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Various pictures from Arny's posts

[attachment=8072:Meridian...eaker_FR.png]

[attachment=8071:PC351_wi...0SC00-04.png]



Various pictures from Arny's posts

Reply #3
Frequency Response

[attachment=8103:FR_DA_FS.gif]

Dynamic Range

[attachment=8099:DR_DA_FS.gif]

Jitter

[attachment=8101:JIT_DA_FS.gif]

S/N Ratio

[attachment=8102:SNR_DA_FS.gif]


Various pictures from Arny's posts

Reply #5
That is truly hilarious. Where did you get that?

Various pictures from Arny's posts

Reply #6
That is truly hilarious. Where did you get that?



I cannot tell a lie - I found the original in the pictures folder of this PC. ;-)

Various pictures from Arny's posts

Reply #7
[attachment=8218:swisha1644.wav]

This is an interesting little file of a signal that is called "A Swish" that just about any FFT analysis will portray as having a flat PSD 20-20 KHz.

It largely avoids the bucket alignment problem with mulitones, and the integration time problem with pseudorandom signals.

If one needs a wide bandwidth version of this, just change the .wav file header to a higher sample rate like 96 KHz.

And while I'm at it - an attempt at a bucket-aligned multitone

[attachment=8219:bucket_a...one_2496.wav]

Various pictures from Arny's posts

Reply #8
Here are two approx 10 second samples of 19 KHz and 19_20 KHz test tones re-recorded by looping through a M-Audio 25192 audio interface running under 64 bit  Win 7.1 with all current windows updates.

19 KHz test tone

[attachment=8220:19_KHz_o..._ap24192.flac]

19+20 KHz test tones

[attachment=8221:19_20_KH...192_2496.flac]

Looks like multiple tones are a more difficult test

and more:

2496 swisha:

[attachment=8227:swisha_2496.flac]

2496 swisha looped through AP24192

[attachment=8226:swisha24..._ap24192.flac]

Bucket aligned multitone looped through AP24192:

[attachment=8225:bucket_a...192_2496.flac]


Various pictures from Arny's posts

Reply #10
Mislabeling alert - the resampling quality in the quality = 100 files was actually quality = 999

The following shows a comparison of the impulse response of the two files


[attachment=8232:impulse_...it_1-999.png]

More detail:

[attachment=8234:impulse_...9_expand.png]


This is the data file:

[attachment=8233:impulse_...it_1-999.flac]

Various pictures from Arny's posts

Reply #11
Comparison of Sox and CEP 2.1 resampling of 24192 impulse:

Sox resampling:

[attachment=8238:sox_resa...r_wombat.png]

Audacity resampling:

[attachment=8240:Audacity...sampling.gif]


Ringing anybody? ;-)

CEP 2.1 resampling  Q=30:

[attachment=8239:CEP_resa..._per_ABK.png]


Various pictures from Arny's posts

Reply #13
Latest keys jangling 2496 tests with IM test tones starting at 12 seconds that are only needed for testing your monitoring system for IM, not needed for the listening test of downsampling.

2496 Reference file:

[attachment=8248:keys_jan...tones_f4.flac]

The above file downsampled to 1644 and upsampled to 2496:

[attachment=8247:keys_jan...tones_f4.flac]

For those who are not familiar with these files, the first 12.5 seconds is the keys jangling test sound, designed to elicit audible differences due to 16/44 versus 24/96.

Do not apply Replaygain. normalizing or other leveling techniques to these files.  Their content 20-17 KHz is correctly level matched.

Beware! These files can fool you. They contain Full Scale test signals that are either not very loud or inaudible. You could conceivably turn your monitoring system up too far and hurt something. They should cause no problems if played at reasonable listening levels. OTOH, some people can't hear 95% or more of these files due to high frequency hearing loss. Hearing nothing, they could conceivably turn their systems up past the breaking point. Don't be that guy!

The remainder of the files are designed to elicit audible misbehavior from monitoring systems that could falsify the key jangling test.

They are composed of a highly audible frequency test tone that you are supposed to hear, followed by 3 sets of ultrasonic twin tones that will elicit no audible response from a monitoring system with adequate quality. They are separated by 2 tics. If your monitoring system has high frequency IM that will invalidate any results from the keys jangling comparisons, you will not hear silence between the tics. Exactly what you will hear is unpredictable, but field reports include hearing low tones similar to the first audible tone, to all sorts of garbagy and distorted sounds. If your monitoring system is adequate you should be unable to hear any difference between the two test files when playing these ultrasonic tones. Both files will produce pure silence between the tics.

Various pictures from Arny's posts

Reply #14
By the way, it seems like a lot of people don't seem to want to take advantage of the following:

[attachment=8249:JAES_Cla...Criteria.png]

Which is not presented ideally and therefore hard to interpret. It is based on listening tests both sighted and blind that were done to determine how well the FR of UUTs have to be matched so that the FR is not a reasonable explanation for any audible differences that are found.  The commonly heard +/- 0.1 dB 20-20 KHz tolerance that is often given is overly-strict. Better to err on the safe side, I guess.

At any rate the way to interpret this chart for the purpose at hand is to understand that there is a built-in safety factor. We're not saying that FR differences outside the limits show on the chart are for sure audible all the time, we're saying that if you are inside these limits, you are safe.

The curves themselves may not be straight forward. The basic idea is the observation that FR differences over narrow bands are far less audible than FR differences over wide bands. Furthermore FR differences at the frequency extremes are far less audible than those near the midband.

For example the chart says that a >5 dB difference over 1/3 octave centered at 20 KHz is safe. That means that a FR error would have to be several times larger than this to be audible. At least twice.

So that is license to let the FR drop by 10 dB or more at 20 KHz if over only a 1/3 octave band. 1/3 octave centered at 20 KHz is 6 KHz wide at the -3 dB points.  Allowing response to drop by something like 10 dB @ 17 KHz and 6 dB or more @ 20 KHz can thus be reasonably expected to be inaudible.

Various pictures from Arny's posts

Reply #15
CEP 4416 Quality=100 tests

Transition band:

[attachment=8245:24192tes...00_24192.png]

Impulse response:

[attachment=8246:24192tes...00_24192.png]

If you want to use a picture of an impulse response as a means to estimate how audible ringing might be, then you should plot power (in dB) vs. time; e.g. see the graphs at the bottom of the page here: http://sox.sourceforge.net/SoX/Resampling

Various pictures from Arny's posts

Reply #16
If you want to use a picture of an impulse response as a means to estimate how audible ringing might be, then you should plot power (in dB) vs. time; e.g. see the graphs at the bottom of the page here: http://sox.sourceforge.net/SoX/Resampling


The chart at the top of that page illustrates the conceptual problem. It portrays signals that are 90 dB down and are also > 20 KHz as if they are easily perceptible by means of making them as visible as signals at FS.

Various pictures from Arny's posts

Reply #17
Arnold, I tested the keys_jangling_full_band_2496_test_tones_f4.flac with ODAC and Xonar Phoebus soundcards using three different headphones (KRK KNS-8400, Sennheiser HD 650 and AKG K601) and I heard a quiet high frequency tone in the IM parts with each setup with moderately loud volume. All these devices should perform quite nicely yet they all fail the IM part. I'm curious to know what kind of hardware does not.

Edit: ran RMAA tests on the soundcards in question. Xonar Phoebus headphone output @ 96 kHz and ODAC into Xonar @ 96 kHz

Various pictures from Arny's posts

Reply #18
I'm curious to know what kind of hardware does not.

  Edit: ran RMAA tests on the soundcards in question. Xonar Phoebus headphone output @ 96 kHz and ODAC into Xonar @ 96 kHz


NWAVguy measured the Behringer UCA202 as having an impressive "IMD of 0.0009% is hard for anyone to argue with" although I don't know if his testing methodology correlates directly with RMAA specs.

I don't hear any faint tone at all through my UCA202 during his test section. [Except when I load the files into Audacity and listen to them there. Then I hear IM.]

Various pictures from Arny's posts

Reply #19
That UCA202 doesn't seem too impressive based on a random RMAA test I found: link. For example ODAC with same sample rate measured with a worse sound card looks like this.

Audacity has option to use WASAPI interface. That would be one explanation for the difference you experience. WASAPI playback would force 96 kHz output and the high frequencies and their problems are heard. If the other program uses DirectSound with Windows mixer set to 44.1 kHz or 48 kHz the excellent resampler in Windows would eliminate those high frequencies and issues would not be heard.

Various pictures from Arny's posts

Reply #20
I don't mind comparing RMAA results when they are carried out with the same peripheral gear, by the same person/conditions, with the same levels, but comparing between Joe's RMAA results  and Bill's RMAA results gets more sketchy. NWAVguy talks more about why here.

Arny, last I heard, also has a UCA202, and hopefully can confirm if it appears as IM free as mine does.

I know there is also a UFO202 version with a phono preamp. I don't care about that part but the nice big ground post looks intriguing. I often have to unplug stuff (unused HDMI cord) to my laptop to eliminate minor ground loops. I wish I had a ground post on my UCA202 to play around with, perhaps it might help in some scenarios.

Various pictures from Arny's posts

Reply #21
I should have checked the specs of that Behringer UCA202 immediately. It's only 48 kHz capable device so it doesn't really quality for this test. You are covered by Windows's excellent resampler and thus free from aliasing and distortion. Audacity uses its own resampler for playback and it defaults to low quality mode.
Testing 96 kHz playback requires device capable of that and unless ASIO or WASAPI is used Windows has to be configured properly too: .

Various pictures from Arny's posts

Reply #22
 OH NOES!! Worst news I've heard all year, but thanks for pointing that out Case.

Sorry Arny if I lead you astray on all your keys tests. Now, using my notebook's internal card, I can still show an ability to distinguish [post t=12.5s] but I definitely hear faint  what I presume is IM [although it doesn't sound like your 4 kHz target tone sine wave, it is more raspy and buzzy, almost like a triangle or square wave, lower pitch, and perhaps dual tone] So I no longer qualify to even take the tests. *&^%$! 

Here's me keying off this faint IM distortion, using my 96k setting of my Asus notebook's 3.5mm analog output, but of course keep in mind that may be EXACTLY what the organic twins are doing to too, even though they won't admit it:

Code: [Select]

foo_abx 2.0 report
foobar2000 v1.3.3
2015-04-02 23:49:44

File A: keys_jangling_full_band_2496_test_tones_f4.flac
SHA1: 5c0d71159fd3702d0515372876e699f1ca8de1d0
File B: keys_jangling_full_band_2496_1644E2Q150_2496_test_tones_f4.flac
SHA1: 6bbc99e2f0ca8f3083096b51fa0221792c6b5b85

Output:
DS : Primary Sound Driver
Crossfading: NO

23:49:44 : Test started.
23:51:20 : 01/01
23:51:24 : 02/02
23:51:28 : 03/03
23:51:31 : 04/04
23:51:35 : 05/05
23:51:38 : 06/06
23:51:42 : 07/07
23:51:45 : 08/08
23:51:45 : Test finished.

 ----------
Total: 8/8
Probability that you were guessing: 0.4%

 -- signature --
c191c2e925611bd953a3489c4d4753e1213b0ebb


P.S. There are also audible differences in this IM distortion I hear when I change my notebook's advanced speaker settings output page from 96k/24 up to 192/24, should that mean anything.

Various pictures from Arny's posts

Reply #23
Although I indeed hear IM issues now,  they are faint and only from some PURE test tones, in isolation from other material, which are extremely high level compared to the actual keys sounds. It seems hard to believe that the keys noise itself, which doesn't sound any different between the two files, is actually being corrupted in an AUDIBLE manner which we need to worry about, that would not be immediately masked by the very broadband and constant sound they make on their own.* [I hope that makes sense. It is hard to verbalize.] I.e. you are shooting yourself in the foot by including the test tones at all. The keys should be a file all by themselves and if you want to tack on a side test for IM detection, so be it.

*It would be like worrying if a 4 kHz pure tone, some down 80 dB from the main signal, might be audible during the chaotic, constant sound of shattering glass. No, it will be masked.


Various pictures from Arny's posts

Reply #24
No IM but the unfiltered version has a tiny click at the very end, so 3 while i hear only 2 with the filtered.
Is troll-adiposity coming from feederism?
With 24bit music you can listen to silence much louder!

 
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