[miceblue]

"Floating ground isn't new stuff and I don't think it has anything to do with the USB 2.0 specifications."

You're 100% wrong, and you can only think as you do because you haven't actually read the standard.

Go to usb.org, http://www.usb/developers/docs/usb20_docs/

download the 2.0 Zipfile

Read page 141-142

Also read page 148, document name usb_20. pdf  figure 7-1

This clearly shows a High Speed USB Tranceiver (transmit/receive circuit; clearly shown is that items must be referenced to ground)

These resistors are in downstream (DAC for audio devices) and the ground is system ground (read PC ground)

Also, from page 142 (pdf page)  "6.8 USB Grounding:  The shield must be terminated to the connector plug for complete assemblies.  The shield and chassis are bonded together.  The user selected grounding scheme for USB devices, and cables MUST (my emphasis) be consistent with industry practices and regulatory agency standards for SAFETY (my emphasis again) and EMI/ESD/RFI."

In other words, there is an implicit requirement to 'do as everyone else'......which is why it is a STANDARD.

Now honestly, it really is black and white, grounded or ungrounded, right and wrong, there is no ambiguity whatsoever.  The LH device does NOT follow the accepted standard, and this is the only reason there are any incompatibility issues.

Supporters of LH should be directing their comments to LH about this, rather than dismissing legitimate concerns about both the product itself, and the way other manufacturers are actually being blamed for making components which are following an accepted industry standard.

1) that link doesn't work
2) whatever PDF you have, it's not the same as mine so the pages and references are all screwed up
3) "This clearly shows a High Speed USB Tranceiver (transmit/receive circuit; clearly shown is that items must be referenced to ground)

These resistors are in downstream (DAC for audio devices) and the ground is system ground (read PC ground)"
I thought these were transmitter/receiver USB ports, what if the Geek LPS does that? Only the output is a floating ground, not the input.

 

[AxelCloris]

To be fair, I have posted criticism on the LH forum, and haven't been banned, pulled off, or had negative consequences. Depends on the level of animus and the reasonableness of the complaint, I suppose.

 
I believe that you're right. A lot of us have posted criticism on both their forums and here without being banned. I think as long as the criticism is just that and not an outright attack against specific members of the LH Labs crew, most often Gavin and Casey it seems, then it's adding something to the topic. Criticism should always be welcomed because the feedback can be used on future ventures if it can't be used immediately.
 
A good example is the survey for the Wave. The Pulse survey was, let's face it, a bit more sloppy than many would have liked. They took that feedback and tried something different with Manny sending out confirmations manually. Now that seems to have faltered and instead of going back to the survey system they already have in place from the Pulse they're working on a new one to try and improve the experience. It's definitely taking time and that's only agrivating the more vocal members further but it's progress. As a backer I like seeing that progress, even if it is slower than I'd prefer. I'm more forgiving of someone making progress at a slower pace than someone sitting on their thumbs and using the same method known to have upset their audience in the past.
 
I've said my piece on crowdfunding and backing many times so I won't bother repeating it for everyone again. But suffice to say, people should be providing feedback and criticism rather than name calling and slandering. Simply saying "I want it now" adds nothing to the discussion, but providing possible methods LH Labs could use to get the parts they need around the strike in the bay helps. Even if they choose not to go that route, it's given them another option to consider.

 

[nudd]

This is only true if you are a day one super early backer though. What if you were a backer at the much higher price points or even the forever funding campaign? These people expected designed, feature complete devices (although I suspect the number of people willing to pay full retail to LHL without being able to transfer warranty or have immediate access to available product us equal to or close to zero).

Later on the LPS alone became offered at around 480.

At the very least they need to tell people their device does not work with all USB DACs (because the LPS itself does not conform to USB standards(?)).

I would have thought the easy solution is to include a ground lift switch for the next version.

Finally it is entirely possible to provide good quality isolation without these issues. Schiit appears to be able to do it with the Wyrd and iFi with the iUSB.

I own both. The Herus could not beat the ODAC as my portable DAC solution but the Geek Out 450 and SE are both better in terms of resolution, dynamics, and timbre. The Herus sounds like **** and Sabre treble grain and harshness is pretty bad. Plus it sounds soulless with mediocre dynamics.

With regard to LH, the thing is, I can acknowledge they made a mistake thinking their LPS would work with every audio device, but jeez, USB support is dicey. I've used the LPS with everything from a mouse to a printer and most devices work just fine. It's only some of my audio devices that take a crap.

It's one thing to buy a production product at MSRP and throw a **** fit when it doesn't work as expected, its another to back a crowdfunding campaign with the promise of a preproduction accessory then raise up pitchforks when a secondary benefit isn't universally compatible with all the weird USB devices out there.

Regardless, I will say I can live with weirdness given the price I paid for the products I've received and how well they perform. When the Pulse + LPS cost me less than $500 combined and end up being a better DAC than the X-Sabre that was in my system previously, I consider it a win.

I think the thing I find amusing is that there is risk associated with this venture from a backer perspective. Looking at all the possible risks, the outcome of a small, well designed linear power supply arriving late to my door that provides a noticeable improvement on the stock unit is a pretty good one for me.

 

[boxinghris]

  You've shown up here recently, intent on really driving this issue home. I consider Larry and Gavin's video to be their word on the subject, and nowhere in the video do they mention "inferior designs." Larry mentions recognizing a connection by sensing the differential pair rather than referencing signal to ground, and says he does not think that referencing the ground is the best design practice. "Inferior designs" are your words not his.

If I wanted to suggest that "inferior designs" were Larry's words, I'd have written "inferior designs" between quotation marks, as you did and as I've repeated.
 
No, I said "we have been led to believe that other DACs which are not compatible with an LH product are inferior designs" which is my understanding of what he says in the video, a direct quote being "...we found that these incompatible USB devices, they don't use the USB differential pair to recognise the signal, they refer to the ground.  Actually if you ask me, I don't think that is good practice..."
 
So, is Larry leading us to believe that the incompatible USBs are superior, as good as, or inferior designs?

 

[boxinghris]

1) that link doesn't work
2) whatever PDF you have, it's not the same as mine so the pages and references are all screwed up
3) "This clearly shows a High Speed USB Tranceiver (transmit/receive circuit; clearly shown is that items must be referenced to ground)

These resistors are in downstream (DAC for audio devices) and the ground is system ground (read PC ground)"
I thought these were transmitter/receiver USB ports, what if the Geek LPS does that? Only the output is a floating ground, not the input.

Try this:  http://www.perisoft.net/engineer/usb_20.pdf

 

[DiscoSmoke]

  If I wanted to suggest that "inferior designs" were Larry's words, I'd have written "inferior designs" between quotation marks, as you did and as I've repeated.
 
No, I said "we have been led to believe that other DACs which are not compatible with an LH product are inferior designs" which is my understanding of what he says in the video, a direct quote being "...we found that these incompatible USB devices, they don't use the USB differential pair to recognise the signal, they refer to the ground.  Actually if you ask me, I don't think that is good practice..."
 
So, is Larry leading us to believe that the incompatible USBs are superior, as good as, or inferior designs?

I think it is you that is doing the leading. I'm done.

 

[boxinghris]

  I think it is you that is doing the leading. I'm done.

You're free to think as you wish, regardless of the evidence.   

 

[miceblue]

1) that link doesn't work

2) whatever PDF you have, it's not the same as mine so the pages and references are all screwed up

3) "This clearly shows a High Speed USB Tranceiver (transmit/receive circuit; clearly shown is that items must be referenced to ground)


These resistors are in downstream (DAC for audio devices) and the ground is system ground (read PC ground)"

I thought these were transmitter/receiver USB ports, what if the Geek LPS does that? Only the output is a floating ground, not the input.

Try this:  http://www.perisoft.net/engineer/usb_20.pdf

Ah, yup that link works just fine. Thanks for that.

For those page numbers, are you talking about the PDF page number (which includes the table of contents and all of that stuff), or the document's page numbers (which excludes the ToC)? I was reading pages 141-142 and page 148 as the document page numbers.

By PDF page number, pages 141-142 are USB cable specifications and tests:
"6.7 Electrical, Mechanical, and Environmental Compliance Standards
Table 6-7 lists the minimum test criteria for all USB cable, cable assemblies, and connectors."

Page 141 has the test procedures for "Propagation Delay Skew" and "Capacitive Load Only required for low-speed"
Page 142 has "6.7.1 Applicable Documents", "6.8 USB Grounding", and "6.9 PCB Reference Drawings"
For part 6.8, it says:

The shield must be terminated to the connector plug for completed assemblies. The shield and chassis are bonded together. The user selected grounding scheme for USB devices, and cables must be consistent with accepted industry practices and regulatory agency standards for safety and EMI/ESD/RFI.

Shield ≠ power ground

Page 148, figure 7-1 has an example circuit. That doesn't mean all USB devices has to look like that.

Figure 7-1 depicts an example implementation which largely utilizes USB 1.1 transceiver elements and adds the new elements required for high-speed operation.

The HiFimeDIY USB Isolator does the exact same thing as the Geek LPS with regards to floating ground:
http://hifimediy.com/usb-isolator

The isolator will create a new ground for the USB device so that it doesn't have to share ground with your computer and other devices you might have connected in the same house.

OOOOOH NOOOOO! They don't follow the USB 2.0 "specifications"! Let's go bash on them now.


http://www.audiostream.com/content/qa-john-swenson-part-2-are-bits-just-bits

So how do we keep all this noise from the USB receiver from getting to our sensitive DAC circuits? It’s called ground plane isolation. You have separate ground planes for the USB receiver and the rest of the DAC circuitry. This DOES prevent ground plane noise from crossing over. BUT if you cut the ground plane there is no way for the return current from the signals crossing the boundary (the I2S signals and clock etc) to get between the “ground domains”. The solution is digital isolators. There are many different technologies to choose from, one most people are familiar with is opto-couplers. Some of these actually add huge amounts of jitter to the signals going through them so are bad choices for our purposes.

A signal from the receiver now has a return current coming from the isolator so it’s happy. On the other side of the boundary there is a return current to the DAC circuitry so it is happy. BUT any jitter on the signal coming out of the isolator is STILL creating ground plane noise with a spectrum related to the jitter it had on the other side of the isolator. In addition it is containing jitter related to the isolation scheme as well, and some of THAT jitter is ALSO related to noise on the ground plane on the receiver side.

So again the ground plane isolation and signal isolators can decrease the jitter and noise going from the USB receiver to the DAC circuits, BUT they cannot eliminate it. Some always gets through.

Looks like the iUSBPower also has a floating ground. Better go attack them too:
http://ifi-audio.com/portfolio-view/micro-iusbpower/

Our engineers developed the advanced IsoEarth technology specifically for the iUSBPower. By breaking the noisy DC ground connection between the computer and your USB audio device, this further reduces the ground noise by a factor of 10.

That device is also "Hi-Speed USB certified." Must be fake marketing because they break the connection to PC ground, which is "clearly" going against USB 2.0 standards.

Differential signalling has no reference to anything, it sends data signals of opposite polarity on the two data legs to the receiver and it adds the signals together. This is what the Geek LPS does as a transmitter to the attached USB DAC. Larry was saying some USB DACs require a reference ground voltage for single-ended signalling, which sends data signals on one data leg, a reference ground signal on the other data leg. The LPS doesn't transmit a reference ground through one of the data legs by design, which is possibly the reference ground signal from the PC's data leg and is the ground signal the LPS is trying to isolate the attached USB DAC from.

 

[evillamer]

difference is ifi allows an easy toggle switch to change between usb grounding or floating ground while geek lps does not currently and geek lps is advertised to be working with all usb dacs.

 

[miceblue]

difference is ifi allows an easy toggle switch to change between usb grounding or floating ground while geek lps does not currently and geek lps is advertised to be working with all usb dacs.

That's true, and I agree with that. One of the comments in the YouTube video said if it was possible to implement a switch for floating/non-floating ground and Larry commented that it was possible.
Commenter:

Can't you just update the design with a ground toggle/jumper switch?

Larry:

Larry Ho
1 day ago

Yes. That is possible.

 

[evillamer]

difference is ifi allows an easy toggle switch to change between usb grounding or floating ground while geek lps does not currently and geek lps is advertised to be working with all usb dacs.

That's true, and I agree with that. One of the comments in the YouTube video said if it was possible to implement a switch for floating/non-floating ground and Larry commented that it was possible.
Commenter:

Can't you just update the design with a ground toggle/jumper switch?

Larry:

Larry Ho
1 day ago

Yes. That is possible.

I felt Larry is always very honest and upfront in his videos and in his replies, however I don't feel the same for the rest of the team.

 

[mscott58]

I felt Larry is always very honest and upfront in his videos and in his replies, however I don't feel the same for the rest of the team.

Having been a technical person (scientist and engineer) and a business person (consultant, operator, entrepreneur) I do have to say that if you let the technical people make the business decisions then most of the businesses would not be around too long. Nothing against them, it's just a total different world. This also means a lot of the "messy" decisions fall onto Gavin's head, while the "cleaner" technical decisions go to Larry - so he comes out looking better. They're both good guys and they've both made mistakes in these campaigns (heck knows I have in leading my company as well) but I do feel that the frame of reference is different enough to call out. Cheers

 

[miceblue]

I felt Larry is always very honest and upfront in his videos and in his replies, however I don't feel the same for the rest of the team.

Having been a technical person (scientist and engineer) and a business person (consultant, operator, entrepreneur) I do have to say that if you let the technical people make the business decisions then most of the businesses would not be around too long. Nothing against them, it's just a total different world. This also means a lot of the "messy" decisions fall onto Gavin's head, while the "cleaner" technical decisions go to Larry - so he comes out looking better. They're both good guys and they've both made mistakes in these campaigns (heck knows I have in leading my company as well) but I do feel that the frame of reference is different enough to call out. Cheers

Hahaha...that reminds me so much of this video. XXD

[video]https://www.youtube.com/watch?v=BKorP55Aqvg[/video]


It's okay, you're an expert!

 

[mscott58]

Hahaha...that reminds me so much of this video. XXD

[video]https://www.youtube.com/watch?v=BKorP55Aqvg[/video]


It's okay, you're an expert!

Love that skit! Thanks

 

[Dithyrambes]

Lol this thread is just Lol. Thx guys for reminding me to never do crowdfunding ^^. Sounds like a mess. LH Labs sucks. If they could only deliver without making so many promises. Like how delayed has the Pulse been and they find all these errors now? Have they been sitting on their As* spending all the money having fun? How the hell is the pulse's msrp 999? I seriously think they should get real, because no one is gonna buy anything above or even at campaign prices with this crap they pulled. I still find it funny people who fall into backing even more money, after this mess. I feel they will follow this vicious cycle of campaigns to stop the company from going bankrupt. I would laugh if they file bankruptcy and a lot of people don't get their stuff.....with their logic.....Because you guys all decided to be backers, and there was no guarantee of anything, we aren't at fault. You guys chose to be in the campaign and we failed. LOL All arguments here are stupid. Their overpriced LPS and other stuff should just ******** work? how can anyone make any excuses if the product doesn't do its job. Its like buying a new Tesla, and the first day you ride it the engine pops, you have mechanical failure in the battery supply, and the Car interface has problems. But its ok because you got the "best" thing in a car for "cheap". Its ok because all other gasoline cars are inferior by design. LOL Don't see Tesla doing business like that. No matter how many puppy faces Galvin puts on or Larry, they should stop making excuses and just apologize, and either refund everyone who wants their money back, or provide free upgrades to show gratitude for people who are currently in the campaign. The fact that they refuse to give refunds back shows their lack of confidence and inability to deliver. People should be clamoring over their stuff, if it really is that good.