MQA part the 3rd - t't't'timing...
- Thread starter Jim Audiomisc
- Start date
davidsrsb
pfm Member
Additional ultrasonic signal is audible when it excites a dome tweeter oil drum breakup modes. This is easily demonstrated.
With real music sources, there is a good case for a gentler filter starting a little lower to remove some of the ~20 KHz "just about ultrasonic" that only children can hear anyway.
With real music sources, there is a good case for a gentler filter starting a little lower to remove some of the ~20 KHz "just about ultrasonic" that only children can hear anyway.
darrenyeats
pfm Member
What I wrote is correct for ADC/downsampling - any energy in transition band of steep filter. I completely agree DAC filters are a different discussion, since their input should be band-limited.
Jim Audiomisc
pfm Member
The reality in practice is that:
1) The mics used to make recordings will disperse the signal anyway to an extent that make lab-bench measurements of DAC/ADC 'ringing' irrelevant.
2) Ditto for essentially all real-world loudspeakers.
As per earlier in this thread, see http://www.audiomisc.co.uk/MQA/OnImpulse/RingingInArrears.html
The DAC impulse responses published in magazines are wildly 'over interpreted'.
1) The mics used to make recordings will disperse the signal anyway to an extent that make lab-bench measurements of DAC/ADC 'ringing' irrelevant.
2) Ditto for essentially all real-world loudspeakers.
As per earlier in this thread, see http://www.audiomisc.co.uk/MQA/OnImpulse/RingingInArrears.html
The DAC impulse responses published in magazines are wildly 'over interpreted'.
Rosewind
Lost in Translation
OK. Long time no see. This evening, I just happened to look up the Norwegian Stereo+ / Stereopluss site, and as it happens, they have published their findings about lossy MQA. It is in Norwegian but I will gladly give translating it a go as I am on sick leave at the moment. Here it is, I suppose that you should be able to look at the nice spectrogram analyses and such:
https://www.stereopluss.no/mqa-for-viderekomne.6410460-355425.html
The title is approximately, "Advanced Lessons in MQA," so not exactly "undergrad stuff".
From the conclusion:
"Det som beskrives over av Craven, er at de som bruker apodising filterteknikk vil oppnå den samme korreksjonen av pre-ringing impulsresponsproblemer fra studio som MQA hevder de gjør. Spørsmålet som da melder seg: Er det eneste MQA egentlig tilbyr en videreutvikling av dette filteret? De ser nemlig ikke ut til å kunne forbedre impulsresponsen i MQA-enkoderen i forhold til native high-res.* og **
Man sitter da igjen med at MQA kanskje kun fikser et problem som i høy grad håndteres av DAC-produsentene selv, med mindre de bevisst har valgt et lineært filter på utgangene."
= [from the conclusion]
"What is described by Craven is the fact that those who use apodising filtering techniques will achieve the [very] same correction of pre-ringing impulse problems from (the) studio that MQA claim to do. The questions then is, "Is the only thing that MQA really offer a further development of this filter?" MQA do not seem to be able to improve the impulse response in the MQA encoder compared to the impulse response of native hi res.
You are left with the impression that perhaps MQA only fix a problem that to a high degree is handled by the DAC manufacturers themselves, unless they deliberately have chosen a linear filter for the output."
https://www.stereopluss.no/mqa-for-viderekomne.6410460-355425.html
The title is approximately, "Advanced Lessons in MQA," so not exactly "undergrad stuff".
From the conclusion:
"Det som beskrives over av Craven, er at de som bruker apodising filterteknikk vil oppnå den samme korreksjonen av pre-ringing impulsresponsproblemer fra studio som MQA hevder de gjør. Spørsmålet som da melder seg: Er det eneste MQA egentlig tilbyr en videreutvikling av dette filteret? De ser nemlig ikke ut til å kunne forbedre impulsresponsen i MQA-enkoderen i forhold til native high-res.* og **
Man sitter da igjen med at MQA kanskje kun fikser et problem som i høy grad håndteres av DAC-produsentene selv, med mindre de bevisst har valgt et lineært filter på utgangene."
= [from the conclusion]
"What is described by Craven is the fact that those who use apodising filtering techniques will achieve the [very] same correction of pre-ringing impulse problems from (the) studio that MQA claim to do. The questions then is, "Is the only thing that MQA really offer a further development of this filter?" MQA do not seem to be able to improve the impulse response in the MQA encoder compared to the impulse response of native hi res.
You are left with the impression that perhaps MQA only fix a problem that to a high degree is handled by the DAC manufacturers themselves, unless they deliberately have chosen a linear filter for the output."
Rosewind
Lost in Translation
Someone else will have to answer that question.
I believe that @Jim Audiomisc came to a similar conclusion about the application of an apodising filter when MQA does the lossy encoding, and the origami folding + secret sauce equalising happens.
I would rather not pay that extra MQA tax that MQA inc. try to force upon music lovers. Their product is most likely pure unadulterated snake oil. Shame on MQA!
I believe that @Jim Audiomisc came to a similar conclusion about the application of an apodising filter when MQA does the lossy encoding, and the origami folding + secret sauce equalising happens.
I would rather not pay that extra MQA tax that MQA inc. try to force upon music lovers. Their product is most likely pure unadulterated snake oil. Shame on MQA!
Jim Audiomisc
pfm Member
I can't comment on specific current 'NOS' DACs as I don't know enough about individual examples. But can make a general point.
NOS may or may not mean the use of a following *analogue* low pass filter. Questions about pre-ringing, etc, then depend on the details of that filter. If there isn't one, the buck gets passed on to the following items in the chain. Which ends, of course, with the speakers... which often 'ring' at HF. (Many examples now shown in HFN speaker reviews as they go up above 20kHz and show this nicely.)
NOS may or may not mean the use of a following *analogue* low pass filter. Questions about pre-ringing, etc, then depend on the details of that filter. If there isn't one, the buck gets passed on to the following items in the chain. Which ends, of course, with the speakers... which often 'ring' at HF. (Many examples now shown in HFN speaker reviews as they go up above 20kHz and show this nicely.)