Disconnect USB ground to eliminate noise ?

[mamba76]

I was reading this blog I found and wondered if there's any truth in it..

Mad Scientist Heretical Digital Cable

I have a MiniDSP 2x4HD in my car but its being fed ground noise from the source tablet's PSU / hub (lavaSync) via the USB connection. So couldn't a solid state relay be used at each end to break the ground cure it (after a delay for the initial handshake) ?
Would be a lot cheaper than a good USB isolator?

 

[NTK]

I was reading this blog I found and wondered if there's any truth in it..

Mad Scientist Heretical Digital Cable

I have a MiniDSP 2x4HD in my car but its being fed ground noise from the source tablet's PSU / hub (lavaSync) via the USB connection. So couldn't a solid state relay be used at each end to break the ground cure it (after a delay for the initial handshake) ?
Would be a lot cheaper than a good USB isolator?

There is a thread here on a similar contraption.

The USB Troll

As we know, USB connections sometimes suffer from computer noise coupling through the Vbus or ground wires and finding its way to the analogue outputs of a DAC. One way of eliminating such noise is to use an isolation device. These are, unfortunately, rather expensive. As a simpler alternative...

www.audiosciencereview.com

 

[Katji]

I was reading this blog I found and wondered if there's any truth in it..

Mad Scientist Heretical Digital Cable

"mad scientist", "heretical"...means very unlikely any truth.

..."digital cable"...ok, that settles it.

 

[mamba76]

Unbelievable lol. I was sure the USB protocol uses polling for plug and play, not gonna happen with no ground.

 

[phofman]

The cable price is ... well for audiophiles. But theoretically it could work as USB ground is required only during enumeration - that's why the switch gets flipped after the DAC is enumerated by the operating system. But the devices should not float against each other which could damage the USB ports on any side... I would not recommend this at all.

However, TI and Analog Devices finally introduced inexpensive USB highspeed isolator chips a few months ago - we can expect reasonably-priced highspeed isolator boards soon, IMO. Even the already available eval board from TI is already cheaper than any legacy highspeed isolation solution on the market https://www.ti.com/tool/ISOUSB211DPEVM#order-start-development

 

[Katji]

^^^That's good to hear. .........I wonder whether many/most high-end/expensive dacs do have proper isolation. ...Don't expect it at the computer end, certainly not with the less expensive laptops...etc.
Anyway, you can get little isolator boards with USB connectors, for a lot less than his $300>

 

[phofman]

Some DACs isolate on data lines behind the USB receiver chip, most don't isolate at all.

I have never seen any isolated USB host (i.e. the PC side).

For existing highspeed isolators - the lowest price I have seen so far is https://www.audiophonics.fr/en/digi...usb-isolator-32bit-768khz-dsd512-p-15805.html But it does not support other speeds than highspeed which can be inconvenient for some devices which also use fullspeed (some soundcards start at fullspeed and when the driver acknowledges the capability, they switch to highspeed).

 

[mamba76]

Iv read that splitting USB to stream into two DACs is a no go so Im now going the optical route. Been meaning to get a MCHstreamer from MiniDSP for a while and just pulled the trigger on another 2x4HD. The idea is a ahort USB cable to the streamer then a 4m toslink cable to the back of the car which will be split then two short toslink cables to each of the 2x4HD's.
My next task is buying the opticle cables.
I messaged 5th element on this and its seems the quality of the optics is the most important aspect. Its a bit of a mine field out there but has anyone have an opinion of Bluerigger or EMK cables?
I have already bought a passive Bluerigger splitter, based on reviews on the net, as I don't like the idea of having another powered device, just another way to introduce noise.
Id like to use all cables from the same manufacturer and realised the splitter I bought will need a female coupler. With every new link in the chain theres potential for problems. Iv not had much experience with optical cabling but TBH Im not very impressed with the wobly connections on cheaper cables and hope more expensive ones will fit better (and take the rubber covers off the end lol)
EMK do a rotating 360 degree right angle connection which may prove handy, then theres couplers to think off.
Can anyone vouch for a specific brand?

 

[JayGilb]

Can anyone vouch for a specific brand?

I use this brand for a 25 foot run and it works just fine: KableDirekt