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exaU2I - Multi-Channel Asynchronous USB to I2S Interface
exaU2I - Multi-Channel Asynchronous USB to I2S Interface
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Old 21st April 2011, 10:13 AM   #401
MrMajestic is offline MrMajestic  Sweden
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Does anybody know the size of the exa board? Would be nice to have when planning for a case layout.
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Old 21st April 2011, 10:39 AM   #402
rsdio is offline rsdio  United States
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Quote:
Originally Posted by qusp View Post
it is clear that you simply believe in perfect models and specifications without loopholes that everyone complies to.
Have you ever actually designed a USB Device? I have designed a number of them for clients that are being manufactured, both custom circuit layouts and custom firmware. I am well aware of the difference between specifications and actual examples in the field - the USB org does a great job of keeping us informed about what to look out for, and they've even been known to revise their specifications to allow for reality. That said, none of your comments make much sense, even considering both the official specs and actual products.
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Old 21st April 2011, 02:01 PM   #403
exa065 is offline exa065  Canada
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Originally Posted by MrMajestic View Post
Does anybody know the size of the exa board? Would be nice to have when planning for a case layout.
Sorry, I will publish a drawing on the website. The board is 89mm by 61mm. The USB daughter board / connector stick out 5mm.
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Old 21st April 2011, 02:13 PM   #404
qusp is offline qusp  Australia
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Originally Posted by rsdio View Post
Have you ever actually designed a USB Device? I have designed a number of them for clients that are being manufactured, both custom circuit layouts and custom firmware. I am well aware of the difference between specifications and actual examples in the field - the USB org does a great job of keeping us informed about what to look out for, and they've even been known to revise their specifications to allow for reality. That said, none of your comments make much sense, even considering both the official specs and actual products.
whatever you say, why are you still going?
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Old 21st April 2011, 06:50 PM   #405
MrMajestic is offline MrMajestic  Sweden
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Originally Posted by exa065 View Post
Sorry, I will publish a drawing on the website. The board is 89mm by 61mm. The USB daughter board / connector stick out 5mm.
Great, thanks.
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Old 22nd April 2011, 01:23 PM   #406
DUC985 is offline DUC985  Germany
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got my device last week and found some time today to get it connected. Setup before was a CPlay tweaked PC with linear power suppy etc. For Audio a ESI Julia with dedicated supply connected to a Buffalo II DAC using I2S was used for quite some time.
Installing the drivers and hooking up the new device was no problem, everything worked initially like it should. There is some crackeling sound when you start the PC or shut it down. Nothing major and it does no harm to the speakers. Might be a driver initialisation issue.
The sound comming out of the Buffalo using the device compared to the Julia is simply amazing. It is not even worth comparing it. It is so much better at all frequencies. 3D image also improved by far.
I found the price initially a little bit high, but when you hear what you get it is worth every penny. I can also confirm that it works like a charm using CMP and CPlay. I have not yet tested Foobar in comparison.
This thing simply rocks !
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Old 23rd April 2011, 02:15 PM   #407
RayCtech is offline RayCtech
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Originally Posted by DUC985 View Post
got my device last week and found some time today to get it connected. Setup before was a CPlay tweaked PC with linear power suppy etc. For Audio a ESI Julia with dedicated supply connected to a Buffalo II DAC using I2S was used for quite some time.
Installing the drivers and hooking up the new device was no problem, everything worked initially like it should. There is some crackeling sound when you start the PC or shut it down. Nothing major and it does no harm to the speakers. Might be a driver initialisation issue.
The sound comming out of the Buffalo using the device compared to the Julia is simply amazing. It is not even worth comparing it. It is so much better at all frequencies. 3D image also improved by far.
I found the price initially a little bit high, but when you hear what you get it is worth every penny. I can also confirm that it works like a charm using CMP and CPlay. I have not yet tested Foobar in comparison.
This thing simply rocks !
Good news!
I was investigating the ESI Julia some time back, but dropped it as I was not satisfied with the information I found..

I hope you compares the CPlay and Foobar as your linear PC power supplies should make a difference...
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Old 23rd April 2011, 02:57 PM   #408
pepetono is offline pepetono  United States
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This is an interesting piece of hardware, and something I have been looking for for some time.

However, I am having some difficulty seeing how to implement what I want to do with it.
I want to have a computer based media source. Sometimes the media will be only stereo music (not interested in multi-channel music), some other times it will be the multi-channel sound track of a movie.

In any case, I need to treat the signal for those sources of material to do some room correction, and derive signals going to my main speakers, a couple of subwoofers placed in my room, and, for movie sound material, the back surround channels.

I can manage to do the DSP handling in the computer, and was hoping to output 6 channels containing the main signals + 2xSW + 2xSR ( = 6 ch)

After reading some of the material in this thread, I though I could get away with a couple of ESS 9018 boards, one in stereo mode, the other in multichannel mode.

At first, I thought the Bufalo II would fit the bill for this, but it is not wired for more than stereo, and, quite frankly, I do not think I want to go for three BII boards.

Thus, I thought a compromise was in order. BII for the mains, and something like the Opus (2 of them) for the rest of my needs.

However, that would mean that the different DAC sections (of all boards) would need to share power supply, wouldn't they?

Wouldn't this pose a problem?

Pardon if the question sounds trivial.

Jose
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Old 23rd April 2011, 03:51 PM   #409
RayCtech is offline RayCtech
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Default USB with galvanic isolation

I have for some time used a local 5 volt supply for the USB parts on the exaU2I with good experience.
The 5 volt line from the PC was simply cut to implement this.

I was wondering how I could implement galvanic isolation of the USB connection as it requires a minimum of 480 Mbit/s speed, and if this would be an improvement of the fidelity at all.

As there are needed only one galvanic isolation in the chain the best place would be between the PC and the exaU2I as long as the exaU2I are supplied with the 5 volt locally.

Today I studied the USB specifications and cut a USB cable in two and implemented galvanic isolation.....

As the 5 volt already was solved I started with ground as this is the easy part.
This worked at the very first attempt.

Then it was the D+ and D- signals..
At the first attempt the downstream functioned and the exaU2I received data and filled the FIFO at all rates,
but the upstream signals was not working properly and the ASIO driver failed.

I tweaked some of the component values and now the galvanic isolation of the USB works reliable, but some more work are needed to perfect the solution.
I have asked exa065 for his help as the component values on the exaU2I and the programming of the ASIO driver together with the component values of the galvanic isolation can for sure be optimized as my implementation are not fine tuned.

The galvanic isolation of the USB does not appear to affect jitter much or at all in my setup, and if it does I was at least not able to quantify it.

But it affects the audio quality in my setup.
The differences are easy to verify in all resolutions from 44.1k/16bit flac and up to 384k/32bit upsampled DXD...
For me there will never again be played music without galvanic isolation of the USB

The next step will be to remove the galvanic isolation after the FPGA as it in theory should improve the jitter and timing in general of the I2S signals.

I expect this will cause some reactions and I will be accused of ing again,
but for those it is simply to implement galvanic isolation of the USB and test...

Last edited by RayCtech; 23rd April 2011 at 04:02 PM.
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Old 23rd April 2011, 11:45 PM   #410
rsdio is offline rsdio  United States
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Originally Posted by pepetono View Post
However, that would mean that the different DAC sections (of all boards) would need to share power supply, wouldn't they?
I believe that the answer is 'no.' At a minimum, you only need to share data across different DAC sections, not power.

What I am unclear about is how you would drive multiple DAC boards from the same exaU2I. The exaU2I allows an external power for the isolation component, so if you run multiple DAC boards then they will need to share digital power unless you add more isolation chips.

Keep in mind that it should be possible to separate analog and digital power supplies for a good DAC board, and thus you could have individual analog power supplies for each DAC board, but only share digital power for the I2S data. As mentioned above, you can even split the digital power supplies if you add isolation, but that might be a bit too much effort.
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