I2s vs USB

[vortecjr]

Remember miniDIN?

 

Turns out those guys are still around and still using that connector:)

 

Jesus R

[vortecjr]

Yes but it was adapted by Audio Alchemy and, later by, Sonic frontiers (predecessor of Anthem) for connecting a disc transport with a DAC. One difference between it and USB/Ethernet is that it is not a general data protocol but, specifically, a digital audio protocol with a library of defined formats. I see that as a downside for future development as it requires defined hardware on both ends.

 

Hey, I was a proponent of I2S back in the mid-90s but, with the multiplicity of formats and multichannel, I am not so sure it fits any more.

 

Any solution will require definite hardware on both sides. Multiplicity of formats is not a good reason for calling the demise of i2s. There are several formats of USB and we don't hold that against it. I don't see any issues with i2s/DSD and even with multichannel support. It still fits IMO and is very much in use as is and in combination with USB.

 

Jesus R

[vortecjr]

There is a reason the Sonore Signature Rendu has Crystek CCHD clocks--and it certainly is not so they can be tossed out.

 

Those expensive clocks have dual purpose. The Rendu's input/output board generates the clock signal for output to devices that will use it (my personal DAC is one such example) and it also sends that clock internally to the Rendu's Ethernet to i2s source board.

 

Jesus R

[vortecjr]

Correct. You just proved my point! Every one of those that say Internal Master uses an ESS DAC.

 

Not all devices on my i2s database that use internal master clock use an ESS DAC.

 

Jesus R

[vortecjr]

I have been reading these posts out of cursory interest but find the idea of greater availability of external I2S connections to be rather quixotic.

 

Maybe so. However, I have no regrets.

 

Jesus R

[Kal Rubinson]

Any solution will require definite hardware on both sides. Multiplicity of formats is not a good reason for calling the demise of i2s. There are several formats of USB and we don't hold that against it.

I didn't express myself properly and, to be sure, I am not sufficiently knowledgeable about the technology.

 

I don't see any issues with i2s/DSD and even with multichannel support. It still fits IMO and is very much in use as is and in combination with USB.

Yup. I Googled a bit and found such devices but have not seen them implemented in consumer devices. Are there any that will support multichannel in various formats?

[vortecjr]

I didn't express myself properly and, to be sure, I am not sufficiently knowledgeable about the technology.

 

Yup. I Googled a bit and found such devices but have not seen them implemented in consumer devices. Are there any that will support multichannel in various formats?

 

No problem. By various formats do you mean the connector or i2s verses LVDS i2s?

 

Jesus R

[Kal Rubinson]

No problem. By various formats do you mean the connector or i2s verses LVDS i2s?

I meant audio formats. Is anyone using I2S for multichannel?

[Tony Lauck]

There are sound quality reasons for sending the clock from the DAC to the transport. However, there are operational reasons why this may be more complex. When the clock goes from the transport to the DAC the clock itself conveys format information. When the clock goes from the DAC to the transport, without some other mechanism there is no way for the DAC to know what speed it should operate at. This requires all files to be at the same sample rate, manual intervention on the part of the user to change the "speed" of the DAC when changing formats, or the transport activating a built in real-time sample rate converter. There are cost, performance, and ease of use issues associated with these tradeoffs.

 

USB has the ability to separate control and data and provide two way transmission of clocking and data. This is why it was possible to build asynchronous USB adapters with clocking located at the DAC. Unfortunately, as a packet based system USB uses data rates that are much higher than actually needed for any given audio format, thereby creating bursts of noise associated with packet processing that are in the audio range. (The same benefits and issues apply equally well with respect to Ethernet based connections instead of USB connections.)

 

It would not be technically difficult to come up with a new audio interface standard that addressed all of these issues. However, the key word is "technically difficult". Getting political agreement among manufacturers would be something else, and getting economic relevance in the marketplace would mean a whole new chicken and egg scenario. Hence the present impasse.

 

Incidentally, I do not necessarily believe that I2S represents a good interface technology, because it doesn't address the issue of galvanic isolation particularly well because of the use of NRZ coding and DC balance. Systems using more advanced coding (even the lowly Manchester code) allow for simple isolation via pulse transformers. I2S was designed to be used on a circuit board, not as a mechanism for connecting across separate boxes, let alone our current emphasis on isolation.

[Superdad]

^^^^^ Yay, Tony is here!! :) ^^^ Great post! Spot on.

[vortecjr]

I meant audio formats. Is anyone using I2S for multichannel?

 

Yes. BluRay players, receivers and processors use it for A/V systems. Closer to this forum exaSound uses it, but derived internally from USB.

 

Jesus R

[vortecjr]

There are sound quality reasons for sending the clock from the DAC to the transport. However, there are operational reasons why this may be more complex. When the clock goes from the transport to the DAC the clock itself conveys format information. When the clock goes from the DAC to the transport, without some other mechanism there is no way for the DAC to know what speed it should operate at. This requires all files to be at the same sample rate, manual intervention on the part of the user to change the "speed" of the DAC when changing formats, or the transport activating a built in real-time sample rate converter. There are cost, performance, and ease of use issues associated with these tradeoffs.

 

I had a R$D project to add a clock input to the Sonore Rendu for use with a popular DAC. The clock tracked and lagged the input and it worked fine.

 

Incidentally, I do not necessarily believe that I2S represents a good interface technology, because it doesn't address the issue of galvanic isolation particularly well because of the use of NRZ coding and DC balance. Systems using more advanced coding (even the lowly Manchester code) allow for simple isolation via pulse transformers. I2S was designed to be used on a circuit board, not as a mechanism for connecting across separate boxes, let alone our current emphasis on isolation.

 

I'm not on board with the on circuit board argument. I have a USB to i2s interface and it employs isolation to keep the noisy USB receiver processor at bay. In fact, we take the "asynchronous" signal and we re-clock it because we can reduce the jitter even further doing so. BTW I'm not down on USB...just down on bad USB implementations:)

 

Jesus R

[Kal Rubinson]

Yes. BluRay players, receivers and processors use it for A/V systems. Closer to this forum exaSound uses it, but derived internally from USB.

Again, I was not explicit. Yes, I know well of its use internally as that has been its original application. But, is anyone using it for external links in multichannel?

[Tony Lauck]

I'm not on board with the on circuit board argument. I have a USB to i2s interface and it employs isolation to keep the noisy USB receiver processor at bay. In fact, we take the "asynchronous" signal and we re-clock it because we can reduce the jitter even further doing so. BTW I'm not down on USB...just down on bad USB implementations:)

 

My comment about I2S design is historical. I2S was a chip interconnect standard. It was never intended to be the basis of a digital to mixed signal isolation barrier. An interconnect standard for use on a single circuit board is technically much easier than one that goes between boxes. Most of the complexity of the inter-box interconnect standardization has to do with flexibility and the potential "finger pointing" issues that can arise when separate designs from different vendors are integrated in the field by customers. (I am familiar with these latter issues having done my time on various LAN standards committees.)

[vortecjr]

Again, I was not explicit. Yes, I know well of its use internally as that has been its original application. But, is anyone using it for external links in multichannel?

 

Yes. Pink Faun makes a multi channel i2s solution that you can use with several compatible DACs.

 

Jesus R

[vortecjr]

My comment about I2S design is historical. I2S was a chip interconnect standard. It was never intended to be the basis of a digital to mixed signal isolation barrier. An interconnect standard for use on a single circuit board is technically much easier than one that goes between boxes. Most of the complexity of the inter-box interconnect standardization has to do with flexibility and the potential "finger pointing" issues that can arise when separate designs from different vendors are integrated in the field by customers. (I am familiar with these latter issues having done my time on various LAN standards committees.)

 

I seems to me they left out some intentions or they just weren't possible way back then. Have you even taken apart a cd player? Rarely do you find a single board solution in a box even on audiophile grade gear. Same comment for some audiophile grade DACs. I'm not on a committee, but I have interfaced with just about every kind of USB and i2s device around and by far USB has given me more aggravation. In fact, i2s usually just works and it works very well. I can't speak for others, but my customers are not integrating anything....that's my job. It's my job to coordinate with the others and that takes place behind the scenes.

 

Jesus R

[Superdad]

I seems to me that left out some intentions or they just weren't possible way back then. Have you even taken apart a cd player? Rarely do you find a single board solution in a box even on audiophile grade gear. Same comment for some audiophile grade DACs. I'm not on a committee, but I have interfaced with just about every kind of USB and i2s device around and by far USB has given me more aggravation. In fact, i2s usually just works and it works very well. I can't speak for others, but my customers are not integrating anything....that's my job. It's my job to coordinate with the others and that takes place behind the scenes.

 

Jesus R

 

Great points!

[Kal Rubinson]

Yes. Pink Faun makes a multi channel i2s solution that you can use with several compatible DACs.

 

Thanks. There is no off-the-shelf MCH solution except the MSB Theater Master 8 Channel Hybrid DAC but that's prohibitively expensive. The other solutions involve stacking DACs or building them (Twisted Pear).

[cchang]

Rockna has an interesting approach for their WaveDream Net Transport.

Their digital board can be clock slaved via the eSata port:

 

The AudioByte Hydra-Z USB bridge has a dedicated Master clock output via BNC for PCM and DSD.

I use the HZ to provide I2s for my Directstream DAC, fed from the Aries USB port.

 

Feeding the Rockna Wavedream via I2S by Hydra Z is much more enjoyable sonically than via USB from same "source".

 

The "source" is a Macbook equipped various software players like HQplayer, Audirvana + an Uptone Regen Amber. USB cable where applied is a Light Harmonic 10GHz. But I eventually manage to use solid usb adaptor all the ways.

[vortecjr]

Thanks. There is no off-the-shelf MCH solution except the MSB Theater Master 8 Channel Hybrid DAC but that's prohibitively expensive. The other solutions involve stacking DACs or building them (Twisted Pear).

 

The MSB Network is a bit of a mystery. The master clock is LVDS, but the rest of the signals are not and they don't resemble i2s as far as I can tell.

 

The exaSound multi channel DAC via USB seems like a pretty simple / affordable solution. You can also make a pretty nice system with a Lynx multi-channel card.

 

Jesus R

[Superdad]

Feeding the Rockna Wavedream via I2S by Hydra Z is much more enjoyable sonically than via USB from same "source".

 

The "source" is a Macbook equipped various software players like HQplayer, Audirvana + an Uptone Regen Amber. USB cable where applied is a Light Harmonic 10GHz. But I eventually manage to use solid usb adaptor all the ways.

 

Very nice. Thanks for sharing your set up.

[toddrhodes]

For whatever it's worth, my introduction to I2S in concept comes from Aqua, whose entry-level DAC is in my room. They interface to their "La Diva" CD transport with I2S (via LVDS) over an RJ45 connection. It is for this reason - right or wrong, just my perception at this point - that if they feel that is their "ceiling" with respect to connectivity, that I would want to source a renderer that uses the same output. Looks like if I ever get to purchase a renderer with I2S out, I'll need to do something to convert to the Aqua connection, but I'm sure that'll be a cakewalk compared to saving up for such a renderer

[Distinctive]

Feeding the Rockna Wavedream via I2S by Hydra Z is much more enjoyable sonically than via USB from same "source".

 

The "source" is a Macbook equipped various software players like HQplayer, Audirvana + an Uptone Regen Amber. USB cable where applied is a Light Harmonic 10GHz. But I eventually manage to use solid usb adaptor all the ways.

[ATTACH=CONFIG]20451[/ATTACH]

Nice

Are you considering the Transport as well as a companion for your Rockna DAC when it becomes ready? Then your HZ will be redundant (more or less).

[Kal Rubinson]

The MSB Network is a bit of a mystery. The master clock is LVDS, but the rest of the signals are not and they don't resemble i2s as far as I can tell.

I have inquired of them but not yet received a reply.

 

The exaSound multi channel DAC via USB seems like a pretty simple / affordable solution.

I own one of those but I am always looking for more/other.

[cchang]

Nice

Are you considering the Transport as well as a companion for your Rockna DAC when it becomes ready? Then your HZ will be redundant (more or less).

 

Yes, I wish I could afford the Transport. I simply find the HZ combo (HZ & H ZPM) a better home then.