Just a few hours ago I managed to finish building a battery powered DAC around AK4396 and test the exaU2I. Listening to some of the high resolution files I've gathered over time, I felt the entire project was very rewarding.
Everything was smooth in installing the exaU2I, driver and player set-up is straightforward, also the connection to various DAC's is easy to get right, even for a beginner.
It quickly became obvious that I was hearing more details than my 96Khz capable soundcard and that it is clearly over a PCM2706 interface I built some time ago. I will come back with some more details, right now I just want to enjoy some music
.Anyhow, this board clearly is of great value considering that technologically is quite advanced. It's great to have the possibility of turning your PC into a digital crossover without the need of other conversion stages as it happens with Behringer for example. Also I plan to experiment soon with 32 bits material on an AK4397/99.
I realize that I replied to this already, but I ignored the details of USB.
Isochronous does not mean what you think it means. Grab the USB Specifications from USB.org and read about USB-Audio and USB 2.0 in general. You will find that there are three Audio Synchronization Types (Chapter 3.3 in the USB-Audio Specification): Asynchronous, Synchronous, and Adaptive. All three of these use Isochronous endpoint data transfer packets. So, you are basically wrong about how USB works. I'm sure you probably read the term 'isochronous' in some online article which used a different definition, and that's probably why you got confused. When in doubt, the USB Specifications are freely available for reference.
To reiterate, neither FireWire nor USB have any problem running the DAC chip as master clock over an isochronous connection. In fact, all commercial audio interfaces use isochronous data transfers, because the data must be delivered in real time, unlike a hard drive.
Just a few hours ago I managed to finish building a battery powered DAC around AK4396 and test the exaU2I. Listening to some of the high resolution files I've gathered over time, I felt the entire project was very rewarding.
Everything was smooth in installing the exaU2I, driver and player set-up is straightforward, also the connection to various DAC's is easy to get right, even for a beginner.
It quickly became obvious that I was hearing more details than my 96Khz capable soundcard and that it is clearly over a PCM2706 interface I built some time ago. I will come back with some more details, right now I just want to enjoy some music
Anyhow, this board clearly is of great value considering that technologically is quite advanced. It's great to have the possibility of turning your PC into a digital crossover without the need of other conversion stages as it happens with Behringer for example. Also I plan to experiment soon with 32 bits material on an AK4397/99.
Thank you for the brief report. Would you mind elaborating on what are you using on the software side, what player, crossover app (if any) etc. That way we could have a more complete picture of what the set up is.
I am looking forward to learn more about your results.
Yep. I'd agree. That's what I felt to be tempting about this device too.
Though if you want to run a crossover and convolution engine, I'd opt for a headless Linux machine with brutefir driving such an interface.
In my case times are over where a Windows PC/Notebook is sitting right next to my stereo.
It's really a pity that this exa device is Windows only.
All we need to do is find a savvy CoreAudio programmer who is familiar with Apple's sample code for an audio device driver. For USB Devices, this can be User-land code, i.e., it doesn't even have to be a kernel driver.
It wouldn't hurt if this hypothetical CoreAudio guru were motivated by the DIY ethic.
I would do this myself, but I am quite busy designing my own USB hardware, firmware, and software. Thus, I'm afraid that if I took on the task, you poor DIY'ers would be waiting too long!
I see. You then must be considered EXA competition.
Let see if you gonna comply to USB 2.0 standards ( as touched upon earlier) once you're finished.
In this case we wouldn't need a "Core Audio" programmer.
Ha! (I see your smiley) Actually, I am working on this: the Madrona Labs "Soundplane A", which is not an audio device. It has on-board DSP and way more than 8 inputs and 8 outputs. The DAC is capable of 125 MHz sampling rates! But, I have no plans to compete with exaDevices any time soon. I prefer FireWire Audio anyway...I see. You then must be considered EXA competition.
It is impossible for the exaU2I to implement USB-Audio unless the hardware is completely redesigned around a new chip. The FTDI Chip used in the exaU2I is incapable of implementing USB-Audio (which is what I assume you mean by "USB 2.0"). The FTDI Chip is locked to a specific USB Device type which is different than USB-Audio. Therefore, the only way for exaU2I to work on Windows or OSX is with custom drivers.Let see if you gonna comply to USB 2.0 standards ( as touched upon earlier) once you're finished.
In this case we wouldn't need a "Core Audio" programmer.
Note that "USB 2.0" refers to a wide range of devices, including the newer High Speed, but also includes the exact equivalent of USB 1.x Full Speed and Low Speed. Actually, USB 2.0 is a rather diluted term which has very little meaning unless specifically qualified. Lots of Full Speed USB-Audio Devices are technically USB 2.0, so you really have to be careful what you're buying.
Hi AR2, sorry for the late reply, only that I was so excited on putting the U2I to work that I missed some sleeping hours this week as I needed to build a DAC with AK4396, a chip I've never used before. However all the efforts paid off when the DAC finally locked on the U2I signal! And as I told in the previous post it was quickly obvious that I had something special in my hands.
I am only now beginning to learn how the U2I is interacting with the rest of the system. Listening impressions are also yet to come. I've used it briefly with cPlay on Windows7 and also with foobar. To early to tell if any differences yet.
The idea of using cPlay came actually when I wanted to listen some 384Khz/32bits files and I was not having any high quality downsampler installed in foobar (it was about 1.00 in the morning
). cPlay immediately recognized all the 8 channels of the U2I and after setting the SRC downsampler to 192Khz it just went playing music.Regarding crossover software, the problem is that I don't have all the resources now to make some tests. I've been thinking at a proper USB implementation for multichannel streaming for years now (ever since peufeu, memeber of this forum, first posted in 2007 - 2008 an experiment with a spartan board streaming to a DAC through ethernet) and the exa board came out quite unexpectedly and when I was starting to loose my hope that we will see something else than two channel devices. Since peufeu's first developments, my goal became also finding a way to do crossovers on a PC environment and the U2I is kind of the device I always wanted to build/develop myself. It seems for now to do everything right: multichannel, galvanic isolation, huge sampling rates and bit depth and proper clock management system.
The challenge now will be to use crossover software able to work with ASIO. I would first look into the well known options in the market: Thuneau and Allocate and check how are these working. The solution KOON developed is also extremely interesting as it works with ASIO and I believe it could be modified for U2I. And while his system is limited to 44.1K, with U2I there are no sampling rate limits, not even with studio master files!
Also, there should be a way of using brutefir and integrate it with ASIO, I'll take a deeper look into the documentation available. I guess that this should be possible through a VST plugin and foobar definitely is capable of managing this, and I've noticed cPlay also seems capable of taking a VST plugin.
Believe it or not but I've even thought of convoluting off-line my entire music collection once I set-up my multichannel music system. Storage space I have plenty, and this would resolve the demanding task of doing real-time fir filters on 192/24bits and 384/32 bits files. Even with CUDA GPU's realtime fir filters on such large files is not an easy task.
Soundcheck, any chances you could give us some more info regarding brutefir and asio? I know that you were hard at work into brutefir a couple of months ago when developing your system and brutefir player. Your input would be very helpful.
Unfourtunately for me a headless linux is not really an option, for the reasons above. Also, I really like Windows environment (I've toyed with linux also) and I like to have easy access to my music, movies and concerts and play them through the same system, at the same quality. I believe U2I is an excellent start for doing this. As I told earlier it's kind of a do it all solution, without compromising on some design principles and this I find really great!
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Sun Ra,
Thank you for the very detailed report. Great info. I see myself very close to your way of thinking. I am glad you are trying AKM 4396. Those DACs I have been using until now in my modified digital crossover. They are really good. I was also very happy and pleasantly surprised when exa announced his device, as I was ready to make a move from my modified Behringer DCX2496 to ether hardware (DSP) or software solution. I was, I have to say, very disappointed since I couldn't find any DSP unit for a similar task. I actually made the decision to purchase RME card with multiple S/PDIF outs and than to take I2S signals before the S/PDIF transmitters. I was extremely frustrated that for that I would need to pay $ 1,1K, and to fuss with that with wires.... Than exa came out, and I remember as I was reading every line of his post I was getting more and more excited. Perfect timing, perfect product and less than half price of comparable solution with RME.
I do not have much of experience with PC as an audio device. I am not even a PC guy, I am Mac addict, but I use PC for measurements and generally to test and play with audio PC specific software. I have not seen a full software that does everything simply and elegantly ether on Mac or PC. I have a full version of Allocator and it is a really well made software with the right features. It works great on cPlay as a VST plug in. So far I was not able to make it work like that in Foobar, but maybe it is just me. The one thing that I would like to see is a software and player that automatically recognize sample rate and automatically adjusts to it without oversampling and restarting, that accepts Allocator as VST and that is comfortable as music file browser as iTunes, but supports FLAC files. Not to mention usage of iPad or iPhone as remote would be a dream comes through. So far PC as an audio device with complex active three way system is a complicated business, compared to just slipping CD in. I am still searching for the best way of doing it, and yet comfortable with that.
Thank you for the very detailed report. Great info. I see myself very close to your way of thinking. I am glad you are trying AKM 4396. Those DACs I have been using until now in my modified digital crossover. They are really good. I was also very happy and pleasantly surprised when exa announced his device, as I was ready to make a move from my modified Behringer DCX2496 to ether hardware (DSP) or software solution. I was, I have to say, very disappointed since I couldn't find any DSP unit for a similar task. I actually made the decision to purchase RME card with multiple S/PDIF outs and than to take I2S signals before the S/PDIF transmitters. I was extremely frustrated that for that I would need to pay $ 1,1K, and to fuss with that with wires.... Than exa came out, and I remember as I was reading every line of his post I was getting more and more excited. Perfect timing, perfect product and less than half price of comparable solution with RME.
I do not have much of experience with PC as an audio device. I am not even a PC guy, I am Mac addict, but I use PC for measurements and generally to test and play with audio PC specific software. I have not seen a full software that does everything simply and elegantly ether on Mac or PC. I have a full version of Allocator and it is a really well made software with the right features. It works great on cPlay as a VST plug in. So far I was not able to make it work like that in Foobar, but maybe it is just me. The one thing that I would like to see is a software and player that automatically recognize sample rate and automatically adjusts to it without oversampling and restarting, that accepts Allocator as VST and that is comfortable as music file browser as iTunes, but supports FLAC files. Not to mention usage of iPad or iPhone as remote would be a dream comes through. So far PC as an audio device with complex active three way system is a complicated business, compared to just slipping CD in. I am still searching for the best way of doing it, and yet comfortable with that.
When the exaU2I have finished OSX drivers you can have your solution with Pure Music / iTunes..
You get automatic sample rate switching or upsampling (integer and 64bit processing), native FLAC support, iPad or iPhone og MacBook as remote, up to 4 way crossover (advanced with 64bit processing)...
I uses this solution (today with M2Tech USB -> I2S) and the only issues I have are the ever changing "bugs" in iTunes
Due to I have a large selection of DXD master files and also uses WAV, AIFF, FLAC I am stuck with iTunes 10.1.2 for the time being.
In iTunes 10.1.2 there are support for tagging and cover art with DXD / WAV
Versions before 10.1 and after 10.1.2 do not have this feature.
When the exaU2I have finished OSX drivers you can have your solution with Pure Music / iTunes..
You get automatic sample rate switching or upsampling (integer and 64bit processing), native FLAC support, iPad or iPhone og MacBook as remote, up to 4 way crossover (advanced with 64bit processing)...
I uses this solution (today with M2Tech USB -> I2S) and the only issues I have are the ever changing "bugs" in iTunes
Due to I have a large selection of DXD master files and also uses WAV, AIFF, FLAC I am stuck with iTunes 10.1.2 for the time being.
In iTunes 10.1.2 there are support for tagging and cover art with DXD / WAV
Versions before 10.1 and after 10.1.2 do not have this feature.
Ray,
Thank you! Yes I tried Pure Music, but I was not aware that there is a crossover there? Or you are using some additional software for that within Pure Music?
Let's discuss the "dream" configuration:
- I can customize the exaU2I ASIO driver to "act as VST host". It will be actually a VST host integrated with the driver.
- Perhaps it is possible to integrate Allocator in some other custom way
- There are VST host plugins for Foobar. For example: George Yohng's VST wrapper for Foobar2000 - Hydrogenaudio Forums
- Foobar has plugins for remote control compatible with iPad. For example: foo_httpcontrol - Hydrogenaudio Forums
- Automatic sample rate switching is not a problem with exaU2I
Exa, I think many people would love that since for now with Allocator I have to use S/PDIF loop in order to use crossover. cPlay supports VST plugins and there is no need to go through the loop. That is also great way to test what S/PDIF conversion does to a sound, although its a double conversion. It is very noticeable, so with your device that is already I2S plus VST... man, that will be just plain awesome. I have been reading a lot on the subject lately, and I came to sensory overload. I tried Jack and virtual cable, to avoid S/PDIF and it is very difficult to align everything... support for W7, support for sampling rates, to recognize Allocator... than add to it convolver, or console and... I mean really... I just try to play sound not to launch rocket.
So yes, that would be such a logical step for Exa to became host for VST plug ins, so that within the same driver we have crossover app and room Eq app. Allocator is good up to 192 KHz and is really good and well executed app.
Allocator's developer Jan, better known on this forum as Thuneau, is great guy and very approachable, so maybe you two guys have a chat. It seems like we are up to something big! Exa you have open such a burst of innovation with your device that I have not seen in a while!
Couldn't agree more
I've been listening through the device all day long, I have to run and buy some rechargeable batteries tomorrow
. It's really hard going back to my sound card now, there's a feeling of natural and realism when playing through u2i. And this is with what I consider a suboptimal DAC implementation. This won't take long though, I have a board in the making that should stretch the limits of AK4396.