Topic: Metrum Acoustics Quad Measurements (NOS Mini DAC) (Read 12357 times)

Solderdude · « **Reply #70 on:** April 04, 2014, 08:38:05 AM »

Can I ask the question that shouldn't/mustn't/oughtn't be asked in these circumstances.

When you were listening, did you know what type of filter was being used or did someone else set the filters and you listened out for differences ?

I know this is the wrong question to ask here but would like to know the test conditions as they were.
My question is not intended dismiss what differences you (and many others) heard nor to invalidate all the hard labour and many hours of intense listening in any way nor to discredit all the work put into it.
It is more to satisfy my own curiosity as I am one of the persons with a reasonable hearing but cannot hear differences between DAC's and 'properly designed' amps. One might call me cloth eared, biased or deaf but recognise the idea that some may have better hearing than I.

I DO know that there are lots of audible differences between down/up-sampling algorithms but this is because they were not properly designed tested.
This doesn'thave anything to do with the ringing in filters which only happens with steps and not with sinewaves and steps do not occur in music signals.
Bad algorithms show all kinds of aliasing products bouncing back into the audible range.
Some even are barely attenuated in some cases.

There seem to be somewhat more well designed than poorly designed algorithms by the way.
See for yourself: http://src.infinitewave.ca/ (set to sweep)
The part to the left and right of the yellow line should be pitch black (maybe dark blue is accepatble) but bright lines, especially on the left of the bright curve are a big nono.
These are ONLY of downsampled samples going from 96 to 44.1 in which case 96 is not a multiple of 44.1.
I am willing to bet that 96 to 48 would have given better results for most resamplers though.

When someone for instance has used a bad downsampling algorithm and compares a downsampled file with the original one they might easily find the downsampled one sounds worse yet done with a good algorithm may find there are no audible effects (when tested blind)

Hands · « **Reply #71 on:** April 04, 2014, 09:04:13 AM »

Oh, I did all the testing myself, so I knew what I was listening to. That's why I try to make sure and put disclaimers with anything I say.

I actually wish I had someone around that was interested enough to put me through blind tests. But, to be honest, I went into these tests expecting I should not hear a difference in these regards, but I'm still fallible and could have fooled myself regardless.

When you say ringing only happens with steps, I'm confused. I have seen graphs of sine waves with pre/post-ringing due to upsampling, but there's a strong chance I'm missing something or misunderstanding entirely. See the link below...I would definitely appreciate an explanation to better understand this!

http://www.cicsmemoryplayer.com/index.php?n=CPlay.Measurements

That's a cool site, for sure. I came across it earlier when looking into different filter types.

Solderdude · « **Reply #72 on:** April 04, 2014, 09:49:41 AM »

What the pictures show is an instantly increasing/decreasing sinewave which is an artificial waveform that doesn't exist in music (unless it is electronically generated and has never been processed along the way) so essentially is forming a step.
Of course an instant 'attack' DOES exist but an instant stop does not... so pre-ringing is a real change to the signal.
What is interesting though is that the sine is stepped as well and not starting from '0' what a real sound would do.
Possibly these plots would not show the pre-ringing so they went with the published plot (really dark thinking of me) that actually shows it is there.

Also it depends on how the filter is made.

What would be more indicative to asses the effects filters have is by downsampling music and upsampling it again to the same file type.
Then digitally null those files and have a look in the audible band for the difference file.
It stands to reason everything above 1/2fs of the lowest sampling rate is also in the difference signal but can most likely tell if it is ringing or US contents by looking at the spectrum.

I am fully aware of the possible dangers in sighted tests and often am convinced I hear 'something' (even when not expecting it) and only after I tested blind it turns out the things I heard (and could even tell with a certain amount of certainty) were not present when tested blind.
The thing is one knows something has changed even when we expect nothing of it.
The most known counterargument is that people independently report the same.

This discrepancy causes the well known debate and will never be resolved I am afraid.

So for this reason my motto is... if it is an improvement, regardless where it comes from, and is worth the effort/money I am all for it.

Hands · « **Reply #73 on:** April 04, 2014, 11:09:41 AM »

Gotcha, makes sense. Thanks for the explanation, as always!

And that's why I don't try to pass my ideas off as anything more than they are (subjective, likely fallible thoughts subject to placebo). Regardless of whether or not I'm actually hearing an improvement with attack/transients, my ears like the laid-back NOS sound for long listening sessions along with some other characteristics I find pleasing (subjectively, not necessarily better or worse, but to my tastes). For other times, upsampling on a NOS DAC does a good job when I'm in the mood for it. The attack/transient thing is by no means my highest priority, but rather something I thought I noticed during listening tests while I was listening more for changes in treble and soundstage characteristics.

Solderdude · « **Reply #74 on:** April 04, 2014, 12:24:42 PM »

The funny thing about 'attacks' in music is that they aren't really fast in most cases.
That is with respect to the level and amount of harmonics present.
The ultrasound content is down 50 dB or so while the measurements are always done near FS to show 'worst case scenario'.

In fact most 'transients' are often sampled taking several samples and thus way below1/2 fs so do not stress the frequency range.
So a NOS DAC can reproduce transients quite accurately (so can OS DAC's).
At the same time the roll-off (for 44/48kHz) is still present yet the transients are not affected so relatively 'more' present.

Depending on the level of the higher harmonic contents and how long higher frequency tones are present there is a continuously change in roll-off.
The 'severity' of this roll-off is thus NOT always the same and depends on the relation between the sample frequency and the to be reproduced frequencies.

If you were to place a (post) analog filter behind an OS DAC with the same roll-offyou would find using a testsignals on a NOS DAC you would NOT end up with a similar tonal balance.
The NOS DAC would sound brighter and even less rolled-off than would it appear to be the case when looking at plots based on a test-sweep.

Yet... rolled off the NOS DAC will always be which many people prefer and may be largely depending on recording quality/music I would add.

OJneg · « **Reply #75 on:** April 04, 2014, 01:03:40 PM »

I think you might be repeating yourself at this point Solder.

Solderdude · « **Reply #76 on:** April 04, 2014, 01:10:03 PM »

Repeating perhaps.
Elaborating and explaining a bit further was the intention.

There is info in there I hadn't touched before...

OJneg · « **Reply #77 on:** April 04, 2014, 01:42:36 PM »

Hans, I think you were talking about the different sort of digital filters that can create pre- and post- ringing. Some might say that that too is inaudible so long as it doesn't effect the passband, but I think differences are there.

I was able to capture those waveforms on my gamma2, but I won't post them until you try listening first. Wouldn't want to bias you of course

Author Topic: Metrum Acoustics Quad Measurements (NOS Mini DAC) (Read 12357 times)

Solderdude

Re: Metrum Acoustics Quad Measurements (NOS Mini DAC) - UPDATED 12/7 w/ new tests

Hands

Re: Metrum Acoustics Quad Measurements (NOS Mini DAC) - UPDATED 12/7 w/ new tests

Solderdude

Re: Metrum Acoustics Quad Measurements (NOS Mini DAC) - UPDATED 12/7 w/ new tests

Hands

Re: Metrum Acoustics Quad Measurements (NOS Mini DAC) - UPDATED 12/7 w/ new tests

Solderdude

Re: Metrum Acoustics Quad Measurements (NOS Mini DAC) - UPDATED 12/7 w/ new tests

OJneg

Re: Metrum Acoustics Quad Measurements (NOS Mini DAC) - UPDATED 12/7 w/ new tests

Solderdude

Re: Metrum Acoustics Quad Measurements (NOS Mini DAC) - UPDATED 12/7 w/ new tests

OJneg

Re: Metrum Acoustics Quad Measurements (NOS Mini DAC) - UPDATED 12/7 w/ new tests

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Author Topic: Metrum Acoustics Quad Measurements (NOS Mini DAC) (Read 12357 times)