Announce: Enhanced Digital Output app - USB Dac and 192k Digital Ouput
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Musical Fidelity V-Dac II
Does someone had this to work for a Musical Fidelity V-Dac II ? Unfortunately I can't get it to work.Comment
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Ok, just checked sample rate with 192 material. Appears it is still playing it at 44.
What's the maximum bit rate the usb interface will play and will it down-sample automatically?
Also, how does one remove the app to install the hub interface version?
Do I need a hub to play anything above 44?
Is there a way to check sample rate using coax?Last edited by CAK1; 2012-04-18, 19:24.Comment
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No idea - the hub is specifically recommended to work around what looks like a limitation of the Touch hardware - you can't extrapolate to other devices but it may be worth worth trying.Comment
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Ok, just checked sample rate with 192 material. Appears it is still playing it at 44.
What's the maximum bit rate the usb interface will play and will it down-sample automatically?
Also, how does one remove the app to install the hub interface version?
Do I need a hub to play anything above 44?
Is there a way to check sample rate using coax?Comment
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There seems to be some confusion about USB audio connections and what works with what etc. I'm going to try and clarify this and explain how these relate to the EDO applet.
There are two speeds that USB DACs can run at: full speed and high speed.
Full speed: 12 mega bits (Mb) per sec. Max sample rate is 96KHz.
High speed: 480Mb/s, supports 192KHz and up.
There are two generic "protocols": USB Audio Class (UAC) 1.0 and UAC 2.0
UAC1.0 was the original which came out before high speed mode was invented, thus it does not support high speed mode, thus it is limited to a max 96KHz sample rate.
UAC2.0: supports both full speed and high speed, DOES support 192 (but only at high speed), multi channel etc. All DACs that use UAC2.0 do so in order to run at high speed and support 192. Some of these will "downgrade" to UAC 1.0 and full speed if the DAC is plugged into a computer that does not support UAC2.0
There are two "modes" in common use: adaptive and asynchronous. In adaptive the DAC has to change the frequency of its internal clock to match the average data rate of whats coming over the USB bus. In asynchronous the DAC uses a fixed frequency clock and tells the computer to slow down or speed up the data transfer rate. Asynch can theoretically sound better.
Any particular DAC will have a mix of these. There are some combinations that don't seem to get built: all the implementations I know of that use UAC2.0 are also Async, and I don't know of any DACs that run UAC2.0 and just full speed. Async can exist in both UAC1.0 and UAC2.0.
So how does this relate to EDO?
There seems to be a bug in the Touch hardware that prevents async from working properly when running at full speed. In this case you need the USB 2.0 hub which talks to the Touch at high speed, but talks to the DAC at full speed. This gets around the bug in the Touch. This is only needed for an async full speed DAC. An adaptive full speed DAC or a high speed DAC of any type can be used without the hub. Thus if your DAC is a full speed only DAC (ie has a maximum sample rate of 96KHz) and you get ticks and pops, it is probably running using async mode and will need the hub to work properly.
Any other DAC does not need the hub to work properly. But should still work even if you do use a hub.
Thus if your DAC supports 192, you do not need the hub. If your DAC only goes up to 96KHz, it may or may not need the hub.
In all these cases the DAC must be plugged into the Touch and turned on before the Touch is booted. This process will tell the server what the maximum sample rate of the DAC is, thus it should automatically downsample in the server only if the DAC does not support the sample rate. (of course this assumes that the DAC is honest about what it tells the Touch)
Now just to complicate things a little bit, EDO supports a "work around" that will let SOME full speed async DACs to work with out a hub, but in this case it ONLY works for 44.1 and 48KHz. Most people are probably better off not even thinking about this and just use the hub.
In addition to all this USB stuff EDO includes a new S/PDIF driver that will go up to 192. This is completely sperate from the USB stuff, but Triode was playing with the driver and wanted to get it to run at 192, so he included it in EDO.
I hope this helps a little in clairifying things.
John S.👍 1Comment
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To add to John's post above - when you select a usb dac, the app will provide an additional menu level in the case when you probably need a hub. This menu offers you the option of enabling the workaround or saying you will add a hub. If you don't see this menu then you don't need a hub.. It is only shown if you select a directly connected full speed async dac.
So the simple option is to try it and purchase a hub if the app recommends you need one.Comment
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Thanks JohnS for the clarification, and again to Triode for doing what Logitech should probably already have done. The recent price drops for the SBT on amazon uk (£139!!!) led me to believe that there'd be a newer one with 192 just around the corner, hence the lack of desire to offer it to us SBT1.0 users. No sign yet...Comment
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To add to John's post above - when you select a usb dac, the app will provide an additional menu level in the case when you probably need a hub. This menu offers you the option of enabling the workaround or saying you will add a hub. If you don't see this menu then you don't need a hub.. It is only shown if you select a directly connected full speed async dac.
I get the menu option regarding enabling the workaround/adding a hub even though I am using a high speed async USB DAC (Cambridge DacMagic 100). Whenever I make the selection the Touch reboots a second time and then connects at high speed.
If I'm reading what you've posted correctly, I don't think I should be getting this message? Thanks.Comment
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Hi Triode
I get the menu option regarding enabling the workaround/adding a hub even though I am using a high speed async USB DAC (Cambridge DacMagic 100). Whenever I make the selection the Touch reboots a second time and then connects at high speed.
If I'm reading what you've posted correctly, I don't think I should be getting this message? Thanks.Last edited by Triode; 2012-04-18, 23:17.Comment
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Thanks, I am keeping an eye on this
Hum - please report again and if possible let me know what dmesg says if it gets into this state.
The issue we have is that the squeezeplay application and LMS expect the output device to be present when Touch is powered up - this is when things like the max sample rate are reported to the server. Hence Touch only really finds the dac when restarted. What I added to this release is something which means that Touch keeps polling a usb dac which has be turned off to see if it returns. This works for short periods, but it may be that it doesn't work after a longer period - in which case I would be interested in any observations you have.
If we could make more significant changes to squeezeplay then it may be easier to work around this, but it requires changes to the Logitech firmware if full features are to be supported.
I do appreciate the hard work you put into making this EDO app and improving upon previous releases!----------------------
"Dreamer, easy in the chair that really fits you..."Comment
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Any sonic benefits going the USB route rather than digital coax out from Touch to digital coax in on DAC?
That still leaves stereo analog outs viable and also USB port available for external HDD.
Only thing worthwhile would seem to be USB or digital/optical coax out from Touch to 24/192-capable DAC.Shephard: "You're taking a gun with you to see your mother?!"
Faraday: "You don't know my mother..."Comment
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