Hypex Nilai500DIY Amplifier Review

[Julf]

not even sure if there is a 30kHz wave to be played by the tweeter.
My impression is that those waves combine (e.g. in the amp already).
An oscilloscope will not show a 30kHz wave, just a 'crooked' 15kHz wave. I assume that is what enters our ears and the 'coloration' that we hear.

Lots of (my) assumptions and impressions here, would surely like to know more/better. Do you have a paper?

A paper on what? How something sounds has very little to do with how it looks on a scope. Are you familiar with Fourier analysis?

 

[Julf]

OTOH, sound and light are both waves.

Well, yes and no. Sound definitely is, with light you get into the whole wave/particle thing.

And acoustic research/phenomena like the missing fundamental and timbre/coloration point out that ears & eyes work similarly (at least in some respects).

No, they don't.

Yes IMD & HD are not the same (not 100% diff either). Anyway, it was just an example of inaudible sounds producing audible effects.

potato, potato...

No, not just "potato, potato". Both are distortions, but if you speculate about missing harmonics intermodulation doesn't enter the picture.

The 15kHz wave is crooked/colored. You can see that on an oscilloscope.

So what color is it on the oscilloscope? Blue? Red?

Sorry, won't take anyone's word/assumption here. Neither will take "common sense logic" (and yours is actually pretty good). I'd like to see some hard proof/study. But that's just me...

Funny, considering how much you speculate and stipulate based on faulty analogies and without evidence.

 

[voodooless]

If you listen at an average level of 110 dB, your 15 kHz content is likely only 70 dB or probably even less. Any harmonics will be at least another 50 dB down from that. No way you’ll hear any of it, even if you had bat ears.

I’d be much more worried about the 110dB average level. You’ll get hearing damage really fast!

 

[Julf]

If you listen to an average level of 110 dB, your 15 kHz content is likely only 70 dB or probably even less. Any harmonics will be at least another 50 dB down from that. No way you’ll hear any of it, even if you had bat ears.

No, but he can see it on the 'scope!

 

[NTK]

not even sure if there is a 30kHz wave to be played by the tweeter.
My impression is that those waves combine (e.g. in the amp already).
An oscilloscope will not show a 30kHz wave, just a 'crooked' 15kHz wave. I assume that is what enters our ears and the 'coloration' that we hear.

Lots of (my) assumptions and impressions here, would surely like to know more/better. Do you have a paper?

Dr. David Griesinger did a study and here is the link to his presentation.

http://www.davidgriesinger.com/intermod.ppt

Slide 19

 

[Julf]

Dr. David Griesinger did a study and here is the link to his presentation.

http://www.davidgriesinger.com/intermod.ppt

Worth noting that the study is specifically about intermodulation, not harmonic distortion.

And even with the intermodulation, the result was:
"Subharmonics of the burst signal can be heard with difficulty…
In a quiet room…
When the ultrasonic level is above 80dB SPL at one meter the subharmonics are below 30dB SPL, at 15cm from the tweeter."

and

"No difference could be heard with and without the ultrasonics"

 

[lashto]

"Probably"? So now you are just speculating?

Yes I am. Hence the word "probably" .
Even if yours ears can't hear 15kHz there is still bone conduction. Can give a headache that one, hence the "speculation". Or you can even hear with your tongue (apparently). So yes, "can't hear a 15kHz wave" does not mean that you are 100% 'safe' from its effects

You won't actually hear THD lower than 0.5% even on a good day at frequencies your ear is most sensitive to, not to mention 10 kHz...

If you listen to an average level of 110 dB, your 15 kHz content is likely only 70 dB or probably even less. Any harmonics will be at least another 50 dB down from that. No way you’ll hear any of it, even if you had bat ears.

Sorry guys, your numbers (0.5% and -50dB) are quite optimistic and quite wrong. 0.1% (-60dB) is actually audible. Well proven multiple times.

And that is just the H2, which is the "least audible" HD. Other studies show that higher Hs are audible at progressively lower levels. Something like H3/H4/H5/.. being audible at -65/70/75/... Archimago also has a DBT study showing -75dB THD to be audible. Google those yourselves, I did enough 'work'.

Well, yes and no. Sound definitely is, with light you get into the whole wave/particle thing.

don't think quantum physics is relevant in audio but be my guest.
People writing music/sound theory seem to think that the sound/light analogy is good enough for them. They use "tone color" as a synonym for timbre, hence my usage of the "colored" terminology.

So what color is it on the oscilloscope? Blue? Red?

That would be the 'color' crooked. For your eyes' pleasure, here's a 50Hz wave crooked by it's harmonics (see the wave's top). That wave is objectively/measurably crooked (or 'tone colored'). Whether you can subjectively hear that, is a question for your ears alone.

P.S.
kind of tired of this thread. If you have some proof please post, I nicely asked for it. Otherwise, the all-knowing-tone together with your very wrong assumptions/numbers about HD audibility do not impress much.

 

[antcollinet]

Yes I (still) can.
Actually, anyone can hear that. Or more precisely anyone who can hear 15kHz.

You may wanna do a bit of research on those harmonics. You do not hear a 30kHz sound, you hear its 'coloring' effect on the 15kHz fundamental. It's so "bad" that even if you do not play a 15kHz sound but only its harmonics, you will hear only one sound: the 'missing' 15kHz. It's called the missing fundamental effect. There are also youtube demos if you still have doubts.

No, you can't

The human ear cannot detect signals above 20KHz (I beleive some exceptional cases have been able to detect freqnecies 1 or 2 KHz above that - but exceptionallly rarely - and only with hearing in prime condition)

So it doesn't matter if it is a harmonic of a lower fundamental - if it is above that threshold, the ear cannot detect it.

 

[voodooless]

Sorry guys, your numbers (0.5% and -50dB) are quite optimistic and quite wrong. 0.1% (-60dB) is actually audible. Well proven multiple times.

And that is just the H2, which is the "least audible" HD. Other studies show that higher Hs are audible at progressively lower levels. Something like H3/H4/H5/.. being audible at -65/70/75/... Archimago also has a DBT study showing -75dB THD to be audible. Google those yourselves, I did enough 'work'.

You graph goes only to 8 kHz…My example was with 110 dB average SPL. Bring that down to a more normal 90, which is still quite loud, and we’re at 50 dB SPL for 15 kHz content on average. I wish you very good luck with your distortion DBT. At 8 KHz your graph already needs 10% at 50 dBSPL. And my 50 dB down was very conservative already. These amps will do much better than that. At 5W there are basically no distortion products to be seen in the audible band.

Let’s also not forget masking of the distortion by all the other content.

Also note that the Archimago test uses equal distortion over all frequencies. That’s not what we’re talking about here at all.

 

[boXem]

Talking about proof, is there one showing that the increase of THD+N is due to THD and not to N?

 

[voodooless]

Would love to see the multitone with expanded bandwidth to 100 kHz, played @20W. That should show what happens to the noise and distortion products for sure.

 

[Julf]

Yes I am. Hence the word "probably" .

So "possibly" or "maybe" would have been better choices, especially, if as you claim, you want to learn.

Even if yours ears can't hear 15kHz there is still bone conduction. Can give a headache that one, hence the "speculation". Or you can even hear with your tongue (apparently). So yes, "can't hear a 15kHz wave" does not mean that you are 100% 'safe' from its effects

True, once you get to extremely high intensity levels. Not relevant here.

Sorry guys, your numbers (0.5% and -50dB) are quite optimistic and quite wrong. 0.1% (-60dB) is actually audible. Well proven multiple times.

@voodooless already responded to this one, so I won't bother. Another straw man.

That would be the 'color' crooked. For your eyes' pleasure, here's a 50Hz wave crooked by it's harmonics (see the wave's top). That wave is objectively/measurably crooked (or 'tone colored').

No, no "color" has changed. The wave shape has changed. Earlier I asked if you are familiar with the concept and theory of fourier analysis, but you didn't answer.

I suggest you take a suitable waveform, such as square or triangle wave, and just change the phase of some of the harmonics. You will see that the "shape" of the wave changes dramatically - with no audible effects.

Whether you can subjectively hear that, is a question for your ears alone.

More your brain and imagination than your ears - and very little correlation with physical reality.

P.S.
kind of tired of this thread. If you have some proof please post, I nicely asked for it. Otherwise, the all-knowing-tone together with your very wrong assumptions/numbers about HD audibility do not impress much.

So much for being curious and wanting to learn more

So you get tired of actual facts if they don't confirm your speculations.... I see...

 

[NTK]

Yes I (still) can.
Actually, anyone can hear that. Or more precisely anyone who can hear 15kHz.

You may wanna do a bit of research on those harmonics. You do not hear a 30kHz sound, you hear its 'coloring' effect on the 15kHz fundamental. It's so "bad" that even if you do not play a 15kHz sound but only its harmonics, you will hear only one sound: the 'missing' 15kHz. It's called the missing fundamental effect. There are also youtube demos if you still have doubts.

The perception of "missing fundamental" only works at low frequencies.
From the same presentation by Dr. Griesinger as referenced in post #265, Slide 50:

 

[lashto]

No, you can't

The human ear cannot detect signals above 20KHz (I beleive some exceptional cases have been able to detect freqnecies 1 or 2 KHz above that - but exceptionallly rarely - and only with hearing in prime condition)

So it doesn't matter if it is a harmonic of a lower fundamental - if it is above that threshold, the ear cannot detect it.

You graph goes only to 8 kHz…My example was with 110 dB average SPL. Bring that down to a more normal 90, which is still quite loud, and we’re at 50 dB SPL for 15 kHz content on average. I wish you very good luck with your distortion DBT. At 8 KHz your graph already needs 10% at 50 dBSPL. And my 50 dB down was very conservative already. These amps will do much better than that. At 5W there are basically no distortion products to be seen in the audible band.

Let’s also not forget masking of the distortion by all the other content.

Also note that the Archimago test uses equal distortion over all frequencies. That’s not what we’re talking about here at all.

Those are both examples of logic. Pretty good logic. But not enough to make any of them certain/true. The sound/light wave analogy is also an example of logic. Also not enough to make its (possible) implications true.

I saw some missing-fundamental papers, none of them clarified whether the fundamental is audible when its HDs were not. Actually the phenomenon is quite poorly understood AFAIK. Not clear if we hear the missing fundamental cause the waves combine like that inside of our ears. Or outside. Maybe you can recomend a paper/test that clarifies ?!

AFAICS, someone needs to do a test. Generate those 30/45/xx kHz harmonics, find a tweeter/supertweeter combo that can play them and test if anything is audible. You'll probably have a AES-worthy paper if you do it properly. And I'll donate €50 to ASR if you are right. And if you devise an experiment that I (and anyone else) can do without needing a special supertweeter, I'll donate €100.
And of course, if it turns out that I was right, you'll take care of those donations

Do the work, do the test and then you can tell with certainty whether this is black or white. Otherwise it's "just logic". And IMO, not far enough from "just anecdote"

 

[voodooless]

Do the work, do the test and then you can tell with certainty whether this is black or white. Otherwise it's "just logic". And IMO, not far enough from "just anecdote"

Well, I call that progress. We went from: it’s certainly audible, to: we’ll need to check. I can live with that

But I do think it’s far better than anecdotes. Logic can help you understand a problem, filter out evidence, help you understand and interpret it.

 

[sarumbear]

Yes I (still) can.
Actually, anyone can hear that. Or more precisely anyone who can hear 15kHz.

As if!

 

[HarmonicTHD]

… I d still like to see the screen shot from the scope with a 15Khz fundamental with 75dB SINAD …. so we can all see its awful crookedness or was it color?

 

[lashto]

The perception of "missing fundamental" only works at low frequencies.
From the same presentation by Dr. Griesinger as referenced in post #265, Slide 50:
View attachment 263433

Interesting one. So, does the paper clearly state that the missing fundamental is inaudible when its HDs are inaudible? Is there a clear test for that?

Here's an experiment that points to the contrary: i.e. the missingF is audible when its HDs are not:
"experiments subsequently showed that when a noise was added that would have masked these distortions..., listeners still heard a pitch corresponding to the missing fundamental, as reported by J. C. R. Licklider in 1954.[4]"
Not exactly 100% proof for this case but might be close enough. Or not.

In any case, this 15kHz missingF question simply requires an experiment. That would save us 100+ posts full of assumptions and "logic"

 

[antcollinet]

Those are both examples of logic. Pretty good logic. But not enough to make any of them certain/true. The sound/light wave analogy is also an example of logic. Also not enough to make its (possible) implications true.

I saw some missing-fundamental papers, none of them clarified whether the fundamental is audible when its HDs were not. Actually the phenomenon is quite poorly understood AFAIK. Not clear if we hear the missing fundamental cause the waves combine like that inside of our ears. Or outside. Maybe you can recomend a paper/test that clarifies ?!

AFAICS, someone needs to do a test. Generate those 30/45/xx kHz harmonics, find a tweeter/supertweeter combo that can play them and test if anything is audible. You'll probably have a AES-worthy paper if you do it properly. And I'll donate €50 to ASR if you are right. And if you devise an experiment that I (and anyone else) can do without needing a special supertweeter, I'll donate €100.
And of course, if it turns out that I was right, you'll take care of those donations

Do the work, do the test and then you can tell with certainty whether this is black or white. Otherwise it's "just logic". And IMO, not far enough from "just anecdote"

Its not logic

It is known physics, and human physiology, and pretty basic at that. So basic that it is taught at high school level, or at least undergraduate level.

Your light analogy is also wrong. The presence of infra or ultra electromagnetic radiation (infra red or ultraviolet) doesn't alter the perception of visible light.

 

[Trell]

Yes I (still) can.
Actually, anyone can hear that. Or more precisely anyone who can hear 15kHz.

I would love to be able to hear anything at 15 kHz.

You may wanna do a bit of research on those harmonics. You do not hear a 30kHz sound, you hear its 'coloring' effect on the 15kHz fundamental. It's so "bad" that even if you do not play a 15kHz sound but only its harmonics, you will hear only one sound: the 'missing' 15kHz. It's called the missing fundamental effect. There are also youtube demos if you still have doubts.

I think that you backup your claim here, and, btw, your Wikipedia link does not support your claim.