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I see all these USB and Firewire audio options out there - soundcards, DACs, recording interfaces - but which one of those really use Asynchronous mode and also I²S (and not spdif) internally.Thought would be nice to create a quick round up/summary. Feel free to add homegrown or DIY designs and kits as well!
Follow Ups:
Add Audioworkshops AW-D3 Dac kit to the list http://www.audioworkshop.com.hk/index_en.htmJohn
Nothing uses Asynchronous mode except Creative Audigy 2 NX (to my knowledge).As for I2S, the Wavelength products, Empirical Audio Off-Ramp I2S, Benchmark DAC-1 with I2S mods, Northstar 192 DAC, the EA "Spoiler" DAC, and soon the Overkill Audio DEQX.
Oohhh... she is a really sweetie - cheap too.Back to the listening.
Best
Gaspode
nt
admin - audioreview.com
> > Nothing uses Asynchronous mode except Creative Audigy 2 NX (to my knowledge).but no I²S, right ? Plus it looks like there is no support ASIO, and it is a re-sampling type card so I guess it might not be worth jumping for just the Asynchronous support.
Well maybe with ASIO4ALL(KS) and using a good resampler like Foobar's might help.Where does the DDDAC stand with the others you mentioned ?
Have not heard the DDAC...
The DDDAC uses I2S direct from the USB receiver, but its still adaptive like everybody else.Gordon has gotten asynchronous to work but I don't think he has any products using it, last I heard he was having major driver issues which were probably not conducive to going ahead with any products.
John S.
John,The drivers worked fine it was the drop outs. On most of the XP machines I had problems with the computer keeping up. I think this is mainly due to OS scheduling or the lack of something in the steaming interface.
Either way it didn't seem worth while to continue down that path. As I found a better one with simple pll with the 1020 that is killer with ISO.
Talking about drivers, interesting enough I did not have to write a 24 bit driver for MAC OS. I plugged it in and it worked.
Anyway, back to work...
Thanks
Gordon
J. Gordon Rankin
would you run into the same issues with Mac or Linux ?
Is there hope with Vista to tap into the full potential of Asynchronous mode ?
Just wondering if exploring alternative O.S. would be worth it or not.
Vista does have new USB audio drivers and async mode has some upgrades. However, the async mode for the drivers in XP also seem to work just fine so doeas 24/96. Gordon mentioned he used some 3rd party drivers which will probably not work on Vista either.
Cheers
Thomas
Thomas,Actually I did not use a 3rd party driver. I wrote it myself and even though it hab been since Win98 that I wrote device drivers it was not that hard to pick up where I left off.
The problem was that on several PC's it would drop out. I mean on music it would work but then it's hard to tell if there is a problem. So what I do for testing stuff like this is use a PC oscillator (Dr. Jordan in this case) and just create a sine wave at 1KHz and let it run. Then I feed this back into the distortion analyzer of Dr. Jordan and when it goes haywire I know the thing crapped out.
This was at 44.1/16 so I didn't even try 24/96 on the PC though the drivers were capable of that.
On a MAC this works all the time without any drivers. It also as a surprise to me worked at 24/96 without drivers.
I have not really played with linux yet not enough time in the day.
Ok why I think async is a waste of time. Most of the new host controllers have built in support for ISO and therefore require less overhead from the host processor. ISO has the highest priority of any interface on the USB chain. Therefore I think this is really the best place to start and build from there.
Thanks
Gordon
J. Gordon Rankin
USB audio async mode is using two isochronous streams! Async refers to the clock in the DAC being independent from the PC.One ISO streams sends the data down to the PC and another ISO stream in the opposite direction tells the PC how much data to send to keep the buffer within limits.
The Audigy 2NX or the older Emagic EMI 2|6 seem to work just fine in async USB audio mode.
Cheers
Thomas
Thomas,I know how it works I wrote the driver. Sometimes the pc does not respond fast enough and that is when there is a dropped sample.
The TAS1020 has limited space for buffering which worked on most PC's but some that have say one 1.1 host controller and then internal crappy hubs seem to be the ones that just can't keep up.
Why not test the 2 you mentioned the way I am and see if they don't miss a sample. It's pretty easy to do since it is a closed system.
Thanks
Gordon
J. Gordon Rankin
Hi Gordon, I am by no means an expert on system programming but doesn't it almost sound like a latency issue ?
Maybe MAC OS and/or USB2.0 do not run into that bottleneck (?)
Btw if you are striving to make it work for v1.1 then IMHO for all practical purposes you could forget about usb v1.1. If you could roll out a "USB 2.0 only" DAC I am sure that would not be a problem at all!
Secondly, I just wanted to throw this out there. I wonder where does PCI-> I²S fit in here ? Say if there was a internal pci soundcard that had I²S output capability then how good would that be as compared what we are trying to achieve with usb and firewire.
PM,I think that actually the problem may have been that the computer misses a request for data and that screws it up. I think and sent the info onto Thomas that I feel the makers of hardware are not including premium USB drivers for their hardware. Or in the other case they have a single 2.0 complient host controller and crap it up with a poorly integrated 1.1 hub. I think that is the case with the HUSH mini ITX I have.
There is no USB Audio 2.0 specification so that is out of the question. Nor can you tell people that it is what they have to have.
But really the point is what is the best sonics you can get. Is Async really better sounding that standard ISO? No not really...
As for I2S there is no spec here so don't expect an PCI card. Actually I don't even like the idea of dragging the clock, data and word clock on a cable. First it would require a secondardy pll & vcxo on the receiver side and then reclock all the lines. AHHHHH really it's a waste of time.
Thanks
Gordon
J. Gordon Rankin
Gordon,I'm assuming you went into the BIOS of your motherboard and turned off usb Legacy support?
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