[sdiy] USB/MIDI ground isolation?

[cheater cheater]

It's just noisy ground.

highspeed optocouplers have existed for years, check them out. I might
be wrong, but I believe lot of firewire audio stuff uses them.

D.

On Thu, Sep 17, 2009 at 11:06 AM, Seb Francis <seb at burnit.co.uk> wrote:
> Colin f wrote:
>>>
>>> -----Original Message-----
>>> From: synth-diy-bounces at dropmix.xs4all.nl
>>> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of
>>> johnspeth at yahoo.com
>>> Sent: 16 September 2009 23:18
>>> To: SDIY
>>> Subject: [sdiy] USB/MIDI ground isolation?
>>>
>>> We all know that the 5 pin DIN version of MIDI provides isolation between
>>> grounds by virtue of the optocoupler.  Can anyone tell me how they addressed
>>> the ground isolation problem with USB/MIDI?
>>>
>>
>> I think in a fair number of cases, the issue of grounding noise problems
>> was
>> resolved by the designers crossing their fingers and hoping all the end
>> users would have laptops with double insulated PSUs.
>>
>
> Are we talking here about 50Hz hum or high frequency whiny computer noise?
>
> When developing digital audio projects via a USB ICD2 programmer/debugger,
> you *really* hear the latter type of noise when you hook it up.  Maybe
> that's more to do with how the power supplies are getting coupled though
> rather than an earth loop?
>
> Perhaps I've been lucky but I've never experienced either type of noise
> using the various USB-MIDI boxes I've had over the years.
>
> Seb
>
>
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