Has anyone experience of SPDIF to AES?

I want to try conecting my ND555 directly to the digital inputs of my Dutch & Dutch 8c speakers.
How do I conver the SPDIF digital output from the 555 into an AES input for the speakers. If I understand correctly I need to somehow match the different impedences/voltage levels of the two formats?

You’ll need a transformer - 75 ohm to 110 ohm. I have used one for taking an AES/EBU 110ohm output to an s/pdif 75 ohm input.

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Wow, use an ND555 only as a renderer! Or are you planning to compare that with feeding the speakers from the ND555’s analogue output?

The answer is that you need a suitable converter not just a cable. Something like a Gustard U12 would do it, though for that you’d need to use a a BNC to RCA cable. There are upmarket products tharpt may have BNC inputs.

Yes, I want to compare with the analogue output. Currently the 555 runs into a cj GAT 2 preamp from which I drive the 8cs. Works extremely well but essentialy the analogue input is then immediately converted back to digital by the 8c’s so I’m hoping that by driving the speakers directly from the 555’s digital ouput I avoid that extra digital to analogue to digital step and see what the effect is on SQ

I take it that the 8c is still not fully Roon ready ?

Not yet they have had issues getting the pairing to stay in sync as essentially it’s streaming to two devices.

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Shame. Could have been another solution as I think the OP uses Roon.

Some people have been using beta firmware with it in as far as I know. Getting anything Roon certified is a long process and they have now stamped out vendors releasing unfinished uncertified Roon code. Some big names were constantly releasing products as Roon Ready when they had not been fully certified. Been a big hoohar over on the forum about it. Its a good thing as bad code diminshes the whole experience so D&D are doing it all the right way. Hopefully they get there.

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Yes, ultimately ROON will be the solution driving the speakers over the LAN, but no time frame given asto when the 8c’s will be ROON ready, no timesoon is my guess having talked to D&D who are clearly cautious having “promised” his capability and not delivered. I have a Nuleus+ ready and waiting :slight_smile:

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Good stuff. Amazing speakers the 8c. Roon ready will be the icing on the cake so hopefully it won’t be too long until they get the issues sorted.

Amazing indeed, lack of ROON isn’t affecting my enjoyment of them , completely redefined what bass definition can be achieved in my listeningroom


Yes, it’s quite a revelation when you hear just the speakers and not the room contribution. Sorry to go off topic, but how do you find the 8c in general. SQ aside, any ownership issues ?

A bit sad to have such wonderful pre as the Conrad Johnson GAT and not use it.
The volume control of the Nd555 is well beyond.

A combination of the onboard DSP and REW analysis deals with bass/room interactions in a very straightforward manner. That aside they do need to be run in, mine are still improving after 3 months as some initial treble glare goes, and they do benefit from experimenting with positioning to optimise soundstaging and imaging. The suggested set up is an isocoles triangle with speakers firing directly at the listner but I found that toeing them out a little and sitting a bit further back worked better in my room. I’d urge anyone to audition them as an alternative to a more conventional set up, I’m not going back!

Don’t worry it will remain at the heart of an all analogue set up! :grinning:

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Hi, the main difference between the physical layer of SPDIF and AES/EBU is the former is unbalanced with CI of 75 ohm, and the latter is balanced and has a CI of 110 ohms. The two use very different voltage levels. There are some protocol differences too, but hopefully this won’t be an issue in how you are using the interfaces.

SPDIF can drive AES over a short distance via a passive transformer as Richard shows above, but reliability might be compromised, or even over a simple wiring ‘kludge’ over very short distances, but AES driving SPDIF would seriously overload SPDIF and likely cause failure or bad errors.

The best way to convert is to use an active format converter such as


You need an impedance transformer as previously mentioned. Neutrik makes one which you can plug directly into the back of the first speaker in the chain. Other than that, you just need a standard BNC to BNC coaxial cable. Alternatively, you can connect it to a standard AES cable, but keep the AES leg as short as possible because you are longer driving it as a balanced line, which hurts noise rejection.

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