Measurements and Conclusion
Contents
We’re going to be very honest: it’s awfully hard to make a good measurement on this kind of product. Because: where are you going to look?
We mainly looked at whether and how much noise these plugs suppress. We did that in two ways: with the LISN (with and without the plug). And through the AC generator by connecting a power strip to it and adding the QRT plugs. Next, we measure the noise via a “step-down” transformer going from 230V to 12V. We connect this transformer to the splitter that splits common-mode and differential mode.
All measurements were done on the Picoscope 5000 series and the Rigol Spectrum analyzer.
Baseline – no plugs
Qsine noise measurements
Qwave noise measurements
Persistence measurements
Okay… cool: all those pictures. The question is are there any differences? Well… yes. But very subtle. An “ordinary” filter shows its effect more obvious. Think of an Isotek Titan or a Yeti isolation transformer. And those devices are also particularly audible in a system, which is not surprising: a hi-fi system modulates energy. And that energy has to come from somewhere.
With these QRT plugs, something else is obviously happening. Because it is not really measurable with a scope and spectrum analyzer. At least: not convincingly. And yet it is audible when we use them. Weird… And again proof that not everything is measurable…. At least: not yet.