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Old 3rd January 2012, 10:42 PM   #951
exa065 is offline exa065  Canada
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Quote:
Originally Posted by greggp View Post
Considering 2 vs. 8 channel?? How about both. Make two 2nd generation interfaces, one optimized for 2 channel, the other for 8.

Ideally, it would be nice to have a single solution with the ability to switch between stereo and multichannel modes, but that would probably need to be accomplished on the DAC board, not the interface.
Thanks, we can build two devices. I am trying to understand what are the important features for the majority of the users.
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Last edited by exa065; 3rd January 2012 at 10:58 PM.
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Old 3rd January 2012, 11:50 PM   #952
greggp is offline greggp  United States
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Quote:
Originally Posted by rsdio View Post
There are FireWire audio interfaces which work without installing any driver at all. Of course, this is on Mac OS X where Apple has implemented the standards. Windows previously had poor support for FireWire, and although people tell me that the support is better, I'm still not sure whether that means these same driver-less FireWire audio interfaces would also work on Windows without drivers.
I have a multichannel firewire interface for Windows 7 and to get Windows to recognize it as a multichannel device, I needed custom drivers. This included both WDM and ASIO drivers. The ASIO driver works great for audio only apps, and the WDM driver works well with apps for watching DVDs and Blu-rays, like Windows Media Center.
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Old 4th January 2012, 12:40 AM   #953
exa065 is offline exa065  Canada
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Rsdio, I've just deleted your post. The point of the discussion here is to go forward in a constructive way and to make exaU2I more useful. This is not the place for another fight.

We say that out drivers are better because we can bypass OS limitations, we have full control over the processing from beginning to end, and we can verify their performance. We say that the sound is better based on subjective personal experience and user feedback. My comments about minimizing noise are not related to driver technology. I was talking about goals for the device.

We are interested to offer an alternative to standards. Our approach is to minimize complexity and processing. We believe in scientifically sound solutions, and we are satisfied when there is correlation between measurements and subjective tests.

Again, different approaches and solutions can be discussed on other forums. This thread is about exaU2I, and exaU2I is an alternative device.
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Old 4th January 2012, 07:52 AM   #954
rsdio is offline rsdio  United States
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Quote:
Originally Posted by exa065 View Post
We say that out drivers are better because we can bypass OS limitations, we have full control over the processing from beginning to end, and we can verify their performance.
Please explain how your control over the processing from beginning to end is superior to bit-perfect, jitter-free transports. All evidence indicates that custom drivers are not necessary to achieve bit-perfect, jitter-free performance.

Please also explain how your custom driver minimizes complexity and/or processing.

Note that my experience is with OSX, where CoreAudio presents the absolute minimal interference between an audio player application and the audio hardware. I realize that most (all?) of your existing customers are using Windows, but I would like to see new exaDevices products fully support the existing, simple, unprocessed options in CoreAudio on OSX.
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Old 4th January 2012, 09:46 AM   #955
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Quote:
Originally Posted by rsdio View Post
All evidence indicates that custom drivers are not necessary to achieve bit-perfect, jitter-free performance.
Good you have evidence @rsdio

I have observed that your statement are not true and that most hardware and most software are ONLY so called bit-perfect in isolated study cases.

I have also observed and verified that most DAC chips are not bit-perfect in their data manipulations either.

I do not need to prove anything as my observations are clearly documented in the standards that are lying in the bottom of digital audio - if you do not agree then start studying the basics.

I may say as much as when a 16 bit audio file are played and the so called bit-perfect chain to the DAC are following the standards - then you may get bit-perfect performance ONLY if you use a pure 16 bit DAC..
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Old 4th January 2012, 10:41 AM   #956
rsdio is offline rsdio  United States
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Originally Posted by RayCtech View Post
I have observed that your statement are not true and that most hardware and most software are ONLY so called bit-perfect in isolated study cases.

I have also observed and verified that most DAC chips are not bit-perfect in their data manipulations either.

I do not need to prove anything as my observations are clearly documented in the standards that are lying in the bottom of digital audio - if you do not agree then start studying the basics.

I may say as much as when a 16 bit audio file are played and the so called bit-perfect chain to the DAC are following the standards - then you may get bit-perfect performance ONLY if you use a pure 16 bit DAC..
It seems that you are not aware that the exaU2I hardware does not include a DAC. Therefore, while your observations would be very important if I was talking about a DAC, they're quite moot in this thread.

I have confirmed bit-perfect performance by looping back the digital data and comparing the source to the final data after it has traveled across the bus twice. Jitter-free performance cannot be affected by host computer drivers when the clock source is the DAC, and so while I have not confirmed this empirically, I have proven it as a priori truth. These feats are accomplished by many audio interfaces, both proprietary and standards-based.

There are plenty of arguments to be made about DAC technology, and I do not want to get into them in this thread, precisely for the reason that the exaU2I (and presumably also the new improved versions) does not include a DAC. I think it's great that exaDevices decided to create a platform where the bit-perfect, jitter-avoiding transport is the entire raison d'etre for the product because it skirts all of these imperfections and leaves them to the particular DAC implementation to solve. Of course, the exaU2I does facilitate certain aspects of the solution with various isolation techniques.
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Old 4th January 2012, 02:15 PM   #957
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Default Back to the topic...

I would like to see:

1. Very low phase noise oscillators, like Crystek CCHD series-reason being that I prefer to synchronously clock my DAC, providing masterclock from the USB interface, so phase noise/jitter in the I2S output is critical.

2. Ultra low noise/impedance local shunt regulators, one for each onboard oscillator to allow the oscillators to perfrom their best, and not back modulate the power supplies.

3. Users choice to use the GMRs or not, with separate output headers, and I would prefer micro bnc (for U.FL) for the non-isolated I2S output.

4. Option to send masterclock back to the exa from the DAC over I2S.

5. Oh yeah, prefer two channel only here.

RSaudio: if you have played around with any music software (Pure Music, Audirvarna, etc) you already know that "bit perfect" is not all that matters-it is pretty easy to get bit perfect output from iTunes alone, but it sounds like crap compared to good player software, eventhough they are all bit perfect. I suspect that the exa drivers just help streamline the data path and processing, just as the better player software does. What this does not help is the compromised USB hardware on most computers-interestingly, I recently switched to a linux based player, with a dedicated SOtM USB output card, better sound... but I digress.
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Old 4th January 2012, 04:00 PM   #958
Bunpei is offline Bunpei  Japan
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Hi, RayCtech!

It's nice to see you again here.
Have you tried 2L 8 channel DXD on e18 or DSD256/DSD512 on ExaU2I?

Bunpei
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Old 4th January 2012, 04:06 PM   #959
Bunpei is offline Bunpei  Japan
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I hope USB High-speed is isolated in the new design by embedding such a technology.
Core Modules, Daughter Boards, Core Development Kits for USB Extension - Icron Technologies
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Old 4th January 2012, 11:23 PM   #960
Javin5 is offline Javin5  Switzerland
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Here is my input of what I would like to see in a revised design:

- Ability to support synchronous operation of the Buffalo DAC. The exa-device has two oscillators. It should therefore be the clock source when operating the Buffalo-DAC in synchronous mode with its ASRC disabled, since it can generate both multiples of 44.1 and 48 Khz. This means that the oscillator on the Buffalo needs to be removed.

- Because of the above, a galvanic connection is needed for this clock. The galvanic isolation should therefore be moved to the USB-side.

Since the synchronous option appears to elevate the sound quality yet another notch (RayCtech, Bunpei), such an implementation would be very desitrable. I also support the suggestion by other posters to incorporate high quality regulators, if this increases the sound quality.
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