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post #301 of 569 Old 05-04-2020, 10:52 AM - Thread Starter
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Originally Posted by m. zillch View Post
This spectral analysis is of the entire song but that loud, deep bass hump is from the "room tone" exhibited in this recording and occurs start to finish.
Here it is again but this time the image is just a snapshot of the "silent" part immediately after she sings the opening verse "We are miners. . ." around 6 seconds into the song:


Notice the skinny spike just below 16 kHz around -84dB down? That's the microphone picking up the high frequency squeal of a CRT TV's flyback transformer in the room. Although inaudible to most people, including apparently the recording engineer at the session, seeing this spike makes audio restoration people jump for joy because that very specific frequency can then act as calibration tone to be sure the playback of an analog recording can be done at the exactly correct speed. Too fast and the pitch will rise and too slow and the pitch will fall. [This is not a concern on digtal tapes like this one though.]

For example, it was not until decades after its release that we discovered the CDs we had been pressing from Miles Davis' classic "Kind of Blue" master analog tape were at the wrong speed for one entire side of the album! The recording studio back in the 50's had failed to properly calibrate their tape machine before that critical recording session so all subsequent playbacks of that master tape on proper speed tape machines were effectively slightly off in pitch, until their error was corrected for in the 1990s.
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post #302 of 569 Old 05-04-2020, 12:26 PM
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Quote:
Originally Posted by m. zillch View Post
I found the GIF animation I had made of this earlier showing Apple DAC's rendition vs. the original measurement, alternating every half second. Here it is:


This spectral analysis is of the entire song but that loud, deep bass hump is from the "room tone" exhibited in this recording and occurs start to finish.

The "added treble" may actually be not so much a change in the frequency response but rather the added upper harmonics which occur from both THD and IM distortions. I'm not sure.

Apple also seems to cut everything above 19kHz.
Interesting. And both ends are where JNDs are much greater than the rest.
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post #303 of 569 Old 05-04-2020, 01:20 PM - Thread Starter
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Interesting. And both ends are where JNDs are much greater than the rest.
Although our JND for level discrimination at 19/20kHz is indeed quite high, as you astutely point out, the main reason content there isn't all that important is that even for a 10 year-old who still hears a 20kHz test tone clear as a bell, in actual acoustical musical instruments there's no such thing as one that has appreciable content there without simultaneously having just as loud or even louder content in the octave just below that, which acts as a masker to the 20kHz target.

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post #304 of 569 Old 05-04-2020, 03:14 PM
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Originally Posted by m. zillch View Post

Actually my spectral analysis shows that the Apple DAC has less very deep bass than the original, although only people who have subs that go down to 11Hz and can "detect infrasonic sound" might, theoretically at least, notice this. I'll post an image shortly, showing this.

The .gif animation is showing slightly more bass at 28Hz which is what I was hearing. The boost is easily masked by the A/C or refrigerator.

The early TV's 16kHz flyback transformer whine was annoying when I was a kid. I would lay on the floor real close for that big screen experience. Black and white of course but that didn't matter because 1957's Tom Terrific with Mighty Manfred the Wonder Dog was only black and white line drawings.
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post #305 of 569 Old 05-04-2020, 03:37 PM - Thread Starter
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The .gif animation is showing slightly more bass at 28Hz which is what I was hearing.
According to this study in the peer reviewed Journal of the Audio Engineering Society the teeny tiny alteration of level change over a very tiny fraction of an octave at 28Hz, shown in my GIF animation, falls well below the expected JND for level discrimination at that frequency and signal bandwidth, as shown here:


Also, according to the ABX tests you took, at least the two of them you posted for us to see, you didn't show an ability to hear any difference of any kind under blind conditions.
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post #306 of 569 Old 05-04-2020, 03:51 PM
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Quote:
Originally Posted by m. zillch View Post
According to this study in the peer reviewed Journal of the Audio Engineering Society the teeny tiny alteration of level change over a very tiny fraction of an octave at 28Hz, shown in my GIF animation, falls well below the expected JND for level discrimination at that frequency and signal bandwidth:


Also, according to the ABX tests you took, at least the two of them you posted for us to see, you didn't show an ability to hear any difference of any kind under blind conditions.
"peer reviewed' pfffft what drivel and nonsense!


On a more serious note, can you tell me what the graph shows? I think it's showing the difference in level able to be discriminated at given frequencies, but how do the three octave bandwidth curves fit in?
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post #307 of 569 Old 05-04-2020, 04:02 PM - Thread Starter
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Originally Posted by mechtheist View Post
"peer reviewed' pfffft what drivel and nonsense!


On a more serious note, can you tell me what the graph shows? I think it's showing the difference in level able to be discriminated at given frequencies, but how do the three octave bandwidth curves fit in?
You pretty much got it. This graph shows the smallest difference in level, measured in dB, between two signals which a human can detect, also called a JND, "just (barely) noticeable difference" that is discernible to human hearing. It depends on both the frequency of the test signal and its bandwidth measured in octaves (or fractions of octaves).

Hearing small level changes that are several octaves wide are much easier to detect than the same level change which happens over only a tiny range of frequencies or octaves.

The reason we usually stop making graphic equalizers with more than say 30 to 50 different sliders is because when the bandwidth of the boost or cut gets any skinnier than that, humans stop hearing a single slider boosting/cutting by itself, especially in the bass.
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post #308 of 569 Old 05-04-2020, 05:24 PM
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Quote:
Originally Posted by m. zillch View Post
You pretty much got it. This graph shows the smallest difference in level, measured in dB, between two signals which a human can detect, also called a JND, "just (barely) noticeable difference" that is discernible to human hearing. It depends on both the frequency of the test signal and its bandwidth measured in octaves (or fractions of octaves).

Hearing small level changes that are several octaves wide are much easier to detect than the same level change which happens over only a tiny range of frequencies or octaves.

The reason we usually stop making graphic equalizers with more than say 30 to 50 different sliders is because when the bandwidth of the boost or cut gets any skinnier than that, humans stop hearing a single slider boosting/cutting by itself, especially in the bass.
Are the signals some kind of noise, like pink noise through a bandpass filter?
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post #309 of 569 Old 05-04-2020, 05:27 PM - Thread Starter
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Are the signals some kind of noise, like pink noise through a bandpass filter?
Yes, probably pink noise bandwidth limited by different amounts and with different center frequencies.
http://www.aes.org/e-lib/browse.cfm?elib=11982

If you want to detect the smallest JND possible you use 3.5-4kHz bandwidth limited PN because we are most sensitive there. We are most sensitive to small changes and to small levels, as seen in the classic Fletcher-Munson equal loudness contour chart.

https://upload.wikimedia.org/wikiped...indos4.svg.png
Notice we are so sensitive in that range we can hear sounds even quieter than 0dB SPL !
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post #310 of 569 Old 05-04-2020, 05:39 PM - Thread Starter
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One theory why we are most sensitive to that range is because it is typical of a crying baby. In our caveman days when the lions and tigers crept into our base camp and the babies cried out only the humans with good sensitivity at 3.5kHz could hear the cries from far away so they ran back to protect the babies in time. The humans with good sensitivity at 8kHz, on the other hand, didn't hear their babies' cries so they didn't get living offspring to carry on their 8kHz sensitivity genes, and they died out. Natural selection.
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post #311 of 569 Old 05-04-2020, 06:15 PM
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If the babies are already crying, you better have evolved some really quick legs to get there before the crying gurgles into slurping and smacking by the cats. Of course, the quiet babies maybe fared better than the noisier ones.
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post #312 of 569 Old 05-04-2020, 06:16 PM
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Quote:
Originally Posted by m. zillch View Post

Also, according to the ABX tests you took, at least the two of them you posted for us to see, you didn't show an ability to hear any difference of any kind under blind conditions.
In my room increase in bass was more of an increase in room pressure than a clear note. Looking at the graph does not effect what I heard.

I did hear a difference, I just wasn't consistent.

How was the David L. Clark ABX graph made? With headphones, anechoic chamber or real life in-room with room nodes that can either increase or decrease bass? I have a feeling the woofers used in 1982 to make this graph were not as light and fast as woofers available today, not to mention today's high current current amps with or without servo control. If you want to learn about state-of-the-art bass contact Danny Richie at GR Research http://gr-research.com/

I was wondering what your agenda is? The Apple DAC sounds exactly like a ripped CD in a recorded .wav file. Now what?
Nobody actually listens to the music recorded from an Apple DAC. I haven't seen a post from anyone plugging the Apple DAC into their stereo for a real world comparison between the Apple and their current DAC.


Maybe, just maybe Julian Hirsch was right in 1977 - "Hirsch was infamous among audiophiles for believing that all audio electronics — amplifiers, CD players, etc. — sound the same. For example, in April 1977, he stated: “I do not believe that any amplifier that is reasonably good and operating as intended has any sound quality of its own, at least not in the sense that phono cartridges, speakers, and listening rooms have their distinctive sounds.”
https://www.soundandvision.com/conte...OWEroBSAWwZ.99


Nah.
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post #313 of 569 Old 05-04-2020, 06:25 PM - Thread Starter
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Originally Posted by WGH View Post
Nobody actually listens to the music recorded from an Apple DAC.
I'm of the mind the direct sound out of this $7.99 DAC (which many people do listen to) is technically even better than my recording of it, because my ADC used to get the signal back into the digital domain introduces some minor quality loss too. (Although so far it seems it is inaudible too.)

I also suspect this DAC is the most wildey used outboard DAC on the planet since every iPhone made since 2014 comes with one for free and as I understand it well over 2 billion iPhones have been sold (2018 data).

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Originally Posted by WGH View Post


Maybe, just maybe Julian Hirsch was right in 1977 - "Hirsch was infamous among audiophiles for believing that all audio electronics — amplifiers, CD players, etc. — sound the same. For example, in April 1977, he stated: “I do not believe that any amplifier that is reasonably good and operating as intended has any sound quality of its own, at least not in the sense that phono cartridges, speakers, and listening rooms have their distinctive sounds.”
https://www.soundandvision.com/conte...OWEroBSAWwZ.99


Nah.
This is a settled question for the most part, settled by double blind testing, for like 30 years. I can't help but be constantly amazed at how many 'audiophiles' can't accept established scientific fact, might as well be flat-earthers--gosh, it sure looks flat to me. I posted this in another thread, it's from the superb audio publication The Audio Critic from its Spring through Fall 1991 issue:


Quote:
Basic Issues of Equipment Reviewing and Critical Listening: Our Present Stance
For the benefit of new readers, as well as longtime readers who may
need to be reminded, here are some of the fimdamental viewpoints that
divide responsible audio reviewers from the tweaks and cultists.
If you read a lot of audio publications and converse
with a lot of audio people, as I do, you know that the line
has been drawn between two opposing factions. The audio
world is at loggerheads as never before. The so-called
objectivists and subjectivists have evolved highly divergent
belief systems; each side shows a basic lack of respect for
the other; accusations of self-serving politics and defective
hearing abound; the general tone is uncomfortably confron-
tational. In the heat of the arguments, science and logic are
forgotten, methods and credentials are left unquestioned,
obfirscation is rampant, and wimpy suggestions to the effect
that the truth lies in between are slipped in sideways by the
knee-jerk conciliators. This is a good time, indeed an obvi-
ous time, for The Audio Critic to restate its position on the
issues that constitute the basis of the ongoing debate.
What sounds different?
To the dyed-in-the—wool subjectivists, everything
sounds different. One of my favorite dirty tricks is to go
through the motions of conducting a single-blind A/B am-
plifier or preamplifier comparison which is actually an A/A
comparison because I only pretend to switch to B but never
do. Lo and behold, some of the audiophiles in attendance
claim to hear major differences in front-to-back depth, im-
aging, "air," etc., and are quite certain they can pick out A
and B blind. A cruel experiment but educational. Thus I
have no fear that such audiophiles will argue with me when
I list the various elements in the audio chain that really do
sound different. To wit:
Listening rooms—and how! Loudspeaker systems,
even the relatively accurate ones. Surround-sound and other
environment processors, obviously. Phono cartridges and
tonearms, if you still care. Microphones—very important
and all very different. Recording studios and concert halls,
for the same reasons as listening rooms, only more so. And
finally, the widely differing recording techniques of differ-
ent record companies, producers, and engineers—even when
they use the same microphones in the same hall. What else
sounds different‘? That's just about all I can think of (No,
I'm not forgetting wires and cables. They constitute a very
special case, subject to serious misrepresentations, and are
treated separately in this issue.)
What sounds the same?
Here we come to highly divisive subject matter, the
major source of hostilities and character assassinations in
the high-end audio press, but there's no reason for rational
audiophiles to doubt what has been demonstrated over and
over again in properly conducted double-blind listening
tests. Power amplifiers, preamplifiers, CD players, D/A pro-
cessors, DAT recorders, FM tuners, and turntables sound
the same—with certain very important qualifications.
What are these qualifications? Power amplifiers must
have high input impedance, low output impedance, no fre-
quency-response anomalies, and be at all times operated
within their voltage and current capabilities in order to
sound the same. Preamplifiers must likewise be without
equalization errors, other fiequency-response anomalies,
and overload problems in order to sound the same. Digital
audio equipment must be up to the present-day level of con-
verter technology and, analogwise, meet the aforementioned
preamplifier qualifications in order to sound the same. FM
tuners will sound the same only when receiving a strong
signal without multipath. Turntables will sound the same
only if adequately isolated, damped, and free from drive ir-
regularities. Without these qualifications all arguments on
the subject are meaningless.
In general, any two components A and B that can be
alternately switched into and out of an audio system in an
AB test will sound the same if (1) their linear characteris-
tics are essentially identical and (2) their nonlinear charac-
teristics are below the threshold of audibility. If you think
about that statement for a minute, you begin to realize that
it‘s a truism rather than a heresy; the trouble is that the
tweaks and cultists often think for less than a minute.
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post #315 of 569 Old 05-04-2020, 06:37 PM - Thread Starter
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Quote:
Originally Posted by WGH View Post
I was wondering what your agenda is?
Have you not read the whole thread? Here:

Quote:
Originally Posted by m. zillch View Post
To see if a very inexpensive $7.99 DAC, specifically this particular one, including it analog output circuitry, is audibly perfect to the ear when reproducing music by converting the digital signal to analog. Does it do it perfectly? Or does it have audibly discernible flaws, like poor sound stage, detail/imaging resolution, or added hum, hiss, buzz, noise, frequency response errors, etc.?
So far no posted ABX test shows anyone can find any perceptible flaws and that includes you using your first choice on a list of your own hand picked music.
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Originally Posted by m. zillch View Post
According to this study in the peer reviewed Journal of the Audio Engineering Society the teeny tiny alteration of level change over a very tiny fraction of an octave at 28Hz, shown in my GIF animation, falls well below the expected JND for level discrimination at that frequency and signal bandwidth, as shown here:


Also, according to the ABX tests you took, at least the two of them you posted for us to see, you didn't show an ability to hear any difference of any kind under blind conditions.
Great post. I was looking for this not long ago but not sure where I hid it.
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Originally Posted by mechtheist View Post
"peer reviewed' pfffft what drivel and nonsense!


...
Hang the messenger.
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Quote:
Originally Posted by WGH View Post
...

I was wondering what your agenda is? ....
I would think getting to some truths?
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post #319 of 569 Old 05-04-2020, 10:36 PM
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The .gif animation is showing slightly more bass at 28Hz which is what I was hearing.
You mean that's "what I thought I was hearing" You failed the test.
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post #320 of 569 Old 05-05-2020, 08:46 AM - Thread Starter
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Quote:
Originally Posted by WGH View Post
The Apple DAC sounds exactly like a ripped CD in a recorded .wav file. . . . Nobody actually listens to the music recorded from an Apple DAC
Why did you twice emphasize this word I've underlined, "recorded," in your post by putting it in italics? Are you implying the $7.99 Apple DAC will sound imperfect, but only when heard live, not recorded? That is, recording it somehow erases all of its faults it imposes on the music and this recording process magically re-instates any lost details and imaging the $7.99 DAC (supposedly) fails to properly resolve? That is the recording process suddenly makes the signal audibly perfect again and indistinguishable from a more expensive DAC?! That sounds like magic to me and impossible.

If my $7.99 DAC has flaws (let's say for example "an inability to resolve subtle details and image properly") those loss of details can't suddenly "re-materialize" out of thin air down the road just because of the ADC one uses to return the signal back to the digital domain in File B. Once the signal is "harmed" by the $7.99 DAC it stays harmed because it is now baked into the signal from that point forward. My $7.99 DAC acts as a bottleneck and any aspect which makes other more expensive DACs supposedly "better" will be audible to a test taker when listening to the original master file directly, called "File A" in the test:
Quote:
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Or if just using the letters A for analog and D for digital:

File A is: D ------------------------------------------------------------------------------------------------------>digital input on audio playback system of the listener's choice.

File B is: D ----->$7.99 D-to-A----->analog RCA wire----->A-to-D --------------------------------------->digital input on audio playback system of the listener's choice.

IF A and B are indistinguishable from each other then all those added steps in B are perfect to the ear: They resolve every single detail/nuance and add no discernible alteration.

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thread cleanup

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thread cleanup
Sorry about drifting off.
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This ABX test also determines if the listener can audibly discern if the RCA wire I selected and the USB cable from the ADC back to the computer's hard drive used to record File B audibly compromise the sound. So far according to all posted results they don't. They seem to be perfect to the ear as well:

File B is: D ----->$7.99 D-to-A------------>analog RCA wire------------------------>A-to-D-------->USB cable back to my laptop's hard drive


The 6ft Monoprice 659 RCA wire is currently $1.05 [I bought them when on sale for 87 cents each]. It was brand new hence "not burned in".

The USB cable was free (it came with the ADC).

So if free USB cables and dirt cheap RCA cables sound perfect, why would we buy anything else?
[The RCA wire has a lifetime warranty by the way and with proper use they last for decades.]
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So if free USB cables and dirt cheap RCA cables sound perfect, why would we buy anything else?
Psst, the correct answer is "marketing".

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Psst, the correct answer is "marketing".
Reliability and durability mostly...having it look good doesn't hurt either...

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post #326 of 569 Old 05-06-2020, 05:22 PM
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I believe you, I really do. Once the stay-at-home order is lifted I would really like to hear the Apple DAC at home, unfortunately I have a Pixel3, someone would have to bring over an iphone (anybody in Tucson?). I have a Tidal subscription, it would be real easy to temporarily install the Tidal app and listen to the same songs using both the iphone and my music server. I have no idea if there would be a difference, and any speculation would be just that, speculation. That's why we listen.



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Originally Posted by m. zillch View Post
The USB cable was free (it came with the ADC).
So if free USB cables and dirt cheap RCA cables sound perfect, why would we buy anything else? [The RCA wire has a lifetime warranty by the way and with proper use they last for decades.]

ooh, ooh, ooh - tangents, I love tangents.


I use the JMaxwell USB, http://www.jmaxwellusb.com/ it is the best sounding USB for my system. I used the Schiit USB (rebranded Staightwire) for years and the JMaxwell is clearly better. Once, when I was troubleshooting my music server I switched USB cables, when everything was working again the music still didn't sound right, it was flat with attenuated bass, then I remembered the Schiit was still in the loop, after replacing the USB with the JMaxwell the magic was back. That was a totally blind test and I passed.

Our Tucson audio group compared the Danacable TruStream USB to a Nobility USB, Supra USB, Schiit USB (rebranded Straightwire USB-Link), and a Curious Cable. Three different systems yielded three different preferences: I preferred the Straightwire, Ben liked the Curious Cable in his system, and Ken thinks the TruStream USB sounded the best at his house. This happened a year before the JMaxwell made it's appearance.


Jitter and error correction? Don't know, I'm not an engineer.



Let the fun begin...

Last edited by WGH; 05-06-2020 at 05:33 PM.
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post #327 of 569 Old 05-06-2020, 05:46 PM - Thread Starter
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Originally Posted by WGH View Post
ooh, ooh, ooh - tangents, I love tangents.
Actually I mentioned the RCA and USB cables aspect as an aside to the very first sentence of the very first post of this thread.

Last edited by m. zillch; 05-06-2020 at 05:54 PM.
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post #328 of 569 Old 05-06-2020, 09:31 PM
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Quote:
Originally Posted by m. zillch View Post
Actually I mentioned the RCA and USB cables aspect as an aside to the very first sentence of the very first post of this thread.

Yup, we all need cables although the Jabra Elite 75t earbuds sound pretty good for bluetooth. I uses them for cardio, great to be wireless.

Have you plugged the iPhone and DAC combo into your stereo yet? Seems like all radio stations stream so you don't need Tidal or Qobuz for a test.
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post #329 of 569 Old 05-07-2020, 03:08 AM
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Quote:
Originally Posted by WGH View Post
I believe you, I really do. Once the stay-at-home order is lifted I would really like to hear the Apple DAC at home, unfortunately I have a Pixel3, someone would have to bring over an iphone (anybody in Tucson?). I have a Tidal subscription, it would be real easy to temporarily install the Tidal app and listen to the same songs using both the iphone and my music server. I have no idea if there would be a difference, and any speculation would be just that, speculation. That's why we listen.






ooh, ooh, ooh - tangents, I love tangents.


I use the JMaxwell USB, http://www.jmaxwellusb.com/ it is the best sounding USB for my system. I used the Schiit USB (rebranded Staightwire) for years and the JMaxwell is clearly better. Once, when I was troubleshooting my music server I switched USB cables, when everything was working again the music still didn't sound right, it was flat with attenuated bass, then I remembered the Schiit was still in the loop, after replacing the USB with the JMaxwell the magic was back. That was a totally blind test and I passed.

Our Tucson audio group compared the Danacable TruStream USB to a Nobility USB, Supra USB, Schiit USB (rebranded Straightwire USB-Link), and a Curious Cable. Three different systems yielded three different preferences: I preferred the Straightwire, Ben liked the Curious Cable in his system, and Ken thinks the TruStream USB sounded the best at his house. This happened a year before the JMaxwell made it's appearance.


Jitter and error correction? Don't know, I'm not an engineer.



Let the fun begin...
It's literally impossible for a cable carrying a digital signal to make a difference in the data transmitted unless it's so bad it's actually failing to send the data. There isn't an avenue going from botched bits to subtle degradations in sound, when bits break, it's dramatic. Plus, that wasn't a blind test, you changed the cable, even if you closed your eyes, you still knew which cable was in the loop.
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post #330 of 569 Old 05-07-2020, 07:45 AM
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Quote:
Originally Posted by mechtheist View Post
It's literally impossible for a cable carrying a digital signal to make a difference in the data transmitted unless it's so bad it's actually failing to send the data. There isn't an avenue going from botched bits to subtle degradations in sound, when bits break, it's dramatic. Plus, that wasn't a blind test, you changed the cable, even if you closed your eyes, you still knew which cable was in the loop.

Your statement does not advance the explanation of why USB cables sound different. More research is needed. Please read the entire paper in the link, cables are mentioned.

http://www.enjoythemusic.com/magazine/manufacture/0509/

Jitter in Digital Audio Data Streams
Article By Steve Nugent Of Empirical Audio

Steve Nugent, who is an Electrical Engineer with 25 years digital design experience in the computer industry designs all of our products. He has a broad experience in digital system and interface design, board layout, transmission-lines and other relevant technologies. Steve was a design-team lead on the Pentium II at Intel Corp. and holds 22 patents in various cable and digital technologies. Steve has had audio as a personal hobby for over 39 years.


"For instance, I use two oscillators that are both specified at 2psec RMS jitter. The two oscillators sound radically different to me when used in a re-clocker in a resolving audio system. This leads me to believe that the spectrum, or frequency content of the jitter is as important or maybe even more important than the amplitude. I also believe that correlated jitter or jitter with a relationship to the data pattern is also more audible than random jitter. This seems to be the consensus in a number of AES papers.
Studies by the AES (analysis, not human testing) conclude that these are the thresholds of audibility:
[1] 120psec P-P jitter audibility threshold for 16-bit DAC and 8psec P-P jitter audibility threshold for 20-bit DAC
[2] 20psec P-P of data-correlated jitter audibility threshold at certain frequencies and "A simple model of jitter error audibility has shown that white jitter noise of up to 180psec P-P can be tolerated in a DAC, but that even lower levels of sinusoidal jitter may be audible"


I guess I wasn't clear about my cable change. I completely forgot I switched cables while troubleshooting. All my wires are in a rats nest behind the electronics so there was no way to visually see what USB wire was hooked up. I made the discovery by listening alone.

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