No, I don't think jitter only comes from exercising it - seeing as you fail to read what I said or misunderstand it - let's see what Julian Dunn, the developer of the J-test has to say - he calls it a DATA Jitter Test SignalYes. It seems that you are thinking jitter only comes out if you feed it J-test signal. If that were the case, it would never show up with music since music never mimics what J-test does! J-test is a square wave with one bit of it toggling. The square wave once it goes through the low pass filter of the DAC becomes a pure sine wave with that very low level toggling embedded in it. If a DAC has jitter, it will show up there as it would show up if you were to feed it a single tone sine wave. What doesn't show up without S/PDIF is the link, i.e. S/PDIF, aggravating because of embedded clock in S/PDIF channel.
As I said already, J-Test is used to stress a particular aspect of the SPDIF transmission protocol & it's receiving/ecovery circuitry. It is not designed as a general purpose jitter test.Data Jitter Test Signal (J-test Signal): A test signal has been developed in order to stimulate worst-case levels of data-jitter. This signal has two components. The first is an un-dithered square wave with a period of 4 samples...........
The effect of data jitter on following equipment depends on their circuit design. Some clock recovery circuits use data transitions throughout the sample frame to derive a timing reference so coupling data jitter to the output.
You yourself have said the same in relation to ASRC tests
Oh, & btw, we don't know if Archimago is using the TEAC's upconverting (ASRC) of the input stream in his tests - he simply doesn't mention itHere is the kicker. Once you have such a circuit, you no longer can test it using jitter test. His J-Test signal he used is not appropriate to detect errors in this circuit. Special tests need to be used based on knowing the design of the sample rate conversion circuit to detect its flaws.
That's my point - he has decided to test for something that is nothing to do with where differences might be found - as you said above "His J-Test signal he used is not appropriate to detect errors in this circuit"In this scenario, we are not interested in what the cable or S/PDIF is doing. We are interested to see if the source induces jitter into the down stream DAC. The use of J-Test here has a superfluous low-order bit toggling. That's all. Otherwise, we have a high frequency tone which is a hard test with respect to jitter.
Now, if we were testing quality of the USB connection then yes, maybe there is a worst case signal for that. But no one has invented one and at any rate, per above is not something we are trying to test.
I would direct you to read what J Dunn's wrote about the J-Test & what it stresses & tests.PLL is not part of the transmission. It is a subfunction of a receiver in order to deal with upstream artifacts caused by the cable or the source. J-Test is designed around what we know the cable can do to digital stream. We have no idea how the downstream PLL is designed as to create a worst case signal for that. As I explained above, if the goal was to agitate down stream devices, a different signal may do better but that is not the goal here. The goal here is to figure out if we just change the source, what happens. In this case, nothing did! .