Topping D50 and D50s coax input hit or miss

[Miska]

What varies between receivers is how much input jitter they accept to stay locked. I wonder if they use the ESS Sabre built-in receiver (which almost nobody does).

 

32 minutes ago, mansr said:

The transceivers are in fact the same as for RS-485.

 

In the 90's for some of my first DACs, I used the standard RS-485 interface chips with good results. Because (IIRC) the YM3623 didn't have the electrical interfacing, but instead required TTL level input.

 

[Miska]

55 minutes ago, mansr said:

Just how bad do you think the sources are? The limit in the spec is rather generous.

 

They can be very bad, something like Airport Express, or some Bluetooth interfaces (IIRC, both typically generate the clocks from the network receive packet interval). But it is more question how bad the receiver can be. I think ESS had some adjustable PLL lock window and people like to run it at tightest setting for some reason. A good but tricky receiver is the Wolfson one too, it has so many configuration parameters and not so easy to get running nicely.

 

But everybody I've talked to just say the S/PDIF receiver in ESS Sabre is so bad that they don't want to use it. Maybe someone made a mistake and actually tried to use it.

 

Anyway, there are huge differences between receivers in how much jitter they can deal with before falling off.

 

Another likely contributing factor may be ground currents adding noise to the S/PDIF reception, since the Topping D50 seems to be missing the isolation transformer it should be having on the coaxial S/PDIF input. Some S/PDIF transmitters have isolation transformer, some don't (they really should). If you combine setup where neither side has it, the likelihood for problems in this area is much bigger.

 

At least on this side of the PCB there's no needed magnetics for the coax S/PDIF:

 

 

[Miska]

8 hours ago, Lightstream said:

The reason was that I used an XLR-to-SPDIF adapter to connect the AES/EBU output between my Simaudio MOON 180 Streamer and the DAC with an SPDIF cable (Oyaide FTVS-510). Neither the Neutrik AES/EBU to SPDIF adapter I used nor a no-name adapter worked. Also an adapter on the input side of the DAC (AES/EBU to SPDIF) using a AES/EBU Cable did not work which is no problem at all with other DACs. When I used the SPDIF cable and the SPDIF in- and outputs everything worked fine. Maybe a highly bred racehorse reacts more sensitively than the average horse... 

 

For AES/EBU <-> coax S/PDIF conversion, there are adapter boxes available, commonly based on pulse transformers. These do the needed level conversions too. There are also active converters that also support conversion to/from optical S/PDIF. You could take a look at some pro-audio shop for such (in Europe, Thomann is good place to start).