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Old 19th October 2006, 10:11 AM   #21
adhoc is offline adhoc  Australia
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How do you all verify that you all have 44.1kHz non-resampled output via USB?
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Old 19th October 2006, 11:09 AM   #22
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Quote:
Originally posted by adhoc
How do you all verify that you all have 44.1kHz non-resampled output via USB?
What are you trying to tell us?

I discussed it at JRMC. They are telling me that they don't resample the stream unless you configure it!
If you run 44,1 16bit as source signal it just passes "untouched",
when it comes to resampling/upsampling.

With foobar afaik you need to get the resampling module in
to do resampling, right?

There is still the USB-Audio ASIO driver left. The guys over there
told me they wouldn't manipulate the source data either.

If they do some kind of resampling or rather reclocking or buffering when it comes to (latency) jitter reduction or
elimination , I don't have a clue.
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Old 19th October 2006, 11:21 AM   #23
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Quote:
Originally posted by rossco_50
I think 'the dream' is very easily realised.

I posted a link to demudi before (in the open source audio thread, but the less said about that the better). It is a linux distribution optimised for pro audio work, low latency with most of the best and most stable linux audio applications. I have installed it before and used the live cd version, looks promising. I failed to get the live cd to boot off a usb pen, but I know its been done with other knoppix cds. I believe it is possible to strip out applications from live knoppix cd's as well, therefore reducing the amount of space taken up in RAM. SOny have used this in an experiemntal Hifi system. An embedded version for low spec machines is being developed at the moment. There is an Amorak live cd.

I spent a some time trying to find a way of getting all the applications I wanted to boot off a 1gb usb pen, but most live/mini distributions come with a limited repository of applications. Slax was the best I could find as anything in the slackware repository can be used, but this was still missing stuff like brutefir. Plenty of people have succeeded in making modules for slax. I believe this could be done but I lack the expertise at the moment. Slax can also be built from within windows and easily loaded onto a pen drive.

In the end I reached the conclusion that where I would be using a harddrive to store music, I might as well have the operating system on it as well, and save the effort of using the usb drive. might be slightly noisier with more hard drive activity, but there are plenty of cheap silencing external enclosures. Would still be nice to have a mini audio distro on a usb pen though.

Ubuntu is by far the easiest os to configure, you hardly even have to resort to the command line. ubuntu studio has lots of information about setting it up for improved audio performance. You simply remove programs to strip it down.

Good to hear some more positive reports about the emu 1212m. Is the crossover implemented on the cards dsp, or are you doing this in software? Im not sure how easy it would be to implement a crossover through a usb device. I havnt noticed any more than two channels being used in diy, but this may just be preference. more than one usb device would be difficult to sync.

Cheers,

Ross

Ross. Very interesting information.

It seems that more Linux lovers respond to this thread until now.

What I miss is some kind of comparision statement Linux vs XP.

Before I start digging more into Unix, because that'll will absorbe
quite some time, I'd like to post the question:

Can I expect better audio results by using Linux? Why would that
be?

Better process/interrupt handling and real realtime operation as well as minimalistic configurations are some arguments I am aware of. What else?

Still - I don't have a feeling if that's gonna improve the audio quality.
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Old 19th October 2006, 11:27 AM   #24
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I believe the standard windows audio drivers do rate convert audio.

The USB RX in the DAC will buffer samples as USB is bursty in nature. Jitter has nothing to do with the software, thats all down to the clock in the DAC.
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Old 19th October 2006, 11:31 AM   #25
adhoc is offline adhoc  Australia
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soundcheck,

thank you for your reply.

first off, i'm using foobar2k and asio4all - but all this time i've never been able to verify or hear from an external source that i'm doing things 'correctly' and not (unknowingly) resampling or altering the digital sound stream.

right now, i'm streaming USB to a HagUSB usb-to-spdif convertor and then connecting that to to a DAC. the HagUSB uses a PCM2704 to do the conversion, and accepts 44.1/48kHz - right now i'm still in a little fluster as i still have no idea regarding whether my audio is somehow being resampled!

i wasn't trying to 'tell anyone anything', but i was definitely a little unclear - apologies for that!
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Old 19th October 2006, 11:32 AM   #26
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Quote:
Originally posted by thomaseliot


Interesting... Can you explain it better?

Look at these threads. The audio is almost an afterthought. It is more like a dog and pony show for computer weenies. All this wrestling with drivers and refrains of " I had to uninstall Umbongo 4 and reinstall Umbongo 3.8 with the 12 Monkeys patch otherwise it wouldn't run with Django 7". Who else but computer people would think USB is a good way of moving multiple channels or the inside of a computer is the ideal home for a ADC. Compared to the pro world some have used to proclaim the superiority of the PC, it is about as user unfriendly as it could be.
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Old 19th October 2006, 11:33 AM   #27
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ASIO drivers should pass the data through un-touched.
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Old 19th October 2006, 11:39 AM   #28
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Quote:
Originally posted by BlackCatSound
ASIO drivers should pass the data through un-touched.
thanks for that reply!

would there then be any advantage to using the USB driver linked earlier in this thread as opposed to ASIO4ALL for simple playback?
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Old 19th October 2006, 11:49 AM   #29
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Quote:
Originally posted by adhoc
How do you all verify that you all have 44.1kHz non-resampled output via USB?
Play a DTS FLAC file and see if my HT receiver receives it fine.

Works fine with my PCM2902 USB-to-Toslink bodge. I use Winamp with the Directsound plugin and volume control disabled.
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Old 19th October 2006, 11:53 AM   #30
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To make that comparison I feel I would need a decent soundcard that works just as well on both platforms. My audigy is great for its dsp through the Kxproject drivers on windows, but Ive never considered it for use in my listening system and it doesnt sound as good as my cd player. RME would be ideal as they attempt to work just as well on both, but I am not willing to spend this much. Maybe the TI chips work with ALSA, but I have yet to come across anyone doing this.

I dont actually think there is any reason to believe you get better sound quality from linux, it is just the ability to do whatever you want if you have the skills, and a often a helpful community with similar goals. There isnt as much choice as in windows, so you would be through checking out all versions of umbungo quite quickly.

Perhaps rfbrw is right, if a little firey - but soundcheck did start the thread based on listening impressions, and it is me who is getting a bit caught up in the software side of things without offering much in terms of listening impressions. It is a useful thread.

Your experience with J river ramdisk is certainly of interest to me, and perhaps the most useful starting point is to identify problems in your current setup. Perhaps the areas to look at are power supply and grounding rather than software.

But if you want to conduct listening tests, download the demudi live cd, if your usb dac is supported it will be recognised upon boot. No cost and only the time to download and burn the image.

Personally Im not particualrly sold on usb - but have yet to try it. I have never heard anyone say the dddac sounds bad, but there are critics of the design on the forum. Perhaps looking at different DACs in comparision with the DDDac could be a next step. spdif vs usb as well.

Cheers,

Ross
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