Attempting to better understanding DAC testing

[Killingbeans]

Can testing differentiate between the two?

Yes. One is part of the source, the other isn't. Look at the difference between input an output. Done.

What do overtones look like on the dashboard?

If you did testing with a recorded sample of a musical instrument, it would be a form of multitone test.

One is considered distortion one is considered timbre can we reduce one without affecting the other?

Yes. In the studio the producer can alter the overtones by applying bandstop filters or other trickery. But the DAC can not reduce them discriminately.

A DAC that measures better will add less distortion than one that measures worse, but none of them will reduce the overtones of the source.

Can overtones even be measured?

Yes. Very easily. It's called recording music

 

[Rednaxela]

A DAC that measures better will add less distortion than one that measures worse, but none of them will reduce the overtones of the source.

Well put. I feel this is the core of the confusion.

 

[solderdude]

See above the spectrum of a violin note.
Notice the amplitude range in which the harmonics are. Up to 18kHz the harmonics are merely 40dB lower than the fundamental.
Also note: When one would look at the SINAD of the fundamental then the SINAD meter in Amir's dashboard would indicate roughly 8.
This is very far removed from say SINAD 100 or even SINAD 120.

Now when we look at a reasonable DAC with a SINAD of 90 the added harmonics are in the order of 80dB or so. Far, far below those of an instrument so these added harmonics do not add to the timbre of the sound.
On the other hand, a speaker (in a room) or a headphone can have peaks at certain frequencies well over +10dB and/or dips 30dB deep or so.
This will certainly change the 'tone' of the violin note when this happens.
DACs and amps... nope.
Well... some tube amp with huge 2nd/3rd harmonics may well change the 'timbre' a bit.

The same 'note' (the fundamental) produced by a different instrument or after the tone is 'struck' will have a very different tonal spectrum which is what determines the timbre of the note and it sound (decay)

 

[Killingbeans]

I'm not sure that's true. All DACs add some distortion just like amps and speakers do. Good measuring DACs just add less. Testing shows that DACs with the same DAC chip measure differently . If the distortion isn't coming from the chip itself (same DAC chip) and one measures better than the other then something is reducing the distortion or at least adding less of it.

Yes. Nearly all high performance DACs has an analog stage after the output of the chip itself. Most of the time it functions as both an I/V stage and a line driver. It will add distortion, but in the top performers the amount is ridiculously tiny. More than 130dB below the test signal. That's practically nothing.

 

[ahofer]

Can testing identify a wave form produced by a Stradivarius violin as opposed to say a Yamaha violin. I can hear the difference between the two (If I can’t I’m sure there are people who can) and I would think it could some how be measurable.

Yes it could*, and no you likely can't.

Science | AAAS

www.science.org

*But good luck getting the violinist to play it with exactly the same bowing, pressure, and timing, to control your experiment. But different instruments have different harmonic content, easily measurable.

 

[DanaGer]

I saw that article and while the Strat was compared to other high end violins it wasn't compared to a lesser student instrument like the Yamaha. So I'm thinking I could (or some people can, I don't listen to lots of violin) tell the difference between the two in a blind test. Synthesizers on the other hand mimic the harmonic structure of the instrument they're trying to sound like so thru a graph like above is it possible to create music indistinguishable from the live performance they are trying to imitate?

 

[ahofer]

I saw that article and while the Strat was compared to other high end violins it wasn't compared to a lesser student instrument like the Yamaha. So I'm thinking I could (or some people can, I don't listen to lots of violin) tell the difference between the two in a blind test. Synthesizers mimic the harmonic structure of the instrument they're trying to sound like so thru a graph like above is it possible to create music indistinguishable from the live performance they are trying to imitate?

Again yes. Measurement equipment is much more sensitive than ears. You can keep trying to come up with differences that you might hear in physical phenomena, and there will always be a difference visible in the measured signal. (Or at least nobody has come up with one yet).

@Stinius suggests there is an example in speech under noise (not sure myself). But that a limitation of recorded vs live music.

 

[Killingbeans]

Synthesizers on the other hand mimic the harmonic structure of the instrument they're trying to sound like so thru a graph like above is it possible to create music indistinguishable from the live performance they are trying to imitate?

Make the output of a synthesizer close enough to a recording of an actual musical instrument to fool a human being? Absolutely.

But that doesn't have anything to do with DACs. A DAC is not a synthesizer. It doesn't mimic anything that implies intelligence.

 

[pkane]

How do harmonic overtones different from harmonic distortion. I would there would be at least some interaction between the two.

The difference between harmonics generated by an instrument and distortion is that distortion is generated by a non-linearity of the device. The result is extra harmonics when a single tone is used for testing, but the same exact non-linearity generates IMD tones when multiple tones are present (music or multi-tone test). IMD tones are often extremely in-harmonic, often not masked by other tones in the original signal, and can fall onto the most sensitive part of human hearing making them even more audible. This is in contrast to instrument-generated harmonics that don't produce IMD and are part of a harmonic sequence that's fully expected from such an instrument.

 

[antcollinet]

I'm not sure that's true. All DACs add some distortion just like amps and speakers do. Good measuring DACs just add less. Testing shows that DACs with the same DAC chip measure differently . If the distortion isn't coming from the chip itself (same DAC chip) and one measures better than the other then something is reducing the distortion or at least adding less of it.

OK - I'll rephrase. A good dac doesn't add any that are audible.

But yes - now you are getting it - they don't remove harmonics - so the timbre of your violin is safe. Well designed dacs (at any price) are designed so any distortion added to the music is below the level any human can hear.

 

[jae]

I'm not sure that's true. All DACs add some distortion just like amps and speakers do. Good measuring DACs just add less. Testing shows that DACs with the same DAC chip measure differently . If the distortion isn't coming from the chip itself (same DAC chip) and one measures better than the other then something is reducing the distortion or at least adding less of it.

Perhaps think of it visually: you have a bathtub with 50 gallons (200 L) of water in it, and without disturbing the surface of the water I take an eyedropper and add one or two drops of water to the bathtub. This is analogous to the amount of distortion modern DACs are adding to an audio signal. You or anyone else simply won't notice it visually and it would even feel identical if you were to take a bath, there would be no perceptible temperature difference, if you took a photo of before and after from any direction or angle you wanted they would look identical to you, and so on. The amount of distortion the DAC chip and/or the rest of the circuitry is adding is well below all measures of human threshold of audibility, so it is irrelevant because it won't change what you hear regardless. It is not altering the signal to a degree where it will sound different because it is infinitesimal, unless there is a 'problem' with the DAC.

 

[AdamG]

I saw that article and while the Strat was compared to other high end violins it wasn't compared to a lesser student instrument like the Yamaha. So I'm thinking I could (or some people can, I don't listen to lots of violin) tell the difference between the two in a blind test. Synthesizers on the other hand mimic the harmonic structure of the instrument they're trying to sound like so thru a graph like above is it possible to create music indistinguishable from the live performance they are trying to imitate?

Science and blind testing all indicate that most failed to identify one from another. Some double blind tests results indicated that many preferred the sound of newer made Violins debunking the belief that the famous old Italian Violins sounded better. Another words once the visual bias was removed no magic dust was detectable.

Double-Blind Violin Test: Can You Pick The Strad?

Researchers presented a group of professional violinists with a set of violins and asked them to play and then determine — based on sound alone — which were made by the famed Italian violin-maker Stradivari and Guarneri. The results surprised everyone, including the pros themselves.

www.npr.org

Pro violinists fail to spot Stradivarius in blind test

Could you tell a new violin from a vintage Stradivarius? Top-notch soloists couldn't in a blind test, and they even preferred new instruments

www.newscientist.com

Sound projection: Are Stradivarius violins really better?

Sound projection is the capacity of a musical instrument to fill the space of a concert hall, to carry to the back of the room, and to rise above the sound of an orchestra. It is particularly important for soloists. Sound projection of 17th and 18th century Italian violins, notably those of...

www.cnrs.fr

Blind playoff of Stradivarius violins and new ones leaves old Italians a little flat

Soloists testing a dozen fiddles surprise themselves by picking modern instruments over multi-million pound ones, study finds

www.theguardian.com

 

[DanaGer]

Science and blind testing all indicate that most failed to identify one from another. Some double blind tests results indicated that many preferred the sound of newer made Violins debunking the belief that the famous old Italian Violins sounded better. Another words once the visual bias was removed no magic dust was detectable

If many preferred the sound of the newer made violins doesn't that debunk the "failed to identify one from the other" statement. The original question was actually the difference between a quality interment and a lesser quality the Strat was just used as a recognizable reference point. I suppose (with no evidence) that a Strat would be preferred over a Yamaha or a Steinway over a Yamaha. (again reference of quality over lesser quality)

Sorry for the delayed response but life keeps happening.

 

[ahofer]

Can testing identify a wave form produced by a Stradivarius violin as opposed to say a Yamaha violin

Much more than humans can tell them apart, absolutely. “Redbook” digital resolution (16 but 44.1k) is generally much better than human hearing.