital ground (which should be shared with the Exa) and the DAC analog ground. Think about it, you are saying that the computer ground is too dirty for the DAC chip digital side, yet just fine for the delicate clock for asynchrous USB. A ground is a reference, if all digital is sharing the same ground it becomes a mute point.
Hi Regal,
We selected the border line for galvanic isolation at the place where it brings the most benefits. It was done in the context of ES9018 applications but it proved to work great for other DACs. It is sufficient to cut the ground loops in one place and we felt that the DAC digital ground should be on the safe side. We don't have control over the DAC so it makes sense to protect it. We do have control over the FPGA implementation so we took the necessary steps to assure it works fine from USB power.
You can apply fuhrer purification and you can introduce independent power sources for the exaU2I subsystems - FPGA and clocks. RayCtech has demonstrated "indefinite power" supplies. As he puts it - eliminating noise in all forms improves sound and there is no end to it.
There is no ground sharing. DAC digital ground is isolated from the PC. In addition the exaU2I FPGA/Clock power is cleaned to our satisfaction. The ground isolation that we offer is a luxury - who else is doing it in this price / performance range?
exa065
----------------
hearing is believing
The way the galvanic isolation is achieved on the EXA board seems to lead to some confusion and speculation. Here is how I understand it after checking the EXA web site:
EXA is powering all the circuitry of the FPGA, the precision xtal-clock and some supporting circuitry, from the USB supplied power. Thus, this digital circuitry shares the same ground with the PC. However, this is no problem, since the resulting I2S-signals are galvanically isolated as they are transmitted outside the board to the DAC. EXA uses Giant Magnetoresistive (GMR) Digital Isolators for this, which are much faster than LED optocouplers; resulting in faster transitions and less jitter. Even with 384 kb/s, the isolaters work only at a fraction of their capability. The coupling capacitance is only about 17 pF, which prevents any coupling of noise on the computer/USB-ground to the DAC-ground.
There is no analog ground involved within the EXA device. Analog circuitry is only used in the final stages of the DAC. And the fact that the PC-ground may be noise infested is actually immaterial since the 5 Volt from the USB is filtered/regulated on the EXA board. Thus the circuitry and the clock on the EXA board have a clean supply, which may move up and down with the noise amplitude on the USB-ground when comparde to a fixed outside reference.
The only power required from the digital supply of the DAC is for the secondary side of the isolators, which optionally could also be delivered from a seperate supply.
If my understandig is correct, I think this is really a clever and well thought out implementation. Fine engineering that leaves nothing to be criticized.
EXA is powering all the circuitry of the FPGA, the precision xtal-clock and some supporting circuitry, from the USB supplied power. Thus, this digital circuitry shares the same ground with the PC. However, this is no problem, since the resulting I2S-signals are galvanically isolated as they are transmitted outside the board to the DAC. EXA uses Giant Magnetoresistive (GMR) Digital Isolators for this, which are much faster than LED optocouplers; resulting in faster transitions and less jitter. Even with 384 kb/s, the isolaters work only at a fraction of their capability. The coupling capacitance is only about 17 pF, which prevents any coupling of noise on the computer/USB-ground to the DAC-ground.
There is no analog ground involved within the EXA device. Analog circuitry is only used in the final stages of the DAC. And the fact that the PC-ground may be noise infested is actually immaterial since the 5 Volt from the USB is filtered/regulated on the EXA board. Thus the circuitry and the clock on the EXA board have a clean supply, which may move up and down with the noise amplitude on the USB-ground when comparde to a fixed outside reference.
The only power required from the digital supply of the DAC is for the secondary side of the isolators, which optionally could also be delivered from a seperate supply.
If my understandig is correct, I think this is really a clever and well thought out implementation. Fine engineering that leaves nothing to be criticized.
I wouldn't put is this way...
1. There is is reason why those external (battery) supplies improve the
performance of that device.
2. I've never seen something powered by USB power performing better
then a well done local supply.
3. Keep in mind the I2S starts on the "messy" side of the fence.
It's IMO more than a good idea to make sure that the messy side
won't be hit by the PC induced mess that hard.
4. The isolator introduces jitter on its own. This leads to an average
(in audiophile terms) performance on the way towards the DAC chip.
5. Propriatary drivers I consider PITA. You 100% rely on that company.
If they'd close down tommorrow you'd be sitting in the dark.
( After 6 years I still receive software "upgrades" for my RME stuff!!!)
6. Beside that, multi OS platform support usually seems to be a
big problem for those companies. Those companies tend to underestimate
initial efforts for multiple OS and revision support and product life
cycle management associated cost. Every platform update can cause driver
instabilities.
I do think that the exa device is a good start into the right direction.
Though from my perspective they are not there yet.
For many people this device will make a nice improvement though. I'm sure about that.
Though I do think certain critism should be allowed. We're at DIY-Audio and not at Computer Audiophile.
I'm looking forward to Rev 2 of that board ( Can we expect a Rev2?) .
I hope they've taken some of the more critical comments made around here into consideration.
I still consider it a pity that I wouldn't be able to use that device on a Linux based system. It would be a great device
for setting up a headless DIY Linux-PC to feed an active system with the filtering done by brutefir.
Cheers
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I wouldn't put is this way...
We're at DIY-Audio and not at Computer Audiophile.
Cheers
Be more respectful to ComputerAudiophile - it is equally tough to be there. It is mostly the competition doing the criticism, not the ones that have tested exaU2I for themselves. Like here, disbelief is always in theory, not quantified, not backed by measurements or first-hand experience.
hearing is believing
Soundcheck's suggestions have been pretty well documented and measured elsewhere, it doesn't take rocket scientist to show that a SMPS degrades clock phase. Its funny when folks don't have a Wavecrest they ask for measurements and facts for their specifics. That's just a smoke screen cause the supplier knows few have a Wavecrest or $70k scope, believe me the FTT plots shown don't impress. And postulated calculated summed jitter proposed hold little water in the real world.
That doesn't mean the Exa is anything but good quality but it certaintly isn't the end all to jitter.
The defensiveness and complete close-mindedness toward CI is dissapointing, this thread belongs in the commercial section if that is the attitude.
unsubscribed
There was only one configuration of the WM8741 that allowed higher sampling rates, so I haven't tried the different filters.
I'm using the exa in standard configuration. No fancy power supplies. Running shunt regulators for the WM8741 though. No output stage. That's the beauty of the Wolfson dac; very low noise, and capable of driving 1 nF 1 kOhm loads. Compared to the First Watt B1 buffer there isn't really any noticable difference.
And all this grounding talk... I'm not into that split isolated grounds stuff. I'd really prefer everything on one board, with shared ground plane for Agnd and Dgnd and Vgnd. Of course, isolating everything from the computer is beneficial. It seems to me that exa have taken the necessary measures to prevent noise from the computer. It's completely noise free compared to the other USB devices I've tried.
A separate psu for the clock would surely be better... in theory. But I believe we're talking minor differences. There's always a question of price vs. performance. Increasing perfomance at this level of quality is usually not worth the cost, IMHO. Of course, there's always one person who wants to spend the extra hundreds of dollars making a cost-no-object setup. But for a commercial product you have to stop at some point. In my eyes exa has hit the right spot. It's a true high end product at an affordable price.
If the competition is nit picking at your product and you haven't over exaggerated its claims then that means you are on the right track
regards
Trev
I wouldn't be doing a Rev 2 just because you wanted something changed. That is the quickest way to go broke in a start up business
The board is obviously of use to others the way it is. It just means that it is not suitable for your needs but doesn't mean that it is of no use to others regards
Trev
As I wrote. Many people will be happy with the device. Enjoy.
I also wrote that I consider that device well done from what I read. I just wouldn't buy it at this stage.
I do have a problem with people who think and communicate it couldn't
be done better.
The first thing Raytech did, was hooking up better PS
with great results. There is nothing to argue about.
Many people around here are also using battery powered devices
since quite some time. We all know what to expect.
It makes sense to everybody who played around with this stuff for a while.
Perhaps some of you know that Jkeny did very similar PS mods on the well regarded buspowered M2Tech devices and even sells his mods.
(I applied those mods a long time ago to my USB DACs and TP Buffalos)
The jitter issues around the isolator we've been discussing earlier. There's nothing to argue about or to measure. It's in the specs. EXA can't get around that.
Many people are happy with Twisted Pear stuff, even though I always considered it average. (BTW: Can't remember if TP has ever started marketing threads like EXA btw - I doubt it.)
You can easily follow the progress TP made from revision to revision.
Well done engineering. Of course. But it's nothing that can't be improved.
They listen to the crowd and do something about it. They won't start arguing about it. Pretty successful strategy so far.
I'm sure there'll be a Rev 2 of the EXA unit sooner or later. Of course they can't talk about it over here. This is a marketing thread about the Rev1 board.
I'd also expect that one day EXA comes up with a 100% commercial USB DAC based on Sabre. There are many people who started up at DIY-Audio
and turned into full open-market commercial operations.
---
Let's talk about respect dear exa065:
You run a commercial marketing thread on a 100% commercial product
at a commercial free forum. It's you who don't respect the rules and members of this forum.
Get this thread moved over where it belongs.
The admins obviously seem to be on holidays and let you run your show.
You even admit how difficult it is for you to get your feets on the ground
in a rather "commercial" forum such as Computer Audiophile where all the manufacturers chime in into the discussions. ( No - you won't see that over here)
DIY-Audio obviously makes your live easier to run your show.
Well done.
Cheer
I also wrote that I consider that device well done from what I read. I just wouldn't buy it at this stage.
I do have a problem with people who think and communicate it couldn't
be done better.
The first thing Raytech did, was hooking up better PS
with great results. There is nothing to argue about.
Many people around here are also using battery powered devices
since quite some time. We all know what to expect.
It makes sense to everybody who played around with this stuff for a while.
Perhaps some of you know that Jkeny did very similar PS mods on the well regarded buspowered M2Tech devices and even sells his mods.
(I applied those mods a long time ago to my USB DACs and TP Buffalos)
The jitter issues around the isolator we've been discussing earlier. There's nothing to argue about or to measure. It's in the specs. EXA can't get around that.
Many people are happy with Twisted Pear stuff, even though I always considered it average. (BTW: Can't remember if TP has ever started marketing threads like EXA btw - I doubt it.)
You can easily follow the progress TP made from revision to revision.
Well done engineering. Of course. But it's nothing that can't be improved.
They listen to the crowd and do something about it. They won't start arguing about it. Pretty successful strategy so far.
I'm sure there'll be a Rev 2 of the EXA unit sooner or later. Of course they can't talk about it over here. This is a marketing thread about the Rev1 board.
I'd also expect that one day EXA comes up with a 100% commercial USB DAC based on Sabre. There are many people who started up at DIY-Audio
and turned into full open-market commercial operations.
---
Let's talk about respect dear exa065:
You run a commercial marketing thread on a 100% commercial product
at a commercial free forum. It's you who don't respect the rules and members of this forum.
Get this thread moved over where it belongs.
The admins obviously seem to be on holidays and let you run your show.
You even admit how difficult it is for you to get your feets on the ground
in a rather "commercial" forum such as Computer Audiophile where all the manufacturers chime in into the discussions. ( No - you won't see that over here)
DIY-Audio obviously makes your live easier to run your show.
Well done.
Cheer
Soundcheck,
There is more to our disagreement than the commercial / DIY aspect and the Jitter / USB power debates. exaU2I is an alternative device and it challenges the conventional thinking and practices. It is about doing more with less. It is about making a statement - good sound can be achieved with good engineering and without doing extreme things. We demonstrate that it is not just this or that parameter taken to the extreme - it's the integrity of the concept and the engineering effort.
We haven't changed the device not because of lack of respect to the DIY community or because we are in denial. We want the alternative message to propagate. It is not the Teflon board or the fancy capacitors that make the big difference. Sure, you can add them and squeeze every last bit of juice. This is not what makes us excited.
exaU2I is on diyAudio because this is the best place to meet open-minded risk-taking audiophiles. Pick a device that you like. Our experiment is about minimalistic approach and integrity.
I don't see exa065 as trying to aggressively promote their product as the only solution, so what's the problem? The thread started with exa telling us of an upcoming board... accepting criticisms and answering questions promptly. I don't see any overt "buy buy buy"-attitude from their part.
I think exa would agree that anybody is welcome to do their own tests on the exaU2I board and post the results. And I'm sure that all of our concerns are being noted and being considered for the next revision - which shouldn't come immediately, but should definitely come at some time. The exaU2I is already a spectacular piece of equipment that I am excited to try.
Any mods to the hardware are certainly fine to be shared in this thread, I think... exa has even gone so far as to post the battery mod on their website. They are leaving this board open to experimentation and mods.
But then again, some people will never be satisfied, which is understandable, since you can't make something that 100% of people will enjoy.
Maybe someone can help me understand... what difference does it make whether the thread is under DACs or Commercial? TPA's BIII DAC is under Commercial, so I suppose this one should be too..?