- Nov 29, 2019
- BC, Canada
Erin’s HF is again showing more rise than in amirm’s measurement.
I did remember what mtg90 had to say:
and was wondering if Alan was actually able to track down that the difference was caused by his own gear and verify the measurement error was happening there.For me it would be very interesting to send this speakers to the more subjectivist prominent reviewers. The outcome would be so interesting. What they hear, how they do descripe. Please do this March Audio !www.audiosciencereview.com
Alan March said:What Erin's final test data revealed was that whilst it is very consistent with our own, there was a difference above about 7kHz with Erin's data showing 1 to 2dB higher amplitudes.
So, as some members have suggested, the design intent was to keep a smooth sound power and PIR. Our data indicated a small HF lift, but this certainly remained well within the +3dB limit band. None of our subjective test subjects found this to be excessively bright.
So working on the basis that Erin's data is absolutely accurate and there was something wrong with our testing regime until proven otherwise, I have been thoroughly examining test set up, calibrations and methods. Now let's be clear, *ALL* measurement systems have tolerances and accuracies, including the Klippel. No one should expect two disparate systems to produce absolutely identical results. The examination of our system has revealed a couple of reasons (one was very interesting in fact ) for about a 1 dB difference. We will be performing some further measurements tomorrow and I am expecting this to come very close to Erin's data, although I still suspect a fraction lower.
Appendix A. Data Acquisition in Non-Anechoic and Non-Open Field Spaces The following techniques are useful in assessing the frequency response of a loudspeaker in the absence of an anechoic chamber. Many of them work well. All measurements have errors, including measurements in anechoic chambers and outdoors, so it is important to validate your own techniques by comparing the results to a measurement made in a free field environment. A good way to do this is to submit one of your speakers to a recognized testing laboratory. An agreement of ± 1.5 dB is considered to be good.
You must not be critical. We appreciate your work, yet it lies in the nature of presenting data that people will not only judge the result, but take close note if it was produced without error. I took note when mtg90 left his impression that the rise in VHF with your rig might have a pattern. If this is happening, it could interest you as well.It seems when a review is posted people focus on the tiniest of nits to drill on and discussion of the performance, design intent/application and practicality of the speaker goes out the window when that happens.
You must not be critical.
I do not question you do your work most rigorously, I was commenting the way you replied to my post. Take it or leave it.
And you can see I am critical and through. Well above what would be expected.
I provided a response outlining why there may be differences and showing proof of where March said he resolved the error in his system and then showed the CTA standard of tolerance.
Then you replied with “you must not be critical”. That’s taking my response and ignoring it.
Take my results or leave them. I don’t need to beat this dead horse anymore.
Although I can empathize that you got sensitive after the previous discussion, this is not a reason to get all excited. There was an observation by a third member, here was another result that has a tendency, I made a note. That is it, easy.