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Which measurements match typical audiophile descriptions?

escksu

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I think WL meant that amp response is typically orders of magnitude faster than the audio signal frequency, and can't really impact timing in any conventional sense.

However, loudspeaker phase response may. For example, if there is phase delay in the woofer response, it may create a sense of sharper low frequencies, as higher frequency content leads (similar to accuttance or edge sharpening in photography). While this may contribute to the "PRAT" quality, it is artificially generated.

I am not sure about this, maybe it doesn't matter but I am not entirely convinced.

OK, check out stereophile's amp reviews, look for their measurements. There is this 1KHz and 10KHz square wave injection test. Can see that different amps perform slightly differently.
 

Beave

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I am not sure about this, maybe it doesn't matter but I am not entirely convinced.

OK, check out stereophile's amp reviews, look for their measurements. There is this 1KHz and 10KHz square wave injection test. Can see that different amps perform slightly differently.

Different amps may have different ultrasonic bandwidth, thus they may reproduce square waves differently. Is it audible if one's bandwidth is larger if they both are flat to 20kHz?
 

ctrl

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I am not sure about this, maybe it doesn't matter but I am not entirely convinced.

OK, check out stereophile's amp reviews, look for their measurements. There is this 1KHz and 10KHz square wave injection test. Can see that different amps perform slightly differently.
Amir made a video about square wave testing and the relationship with bandwidth. There he presents the facts in an understandable way.
As others have said, the wider the bandwidth of the amplifier, the "nicer" the square wave looks - especially at high frequencies like 10kHz.

 

escksu

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Amir made a video about square wave testing and the relationship with bandwidth. There he presents the facts in an understandable way.
As others have said, the wider the bandwidth of the amplifier, the "nicer" the square wave looks - especially at high frequencies like 10kHz.

It would be great if he could show some real circuitry and amp designs (what he meant for wide bandwidth etc) or test it on a real amp than just to simulate using software.
 

Plcamp

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I am not sure about this, maybe it doesn't matter but I am not entirely convinced.

OK, check out stereophile's amp reviews, look for their measurements. There is this 1KHz and 10KHz square wave injection test. Can see that different amps perform slightly differently.

You will see the same effects with different DACs or even different filters on the same DAC…(the amp won’t ever get a square wave command anyway). The limitation of bandwidth prescribes the resulting squarewave shape you see, independently of the slew rate capability of the devices in the amp.

Imagining an amp that had very wide bandwidth, you would get very clean reproduction of square waves the amp would never see in real use, and you would likely annoy any cats and dogs in the immediate vicinity!
 

Trif

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OK, check out stereophile's amp reviews, look for their measurements. There is this 1KHz and 10KHz square wave injection test. Can see that different amps perform slightly differently.
As a sidebar for the mathematically inclined - since they 'inject' the same test signals every time, and narrow FR events are usually overlooked (we don't hear them; they get smoothed out of a graph) would it be possible to put a deliberate spike in a speaker's response (cross-over tweak, or maybe we get a free bump from the Fc of the upper driver) such that it improved Stereophile's square wave test?
 

Weeb Labs

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OK, since this is your field of expertise. Let me ask you regarding the rise/fall times stated in the spec sheet. Could you explain to me if those test conditions are similar to an amp in operation? What condition would best describe those test conditions? Max load? min load? 50% load?
When implementing an audio amplification circuit using transistors such as the common BC337, the base of the junction is biased using a DC voltage. This ensures that the transistor operates exclusively within its linear region and does not enter cutoff or saturation. Under these circumstances, there exists a linear relationship between the input voltage and output voltage, which is ideal when the objective is to produce a sinusoidal output. We would typically make use of a PNP and NPN pair in push-pull configuration rather than a singular transistor but that isn't particularly important, here.

The rise and fall times most commonly specified pertain to the 10% to 90% transition and so within the context of amplification, these values are fully applicable.

It is important to bear in mind that amplification within the audio band is not a particularly challenging application. Transistors are utilized not only within the context of audio amplification but also RF amplification, often at frequencies of several hundred gigahertz where linearity is equally as important.

With regard to your mention of square waves, this really has no bearing on the performance of an amplifier. The first thing to understand is that there is no such thing as a perfect square wave in reality. Illustrations such as the one below depict a purely mathematical concept, which is a square wave composed of an infinite series of sine waves. In order to produce or amplify a square wave such as the one below, you would require an infinite amount of bandwidth.

1628032826196.png


When a square wave is passed through an amplifier or DAC, the resulting waveform can only be composed of sine waves representing the highest frequency that is possible within said amplifier's bandwidth. That is why the output sometimes exhibits a different appearance from that of the input when viewed on an oscilloscope, if the input contains harmonics beyond the amplifier's bandwidth. It has the effect of a low pass filter.

1628033146915.png


Note that this has no bearing whatsoever upon the audible performance of the amplifier. A square wave composed of 20KHz sine waves already represents the highest frequency content that is audible to human beings and the vast majority of music is published at a sample rate of 44.1KHz.
 
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escksu

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When implementing an audio amplification circuit using transistors such as the common BC337, the base of the junction is biased using a DC voltage. This ensures that the transistor operates exclusively within its linear region and does not enter cutoff or saturation. Under these circumstances, there exists a linear relationship between the input voltage and output voltage, which is ideal when the objective is to produce a sinusoidal output. We would typically make use of a PNP and NPN pair in push-pull configuration rather than a singular transistor but that isn't particularly important, here.

The rise and fall times most commonly specified pertain to the 10% to 90% transition and so within the context of amplification, these values are fully applicable.

It is important to bear in mind that amplification within the audio band is not a particularly challenging application. Transistors are utilized not only within the context of audio amplification but also RF amplification, often at frequencies of several hundred gigahertz where linearity is equally as important.

With regard to your mention of square waves, this really has no bearing on the performance of an amplifier. The first thing to understand is that there is no such thing as a perfect square wave in reality. Illustrations such as the one below depict a purely mathematical concept, which is a square wave composed of an infinite series of sine waves. In order to produce or amplify a square wave such as the one below, you would require an infinite amount of bandwidth.

View attachment 145343

When a square wave is passed through an amplifier or DAC, the resulting waveform can only be composed of sine waves representing the highest frequency that is possible within said amplifier's bandwidth. That is why the output sometimes exhibits a different appearance from that of the input when viewed on an oscilloscope, if the input contains harmonics beyond the amplifier's bandwidth. It has the effect of a low pass filter.

View attachment 145344

Note that this has no bearing whatsoever upon the audible performance of the amplifier. A square wave composed of 20KHz sine waves already represents the highest frequency content that is audible to human beings and the vast majority of music is published at a sample rate of 44.1KHz.

OK, thank you for taking time to explain this.
 

Doodski

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Note that transistors have a rise and fall time as well. So, it affects what you call "timing".
I thought the bandwidth of a modern transistor is so large that the slope/rise and fall time when used for audio becomes trivial.
 

escksu

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I thought the bandwidth of a modern transistor is so large that the slope/rise and fall time when used for audio becomes trivial.

I don't think there is any need to talk about this anymore.
 

JeffS7444

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From this you can see when when we inject a square wave, the output is not perfectly square.

You are aware that a square wave is actually not a pure tone, but rather, a composite of a bunch of sine waves, right? And in the case of a 1 kHz square wave, some of those harmonics will extend well beyond 20 kHz. When I see amplifier output which rounds off the corners of those square waves, it doesn't mean that the amp is "slow", it means that it's bandwidth-limited, and that's not necessarily a bad thing.
 

escksu

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This is a very interesting discussion. Here’s something for perspective:


Jim Taylor Ph.D.
The Power of Prime
Perception Is Not Reality
Just because you think something is reality doesn't make it reality.

https://www.psychologytoday.com/us/blog/the-power-prime/201908/perception-is-not-reality

Yes. Esp. this:

  • Be respectful of others’ perceptions (they may be right)

IT took me quite sometime to actually learn this. So now, I no longer argue with people over the internet. Regardless of right or wrong, I should respect what others believe.
 

pogo

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Back to the initial question: 'Which measurements match typical audiophile descriptions?'
Here are some of them:
sound_quality_algorithms
 

Geert

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oops... there it is.

at least my version of the descriptors.
I still miss the descriptor that has become one of the most popular ones; 'calm'. It seems to apply to about 90% of system upgrades.
 

solderdude

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If you know what they mean and can tell me what technical properties are tied to it I will include it.

Calm, to me, would probably mean... not overly dynamic, not bass heavy, low distortion.
I would call this 'polite' sounding. Not aggressive nor boomy 'sweet' background type of music.
Perhaps the one using the word 'calm' could give his/hers/LGBTQWZX+ opinion on the descriptor
 

Geert

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On more subjective forums it's used on a daily base for almost any change in a system, or to describe the sound of any system they reviewed. So one day it can point to more of "X" and the next day to less of "X", or suddenly to 'Y'. And since it has become more popular also manufacturers are starting to adopt it, like "mains cable Z provides more calm".

To me it's clear what it is, an emotion instead of a sound attribute. Nevertheless people claim to hear it.
 

solderdude

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Yes, I think most folks have experienced the same system on different parts of the day or on different days the same music can sound very different even sitting in the exact same loaction (or with a headphone).
To others (that value different aspects of music listening) they might experience it less if even any different sounding.
Perception is a weird thing, tied to emotions, listening levels and circumstances. Funny how a lot of people simply trust their audio experience.
The actual audio signal would be the same in all cases. It's the brain that interprets the same auditory input differently.
 

PeteDzi

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I was going to start a new thread to ask a question, but clearly this is already being discussed here.
My question is, how do you measure the subjective dynamics of a headphone? My most dynamic or lively sounding headphones are HM he6se so clearly dynamics is not correlated to the efficiency or the maximum SPL of a headphone, because he6se is one of the least efficient headphones.
Is there, in fact, a way of measuring this?
 
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