1 (edited by Sequenza 2013-02-20 14:52:04)

Topic: Galvanic Isolation

Although I have no hum issues in the studio, opening any possible ground loop is always good practice so I have a question regarding my RME cards (MADI/AES/ADAT). In particular I was wondering if the MADI (coax), AES and MIDI interfaces provide galvanic isolation?

More on the subject here.

Thanks & Regards,
Thomas

Sequenza Studios - Acoustic Recordings
http://www.sequenza.fr

2

Re: Galvanic Isolation

MADI no, AES and MIDI yes.

Regards
Matthias Carstens
RME

3 (edited by Sequenza 2013-02-20 14:54:06)

Re: Galvanic Isolation

Thank you. I forgot to ask about the WC, but I guess it is similar to MADI, right?

Best,
Thomas

Sequenza Studios - Acoustic Recordings
http://www.sequenza.fr

4

Re: Galvanic Isolation

Yes.

Regards
Matthias Carstens
RME

Re: Galvanic Isolation

I thought the WC BNC was transformer isolated on RME products?

cool

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8

6

Re: Galvanic Isolation

Has been, but was changed on most products to not isolated. You can easily see: plastic socket = isolated, metal socket = not.

Regards
Matthias Carstens
RME

Re: Galvanic Isolation

MC wrote:

Has been, but was changed on most products to not isolated. You can easily see: plastic socket = isolated, metal socket = not.

Ah - That likely explains an odd BNC grounding/clocking issue I was having a while back :-)  And by "Socket" - I assume you mean the threaded portion of the BNC receptacle?

cool

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8

8

Re: Galvanic Isolation

Exactly.

Regards
Matthias Carstens
RME

Re: Galvanic Isolation

Thanks for the clarification, MC.

Additional Q:  I'm not in front of my MADI cards at the moment, so I'm not 100% sure of their BNC configuration.  If one of my older PCI MADI cards (a spare) has the transformer on the Wordclock board, and my newer primary PCIe MADI card doesn't have a transformer, can I simply swap the WordClock boards between them and get the BNC isolation on the PCIe MADI card?

Thanks! cool
Randy V.

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8

10

Re: Galvanic Isolation

Yes.

Regards
Matthias Carstens
RME

Re: Galvanic Isolation

Why was this change made? I have been having issues with using an Apogee Word Clock to pass the M-32DAs clock to another audio device. Simply  connecting the WC cable from the Apogee to the M-32DA creates a change to the M-32DA outcomes. After reading this, it seems that I need to completely revise my rack grounding.

Cheers,

Ian

Re: Galvanic Isolation

One more Q:  I believe my PCIe HDSPe MADI card has the small donut transformer on the Wordclock card, however, the BNC Wordclock jacks are all metal!!??!!  My older PCI HDSP MADI Card also has the donut transformer on the WC Card, but has the plastic threaded BNC Connections on the Wordclock card (as expected).

Was there a point in time that RME was still utilizing the Transformer on the Wordclock card, but swapped to all metal BNC Wordclock Jacks?  HeadScratch  And if so - Why? (since this would seem to kill the galvanic isolation provided by the transformer)

cool

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8

Re: Galvanic Isolation

Bump - My suspicions were confirmed.  My PCIe HDSPe MADI Card has the Wordclock transformer yet has metal BNC Jacks (right), where my older PCI HDSP MADI Card has the Wordclock Transformer and Plastic BNC Jacks (left).  Both are labeled as "rev 1.1.2".

http://i1343.photobucket.com/albums/o788/Randymanz/IMG_0875_zps4597fefd.jpg

What is the rationale for this other than RME might have run out of plastic BNC Jacks before they ran out of Transformers (before doing away with the transformer isolated wordclock circuit altogether)?

In the meanwhile, my old PCI card is in a spare backup DAW, so I swapped the wordclock cards to give my main DAW the galvanic isolation I need.  The metal jacks and lack of galvanic isolation of my original wordclock card seem to be the reason I was having odd sync issues with one of my my slave DAW's over BNC - the slave DAW sync's fine over ADAT.  I recall the old PCI HDSP equipped DAW not having this same issue (swapped primary DAW's including the metal BNC card, but was using the same slaves).  I'll try this again with the cards swapped and see what happens later this week...

cool

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8

Re: Galvanic Isolation

Bump for my above discovery - Is there any reason my HDSPe MADI card has the transformer isolated Wordclock daughter card yet has metal BNC Jacks on it (negating any galvanic isolation offered by the transformer)?

Thanks cool

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8

Re: Galvanic Isolation

Ok. Since transformers no longer exist on WordClock-Ins:

Whats the manufacturer / part-no. of the previously built-in pieces?

Then I could built my own galvanic isolation direct into the WC-cable if necessary!


Thanks and Regards,
Daniel

16

Re: Galvanic Isolation

Randy - the answer is as obvious as you gave it already under the photo.

Daniel77 - we made those ourself, you cannot buy it somewhere else. If at all as spare part via our distribution, which will be quite expensive IMHO.

Regards
Matthias Carstens
RME

Re: Galvanic Isolation

MC wrote:

Randy - the answer is as obvious as you gave it already under the photo.

Understood.  Just thought there might be some other rationale for this odd conundrum.

One more clarification: Seeing just the 1 transformer, does this isolate the BNC Wordclock input or output?  (I assume the input since its closest to it).  And then: is it is assumed any devices connected to the WC Out would deal with galvanic isolation on their respective inputs?

Finally, does/will the MADIface-XT have transformer isolated wordclock connections (Input or Output or both)?

Thanks cool

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8

18

Re: Galvanic Isolation

Only the input. The XT is not isolated.

Regards
Matthias Carstens
RME

Re: Galvanic Isolation

Thanks for your prompt response.

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8