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MDAC First Listen (Part 00101010)

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JohnW said:
I'm not advocating a solid USB link as the Detox with its soild RF screening will be heavy, I cannot recommend "hanging" it off the rear of a DAC's USB socket.

I "believe" the thinking of the ReGen was to design to be as small and a light as possible so it could be safely hung of the rear a DAC - but to achieve this the designers had no choice but to limit the designs potential (limited PSU filtering, not the greatest clock, no RF filtering etc).

You have to weigh the Pros and Cons of these limitation - while a direct connection is "nice" IMO better RF & PSU filtering is more important.
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John,

Wouldn't it be possible to fit the Detox with USB A plug and USB A socket (as it happens in the Jitter Bug) so that in some cases only one USB cable is needed?
 
radamel said:
John,

Wouldn't it be possible to fit the Detox with USB A plug and USB A socket (as it happens in the Jitter Bug) so that in some cases only one USB cable is needed?
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Let's not do that, using USB B on the device side is a good convention and it allows for easy "detox" bypass if necessary (PC A -> detox B -- detox A -> DAC) or easy plug-in into existing setups (where the DAC has type B).
 
radamel said:
I see no reason for necessarily being A and B as electrically they are exactly the same...

I would definitely prefer A and A (like the jitter bug) in my case.
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Yes, but its strictly frowned upon by the USB standards committee. As a designer is good not to upset such committees... Some battles are worth fighting others not... :)

"Unlike other data cables (e.g. Ethernet, HDMI), each end of a USB cable uses a different kind of connector; a Type-A or a Type-B. This kind of design was chosen to prevent electrical overloads and damaged equipment, as only the Type-A socket provides power. There are cables with Type-A connectors on both ends, but they should be used carefully.[4] Therefore, in general, each of the different "sizes" requires four different connectors; USB cables have the Type-A and Type-B plugs, and the corresponding receptacles are on the computer or electronic device. In common practice, the Type-A connector is usually the full size, and the Type-B side can vary as needed."
 
jirij said:
Let's not do that, using USB B on the device side is a good convention and it allows for easy "detox" bypass if necessary (PC A -> detox B -- detox A -> DAC) or easy plug-in into existing setups (where the DAC has type B).
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Not saying it's not a good convention but it will make you use two USB cables.

With A to A you could have only one.

PC -> Detox -> USB cable-> DAC.

If it could be an option I would have the A to A.
 
JohnW said:
Yes, but its strictly frowned upon by the USB standards committee. As a designer is good not to upset such committees... Some battles are worth fighting others not... :)

"Unlike other data cables (e.g. Ethernet, HDMI), each end of a USB cable uses a different kind of connector; a Type-A or a Type-B. This kind of design was chosen to prevent electrical overloads and damaged equipment, as only the Type-A socket provides power. There are cables with Type-A connectors on both ends, but they should be used carefully.[4] Therefore, in general, each of the different "sizes" requires four different connectors; USB cables have the Type-A and Type-B plugs, and the corresponding receptacles are on the computer or electronic device. In common practice, the Type-A connector is usually the full size, and the Type-B side can vary as needed."
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OK. I understand but I think that it would be a better solution for many who would use it carefully. :)
 
jirij said:
Let's not do that, using USB B on the device side is a good convention and it allows for easy "detox" bypass if necessary (PC A -> detox B -- detox A -> DAC) or easy plug-in into existing setups (where the DAC has type B).
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Yes, being able to directly compare is very useful!
 
ChrisPa said:
Audio over Ethernet

https://en.wikipedia.org/wiki/Audio_over_Ethernet
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Interesting list, however
  • you can discard layer 1 as it doesn't even traverse across switches, so it would be even "worse" than USB in terms of ease of connection
  • AES51 - great, could be used, but ... it's AES3 (SPDIF), not really perfect
  • Audio Video Bridging - looks interesting (but would need to pay $50 to see the full spec), however it seems to be "just" acceleration for RTP and other high level streaming
  • "layer 3" is essentially "layer 5" (ISO/OSI) as it builds on top of a transport layer (TCP/UDP payload), virtually all use RTP for the stream itself
I didn't find anything as "simple" as USB with a feedback channel - there is ie. EtherSound, but that's proprietary / spec not available and is limited to 24b/48KHz. That's kind of a pattern with these custom protocols - they're often fit for one particular purpose (64 channel streaming in this case) and not very useful otherwise. :(

There are basically two ways to implement "DAC over network",
  1. using a custom L2 protocol (above the Ethernet header / 802.11 (wifi) radio header), meaning custom drivers, custom everything
  2. using RTP managed by RTSP/HTTP/etc.
The former can be very fast, efficient, with feedback channel, with custom features (HID emulation), etc. .. but it would need to be developed from scratch by John/Dominik and maintained. The latter has a lot of overhead and has reasonably big buffers, likely doesn't have a feedback channel, but it's very much standard, supported by players, etc., but it cannot be easily used as a generic-purpose DAC ("sound card").

As mentioned before, both have their use cases and advantages, but they're rather complementary, one not being able to fully replace the other (at this point in time), as far as I know.

edit: If one was to implement a network streaming solution closest to what USB does, one should probably go for RTP/AVB. At least Intel seems to be providing drivers and the promise of self-adjusting buffers and low latency being part of the standard seems promising.

jamjar784 said:
As I already mentioned Swiss co Merging Technology make professional recording studio gear and a new DAC based on Ethernet:

This uses the RAVENNA protocol
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RAVENNA is actually not a protocol, it's again (like DLNA) a set of guidelines, it uses RTSP/RTP for the stream itself. It really looks like a copy of DLNA minus a lot of the video stuff. :)

Richard Kimber said:
This doesn't mention UPnP which I guess is mostly used in domestic systems.

https://en.wikipedia.org/wiki/Universal_Plug_and_Play

- Richard.
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UPnP is a generic autoconfiguration / discovery "protocol" (actually again a set of protocols), not really tied to audio streaming in any way. It can be used for anything like printer discovery on a network, to automatically forwarding a port on your router (for computer games), to ie. discovery according to DLNA. It's "just" a convenience protocol, all the stuff it does can be done manually.
 
Can we postpone the A/B connector discussion until we know the Detox's dimensions?

Direct connection to Host or DAC might not be possible if it's to big.
 
fusion5 said:
Can we postpone the A/B connector discussion until we know the Detox's dimensions?

Direct connection to Host or DAC might not be possible if it's to big.
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It will definitely be too big for direct connection, maybe I should say too heavy...
 
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