|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
101.183.6.119
Hi all - thanks for taking the time to read this.My attitude towards USB 2.0 compliance has been turned upside down. Well, my understanding of where potential incompatibility issues reside has.
In fairly recent history, based on DAC manufacturers demanding USB Audio 2.0 compliance from audio source (server/ renderer/ et al) vendors and what I perceived as a cavalier approach by some of the source vendors to squeeze the last bit of performance from an adapted protocol, I assumed that incompatibility was most likely to reside server-side or perhaps with the USB cable. My experience has backed this up. Until now.
In the past, a Linux-based server connected by USB to my DAC produced frequent, but irregular blips of varying duration and amplitude. Dropped samples? Windows and Mac exhibited no such behaviour. The DAC manufacturer suggested the cause was server-side: its hardware did not reflect the USB 2.0 standard and I had concerns about the compliance of their USB Audio 2.0 code. The server manufacturer claimed their implementation was compliant... The server went back to the retailer.
Another Linux-based server was much better, but on occasion I sensed similar issues, but more subtly; it could have been expectation effect on my part. I persisted and continued to use this server for a year or more, although it is not an ideal sonic match for my system.
Enter my new Linux-based server. You know what's coming: the issue recurred, big time. The manufacturer of my new server is adamant that it's hardware and software are unquestionably USB Audio 2.0 compliant. They make a convincing argument and by all accounts are of high integrity. I will know more after the manufacturer remotely accesses my set-up in a couple of days (they have also been very responsive to questions etc - impressive!).
But all this has me wondering: despite the demands and claims, really, how compliant are DAC manufacturers with USB Audio 2.0? Apparently XMOS was one of the earliest manufactures to provide compliant USB Audio 2.0 firmware with their hardware. What happened before XMOS hit the scene - from where did DAC manufacturers source their firmware? Was the firmware USB Audio 2.0 compliant and how can they prove it? Why the need for frequent firmware updates if compliant? Even with compliant firmware available, are manufacturers hacking their USB firmware, that potentially is non-compliant - again, how would they prove compliance... how thoroughly do they test... across what platforms? Wouldn't a compliant DAC work with compliant servers irrespective of whether Mac, Windows, Linux, or...?
I'll be following-up with my DAC manufacturer, who states its USB input is Linux USB Audio 2.0 compliant. Still, I am wondering what others think?
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Edits: 12/02/16 12/02/16 12/03/16Follow Ups:
In the past I ran into several issues in that area.
ClassCompliancy doesn't mean to stay 100% generic with your firmware.
As soon as manufacturers add certain specific configurations on top of the generic features to the firmware, there's a good chance that these devices won't work at all.
Last time I ran into that issue was a NAD M51 2-3 years ago.
Adding a so called "quirk" to the driver helped me more than once.
But that can't be done by a normal user.
You need to be able to patch a driver and then you need to compile
a new kernel.
Bottom line. Blame the DAC manufacturer for not testing his device under Linux/Android!
... and is what I suspect is going here.
In response to my polite and genuine question about UAC2 compatibility - as an owner of the product - I hear only silence; zero response.
Oh well, thankfully the SPDIF inputs sound nice.
Thanks all.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
You might try to contact this forum member :)
http://cgi.audioasylum.com/cgi/mail.mpl?user_ID=7307&f=pcaudio
The Well Tempered Computer
Yes, Thorsten designed (at least part of) the DAC. I have learned much from him over the years, especially in relation SET amps.
Not sure Thorsten can add much more than Owen, who confirmed AMR does not develop their firmware to be compatible with Linux... despite what is posted on their website and previous emails. Thorsten is largely a Windows guy, so I guess I should not be surprised.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Agree Many main stream makers do not update their XMOS drivers for windows because they have to customise, test, and also pay for them. To continue with Thyscon v1.6 drivers when the latest release is v3.34 is, to say the least, a remiss.
The latest XMOS drivers sound better but most manufacturers also remove the ability to set things like latency and buffers from their Theyscon origin drivers. These are settings that allow for the fine tuning of SQ.
They are not interested in (firmware-) updates/upgrades.
My guess. Product support/maintenance/life cycle management cost are not build into the business cases at all.
It's "sell and forget" most of the time.
And they know, audiophiles will open their pockets for tiniest changes (some might also call these improvements).
They rather sell new devices instead of getting into trouble with the old stuff.
I think you'll agree. There won't be any change soon.
Hi all,In my initial email I raised some general questions about the responsibility of DAC producers to be able substantiate claims regarding their USB Audio 2.0 (UAC2) compatibility. I have since looked into this regarding specific issues between my DAC and server.
HistoryAMR website FAQ:
The DP-777 requires a minimum of USB 2.0 AND USB Audio Class 2.0 compliant Operating Systems (Mac OS X, select distributions of Linux) or a USB Audio Class 2.0 Driver (supplied for Windows) in order to have sufficient bandwidth for 24-Bit 176.4/192kHz audio.
There is nothing specific, except positive magazine reviews, in relation to the SE version of the DAC on AMR's site. However they discuss the importance of USB compatibility in general...
AMR via email in April-2015 suggested the server I was using at the time was Linux-based and as such, it is not standardised across the board eg USB Audio Class 2.0. This implies that it was not working because it was not UAC2 compatible... conversely, if compatible, it should work.
AMR via email yesterday:With regards to Linux we do not support this as there are too many variations...
The implication of this is that the DP-777SE USB firmware is not truly UAC2 compliant. AMR develops their input firmware and drivers for OSX/Win; they don't provide drivers for Linux because of the variety of distros. I am awaiting further confirmation of UAC2 (in)compatibility.
The problemThis would be fine except AMR have clearly given the impression - and it's a reasonable expectation - that their products are UAC2 compliant and should work with UAC2 compatible sources. IME and (finally) by their own admission they don't.
I feel for the distributor over here in Australia - a nicer, more professional, more helpful person you are unlikely to meet.
Buyer beware.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Edits: 12/04/16
"AMR develops their input firmware and drivers for OSX/Win"
According to this page: http://www.amr-audio.co.uk/html/dp777_driver-download.html
They do supply a driver for Win. Small wonder as Win doesn't support UAC2
They don't supply a driver for OSX.
OSX is UAC2 compliant.
Likewise the iFi products: http://ifi-audio.com/downloads/
It looks like they do use UAC2.
Not to be mistaken for a good implementation.
A rule of the dump is that if a USB DAC works with OSX without installing a driver, it is UAC2 compliant.
Hence it is reasonable to expect it to work with recent Linux as well.
The Well Tempered Computer
that relates to the DP-777, not the DP-777 SE. It is my understanding that the SE uses a different USB input. The firmware is likely different, but I take your point about the driver download (no OSX) and the likelihood of compliance.
However, AMR has clearly stated in recent correspondence that they don't support Linux - why not if the Linux driver is UAC2 compliant? Could they be UAC2 non-compliant but still work with OSX?
Let's see what AMR comes to me with.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Interesting. It wouldn't be smart of them to not support Linux with the DP-777 SE. If this is true, then they may not support several dozen popular audiophile music servers and network streamers out there that are based on Linux.
A lot of servers are Linux-based!
Unless there is something I'm missing, if the DP-777SE was UAC2 compliant it should work with UAC2 compliant Linux servers.
Thankfully the DP-777SE has a nice SPDIF in and the Antipodes can do SPDIF out... though I'd rather be using USB.
I want to get off system merry-go-round, but might take a look at a different DAC if I feel like leaking a few more $.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
I'm trying unpack what you're really trying to say.
If your profile is current your linux based music servers include the commercially made Antipodes DX Gen-2 and Bryston BDP-2 . If I'm reading your post correctly you allude to possibly having owned another linux based music server as well. I'm not sure.
Yes, the underlying OS is Linux in many of these commercially manufactured devices (including the Antipodes and Bryston). But unlike DIY linux servers you are at the mercy of the manufacturer to update and fix their OS.... if they are in fact at fault.
And again, if your profile is current your DAC is the AMR DP-777 SE . Has that been the constant throughout your experience with these 'incompatibilities' and history of drop outs? Is this the same DAC that appears to be producing 'drop outs' with at least two of your music servers? If so...
Here's what I would do. I would try another USB DAC or two. AND I would make sure that I am NOT using some audiophile super optimized megabuck USB cable that some bozo is selling from his garage shop. Get an inexpensive but decent basic USB cable (just to eliminate your current cable as a possible problem).
Borrow a couple recent and modestly priced DACs. There are several fine USB DACs out there for well under $1000. Borrow one from your dealer. Borrow one from a friend. Try them on your linux based music servers. Did the problems go away? If yes, I would point my finger squarely at your current DAC.
It's really curious to me that you're having these problems as many inmates here have been running DIY Linux based music servers across several DAC brands for years with no such issues.
I've been running Mac music servers (UNIX based) on USB DACs for nearly 10 years and scratch my head when I hear of people experiencing dropouts and such on computer based music systems. The only time I have ever experienced drop outs or erratic behavior was if I were using my Mac for some other very heavy duty task (like video transcoding) while listening to music. I have separate systems now for music and my other hobbies.
Good luck, and please let us know what you discover once the issues are resolved.
Hi Abe,You are correct re the equipment I currently using, and yes, an Aurender was the first server I used.
I have also tried a W4S DAC2 with the Bryston and Aurender - no issues at all; I will try it with the Antipodes later today. OTOH, the AMR has worked fine Mac and Windows... just not Linux. Thanks for the advice.
My questions were general than that though: DAC manufacturers place demands on server manufacturers re compatibility with USB Audio 2.0; however, how do we know that the DAC manufacturers are compliant?
Edit: I have also used a few different USB cables - the Curious Cables, a Kimber, and a couple of generics; no difference.
Update: Just tried it with the W4S DAC2 - not even a hint of an issue. Rock solid, and sounds nice too.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Edits: 12/03/16 12/03/16
In the past some manufacturers developed their own drivers.
Of course they had to comply with USB standards anyway, otherwise it wouldn't work but they were using bulk mode instead of isochronous mode (UAC1/2).
M2Tech was one. If I remember correctly they got a lot of complains about their drivers with the HiFace 1 and later switched to UAC1/2.
Centrance and TheSycon developed drivers for Win.
Today it is most of the time TheSycon / XMOS powering USBDAcs on Win.
OSX and Linux are UAC2 compatible from mid 2010.
I don't know if they are certified as well. In case of Linux I expect not simply because Linux is not a big company.
Most of the time the moment a new driver is released, there is a plethora of bug reports. Overtime this dies downs as the product matures.
I expect the same to happen in a couple of month when MS releases their implementation of UAC2.
In your case Google is your friend.
Do Google the brand/model of the products you are using and check for USB issues.
The Well Tempered Computer
Thanks for the info. The UAC2 acronym has improved the quality of my search to understand the history, compatibility etc!
I had searched re my DAC, but there doesn't seem to be much info available from users. The manufacturer's website states compatibility, but I'm not so sure at this point - I have no idea what their USB implementation entails and they tweak their firmware very frequently for their other DACs.
That said, i am thinking more generally: under what obligation is a DAC manufacturer to prove compatibility as claimed?
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
No problems with USB 2.0 compliance since Windows 7 (actually before that). Your mileage may vary.
and none have any glitches with any of my Apple Mac Computers.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: