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Audibility thresholds of amp and DAC measurements

flipflop

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#81
I'm speaking from my hearing experience here and I wasn't able to pick up the 2nd nor the 3rd harmonic out of the fundamental on a -60dB difference
Maybe your ears just aren't good enough ;)
My thresholds are based on the sources I've cited. Earlier in this thread, @mitchco brought up the topic of what realistic thresholds for an average Joe could be. Nothing wrong with the discussion, but I don't really have any comments on it and my thresholds will remain the same.
Or you are probably referring to dynamic as the difference between the loudest and the barely perceivable sound
Yes, the basis for the threshold is Amir's article on dynamic range: https://www.audiosciencereview.com/forum/index.php?threads/dynamic-range-how-quiet-is-quiet.14/
Anything below -120 dBFS is inaudible, be it noise, distortion, or imaginary Head-Fi concepts.
 

Blumlein 88

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#82
I'm speaking from my hearing experience here and I wasn't able to pick up the 2nd nor the 3rd harmonic out of the fundamental on a -60dB difference: https://www.audiosciencereview.com/...can-we-trust-our-ears.3884/page-4#post-136991 and here: https://www.audiosciencereview.com/forum/index.php?threads/can-we-trust-our-ears.3884/post-125971.

I don't get the -120dB, sorry, so I don't get the point. I know that AP has around -140dB of noise and -120dB of noise out of a Hi-Fi system will most likely not be audible. Instead -85 dB of noise is a crappy noisy DAC/amplifier, but like I said...not sure I got the point, so I'll re-read your post carefully tomorrow morning. Or you are probably referring to dynamic as the difference between the loudest and the barely perceivable sound, like here: https://www.audiosciencereview.com/...-noise-heard-in-your-system.1013/post-127920? If so, then I can hear up to about -84dB @1Khz and few dB lower @ 440Hz, so a 96dB dynamic range of the Audio CD seems more than reasonable to me. Thanks for understanding! :)
In many domestic listening rooms in the 3 to 5 khz band your noise level will be within about 10 db of 0 db dpl. We can hear into noise some 10 to 15 db. So roughly speaking at least a little part of the bandwidth we have a 0 db spl noise floor. If you listen at times at the Dolby suggested reference level of 83 db SPl average with 20 db of headroom you'd need at least 103 db useful dynamic range per channel.. Dithered 16 bit can do that fine.

Which why I think if you can get the entire system to have a spurious free dynamic range of 100 db there is little or nothing that could sound better. You'll need to properly gain stage the system to do that without needing excessively good components.
 
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#83
Simple question here: we measure and critique dacs/amps for 0.01% vs 0.0001% THD (SNR/ etc) yet some of the most exquisite headphones or speakers have much much higher distortions than these. Just look at the top of the line in Stax / Audeze / Senny / Beyer. My question is - how are we supposed to make the difference between 2 dacs / amps when our headphones / speakers are much much lower precision?
 

RayDunzl

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#84
Simple question here
You made me think, I come up short, sorry.. original post deleted for making a boo boo.

1547011242934.png


Third harmonic at 0.012%.

Is it the speakers?

Or is it the power amp?

Or the DAC?

Looks pretty low, in any case, just barely poking out of the noise floor, as it were...
 
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trl

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#86
You made me think, I come up short, sorry.. original post deleted for making a boo boo.

View attachment 20105

Third harmonic at 0.012%.

Is it the speakers?

Or is it the power amp?

Or the DAC?

Looks pretty low, in any case, just barely poking out of the noise floor, as it were...
2nd harmonic is about -68dB from the fundamental, can't be the amplifier for sure, nor the DAC. Why don't you loop DAC+amp iwth an ADC and and check with ARTA? Then you can compare the graphs later.
 

RayDunzl

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#87
2nd harmonic is about -68dB from the fundamental, can't be the amplifier for sure, nor the DAC.
Maybe.

-68dB = 0.012%

edit:
-68dB = 0.04% - visually on the distortion measurement graph, noted by @trl
-78dB = 0.012% - reported on the distortion info box


Similar amp (year 2000), mine aren't much newer:

1547068843858.png


(just for the sake of argument over absolutes)

Why don't you loop DAC+amp iwth an ADC and and check with ARTA?
Don't have one that measures quietly enough...
 
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trl

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#89
Totally (http://www.sengpielaudio.com/calculator-thd.htm), but if speaking about 2nd or 3rd harmonics, they're still inaudible, no matter it's -68dB or -78%.

I wasn't able "feel" the 2nd nor 3rd harmonic at -60dB (0.1% THD) @ 1 KHz and above assertion "Maybe your ears just aren't good enough ;)" is completely false. ;) There are couple of thread on ASR where everyone can test the hearing, feel free to update those threads with your own findings. Thank you!
 

RayDunzl

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#90
-68 dB = 0.040%
0.012% = -78 dB
Yes.

0.012% reported by the Distortion measurement.

-68dB quoting/responding to @trl - and what eyeballing the visual graph shows.
 
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#91
If I am not mistaking the speaker / headphone is most the time the weakest link by a good margin... It doesn't mean we shouldn't pay attention to the dac/amp but it puts their measurements in perspective. Today the average dac / amp is much better than the average speaker / headphone I think.
I tend to put more of my money towards the headphone or speaker rather than electronics.
 

Blumlein 88

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#92
How about looking at these spectrograms. Now I thought if a device has 100 db of Spurious free dynamic range it is probably not going to be a bottleneck to sound quality. What you are seeing below is three spectrograms of a single tone max level sweep and a twin tone max level sweep with the tones 1 khz apart in frequency. The background goes to light gray at -100 db. Anything lower than that does not show up. Anything above that level whether distortion or jitter or idle tones or anything will show up in the spectrogram.

First spectrogram is the original digital signal at max level.
Second is the spectrogram of an LSR 305 recorded by a Shure KSM44 at 10 inches distance. The SPL at the mic was 101 db more or less. Which out at the listening position is something in the mid 80 db SPL range.
The 3rd spectrogram is for my Marantz pre/pro. It is pretty good, but not SOTA as a DAC/Source. If not for some -92 or -93 db 2nd harmonic it would be fully clean to below -100 db.

The spectrogram of the LSR305 shows that other than maybe amps and speakers we don't have a lots to worry about upstream of the speakers themselves. Distortion of the LSR305 fluctuates around or a bit below -50 db to -55 db. You can see it is more disconcerting with the IMD in the twin tone sweep. Even though the 1 khz difference tone is around - 60 db, and the sum and difference tones also cluster around -60 db.

My guess is the very best speakers are some 10 db better than this though plenty of highfalutin brands aren't.
LSR305 sweep.png
 
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#93
@flipflop can you add how to interpret SINAD numbers with Strict and Lenient plz?
 

flipflop

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#96
Lenient THD with Lenient SNR should be = Lenient SINAD, no ?
Correct. THD and noise have different lenient thresholds, but since the noise threshold is lower, that's the one to go by when combining them into a single THD+N figure. SINAD is the inverse of THD+N, so when the lenient THD+N threshold is 85 dBFS, the lenient SINAD threshold is consequently 85 dB.
EDIT: by 'SNR', I assume you mean 'noise'.
 
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Blumlein 88

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#97
Correct. THD and noise have different lenient thresholds, but since the noise threshold is lower, that's the one to go by when combining them into a single THD+N figure. SINAD is the inverse of THD+N, so when the lenient THD+N threshold is 85 dBFS, the lenient SINAD threshold is consequently 85 dB.
EDIT: by 'SNR', I assume you mean 'noise'.
If people would just quote THD+N using the decibel scale there is no difference vs SINAD. And you can do that and sometimes makers do. Most of the time THD+N is in % and SINAD in db. That really is all that is different about the two.
 
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#98
11.png


I am just trying to wrap my mind around this particular graph and would appreciate if one of the more math-oriented experts could clarify something for me. In this particular example, at 0 dBFS, IMD distortion is -96 dB below the signal. Does this mean that as long as your headphone volume output is calibrated below 96db SPL at the 0dBFS signal level, this distortion is empirically inaudible?
 

DonH56

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#99
If you are playing 0 dBFS (max output) into headphones, and they and your ears can take it, then IMD products are at least 96 dB down and yes that to me would be inaudible. As would be anything else for a while after I took off the headphones. If you turn the volume down by half, or 10 dB, the distortion has not changed much and is still about maybe 93 dB below the signal level. Moving to something more sane, like -30 dB, the IMD is now about 76 dB below the level at which I am listening, or about 106 dB below full-scale output. Deep in the noise floor to me.

HTH - Don
 
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If you are playing 0 dBFS (max output) into headphones, and they and your ears can take it, then IMD products are at least 96 dB down and yes that to me would be inaudible. As would be anything else for a while after I took off the headphones. If you turn the volume down by half, or 10 dB, the distortion has not changed much and is still about maybe 93 dB below the signal level. Moving to something more sane, like -30 dB, the IMD is now about 76 dB below the level at which I am listening, or about 106 dB below full-scale output. Deep in the noise floor to me.

HTH - Don
Hi Don,

What I actually meant is if your source music being played is recorded at 0 dBFS or close to it (like most pop music). The volume level of the amp would be calibrated to output 96 dB when your source music is recorded at 0 dBFS. Now, 96 dB is very loud, and I usually listen at much lower levels, but I used it for argument's sake.
 

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