runeks

Cool. Good to hear. If it works with other async DACs it certainly isn't the async USB implementation that is the problem. It would be interesting to know what is causing this though, since - as far as I know - the two DACs (rDAC and HRT II+) use the same async USB chip.<br /> <br /> The HRT Music Streamer II+ actually seems to be exactly what I'm looking for. Async USB to analog, nothing else.<br /> I must admit that I have a hard time seeing what justifies the $350 price tag, though. It looks like a very simple design, based on the pictures you've posted. Perhaps the async USB chip licensing fee is what keeps the price up there?<br /> <br /> <i><b>EDIT:</b> It turns out they developed the code for the USB chip themselves, so it's not licensed. From this article:<br /> http://www.6moons.com/audioreviews/hrt2/pro.html<br /> <br /> On further thought I guess it's a little too simplistic to expect a DAC's price to be proportional to the cost of the components it contains. It makes sense that the vast majority of the cost is from developing the actual design, and not realizing this design as an actual PCB.<br /> <br /> I read that Gordon Rankin spent several months developing the async code for the TAS1020B chip, so it makes sense that all this development effort would increase the price of the product.<br /> <br /> Still, I would really appreciate an in depth explanation of all the hurdles one must overcome to develop a good sounding USB DAC. It would be very interesting to hear, plus I might be able to convince myself to spend $350 on it then .<br /> <br /> One thing I'm interested in specifically is that a lot of other manufacturers of DACs stress the importance of a clean power source to produce clean audio. As far as I've understand the power source is used to drive the clock, and the more clean the power is the more precise the clock will be. But these HRT DACs all use the USB 5V line, which by many is said to be very noisy because it comes from the PC with all its many many components.</i>

Hi Schneider<br /> <br /> Sounds good. You were just the only one I could find via Google that had tried the rDAC on Linux, so I figured I'd ask you. But if you've heard that it's working on Linux then that sounds good. The only thing I wondered about, is whether the chip in the DAC had some way of defaulting to non-asynchronous mode in case the OS doesn't support it. And if so, if it was this that was happening when it was plugged into Linux. I can't seem to get any confirmation that Linux support synchronous USB audio by Google searching. But again, it sounds like it does.<br /> <br /> Concerning the problem running the DAC from you ARM system; have you considered that the system just might be too slow to feed DAC through asynchronous USB? I would imagine that Seagate has equipped that Dockstar with a fairly slow CPU, and dedicated chips are taking care of all the high speed transferring of data. And as ALSA is running on the CPU, it might just be too slow to keep up with it.<br /> Have you tried playing some WAVE files at a lower sample rate/bit rate, to see if it can keep up with, for example, 8 kHz/8 bit WAVE? If it can, it would point towards a bottleneck in the system, rather than a bug.<br /> Or have you managed to play audio fine over the USB port from the Dockstar with other, non-asynchronous DACs? It *could* just be the Linux implementation of asynchronous USB audio syncing that's implemented in a way that is too slow to work on low end ARM CPUs. Have you tried loggin in to the device via SSH (howto: http://ahsoftware.de/dockstar/#backup) and seeing what kind of CPU it has (cat /proc/cpuinfo)?<br /> <br /> But thanks for that link to the Music Player Daemon thread! I had never heard of that program, but it seems to be exactly what I was looking for to put on a low power audio server, when I get to doing that. Has an Android app and everything, so it seems to be just what I need.

Hi Schneider<br /> <br /> I'm very interested in asserting once and for all, whether Linux really is using the asynchronous USB transfer mode with this DAC. I'm wondering if you could do me a favor, and post the output of the below command when the DAC is connected to some Linux box? The command is:<br /> <br /> lsusb --verbose > usb-info.txt<br /> <br /> This will dump information to the file usb-info.txt, concerning USB devices connected to the system. It should state, among other things, if the synchronization used with the DAC is either "asynchronous", "adaptive" or "synchronous".<br /> <br /> If you do this, you could copy and paste the information from the file to, for example, pastebin.com, and post the link here.<br /> <br /> Thanks for your assistance!

Hi Judging from the below question and its response, it seems like asynchronous USB audio is supported in Linux. http://www.mail-archive.com/[email protected]/msg54309.html But to be completely sure you could post a message on that mailing list, and someone would definitely know for sure, I think.