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exaU2I - Multi-Channel Asynchronous USB to I2S Interface

GMR's are easy to bypass, however I wouldn't recommend it. There is a certain integrity in the design and taking away any piece will deteriorate the overall quality and stability of the exaU2I device. In some of our test environments the impact of noise due to ground loops, especially when a TV is involved in the setup was huge compared to the undetectable increase of jitter. The overall sonic performance will be limited by the weakest, worst performing link in the data processing chain. It is unlikely that the GMR's are on the priority list.

From our perspective, not having to worry about ground loops and common noise is one of the main advantages of exaU2I that can increase the likelihood of success for a DIY project.
 
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Sorry, EXA, I'm not being critical or putting down your product - I think it's great to see all these offerings for USB audio. In the context that you state TV use, I have no experience & you are probably correct - I was just trying to relate my experiences in audio.

I can't prove it (I don't have the equipment) but I'm pretty sure that jitter (I know it's meaningless to state a single figure without a spectrum analysis but I'm going to do so anyway) way below 100pS is audible a good audio set-up.

I'll not butt in on your thread any more.
 
I am very pleased to announce that exaU2I is now officially the first asynchronous USB to I2S interface capable of streaming multichannel 32bit / 384 kHz data.
Congratulation! I think your achievement is truly plausible. As far as I know, the only other USB audio interface which covers 32bit / 384 kHz is USB 2 input option of MSB Diamond DAC IV.
USB 2 Input Option
However, I think it is neither asynchronous nor I2S output. Moreover, it's just a proprietary option for their DAC.

I convince the value of high sampling audio of fs >= 352.8 kHz. I hope your exaU2I products will boost the number of DIY users those who can enjoy those audio and that will encourage the rapid increase of attractive sources available in this market. This will also make SDTrans users happy.
 
Thanks! I am very grateful for the good words. After all this thread has been a great forum for free speech and critical evaluation. We have established what is achieved so far and what can make the exaU2I a better product.

I am considering creating an alternative device for use with non-reclocking DACs. Deploying a jitter canceling stage after the GMRs and allowing the use of external master clock will benefit the most demanding users. When I am redy to start this discussion I will create a new thread. Hopefully by that time I will be able to establish a Forum in the Manufactures' area.

I am really eager to see feedback from people that are using exaU2I in simple environments. Connecting a Buffalo DAC or an AckoDAC should be simple and straight-forward. Enabling a multi-channel setup will be a very exciting experience.
 
And without a clock line. SP/DIF clock is derived from the data and it is causes huge jitter compared to the jitter caused by the GMRs. You also have bandwidth limitations. Optical SP/DIF is even more constrained and more jittery than co-axial SP/DIF.

The question really is , what's done with SPDIF signal before converted to I2S.

You can't compare I2S and SPDIF that easily.
 
The question really is , what's done with SPDIF signal before converted to I2S.

You can't compare I2S and SPDIF that easily.

You shouldn't convert SPDIF to I2S. Why degrade the signal and then try to recover the lost information? SPDIF is an antiquated consumer interface. I2S is an opportunity to bypass the bandwidth bottle neck and the clocking limitation. Jitter from SPDIF is one of the major contributors to the "digital sound" of CD players.

It is quite easy to compare the two interfaces. The difference is like night and day.
 
You shouldn't convert SPDIF to I2S. Why degrade the signal and then try to recover the lost information? SPDIF is an antiquated consumer interface. I2S is an opportunity to bypass the bandwidth bottle neck and the clocking limitation. Jitter from SPDIF is one of the major contributors to the "digital sound" of CD players.

It is quite easy to compare the two interfaces. The difference is like night and day.

To my understanding you feed DACs I2S and not SPDIF. You gotta convert SPDIF at one point.

You can IMO achieve highest qualities with SPDIF if properly implemented.
 
To my understanding you feed DACs I2S and not SPDIF. You gotta convert SPDIF at one point.

You can IMO achieve highest qualities with SPDIF if properly implemented.

Would you explain the need to involve SPDIF in the signal path? To use exaU2I USB to I2S interface you need a computer, USB cable, the exaU2I kit, short twisted pair wires and a DAC kit with an I2S input. The popular ES9018 DAC kits like the Buffalo DAC and the AckoDAC come with I2S inputs. There is plenty of information on their respective forums about using I2S. On our website we also provide the necessary information and schematics: www.exadevices.com > exaU2I > D.I.Y. Guide.
 
Would you explain the need to involve SPDIF in the signal path? To use exaU2I USB to I2S interface you need a computer, USB cable, the exaU2I kit, short twisted pair wires and a DAC kit with an I2S input. The popular ES9018 DAC kits like the Buffalo DAC and the AckoDAC come with I2S inputs. There is plenty of information on their respective forums about using I2S. On our website we also provide the necessary information and schematics: www.exadevices.com > exaU2I > D.I.Y. Guide.

Read my earlier post, responding to jkenny. Than it might dawn on you, why SPDIF is on the table.

Finally it's all about your great, to me unacceptable high, 108ps jitter value on the output.

Anyhow. TP didn't make it on the first shot either.
 
Read my earlier post, responding to jkenny. Than it might dawn on you, why SPDIF is on the table.

Finally it's all about your great, to me unacceptable high, 108ps jitter value on the output.

Anyhow. TP didn't make it on the first shot either.

You haven't answered my question. You just jitter around it. You propose huge unknown jitter as a remedy to quantified minuscule jitter that is proved to be within the jitter cancellation capability of ES9018.

exaU2I is not perfect and it will never be. See jkeny's signature. However for now it is the only device in its class. It creates the possibilities for DIY enthusiasts to compete with vey high-end $5,000 equipment. I mean equipment without SPDIF outputs.
 
exa065, i think you're the first person to provide jitter specifications of a USB~i2s device. Given the topology used, I'd be very surprised if any of the other available DIY solutions can better this by a considerable margin as a standalone unit on jitter, and that's without taking into account the limited channel functionality of most other kit based products.
 
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The evaluation of the exaU2I continues and I have hooked up a old Buffalo32S DAC with a volumite control unit.
It was easy to connect - just follow the instructions for Buffalo´s www.exadevices.com > exaU2I > D.I.Y. Guide

As this is a Buffalo with 80Mhz clock it performs excellent at up to 192k/32bit.
If the clock was replaced with a 100MHz clock I expect even 384k/32bit should perform as well.

The following are my own calculations and valid for ALL ES9018 based DAC´s:
To run 352.8k/32bit with OSF enabled the clock need to be minimum 90.3168MHz.
To run 384k/32bit with OSF enabled the clock need to be minimum 98.304MHz.
If it is possible to disable the OSF a 80MHz clock will allow it to play 384k/32bit..
 
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The following are my own calculations and valid for ALL ES9018 based DAC´s:
To run 352.8k/32bit with OSF enabled the clock need to be minimum 90.3168MHz.
To run 384k/32bit with OSF enabled the clock need to be minimum 98.304MHz.
If it is possible to disable the OSF a 80MHz clock will allow it to play 384k/32bit..
Is this inductive rule set also applicable to your home-brew ES9018 DAC?
Exceptionally, can your home-brew DAC play 352.8 kHz and 384 kHz audio files without noises even on OSF enabled mode with 80 MHz oscillator?
Is the rule above also applicable to your deeply upgraded SDTrans?
 
Is this inductive rule set also applicable to your home-brew ES9018 DAC?
Exceptionally, can your home-brew DAC play 352.8 kHz and 384 kHz audio files without noises even on OSF enabled mode with 80 MHz oscillator?
Is the rule above also applicable to your deeply upgraded SDTrans?

Bunpei, your posting are far off topic this treads topic :D:D
Due to this you should post issues like this in your own SD card player tread..

The only issue I have had with 352.8k files on a SDTrans192 was when I was playing 352.8k and the next song had a different samplerate.
Due to the FPGA on the SDTrans192 do not reset the clocks when a song is finished (you might even take out the SD card) it continues to clock at 352.8k until a new song suddenly changes the samplerate and clocking.
This samplerate change I was able to hear as a short click noise until I changed the programming and cured that also.
For a long time I believed this was the noises you was talking about..

Bunpei - you may "jitter" around with your noise issues, but I do not think you will not get any more help due to that..
 
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Since Exadevices have not yet delivered exaU2I to us here in Japan, all we can do is to excitedly watch developments on this thread :) The issue being talked about "on topic" here is playback of high sampling files from 352.8kHz/24bit up to 384kHz/32bit into any Sabre ES9018 based DAC. Our own experience so far is to play 352.8kHz/24bit files using the SDTrans 192, and we are looking forward to playing 384kHz/32bit when we can receive the exaU2I. RayCtech has kindly informed us his own test results that:
If it is possible to disable the OSF a 80MHz clock will allow it to play 384kHz/32bit..

I think this means that any ES9018 based DAC with an 80MHz clock will be able to noiselessly play up to 384kHz/32bit files regardless of the player being used (as long as the player is capable of playback) WITH OSF IS DISABLED, which then of course means that it will NOT be able to play 352.8kHz/24bit and above with the OSF being enabled (turned on).

It is probably interesting for us here in Japan to experiment more with our ES9018 based DACs and OSF disabled when using lower clock frequencies like 80MHz to play 352.8kHz/24bit files, until the exaU2I arrives and we also get to try 384kHz/32bit files as well :)

I appreciate RayCtech telling us about his experience, and I think Bunpei's observations regarding experiencing noise during playback into ES9018 based DACs when clock frequency is too low (and OSF is enabled) is relevant for this thread too ;-) Point is of course to turn OSF off (disable).
 
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Would you explain the need to involve SPDIF in the signal path? To use exaU2I USB to I2S interface you need a computer, USB cable, the exaU2I kit, short twisted pair wires and a DAC kit with an I2S input. The popular ES9018 DAC kits like the Buffalo DAC and the AckoDAC come with I2S inputs.

As I am an "I2S fundamentalist", I completely agree with exa065's concept.

I agree with EXA why bring SPDIF into this - a fundamentally flawed technology?

The problem of intrinsic jitter in S/PDIF is well-illustrated in the following technical document,
Jullian Dunn, Audio Precision Application Note #5: Measurement Techniques for Digital Audio, Chapter 1. Jitter Theory.
(In this article, you can read technical details of J-Test signal measurement that is used in Stereophile measurement series and becomes very popular.)

However, employing I2S is just one element of a total audio system.
In my case, though I make efforts not to use S/PDIF, a vast amount of interfaces are S/PDIF in practical situations. Therefore we need to deal with S/PDIF well.

As eventually described in this message, around me, I know at least two actual examples that fit this description.
You can IMO achieve highest qualities with SPDIF if properly implemented.
Total performance of DAC is not merely determined with signal interfacing method of I2S or S/PDIF.

Anyway, as much as we provide good performance of I2S interface used between transport and DAC in realized products, the number of people those who perceive the merit will increase.
I hope exaU2I will lead this trend.
 
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