@Jean-Marie - To clarify, yes it is a digital multi-meter. As for its accuracy, as I mentioned in my earlier post the readings are not even consistent between the 2V and 20V settings, and as I also said earlier I am not trying to challenge ASR or Stereophile, I am just trying to improve understanding, and not claiming to be making definitive measurements here.
As for the difference between the 10kHz and 15kHz, the test tones were taken from the internet and happened to be from different sources, so it is highly likely that most of the 3dB difference is accounted for by differences in the test tone. I agree that the multi-meter may lack accuracy, but I doubt its behaviour differs much between 10kHz and 15kHz, when it is probably optimised for nearer 50Hz. That said, this was not intended as test for linearity, just a simple test to try and improve understanding.
Anyway, I am very pleased to see you are taking an interest in this thread. One thing we have all failed to understand is exactly why a Devialet Expert amp will shut down at very low watts during certain high frequency test scenarios. I believe you might have a contact who could perhaps provide some technical insight here? If you could find some relevant information, that would be greatly appreciated.
@thumb5 - you make a very good point regarding the actual input level resulting from the test tone. I had a quick look at the input level meters on the amp itself. I have no idea how accurate this meter is but with the test tone it was just running into the "orange zone", it is a tiny scale, but it looks to be maybe -18dB or so. I certainly have actual real recorded music that will push these meters higher into the red zone. This is very interesting, at it shows that overall my test was running maybe -18dB gain with respect to a "full voltage" test tone, not the full 0dB that I mentioned. In a way I am quite pleased about this, I am slightly uncomfortable about possibility of causing damage running pure tone tests, so it looks like the test tone itself provided a little headroom here. I'm thinking that it would be easy enough to analyse the test tones to get a very accurate idea of the absolute level of the signal, but as the multi-meter is likely inaccurate, this is a fairly moot point.
@"alaw" - enthusiasm can get you into trouble sometimes, I am more than happy that I have tried this with the amp and speakers unscathed. An exploded Blade tweeter or something during the current UK "lockdown" would not be good. I am happy to give testing a rest now and return to the listening of music.
As an aside, the multi-meter issues raised here reminds me of an old article by Archimago
http://archimago.blogspot.com/2017/09/mu...o-you.html
The multi-meter shown in the article is not that different to mine, so as an open question for anyone wanting to take such measurements with a multi-meter, what type is best for high frequency audio? Archimago seamed happy enough with his, but maybe he was wrong? Is there something more suitable? Maybe analogue is better? Are there issues with multi-meters presenting a resistance of their own? There is a whole topic here I think.
As for the difference between the 10kHz and 15kHz, the test tones were taken from the internet and happened to be from different sources, so it is highly likely that most of the 3dB difference is accounted for by differences in the test tone. I agree that the multi-meter may lack accuracy, but I doubt its behaviour differs much between 10kHz and 15kHz, when it is probably optimised for nearer 50Hz. That said, this was not intended as test for linearity, just a simple test to try and improve understanding.
Anyway, I am very pleased to see you are taking an interest in this thread. One thing we have all failed to understand is exactly why a Devialet Expert amp will shut down at very low watts during certain high frequency test scenarios. I believe you might have a contact who could perhaps provide some technical insight here? If you could find some relevant information, that would be greatly appreciated.
@thumb5 - you make a very good point regarding the actual input level resulting from the test tone. I had a quick look at the input level meters on the amp itself. I have no idea how accurate this meter is but with the test tone it was just running into the "orange zone", it is a tiny scale, but it looks to be maybe -18dB or so. I certainly have actual real recorded music that will push these meters higher into the red zone. This is very interesting, at it shows that overall my test was running maybe -18dB gain with respect to a "full voltage" test tone, not the full 0dB that I mentioned. In a way I am quite pleased about this, I am slightly uncomfortable about possibility of causing damage running pure tone tests, so it looks like the test tone itself provided a little headroom here. I'm thinking that it would be easy enough to analyse the test tones to get a very accurate idea of the absolute level of the signal, but as the multi-meter is likely inaccurate, this is a fairly moot point.
@"alaw" - enthusiasm can get you into trouble sometimes, I am more than happy that I have tried this with the amp and speakers unscathed. An exploded Blade tweeter or something during the current UK "lockdown" would not be good. I am happy to give testing a rest now and return to the listening of music.
As an aside, the multi-meter issues raised here reminds me of an old article by Archimago
http://archimago.blogspot.com/2017/09/mu...o-you.html
The multi-meter shown in the article is not that different to mine, so as an open question for anyone wanting to take such measurements with a multi-meter, what type is best for high frequency audio? Archimago seamed happy enough with his, but maybe he was wrong? Is there something more suitable? Maybe analogue is better? Are there issues with multi-meters presenting a resistance of their own? There is a whole topic here I think.
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