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Author Topic: Alternative transports to USB/PC or 'Spinning a disc'?  (Read 7864 times)

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Hands

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Re: Alternative transports to USB/PC or 'Spinning a disc'?
« Reply #140 on: August 17, 2015, 08:06:03 PM »
Haha, I'll take your word for it.
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Azteca X

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Re: Alternative transports to USB/PC or 'Spinning a disc'?
« Reply #141 on: August 17, 2015, 08:55:47 PM »
Quote from: madaboutaudio on August 17, 2015, 07:26:35 PM
USB 2.0 full speed galvanic isolation

I'm pretty sure I've heard Jason from Schiit say this doesn't actually exist.
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madaboutaudio

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Re: Alternative transports to USB/PC or 'Spinning a disc'?
« Reply #142 on: August 17, 2015, 09:14:33 PM »
Quote from: Azteca X on August 17, 2015, 08:55:47 PM
I'm pretty sure I've heard Jason from Schiit say this doesn't actually exist.

Maybe Jason can be wrong(times have changed too, Bill Gate's 640k comment anyone?) Or Rockna/Audiobyte found a nifty engineering method to do so.

Quote (selected)
A 5KV isolation barrier is used to prevent any leakage of the noise from PC to your sensitive audio system. The USB isolation for audio devices is nothing but tricky. If you choose to use USB isolators, then sample rate will become limited, which is not an option. If you choose to isolate the output, you are adding significant amounts of jitter to the signal. By using a clever circuit topology, the Hydra design avoids these two bottlenecks. The isolation is placed between the ARM processor and the FPGA audio core, therefore not limiting the bandwidth. Being before the clocks, its jitter contribution becomes irrelevant.

http://headmania.org/2015/04/23/audiobyte-hydra-z-review/

In order to support anything above 24/96, you need USB2.0 speeds

Quote (selected)
USB Audio Class 2 standard (2009)
It is downwards compatible with class 1.
USB Audio Class 2 additionally supports 32 bit and all common sample rates > 96 kHz
Class 2 uses High Speed (480 MHz). This requires USB 2 or 3.
As the data rate of High Speed is 40 X Full speed, recording a 60 channel using 24 bits at 96 kHz  (132 Mbit/s) is not a problem.
From mid-2010 on USB audio class 2 drivers are available in OSX 10.6.4 and Linux.
Both support sample rates up to 384 kHz.
It is unclear if Microsoft is going to support USB Audio 2.
You need a third party USB class 2 driver on Windows.
Companies like Thesycon or Centrance have developed  a USB Class 2 Audio driver for Windows.
Using High Speed USB for playback  there are no limits in resolution.

http://www.thewelltemperedcomputer.com/KB/USB.html
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DaveBSC

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Re: Alternative transports to USB/PC or 'Spinning a disc'?
« Reply #143 on: August 18, 2015, 01:14:24 AM »
Quote from: Azteca X on August 17, 2015, 08:55:47 PM
I'm pretty sure I've heard Jason from Schiit say this doesn't actually exist.

There's some disagreement about what is and isn't galvanic isolation. The Berkeley Alpha USB uses an Analog Devices ADuM chip - an opto-isolator, to separate the noisy incoming path and the USB receiver section which is bus powered, from the output section which is internally powered.

Steve from Empirical Audio believes he can do one better than the Berkeley folks. The upcoming Off-Ramp 6 is switching to an XMOS interface similar to the Alpha USB, and unlike the Off-Ramp 5, it requires some bus power in order to function. In order to deal with the incoming noise, Steve has implemented some type of galvanic isolation, though I'm not sure he's gone on record yet as to what exactly it entails. It would therefore be news to him that GI on high-speed USB 2.0 "doesn't exist."
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keanex

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Re: Alternative transports to USB/PC or 'Spinning a disc'?
« Reply #144 on: August 18, 2015, 01:42:47 AM »
Quote from: madaboutaudio on August 17, 2015, 07:26:35 PM
Anyone tried audio byte hydra z? I recall in an old 6moons article that audiobyte designer designed the MSB digital audio interface. Hydra Z features USB 2.0 full speed galvanic isolation with dsd512 support and femto class clocks, bnc,coax,aes. It should pair up nicely to Yggdrasil via AES I guess.
G wizz, a full USB 2!? Wow Mister all of that stuff sounds super fancy and super expensive, I'm sure it's worth the money! Buy it!

Edit: Like seriously what the fuck? Are products being released in 2015, let alone 2008, that advertise USB 2.0 as a selling point? Holy shit, no wonder these products sell at the crazy prices they do.


Edit: I should probably not post while drinking because I'm sure to share how fucking stupid all of this transport nonsense is. But hey man, I've got a CD transport I'll sell for $10,000, it's fully...uh protected from martian harm and sun rays. And let's REALLY talk about 24 bit audio, ROFL. Jesus fuck.
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madaboutaudio

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Re: Alternative transports to USB/PC or 'Spinning a disc'?
« Reply #145 on: August 18, 2015, 01:50:49 AM »
There's plenty of measurable(as well as audible to some with trained ears) noise in USB:
http://archimago.blogspot.com/2015/05/measurements-usb-hubs-and-8khz-phy.html
http://archimago.blogspot.sg/2015/05/measurements-corning-usb-3-optical.html

There's a reason why Mike Moffat dislikes USB. Because it still doesn't sound as good as a dedicated transport.
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keanex

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Re: Alternative transports to USB/PC or 'Spinning a disc'?
« Reply #146 on: August 18, 2015, 01:53:50 AM »
OK
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madaboutaudio

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Re: Alternative transports to USB/PC or 'Spinning a disc'?
« Reply #147 on: August 18, 2015, 02:08:45 AM »
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BassDigger

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Re: Alternative transports to USB/PC or 'Spinning a disc'?
« Reply #148 on: August 18, 2015, 02:36:33 AM »
@keanex

Sure, there's a lot of snake oil and profiteering in this industry. Maybe some of these knowledgable folk can help us avoid some of it.

But, before that: get some sleep.  :)p5
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DaveBSC

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Re: Alternative transports to USB/PC or 'Spinning a disc'?
« Reply #149 on: August 18, 2015, 03:00:39 AM »
Among the various digital connection methods (I2S, AES/EBU, S/Pdif via coax, Toslink, ST glass fiber, FireWire, and USB) USB is uniquely ill suited for streaming audio. The FireWire protocol is actually much better for audio than Isochronous mode USB streaming, which is why Weiss was so resistant to using USB instead of FireWire for such a long time.

You've got a very noisy ground path, a very noisy powerline loaded with DC ripple (500mV+ from a typical motherboard USB port) and a data connection that streams whenever the CPU can be bothered to get around to sending it, not necessarily when the DAC might want it. If you were designing a digital streaming connection from scratch, USB is pretty much the worst thing you could possibly come up with.

Slowly but surely over the years, designers and engineers have figured out how to work around the problems, starting with asynchronous mode, adding electrical isolation, etc. With a well designed input, and a computer with a well designed dedicated output card as opposed to a standard shared bus port, in my experience you can match or exceed the performance of most conventional digital transports with a computer and USB.

And yes, you can say "digital is digital its all 1s and 0s bit-perfect LOLLOLOLOLOL" all that says to me is "I don't know what I'm talking about."
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