Higher End DACs

@geoffkait
I considered the problem as a DAC being an antenna. I analyzed the DAC outputs while the DAC and device-under-test was in a Faraday cage. So it’s quite clear that when a generator of RF is even just proximate to a DAC (no connection) the outputs of a DAC are affected. This means the energy gets inside the DAC. And I have the corollary that when the energy bis there (even a high MHz) the sound is less transparent. So the DAC’s designed performance is affected by:
- the xtal clocking the output is perturbed
- the multiple harmonics at MHz affect the noise floor in the audio band
- reference voltage levels disturbances

None of this is measurable directly. The audio band (to 21khz in my case) shows no added jitter or noise floor changes to 150dB. Even in my conversation with Rob Watts, he says he can see nothing to 190dB. But we’re talking High End DACs here...where these effects are plainly audible.

@dmance  Any reason why you are unable or unwilling to start a thread focused on your own product?  

There is value in what's been recently discussed. There's also value in having focused discussions that are on topic and are not disjointed because of thread drift. 

dmance

I considered the problem as a DAC being an antenna. I analyzed the DAC outputs while the DAC and device-under-test was in a Faraday cage. So it’s quite clear that when a generator of RF is even just proximate to a DAC (no connection) the outputs of a DAC are affected. This means the energy gets inside the DAC ... None of this is measurable directly ... But we’re talking High End DACs here...where these effects are plainly audible.

How did you "analyze" the DAC output to conclude its outputs were "affected?" How do you account for the fact that you consider the affects "plainly audible," but can’t show that with measurements?

The problem is that everything is affected by RF. I’m not sure that’s saying anything new. But that shouldn’t be terribly surprising since the signal itself is RF, no?

@cleeds 
I have a signal hound BB60 and have done the tests (see my whitepaper). I have done the checks for alternative explanations. Repeated the tests. It's quite clear that a DAC fully isolated (say runing off a battery with a source chain buried in a Faraday cage and only optical I/O) sounds better ...and by that I mean exposes increased transparency. Open the lid of the cage or get lazy with what could be a source of RF...and the magic goes away.

And I'll have to say again. If you are asking questions about measurements to point the finger at a causal issue ...no test gear will suffice to find those for you.. the effects are real but must be down below 200dB.  There is something remarkable going on with our ear/brain that lets us hear these things.