DIY wiring of RCA-to-XLR umbilical cable

[audio_engr]

The first version uses a 75Ω coaxial cable and the shield is also a continuous conductors whereas the shield is lifted in the second version. I used this cheap Neutrik adapter http://www.neutrik.com/en/accessories/ci...rs/na2mpmf with my 75Ω coaxial cable the test which input has better sound quality using the same source output: AES or RCA and found that AES sounded much better. So something easy to try!

Thanks for your inputs ... 

At this moment, I'm using the Neutrik XLR adapter over the crystal RCA-RCA cable supplied by Devialet to enable the digital link as RCA(master) to XLR(companion) ... 

And no two doubts, it sounds much superior to the standard RCA-RCA version. 

I find the imaging becoming much sharper with a wider yet much more focussed soundstage. The midrange has slightly become more FWD and I will need to try other digital cables to figure out how to fix this ...

Nice to know that you're getting good service from DH Labs, they certainly know how to look after their customers.
What resistance value did you end up going for?

Hi Axel :

After a lengthy telecon with Greg of DH Labs, he explained : 

1. That their 75 Ohms cable has a central core and a screen with overall impedance @ 75 ohms (+/- 5%). So if we take in account the tolerance of 5%, then its 71.25 to 78.75 ohms. 

2. Their 110 ohms cable has 2 internal core and a screen .. thus following Devialet's suggested schematic, they'd use the 2 internal cores for RCA & XLR, shorting pins 1 & 3 for XLR. The screen would be left alone. Again, this is 110 ohms with (+/- 5%) comes to 104.5 to 115.5 ohms.

In fact, Greg has already made several of these custom cables for Devialet customers so he's pretty much accustomed with the stuff. He strongly recommended that the 110 cable sounds WAAAYYY better than the 75 ohms cable with the RCA to XLR connectors on them. 

Thus, I went for the 110 cable with a cable length of 1.5 metres as I wanted to spread out the Devialets a bit and get each of them a bit closer to the speakers.

Cheers !
- Arup (aka audio_engr)