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firewire galvanic isolation [message #85630] Wed, 16 January 2013 14:05 Go to next message
fever is currently offline  fever
Messages: 13
Registered: September 2012
Location: Zurich, Switzerland
Junior Member
hi all

i've been looking for firewire isolation transformers, but haven't found any (i'd like to isolate the computer's "dirty" ground from the LIO's "clean" ground).

there are a number of repeaters that convert firewire>optical>firewire or firewire>cat5>firewire. newnex, one of the manufacturers of such devices (<http://newnex.com/FireNEX-CAT5-S400.php>), has assured me that their cat5-repeaters in fact offer complete galvanic isolation between firewire and cat5.

- has anybody actually tried such a device (cat5 or optical) with a MH interface?

- and does it work?

- is a firewire 400>cat5 repeater fast enough or should it be a firewire 800?

does the conversion affect jitter or is that no issue with MH's firewire protocol?

thanks for experiences and opinions!

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Re: firewire galvanic isolation [message #85633 is a reply to message #85630] Wed, 16 January 2013 16:39 Go to previous messageGo to next message
Allen is currently offline  Allen
Messages: 156
Registered: July 2011
Senior Member
Many of our customers use FW repeater systems for long length connections, i.e. between a recording stage and mix booth.

There is no advantage to using a FW800 repeater with our interfaces.

I'm not aware of any jitter issues induced by using a repeater.

Metric Halo
www.mhlabs.com
727-725-9555

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Re: firewire galvanic isolation [message #85634 is a reply to message #85633] Wed, 16 January 2013 16:47 Go to previous messageGo to next message
fever is currently offline  fever
Messages: 13
Registered: September 2012
Location: Zurich, Switzerland
Junior Member
allen,

thanks for your reply.

do you mean "true" FW repeaters (i.e. some sort of FW signal booster for long distances) or repeaters/transceivers that change the format (i.e. FW > optical or FW > cat5)? i'm not aware of "true" FW repeaters that offer galvanic isolation.

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Re: firewire galvanic isolation [message #85635 is a reply to message #85634] Wed, 16 January 2013 17:00 Go to previous messageGo to next message
Allen is currently offline  Allen
Messages: 156
Registered: July 2011
Senior Member
I'm referring to CAT5 and optical format converters.

Are you experiencing grounding issues?

Metric Halo
www.mhlabs.com
727-725-9555

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Re: firewire galvanic isolation [message #85639 is a reply to message #85635] Wed, 16 January 2013 17:13 Go to previous messageGo to next message
fever is currently offline  fever
Messages: 13
Registered: September 2012
Location: Zurich, Switzerland
Junior Member
not exactely "issues". i just can't imagine that apple pulled all the stops to get a clean ground in a $600 retail mac mini... i waiting for delivery of a linear supply to replace the mac's stock SMPS and figured it might be a good idea (at least worth a try) to galvanically isolate the computer from the audio interface.

do you happen to know of a more elegant (and probably also cheaper) solution for galvanic isolation of FW than adding two repeaters, two firewire cables, and one cat5 or optical cable between computer und audio interface?

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Re: firewire galvanic isolation [message #85641 is a reply to message #85639] Fri, 18 January 2013 16:34 Go to previous messageGo to next message
Allen is currently offline  Allen
Messages: 156
Registered: July 2011
Senior Member
Your LIO should not pick up any noise that is on the Mac's ground. However, you could look for a FireWire power isolation cable with a lifted ground.

Metric Halo
www.mhlabs.com
727-725-9555

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Re: firewire galvanic isolation [message #85642 is a reply to message #85641] Fri, 18 January 2013 17:29 Go to previous messageGo to next message
fever is currently offline  fever
Messages: 13
Registered: September 2012
Location: Zurich, Switzerland
Junior Member
i already have a FW cable without the power connection. i thought FW needs a ground connection to operate properly??

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Re: firewire galvanic isolation [message #85643 is a reply to message #85642] Mon, 21 January 2013 10:32 Go to previous messageGo to next message
Allen is currently offline  Allen
Messages: 156
Registered: July 2011
Senior Member
I was told the ground could be lifted, but that might have been an error.

Metric Halo
www.mhlabs.com
727-725-9555

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Re: firewire galvanic isolation [message #85644 is a reply to message #85643] Mon, 21 January 2013 10:45 Go to previous messageGo to next message
fever is currently offline  fever
Messages: 13
Registered: September 2012
Location: Zurich, Switzerland
Junior Member
could you please verify with your tech department whether the ground is neccessary for proper FW operation or if it is possible to lift the ground?

thanks for checking!

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Re: firewire galvanic isolation [message #85648 is a reply to message #85644] Wed, 23 January 2013 11:26 Go to previous message
Allen is currently offline  Allen
Messages: 156
Registered: July 2011
Senior Member
It is not possible to lift the ground- sorry for the error.

If you want to completely isolate the two units you will have to use a CAT5 or fiber optic format converter. That said, our interfaces should not be affected by noise (if present) on the computer's ground, so these measures should not be necessary.

Metric Halo
www.mhlabs.com
727-725-9555

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