audio_tony
Addicted to Fun and Learning
Yes, I did have a few concerns about some of the THD figures. I had seemingly thought that I could convert the dB figure into % directly?Thanks your for your interest in this data table and congratulations for your effort to put your site together .
However, I see that harmonics and THD which are clearly distinguished by the metrics (dBV or dBr) in the original tables are mixed up on your site and the quoted THD in dBV is directly converted to percentage. To my mind, this is wrong.
For instance, the translation of the quoted -104 dBV THD of the Sony CDP-XA7ES on your site is 0,00063 %, as if the 100% level from which the percentage are calculated is 0 dBV, which is 1 V RMS. But the nominal maximum output level of the Sony CDP-XA7ES when 0 dBFS is played is not 1 V RMS. It is 2 V RMS (about 6 dBV). Actually it is well documented (Stereophile or Audio reviews) that the output level is a bit higher, about 2.5 V RMS (which is about 8 dBV). Thus, the actual THD is not 104 dB under 1 V RMS output level, but 112 dB under 2.5 V RMS, which corresponds to 0.00025 % THD relative to 8 dBV.
Problem is : I was not able to compute harmonics relative to full scale output neither calculate THD in percentage for every source for which the measurements have been showed in dBV by the magazines, because the analogue output level with 0 dBFS digital input of each and every source were scarcely documented.
In conclusion, I recommend that measurements in dBV remain clearly separated from the others and stated in dBV. Otherwise, readers would be mislead.
Also, the nature of the test signal become undocumented on your site.
Perhaps the "Note" column (in which I originally only put casual information about each device) could be replace by a "Test signal" column.
May I suggest a relabeling of the title of each column on your site :
View attachment 323062
I do however need to get them into % because I use that to determine the row colour - so to have a mix of dB and % messes things up somewhat.
I am looking at a way to work the test signal into the data - although it's a bit tricky to match the entries, however your suggestion looks like it might be plausible.
I'll be putting more work into it over the next few days, as there are a few others things I'm not happy with.