[Blu99Zoomer]

Hi All,

I have been having an interesting exchange with a consumer audio products tech rep about why I could play music from my iPhone 5 into my stereo system through a $99 Schiit Wyrd "http://schiit.com/products/wyrd" and couldn't through their $800 plus linear power supply "http://marketplace.lhlabs.com/products/linear-power-supply".  Both products work very well when I use my computer as the player by the way.  Their most recent comment concerned the "floating ground" concept.  "This would be a floating ground issue. The DAC you are using would need the LPS to ground to the board. Our LPS units stay floating to remove any unwanted noise to our DACs. We cannot ensure interoperability with other manufacturers because we do not know how they treat their USB grounding."

I get one of those"your Benchmark 2.0 DAC2 HGC draws too much to play well with our phone" pop ups when I try to play music from my phone.  Is this a "floating ground" issue really?  Or is it really a "We cannot ensure interoperability with other manufacturers" issue?  I am getting a "BS warning" from my brain even though the idea of "floating ground" is an interesting one.

Best Regards,

Blu99Zoomer

[JohnR]

Well, the simple solution would be to just use the Wyrd.

[Davey]

+1 on John.
And, I would see if I could get my $800.00 back. 
My goodness.

Dave.

[Blu99Zoomer]

lol.

You guys are both right. More than once I have wished to "get my money back".  "A fool and his money..."and all that.  I am happy to use the Wyrd for those few times I want to plug my phone into my stereo.  They both clean up the sound coming from the computer very nicely.  I seem to have a blacker, quieter background.  Real or imagined I am not sure which.  But I like what I hear using them.  Being a lay person,  I am just curious is all.  Is floating ground the why that one works while the other doesn"t?

Blu99Zoomer

[Davey]

I'm not sure I understand what the (conceptual) difference is between the Schiit and the LPS.  It seems they both do (functionally) the same thing and provide an alternate power source.  I believe the Schiit would have a "floating ground" also.

Anyways, I think the term "floating ground" is an oxymoron.  "Ground" should be referenced to the ground (earth) in some way.  When it's "floating" it's no longer a ground, but now some sort of alternate "reference" that could be at any potential relative to a real "ground" or ground. 

Cheers,

Dave.

[ctviggen]

It does seem like an oxymoron, but also makes sense.  Everything is still "grounded", it's just that the "ground" is at a different potential and unconnected to the "building" ground (assumed to be connected to earth), and therefore "floating".  You have to think about a "ground" as in a point of reference for potential. 

As for USB grounding, isn't that defined by a specification?  Of course, then you'll have to get into the gory detail about what's "grounded". 

[Blu99Zoomer]

Thanks to all who have responded. 

I really don't want to grind this grounded discussion into the ground , whether or not it is floating or fixed .  Hmmm.  But I would like to understand when a fixed ground is appropriate and when a floating ground is.   I believe a ground in the traditional sense as ctviggen points out does return the signal or charge safely to the earth.  That's an important safety feature.  I get that part.  When one designs a circuit, the option of having a floating ground depends on the amount of current circulating through it?  After watching my brother jump when I touched him then touched the electric fence around the cow pasture, I understand 6 volts can be more than enough juice circulating in a circuit.  Wet bare feet make a really great ground.  I get that too.  So the amount of energy circulating does not have to be a lot to present a need for an earth based ground and safety or isolation of noise, my brother's or audio/electrical.  So is Apple trying to protect its circuits electrically by allowing only certain usb connections?

I know the two devices I mentioned provide a cleaner usb signal to the receiving DAC.  The LPS also is a linear power supply.  The Wyrd is just an isolation device if just is the correct term(?).  It has its own linear power supply.  Maybe it does provide power to the DAC.  I don't know at this point.  I may have to look at the usb specification...But I thought that both products would provide the isolation needed for the iPhone 5 to be used safely.  There must design differences in the respective circuits?

Anyway, thanks again for your thoughts. 

Best,

Blu99Zoomer

[JohnR]

I'm not sure it's anything to do with the ground. IIRC at one point LHL claimed that some devices connected one of the data lines to ground, or something along those lines. However the error you get on your phone is too much power. If you look at this page here:

http://www.beyondlogic.org/usbnutshell/usb5.shtml

And search for bMaxPower, this is the current that the device says it wants to use (in mA, divided by two). So my guess is that the LPS is passing this value straight through to the upstream device, whereas the Wyrd will send 0 to the upstream device. The phone therefore thinks it can't power the Benchmark via the LPS. Although... why the Benchmark would say it uses USB power when it's self-powered is a bit of a mystery though... which sorta ruins that theory...

um, if you connect the phone directly to the Benchmark, does it work?

[Davey]

It does seem like an oxymoron, but also makes sense.  Everything is still "grounded", it's just that the "ground" is at a different potential and unconnected to the "building" ground (assumed to be connected to earth), and therefore "floating".  You have to think about a "ground" as in a point of reference for potential. 

I think that's what I said.   

Anyways, there are plenty of "points of reference for potential" inside electronic gear that aren't grounds....or even floating grounds.  When you start having to put quotation marks around terms it's clear there is confusion. 

Good post by JohnR regarding USB reporting to devices.

Regardless, of how "floating" or not "floating" the "ground" is in the LPS, it's a horribly expensive gadget for such a simple job.  The primary objective seems to be to separate audiophiles from their money.  I have little tolerance for products like that.

Dave.

[Blu99Zoomer]

Thank you to John for the nice link.  I have some more reading to do now...

Thanks too Dave for the primary objective observation.  I do really appreciate the sympathy.  I agree that for some merchants that may be their goal.  Thankfully there are some serious builders who care about putting out high quality products first and making $$ comes because of their commitment to quality.  I should have known better when I got involved at the floating grounded, purchase point.   Better to be an informer consumer.

It is possible to fool an iPhone 5 and an iPad with a Dr Bot T3 usb hub.  I did both at a recent head-fi meet in NYC to very pleasurable results.  Unfortunately the Dr Bot is no longer available for sale.  Back to my reading.

Best,

Blu99Zoomer

[Blu99Zoomer]

That being said, I do believe that LH Labs is committed to putting out the best products and honestly as is Schiit.

Best Regards,

Blu

[Blu99Zoomer]

In answer to JohnR's question, "if you connect the phone directly to the Benchmark, does it work?"

The DAC2 HGC has a usb 2.0 mode and a usb 1.1.  I tried both modes just now.  Neither work when the iPhone 5 is directly wired iPhone5>camera kit>usb cable>DAC2 HGC.  I powered everything off then turned them on starting with the phone.  Guess I will give Benchmark a chance next as their literature says no drivers are required for Apple operating systems.

Best,

Blu99Zoomer