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Old 14th April 2015, 01:37 AM   #721
spzzzzkt is offline spzzzzkt  Australia
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Quote:
Originally Posted by AndrewCee View Post
Running the C128 - just put on some Diana Krall - very nice! Rater, more like very, very nice!!! Sounds good on both 16/44 & 24/384 albeit a tiny bit more atmosphere and space in the music with the high frequency input.
Out of interest is the 24/384 up sampled in software or is it a hi-res version of the same recording?
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Old 14th April 2015, 03:38 AM   #722
ylingf is offline ylingf  United States
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I briefly listened to zfe's NOShalf filter as well, found it to be excellent. Did not have time to do extended comparison between NewNOS, C128 and NOShelf. But love to hear other peoples opinions.
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Old 14th April 2015, 03:54 AM   #723
ylingf is offline ylingf  United States
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Quote:
Originally Posted by spzzzzkt View Post
Søren has said that the filters reload whenever the loses a lock on input.
Just make sure you see feedback on the terminal/putty that indicates the DAM has locked to a sample rate, i.e. L044.

You should get Ix, L044, V-xx whenever the DAM relocks.
Code:
# exit
I1
L044
V-35
I2
I1
L044
V-35
Try using I3 if you only have one active input, and remember you need to enter the Ix twice when you first exit from uManager. The DAM will not respond the first time.
Exactly what I need to know, thank you!
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Old 14th April 2015, 09:46 AM   #724
zfe is offline zfe
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Quote:
Originally Posted by spikestabber View Post
I also began comparing 44.1k flac's to vinyl releases and its to the point now where the DAM is making me feel like my vinyl collection/turntable was a waste of money.
My overlap between vinyl and digital is not that huge (and you also do not know if not something was altered between the two releases).
However I can not yet say that I would throw away my vinyl for the digital. There are sometimes distortions on the vinyl (mostly dynamic issues I think) that are not at the digital side, which is somehow a bit cleaner. But I have the impression that the vinyls have a bit more body, are somehow less flat (if that makes any sense).

The most obvious difference is that I frequently can listen relaxed to vinyls at a volume that I do not support for a long time on the digital side.
Of cause this may be some technical problem with the dynamic (or the HF comming through) somewhere in my chain.
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Old 14th April 2015, 09:51 AM   #725
oneoclock is offline oneoclock  Europe
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While 1021filtNQ_C128x110 is perfect for listening, can always criticize it is not perfect at high frequency. A manufacturer needs to make one more perfect frecuency response to look good with the press.

Until you can get a gradual transition IP filter, you can make an IP filter previous approach, would be to half of short NQ filter, and later to half of long NQ filter like this or more long.
Click the image to open in full size.
Attached Files
File Type: txt 1021filt-cuasi-NOS-IP.txt (31.0 KB, 25 views)

Last edited by oneoclock; 14th April 2015 at 10:10 AM.
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Old 14th April 2015, 10:39 AM   #726
AndrewCee is offline AndrewCee  United Kingdom
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Hi Paul, Yes, I guessed as much. Thank you however, for making the point. Until now (having now built the Dac into the case with all inputs available) I've been using the optical input switching between 16/44 and 24/96 on the PC. I tend to think this offers a 'more realistic' comparison, likewise arguably 16/44 and 24/384, to immediately hear the difference between 'filter in/filter out’. I have been listening principally to 24/96 material, theory being the file has the maximum resolution available - assumes the recording, production, etc, is of high order and not some compressed junk! I have a couple of 384k files somewhere for testing, but have yet to try them out. I use a TAG McLaren DVD32 as CD transport, will connect that up at some point and have a listen. I've also a TAG AV192 to fix, which has a 2-way digital connection between DVD to sync clocks, etc. Be interesting to compare CD between an 'all TAG' setup and our Dac.

I have now fired up NI Signal Lab, Tektronix Edition, and connected up the scope. Going to have a play, will report back. Last night was still unable to get the FFT plot to show the noise floor anything below about -70/80dB at best, way higher than I expect.
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Old 14th April 2015, 12:47 PM   #727
jaffar is offline jaffar  Russian Federation
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Quote:
Originally Posted by spzzzzkt View Post
The only way I can see that issue can be addressed is to make the filter steeper but that would require a longer filter and more ringing. I think it might be possible to tweak so the time smear is shifted higher but that will require some experimentation.
Some thoughts on IR spectrograms and time smear detection.

I think they should be done with a broader perspective: FR up to 100k and at least 120-140dB of dynamic range.
85dB is insufficient - too flattering, we can't really see the ringing.
The analyzer software do some averaging, so the real amplitudes are at least 30db higher.

140dB is more revealing, "log squared"

Examples below (done with SoX).

IR of an IP filter, upscaling from 44k to 352k, 85dB:
spectrogram_z85_crop.png
Nice! No ringing

If we dig a little deeper...
spectrogram_z140_crop.png
With 140dB we start to see something.

Finally, full scale DR:
spectrogram_z180_crop.png
Now we see everything, even the dither @ -140dB. The ringing starts from around 17kHz and should be inaudible.
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Old 14th April 2015, 03:07 PM   #728
zfe is offline zfe
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While it is clear what the log square impulse response tells us, it is just the plot of the magnitude of the filter coeficents in dB, I am not so sure about the actual information content of the spectrogram of the impulse response.
There is nothing such as spectral distribution of a single sample. What is done is you pick an certain amount of the samples (of the impulse response in our case), by multiplying it with an suitable placed "window". Then do the DFT which gives you a frequency distribution. Then move the window ahead some samples and repeat the process.
The narrower you choose the window the better is your time resolution, but the coarser the frequency resolution.

So what we see is the frequency response of the part of the impulse currently under the window plus effects of the chosen window function.

As the impulse response contains relatively few samples, it is probably more important than usual to choose the parameters (time resolution, windowing function) carefully so that you see some detail information of the impulse response and not only of the applied window sliding over some kind of peak.

Again, I am no expert in digital audio processing, I just try to understand the theoretical part, and see here potential dangers. Maybe I am totally wrong.
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Old 14th April 2015, 09:30 PM   #729
spzzzzkt is offline spzzzzkt  Australia
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Jaffar/zfe...

The point here is as Pflaumer indicates in his patent is that a log representation of the impulse is better correlated with what we hear than linear representations.
Secondly, Pflaumer indicates that only smear above -80dB has any audible effect.

I find it a pretty useful tool, and it seems to reflect what I'm hearing.

Of course if you feel the need to stick to textbook approved theory or plots that show the movement of atomic particles you are more than welcome to do so...

The spectrogram is done with Isotope RX which uses Auto adjusting Short-time Fourier Transform, and the window is a Kaiser beta = 20.

Remember that I am analysing the single sample after if has been up sampled using FIR1 and FIR2. There are well over 1000 samples within the length of the sample, not just one...

Attached is a screen shot of the very start of the ringing of an impulse showing the sample points. Obviously there a few more than one.
Attached Images
File Type: png SamplePoints.png (85.9 KB, 96 views)

Last edited by spzzzzkt; 14th April 2015 at 10:00 PM.
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Old 14th April 2015, 09:59 PM   #730
zfe is offline zfe
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Quote:
Originally Posted by spzzzzkt View Post
Jaffar/zfe...

The point here is as Pflaumer indicates in his patent is that a log representation of the impulse is better correlated with what we hear than linear representations.
Secondly, Pflaumer indicates that only smear above -80dB has any audible effect.

I find it a pretty useful tool, and it seems to reflect what I'm hearing.

Of course if you feel the need to stick to textbook theory or plots that show the movement of atomic particles you are more than welcome to do so...
Ay What in my post goes in the direction you complain about.
I do not complain about squared log and only say you need to be carefull to interpret the Elephant diagrams.
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