Proposed Amplifier Differentiation Experiment - Page 4 - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 102Likes
 
Thread Tools
post #91 of 227 Old 02-20-2016, 10:53 AM
Member
 
Join Date: Oct 2014
Posts: 91
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 58 Post(s)
Liked: 16
Quote:
Originally Posted by Bigus View Post
LOL. Really? Assume I'm an idiot and explain how coaxial guarantees a speaker is transparent without even looking at its specs. This should be good.
I said in terms of soundstage, if you had read the sentence fully you would have not shown your lack of reading comprehension with that reply. A single point, coxial design is the superior choice for stereo, point-source accuracy.

Video Pioneer PDP-LX5090 (calibrated)
Audio Benchmark AHB2, Chord Hugo 2, KEF LS50 (Frosted Black), Custom Design FS104
Cables QED Reference HDMI, QED Reference Optical Quartz, QED Reference USB A-B, QED Supremus, QED Signature Audio 40
Sources PlayStation 3, PlayStation 4, MacBook Pro, AirPort Express
W4RLORD is offline  
Sponsored Links
Advertisement
 
post #92 of 227 Old 02-20-2016, 12:40 PM
Member
 
Join Date: Oct 2014
Posts: 91
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 58 Post(s)
Liked: 16
Quote:
Originally Posted by Bill Fitzmaurice View Post
0.3% is as good a figure as any. That's -50dB from the content level. No one, not even the most 'golden eared', can hear that. For that matter it's exceedingly unlikely that even -30dB can be heard by the average human. That's 3%. But for the sake of argument I'll go with 0.3%.
I'm sure that he has, in advertising copy. Knowing what the numbers actually mean, that's a different story.
Again, it depends on the type of distortion. If you for example, play a 17khz (average upperlimit for most people) sine wave at 90dB through an amplifier which has a THD+N rating of your quoted 0.3%, you will also output any odd or even harmoics -50dB below the sine wave. An amplifier with odd harmoics in the bass region for example would also output an 80hz sine wave (as an example). We as humans are a lot more sensitive to low frequencies than high frequencies, unless you go above 100dB where the ears response becomes more linear. An 80dB sine wave at 100hz for example will be subjectively a lot louder than an 80dB sine wave at 17khz. Going back to the first example, your speaker would be playing audible bass while also playing the frequencies near your upper limit. You could refute by saying this will not be audible unless in rare circumstances where the media has such high frequenies. You could also refute by saying in a surround sound setup, with a subwoofer connected, that you would not hear your amplifiers harmonics at 80hz as the crossover for your sub is at, or higher than 80hz which would be true in that regard, but harmoincs can be anywhere in audible bandwidth, not just in lower frequenices. A worst case scenario for example, is if the added odd harmonics were in the 2khz to 6khz range (where we are most sensetive). Playing that same 17khz sine wave through the 0.3% THD+N amplifier, with added harmonics at say 3khz, nothing apart from the 3khz signal will be audible. If you did a frequency hearing test with said amplifier for example, you would still hear very audible sound at even above 20khz as the sound is not actual the frequency you wish to output.

These added hamronics limit audible bandwidth. If the source media has a combination of low, mid and high frequenices at once (like a shootout in a movie) then it will be a lot less audible, or even inaudible. Quieter passages of audio though, like a violin solo in an orchestral recording for example will show up the amplifers distortion.

Most manufacturers are shy at showing equipment measurements and do not boast about specs much. Why? Becuase they do not measure well and have not gotten distortion into inaudible levels. Most quote their THD+N percent at 1khz or even give no frequency at which they tested at (which allows them to quote the best case scenario rather than the average or worst case scenario), which does not say much in terms of the amplifiers full distortion figure. Most quote that very same number at a given impendance level (or even don't disclose the level they tested at), with no other impedance level measurements (as amplifiers usually increase in distortion as impedance drops, which most speakers do drop low, meaning THD+N will rise at certain frequencies for the output of the speakers).

As you can see, it will be audible in a lot of circumstances. I'm not going to give a percentage figure (for the full system, not just at 1khz) as to where distortion or noise would be inadible as I do not have a lab or such equipment to accurately state such a thing, but a rating of 0.3% is definitely not low enough. Sure, some people may not even care about such things and are happy to just go with equipment that are good enough for their needs, but to refute better equipment (objectively speaking) as sounding the same or technical (aka objective) improvements as being inadible is outright ignorant.

It's funny how the people in this thread argue objective improments in sound are inaudible, yet happily accept that even slight video improvements are visible. You cannot argue against science, as much as you want to.

Video Pioneer PDP-LX5090 (calibrated)
Audio Benchmark AHB2, Chord Hugo 2, KEF LS50 (Frosted Black), Custom Design FS104
Cables QED Reference HDMI, QED Reference Optical Quartz, QED Reference USB A-B, QED Supremus, QED Signature Audio 40
Sources PlayStation 3, PlayStation 4, MacBook Pro, AirPort Express
W4RLORD is offline  
post #93 of 227 Old 02-20-2016, 01:35 PM
AVS Forum Special Member
 
Join Date: Jan 2007
Posts: 2,630
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1331 Post(s)
Liked: 816
Proposed Amplifier Differentiation Experiment

Quote:
Originally Posted by W4RLORD View Post
Again, it depends on the type of distortion. If you for example, play a 17khz (average upperlimit for most people) sine wave at 90dB through an amplifier which has a THD+N rating of your quoted 0.3%, you will also output any odd or even harmoics -50dB below the sine wave.
Not necessarily. Amplifiers don't often have consistent distortion figure across the spectrum, and the 3rd harmonic of 17kHz is 51kHz, which could be above the amps flat power bandwidth, pretty much messing up your "theory".

Quote:
Originally Posted by W4RLORD View Post
An amplifier with odd harmoics in the bass region for example would also output an 80hz sine wave (as an example). We as humans are a lot more sensitive to low frequencies than high frequencies, unless you go above 100dB where the ears response becomes more linear.
False. Human hearing is less sensitive to bass. You have it backwards.
Quote:
Originally Posted by W4RLORD View Post

An 80dB sine wave at 100hz for example will be subjectively a lot louder than an 80dB sine wave at 17khz.
Perhaps, perhaps not. To try this in an average room/system introduces far too many variables.

Quote:
Originally Posted by W4RLORD View Post
Going back to the first example, your speaker would be playing audible bass while also playing the frequencies near your upper limit. You could refute by saying this will not be audible unless in rare circumstances where the media has such high frequenies.
I would refute this on the basis that your science is bad.

Quote:
Originally Posted by W4RLORD View Post

You could also refute by saying in a surround sound setup, with a subwoofer connected, that you would not hear your amplifiers harmonics at 80hz as the crossover for your sub is at, or higher than 80hz which would be true in that regard, but harmoincs can be anywhere in audible bandwidth, not just in lower frequenices.
You will never hear harmonic distortion in a sub amp operating in its linear range because the drivers distortion is several orders of magnitude higher, and this has nothing to do with the crossover.
Quote:
Originally Posted by W4RLORD View Post
A worst case scenario for example, is if the added odd harmonics were in the 2khz to 6khz range (where we are most sensetive). Playing that same 17khz sine wave through the 0.3% THD+N amplifier, with added harmonics at say 3khz, nothing apart from the 3khz signal will be audible. If you did a frequency hearing test with said amplifier for example, you would still hear very audible sound at even above 20khz as the sound is not actual the frequency you wish to output.
False. You are not aquatinted with masking curves.

Quote:
Originally Posted by W4RLORD View Post
These added hamronics limit audible bandwidth.
False. Adding harmonics never limit audible bandwidth. No science to that at all.
Quote:
Originally Posted by W4RLORD View Post
If the source media has a combination of low, mid and high frequenices at once (like a shootout in a movie) then it will be a lot less audible, or even inaudible. Quieter passages of audio though, like a violin solo in an orchestral recording for example will show up the amplifers distortion.
Its true that spectral density masks distortion products, but a solo violin at any level is rich in harmonics, not a good test signal at all.
Quote:
Originally Posted by W4RLORD View Post
Most manufacturers are shy at showing equipment measurements and do not boast about specs much. Why? Becuase they do not measure well and have not gotten distortion into inaudible levels.
False. Even the incomplete specs some publish typically show no audible distortion levels.
Quote:
Originally Posted by W4RLORD View Post
Most quote their THD+N percent at 1khz or even give no frequency at which they tested at (which allows them to quote the best case scenario rather than the average or worst case scenario), which does not say much in terms of the amplifiers full distortion figure. Most quote that very same number at a given impendance level (or even don't disclose the level they tested at), with no other impedance level measurements (as amplifiers usually increase in distortion as impedance drops, which most speakers do drop low, meaning THD+N will rise at certain frequencies for the output of the speakers).
I will agree that amplifiers should be profiled for distortion in what would end up a 3D data matrix, but I do not agree that all of this horrible audible distortion you refer to is being totally hidden by single figure distortion specs, with a few low-end exceptions.
Quote:
Originally Posted by W4RLORD View Post
As you can see, it will be audible in a lot of circumstances.
You have not defined a single one of those circumstances.
Quote:
Originally Posted by W4RLORD View Post
I'm not going to give a percentage figure (for the full system, not just at 1khz) as to where distortion or noise would be inadible as I do not have a lab or such equipment to accurately state such a thing, but a rating of 0.3% is definitely not low enough.
This statement explains pretty much the entire post. No experience in a lab, no actual testing or auditioning of distortion mechanisms, no reference to any even partially authoritative work, and yet there is a definitive single-figure distortion audibility threshold given. Even though the variable nature of distortion audibility vs frequency was alluded to, we're back to a single figure with no reference to frequency, SPL, or test signal characteristics. This is even worse than manufacturers not fully stating specs of their products.
Quote:
Originally Posted by W4RLORD View Post
Sure, some people may not even care about such things and are happy to just go with equipment that are good enough for their needs, but to refute better equipment (objectively speaking) as sounding the same or technical (aka objective) improvements as being inadible is outright ignorant.
Statements about distortion audibility expressed in a manner that reveals true ignorance should probably be taken with a large block of salt.
Quote:
Originally Posted by W4RLORD View Post
You cannot argue against science, as much as you want to.

Finally, we agree on something. Now all you need to do is actually apply some science, and we'll eventually agree on even more.
jaddie is offline  
Sponsored Links
Advertisement
 
post #94 of 227 Old 02-20-2016, 02:40 PM
AVS Forum Special Member
 
Bigus's Avatar
 
Join Date: Feb 2003
Location: The South
Posts: 5,591
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 594 Post(s)
Liked: 558
Quote:
Originally Posted by W4RLORD View Post
I said in terms of soundstage, if you had read the sentence fully you would have not shown your lack of reading comprehension with that reply. A single point, coxial design is the superior choice for stereo, point-source accuracy.
Lol, you're one to be complaining about reading comprehension! Sorry, your blanket statement is just too broad to be universally true. There are other designs that can give phase aligned pinpoint imaging as well, and its easy to make a coaxial sound horrid. In fact, it takes quite a bit of effort in driver design to keep it from being so. But you'd have to glance at specs to get some insight into that, so...
Bigus is offline  
post #95 of 227 Old 02-20-2016, 02:49 PM
AVS Forum Special Member
 
Bigus's Avatar
 
Join Date: Feb 2003
Location: The South
Posts: 5,591
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 594 Post(s)
Liked: 558
Quote:
Originally Posted by W4RLORD View Post
If you for example, play a 17khz (average upperlimit for most people) sine wave at 90dB through an amplifier which has a THD+N rating of your quoted 0.3%, you will also output any odd or even harmoics -50dB below the sine wave. An amplifier with odd harmoics in the bass region for example would also output an 80hz sine wave (as an example).
Are you saying an amp playing a 17kHz fundamental can have an ~80Hz harmonic? Whilst subharmonics are possible particarly as a form of IMD when two+ tones are played, that is quite a complex topic and I'm pretty sure that isn't at all what you had in mind... at this point I'm happy to write this off as your complete ignorance of the subject your trying to educate everyone about.
Bigus is offline  
post #96 of 227 Old 02-20-2016, 03:22 PM
Member
 
Join Date: Oct 2014
Posts: 91
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 58 Post(s)
Liked: 16
Quote:
Originally Posted by jaddie View Post
Not necessarily. Amplifiers don't often have consistent distortion figure across the spectrum, and the 3rd harmonic of 17kHz is 51kHz, which could be above the amps flat power bandwidth, pretty much messing up your "theory".

False. Human hearing is less sensitive to bass. You have it backwards.
Perhaps, perhaps not. To try this in an average room/system introduces far too many variables.

I would refute this on the basis that your science is bad.


You will never hear harmonic distortion in a sub amp operating in its linear range because the drivers distortion is several orders of magnitude higher, and this has nothing to do with the crossover.
False. You are not aquatinted with masking curves.

False. Adding harmonics never limit audible bandwidth. No science to that at all.
Its true that spectral density masks distortion products, but a solo violin at any level is rich in harmonics, not a good test signal at all.
False. Even the incomplete specs some publish typically show no audible distortion levels.
I will agree that amplifiers should be profiled for distortion in what would end up a 3D data matrix, but I do not agree that all of this horrible audible distortion you refer to is being totally hidden by single figure distortion specs, with a few low-end exceptions.
You have not defined a single one of those circumstances.

This statement explains pretty much the entire post. No experience in a lab, no actual testing or auditioning of distortion mechanisms, no reference to any even partially authoritative work, and yet there is a definitive single-figure distortion audibility threshold given. Even though the variable nature of distortion audibility vs frequency was alluded to, we're back to a single figure with no reference to frequency, SPL, or test signal characteristics. This is even worse than manufacturers not fully stating specs of their products.
Statements about distortion audibility expressed in a manner that reveals true ignorance should probably be taken with a large block of salt.



Finally, we agree on something. Now all you need to do is actually apply some science, and we'll eventually agree on even more.
I don't use this forum much and do not know how to quote individual sentences so I'm going to reply in numbered bullet points:

1. The example I used was not a scientific example, it was an extreme non-scientific example to explain the hamonic correlation to uninformed users. A scientific example would be a frequency of 40hz. The 2nd harmoic of this particular frequency would be 80hz (even order). If played back on this 0.03% THD+N amplifier, an 80hz tone will be audible. 40hz is harder to produce than 80hz and in a non-subwoofer setup, will be heard louder on most speakers. Unless the speakers have a flat response below 40hz upwards, 80hz will be heard in most circumstances. Lets take an extreme example, at 20hz in a stereo 2.0 system. Most speakers of all different speaker technologies usually cannot produce 20hz audibly, with the rare ones that do not able to do it within +/-3dB of the rest of the outputeed frequency spectrum. That's forgetting the fact it's in the lower limits of what we can hear (though not the absolute limit as some claim, many can hear down to 16hz, at extreme volumes of course) and the fact that the speakers have their own distortion too. The 2nd harmonic of 20hz, is 40hz (even order). On the 0.03% THD+N amplifier, this will be heard and one cannot refute that. The THD+N for low frequency content would have to be a lot lower for 20hz to be played back correclty.

2. Actually, bass is defined as being above 60hz leading up to roughly 200hz. Below 60hz is defined as sub-bass, above 12khz (or 10khz) is usually defined as high frequency. My statement is not incorrect, as high requencies close to your audible limit will be quieter than a 100hz tone for example. You're arguing sematics, in which I am not incorrectly using.

3. I am talking in absolute terms, with no outside factors distorting results such as room reflections.

4. Refer to point 1.

5. I am not talking about subwoofer amplifiers.

5. Sound masking is not an optimal way of making certain frequencies inaudible. The optimum is to have lower distortion, period. Rather than using human ear trickery (which doesn't always work).

6. It does not reduce bandwidth in absolute terms, but if a frequency is masked by harmonics you are figuratively limited.

7. It does not matter if the signal media is rich in harmonics, there should be no additional frequencies to the original sound unless for subjective reasons.

8. There is no "false" about it. The fact that they have "incomplete" spec sheets shows that they hide results. If they quote there THD+N at 8Ω only and the amplifier has the abilty to dip down to 4Ω, they are hiding that particular measurement (or stupidly did not measure it). It's as simple as that.

9. Why do you not agree? If a company gives a single measurement of THD+N for example with no reference of a level they tested at (whether it be at a particular voltage, frequency or impedance) then they are masking the whole performance of the amplifier under one isolated measurement (which is usually the best case scenario measurement). Only if they state it as an average measurement is it an accurate depiction of the equipment.

10. How are they not defined?

11. I have not given a single, definitve distortion threshold in the slightest. As I said, only in an isolated lab would anyone be able to come to such a figure. Which is directed at people claiming there's no audible difference between THD+N levels and objectivly better equipment. They have not done any tests in such isolated conditions and also cannot prove a single thing. Having an A/B test in a persons home is a laughable way to come to any conclusin of that nature.

12. There is no ignorance at all, refer to point 1.

13. Science has been used sir.

Video Pioneer PDP-LX5090 (calibrated)
Audio Benchmark AHB2, Chord Hugo 2, KEF LS50 (Frosted Black), Custom Design FS104
Cables QED Reference HDMI, QED Reference Optical Quartz, QED Reference USB A-B, QED Supremus, QED Signature Audio 40
Sources PlayStation 3, PlayStation 4, MacBook Pro, AirPort Express

Last edited by W4RLORD; 02-20-2016 at 04:08 PM.
W4RLORD is offline  
post #97 of 227 Old 02-20-2016, 08:20 PM
AVS Forum Special Member
 
Join Date: Jan 2007
Posts: 2,630
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1331 Post(s)
Liked: 816
Quote:
Originally Posted by W4RLORD View Post
I don't use this forum much and do not know how to quote individual sentences so I'm going to reply in numbered bullet points:

1. The example I used was not a scientific example, it was an extreme non-scientific example to exaplain the hamonic correlation to uninformed users. A scientific example would be a frequency of 40hz. The 2nd harmoic of this particular frequency would be 80hz (even order). If played back on this 0.03% THD+N amplifier, an 80hz tone will be audible.
Absolutely not. Dead wrong. If you don't have a lab and have not tried it, or bothered to ready any existing literature on the subject, you wouldn't know. First off, even order, particularly second order harmonic distortion is very hard to hear. Typically it has to be well over a couple percent to become audible at all. But it doesn't matter because the sub driver itself will have THD that will completely swamp that of the amp. There's not a sub made that can get ANY frequency out if its driver at .03%! None. Ever tested THD on a sub? Oh, yeah, no "lab".
Quote:
Originally Posted by W4RLORD View Post
40hz is harder to produce than 80hz and in a non-subwoofer setup, will be heard louder on most speakers.
No, dead wrong again. Hearing is less sensitive as frequency goes down. Given equal SPL for both, the 80Hz will always sound louder until you go above 85dB SPL or so. But in-room response will completely confuse this anyway.
Quote:
Originally Posted by W4RLORD View Post
Unless the speakers have a flat response below 40hz upwards, 80hz will be heard in most circumstances.
Both will be heard, not sure what you mean.
Quote:
Originally Posted by W4RLORD View Post
Lets take an extreme example, at 20hz in a stereo 2.0 system. Most speakers of all different speaker technologies usually cannot produce 20hz audibly, with the rare ones that do not able to do it within +/-3dB of the rest of the outputeed frequency spectrum. That's forgetting the fact it's in the lower limits of what we can hear (though not the absolute limit as some claim, many can hear down to 16hz, at extreme volumes of course) and the fact that the speakers have their own distortion too.

The 2nd harmonic of 20hz, is 65hz.
Wrong. The second harmonic of 20Hz is 40Hz.
Quote:
Originally Posted by W4RLORD View Post
On the 0.03% THD+N amplifier, this will be heard and one cannot refute that.
Easily refuted on two counts. 1: You can't get a speaker to produce a tone that pure at ANY frequency, so talking about amplifier distortion hear through a speaker is just silly. And 2: Even order harmonics, particularly second, is very hard to hear. Typically it has to be way above a percent or two. To understand this, you need to study critical bands and masking, as well as distortion audibility. But your assumption is dead wrong.
Quote:
Originally Posted by W4RLORD View Post
The THD+N for low frequency content would have to be a lot lower for 20hz to be played back correclty.
The above statement makes no sense.

Time to get something else straightened out. When speaking of distortion, we use the term Total Harmonic Distortion, which is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency. THD can be measured with spectrum analysis. However, there are other ways to measure THD, typically with a distortion analyzer, which removes the fundamental and meters whatever is left, which is a signal comprised of all harmonic content (THD) PLUS all noise content. THD+N, therefore, is applicable ONLY to measurements made that include noise. Noise can bias a THD figure if high enough, but a realy THD+N figure should also include a statement of measurement bandwidth.

You can stop using THD+N in this discussion. Our ears are not distortion analyzers.

Quote:
Originally Posted by W4RLORD View Post
2. Actually, bass is defined as being above 60hz leading up to roughly 200hz.
Or...perhaps another definition of bass...

Quote:
Originally Posted by W4RLORD View Post
Below 60hz is defined as sub-bass, above 12khz (or 10khz) is usually defined as high frequency.
They most common subwoofer crossover frequency in the world is 80Hz, not 60Hz. The LFE channel is defined as passing up to 120Hz, and is directed to the subwoofer. HF can be defined any number of ways, it doesn't matter that much but...

Quote:
Originally Posted by W4RLORD View Post
My statement is not incorrect, as high requencies close to your audible limit will be quieter than a 100hz tone for example. You're arguing sematics, in which I am not incorrectly using.
No, not semantics (as it is often spelled), but facts about human hearing. The response of ears is not flat. Your statement is too non-specific to make any sense. It depends on the specific frequencies and absolute SPL, as well as the individual.
http://philotone.com/wp-content/uplo...y-Response.jpg
Quote:
Originally Posted by W4RLORD View Post
3. I am talking in absolute terms, with no outside factors distorting results such as room reflections.

4. Refer to point 1.

5. I am not talking about subwoofer amplifiers.
Sorry, without quotes I can't follow your points. But picking on the second #5...
Quote:
Originally Posted by W4RLORD View Post
5. Sound masking is not an optimal way of making certain frequencies inaudible. The optimum is to have lower distortion, period. Rather than using human ear trickery (which doesn't always work).
Masking is a fact of life, it's not trickery, it works, and is always working, like it or not. I have no objection to lower distortion, but your concept of what's audible as far as distortion is concerned is just not based in reality.
Quote:
Originally Posted by W4RLORD View Post
6. It does not reduce bandwidth in absolute terms, but if a frequency is masked by harmonics you are figuratively limited.
Your statement was, "These added hamronics limit audible bandwidth." That statement is incorrect. And it's spelled "harmonics".
Quote:
Originally Posted by W4RLORD View Post
7. It does not matter if the signal media is rich in harmonics, there should be no additional frequencies to the original sound unless for subjective reasons.
Simple harmonic distortion is more audible when the stimulus is free of harmonics to begin with. A violin is rich in harmonics, so changes caused by nonlinearities become difficult to separate. See attached spectrum comparisons. The violin signal is an actual solo violin sample. The sine wave is generated at the same fundamental. Both were analyzed "raw", then analyzed passed through a distortion generator covering a wide dynamic range. While THD figures are level dependant, this specific nonlinear function was chosen to be relatively constant over a few decades. Note the differences in spectrum for the sine vs violin. Which do you think would be more clearly audible? (anyone feel free to chip in here)
Quote:
Originally Posted by W4RLORD View Post
8. There is no "false" about it. The fact that they have "incomplete" spec sheets shows that they hide results. If they quote there THD+N at 8Ω only and the amplifier has the abilty to dip down to 4Ω, they are hiding that particular measurement (or stupidly did not measure it). It's as simple as that.
While I don't disagree that simple THD (no N unless you measure with a distortion analyzer) figures don't tell the story, they are so vanishingly low that unless the amplifier becomes unstable at 4 ohms no audible change will be apparent. You must also try to understand that while the impedance curve of a speaker presents a non-flat load to the amplifier, the changes are only seen by the amplifier when stimulated in those frequency ranges. It's anything but a constant.
Quote:
Originally Posted by W4RLORD View Post
9. Why do you not agree? If a company gives a single measurement of THD+N for example with no reference of a level they tested at (whether it be at a particular voltage, frequency or impedance) then they are masking the whole performance of the amplifier under one isolated measurement (which is usually the best case scenario measurement).
THD figures are general specified at a signal level where they look best, ususally at full output just before the amp becomes nonlinear. That's usually pretty much full power. They don't have to clarify that to anyone who knows what's going on. This is one of those things you wouldn't understand without doing your own testing. I've never found an amp that is specified at very low distortion levels but tests very badly, with one exception, a very cheap "T-power" amplifier that also specified output power at 10%THD. While meaningless, they were actually truthful. Otherwise, test a few amps, see if the specs are really wrong enough to impact distortion audibility. Or read some thorough reviews where the amp as been lab test with an Audio Precision or similar system, and a simulated speaker load. Yes, they look different, but the distortion figures do not suddenly become horribly audible just because there's now a real world test.
Quote:
Originally Posted by W4RLORD View Post
Only if they state it as an average measurement is it an accurate depiction of the equipment.
Can't use "average" because that raises the question, "average of what?" An average must include more than one data point.
Quote:
Originally Posted by W4RLORD View Post
10. How are they not defined?
Since distortion is generated by a nonlinear mechanism, and subject to radical change with signal level, if we are to talk about distortion audibility we MUST define the exact conditions. You haven't done this.
Quote:
Originally Posted by W4RLORD View Post
11. I have not given a single, definitve distortion threshold in the slightest.
Here's your quote from Post #93.
"As you can see, it will be audible in a lot of circumstances. I'm not going to give a percentage figure (for the full system, not just at 1khz) as to where distortion or noise would be inadible as I do not have a lab or such equipment to accurately state such a thing, but a rating of 0.3% is definitely not low enough.

You said you weren't going to give a figure beause you don't have a lab...etc., then you went and gave .3% as "definite". Prove it.

Quote:
Originally Posted by W4RLORD View Post
As I said, only in an isolated lab would anyone be able to come to such a figure. Which is directed at people claiming there's no audible difference between THD+N levels and objectivly better equipment. They have not done any tests in such isolated conditions and also cannot prove a single thing. Having an A/B test in a persons home is a laughable way to come to any conclusin of that nature.
Test have been done for decades. Distortion audibility is an ongoing sector of research. So far we know there's no single figure of merit that describes it well, it's multi-dimensional covering frequency, amplitude, temporal character, and the complexity of the waveform. We do know (have known since the early 1980s) that what we thought was fairly high distortion levels actually aren't so audible. David Clark built an audio "chamber of horrors", a bank of various distortion generating circuits, then conducted ABX tests with hundreds of listeners, mostly trained audio professionals. I participated. It was shocking how much distortion we couldn't hear. I don't think he compiled it into a formal paper, but others have worked on the issue. Do your own research, you won't believe me anyway.
Quote:
Originally Posted by W4RLORD View Post
12. There is no ignorance at all, refer to point 1.
point 1 proves my point.
Quote:
Originally Posted by W4RLORD View Post
13. Science has been used sir.
Ok, so now we need to define science?
Attached Thumbnails
Click image for larger version

Name:	sine-thd.jpg
Views:	29
Size:	174.1 KB
ID:	1267969   Click image for larger version

Name:	violin-thd.jpg
Views:	31
Size:	179.2 KB
ID:	1267977  
jaddie is offline  
post #98 of 227 Old 02-21-2016, 07:01 AM
AVS Forum Special Member
 
Join Date: Jan 2007
Posts: 2,630
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1331 Post(s)
Liked: 816
The link below is to a web page about an interesting experiment. They set out to find how audible distortion becomes in the presence of music. What the actually tested was the masking of fixed frequency tones by music, but this differs from distortion products only in that the tones are not harmonically related to the music, and are fixed. Distortion products are harmonically related, and are variable with the signal. There would be differences between the two mechanisms. The harmonic level variance with signal would tend to reduce their detectability, but the wider spectral disbursement of many harmonics would tend to increase their detectability in some cases, depending on the desired signal's masking capability. The two properties don't necessarily compensate for each other as they don't exist to the same degree temporally, but the experiment is none the less interesting. The graphs take a bit of study, but the key is the red zero line represents music level average, the data points are the audibility points of the tones.

http://www.axiomaudio.com/distortion
jaddie is offline  
post #99 of 227 Old 02-21-2016, 08:11 AM
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 15,491
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 5770
FWIW THD of 3-5% in loudspeakers is normal. You can find THD measurements of many speakers here:
http://www.soundstagenetwork.com/ind...d=16&Itemid=18

For example, this SPL/THD chart of the ACI Sapphire:



THD averages -30dB, which is 3%. That's measured at 90dB. You might see lower figures quoted with 1 watt input, but who listens with 1 watt input?
Bill Fitzmaurice is offline  
post #100 of 227 Old 02-21-2016, 11:45 AM
AVS Forum Special Member
 
PrimeTime's Avatar
 
Join Date: Mar 2003
Location: Lower California
Posts: 3,243
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 798 Post(s)
Liked: 491
Paul Klipsch (when he was with us).
PrimeTime is offline  
post #101 of 227 Old 02-27-2016, 07:24 PM
Member
 
upsetter's Avatar
 
Join Date: Jan 2006
Location: SF Bay Area, CA
Posts: 181
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 86 Post(s)
Liked: 49
Quote:
Originally Posted by W4RLORD View Post
Unless you do a A/B test with people that still have full-range hearing (from 20hz up to 18khz+) to come to the conclusion that everything sounds the same, in a sound-treated room, with every other piece of equipment being technically transparent (inaudible distortion and linear) so that the only possible difference in sound if from the amplifiers you're A/B testing, you cannot say anything akin to all amplifiers sound the same.

Honestly, the people that say everything sounds the same are worse than the 'audiophile grade power cables' type community.

Why do you think such things as the 35W DA101 exist? Why do recording studios use very high spec, low distortion equipment? Why does Abbey Road Studios use Electrocompaniet Nemo's with their Bowers and Wilkins Nautilus?

If you said something akin to all ADC's sound the same to someone like Dan Lavry, you would get laughed out of the studio.
I have both Benchmark AHB2 and Parasound Halo A23 and difference in sound is shocking stark. A23 has very unpleasant noise (far from white noise) when idle and sound is dirtier and thicker, as if some dirt is attached to sound. AHB2 has zero noise even when I put my ear to midrange driver/tweeter, sound is extra clean and some may consider it even as thin. AHB2 also has better resolution. E.g. Ozzy Osbourne's voice on Vol.4 Japanese SACD kind drowns in other sounds on A23 but on AHB2 it is well shaped and localized and has much more details and definition as all other sounds. And I am not talking about modern records like classical orchestra on BDA. The difference in sound is not subtle - it is substantial - makes you scratch your head how drastically sound may change from one amp to another.
W4RLORD likes this.

Source/Dac/Pre: OPPO-105
Fronts: Benchmark AHB2 -> DefTech Mythos ST-Ls
Surrounds: Parasound Halo A23 -> DefTech Mythos Gems
upsetter is offline  
post #102 of 227 Old 02-27-2016, 08:31 PM
AVS Forum Special Member
 
Bigus's Avatar
 
Join Date: Feb 2003
Location: The South
Posts: 5,591
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 594 Post(s)
Liked: 558
Quote:
Originally Posted by upsetter View Post
The difference in sound is not subtle - it is substantial - makes you scratch your head how drastically sound may change from one amp to another.
Not at all - this has been well researched for a few decades now. What makes me scratch my head is that some people still aren't aware of and/or refuse to accept the mechanism for the drastic change.
Bigus is offline  
post #103 of 227 Old 02-28-2016, 01:16 AM
AVS Forum Special Member
 
Join Date: Jan 2007
Posts: 2,630
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1331 Post(s)
Liked: 816
Quote:
Originally Posted by upsetter View Post
I have both Benchmark AHB2 and Parasound Halo A23 and difference in sound is shocking stark. A23 has very unpleasant noise (far from white noise) when idle and sound is dirtier and thicker, as if some dirt is attached to sound. AHB2 has zero noise even when I put my ear to midrange driver/tweeter, sound is extra clean and some may consider it even as thin. AHB2 also has better resolution. E.g. Ozzy Osbourne's voice on Vol.4 Japanese SACD kind drowns in other sounds on A23 but on AHB2 it is well shaped and localized and has much more details and definition as all other sounds. And I am not talking about modern records like classical orchestra on BDA. The difference in sound is not subtle - it is substantial - makes you scratch your head how drastically sound may change from one amp to another.
Was the comparison made with instantaneous switched ABX/DBT?

Didn't think so.
jaddie is offline  
post #104 of 227 Old 02-28-2016, 10:11 AM
AVS Forum Special Member
 
CruelInventions's Avatar
 
Join Date: Mar 2004
Location: Chicago-ish
Posts: 6,548
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 1209 Post(s)
Liked: 1415
"shocking stark"

The disappearing use of the '-ly" suffix is one of the weirder grammatical trends of our time. It's kind of like watching someone walking around all day long with an untied shoe lace; I can't help but want to fix it because it looks so distractingly unfinished!

Quote:
The first principle is that you must not fool yourself and you are the easiest person to fool. ~ Richard P. Feynman
CruelInventions is offline  
post #105 of 227 Old 02-28-2016, 10:32 AM
 
LFEer's Avatar
 
Join Date: Jun 2013
Posts: 1,243
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 818 Post(s)
Liked: 532
Quote:
Originally Posted by upsetter View Post
The difference in sound is not subtle - it is substantial - makes you scratch your head how drastically sound may change from one amp to another.
Was your listening position exactly the same within tiny fraction of an inch when the components were switched? If not, there is the explanation for drastic sound change, assuming that it was a level matched comparison.
LFEer is offline  
post #106 of 227 Old 02-28-2016, 11:23 AM
Member
 
upsetter's Avatar
 
Join Date: Jan 2006
Location: SF Bay Area, CA
Posts: 181
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 86 Post(s)
Liked: 49
Quote:
Originally Posted by LFEer View Post
Was your listening position exactly the same within tiny fraction of an inch when the components were switched? If not, there is the explanation for drastic sound change, assuming that it was a level matched comparison.
No, since Earth rotates around its axis AND moves around sun my position was different and I also guarantee air molecules around me were in different configuration state. Seriously though - if you guys think all amps sound the same I am not going to argue with you. Enjoy you Marantz or whatever receiver you have and lets end this fruitless discussion right now.

Source/Dac/Pre: OPPO-105
Fronts: Benchmark AHB2 -> DefTech Mythos ST-Ls
Surrounds: Parasound Halo A23 -> DefTech Mythos Gems
upsetter is offline  
post #107 of 227 Old 02-28-2016, 01:45 PM
 
lovinthehd's Avatar
 
Join Date: Dec 2007
Location: OROR
Posts: 16,231
Mentioned: 50 Post(s)
Tagged: 0 Thread(s)
Quoted: 4588 Post(s)
Liked: 4794
Quote:
Originally Posted by upsetter View Post
No, since Earth rotates around its axis AND moves around sun my position was different and I also guarantee air molecules around me were in different configuration state. Seriously though - if you guys think all amps sound the same I am not going to argue with you. Enjoy you Marantz or whatever receiver you have and lets end this fruitless discussion right now.
The whole discussion ends because you think you can differentiate between your two amps under your own conditions? Listening position can affect your experience as can mood, level, etc. Why on earth did you buy, let alone keep, the Parasound if it sounds so bad?
lovinthehd is offline  
post #108 of 227 Old 02-28-2016, 01:51 PM
AVS Forum Special Member
 
Sean Spamilton's Avatar
 
Join Date: Jul 2012
Location: Toronto, ON
Posts: 1,344
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 443 Post(s)
Liked: 544
Quote:
Originally Posted by lovinthehd View Post
The whole discussion ends because you think you can differentiate between your two amps under your own conditions? Listening position can affect your experience as can mood, level, etc. Why on earth did you buy, let alone keep, the Parasound if it sounds so bad?
From his description of the 'difference' it sounds like his Parasound has developed a fault, and he's equated this failing to proof positive of the difference in sound between amps in general. Perhaps he should take it in for repair and reexamine his theory.
lovinthehd likes this.
Sean Spamilton is offline  
post #109 of 227 Old 02-28-2016, 01:59 PM
 
LFEer's Avatar
 
Join Date: Jun 2013
Posts: 1,243
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 818 Post(s)
Liked: 532
Quote:
Originally Posted by upsetter View Post
Seriously though - if you guys think all amps sound the same I am not going to argue with you. Enjoy you Marantz or whatever receiver you have and lets end this fruitless discussion right now.
I don't know about others but I've never said or implied that all amps sound the same. Where do you get such notion from?
BTW, there is a simple way to silence the critics, show them the proof of what you claim. When I say proof, I don't mean opinion or speculation.
LFEer is offline  
post #110 of 227 Old 02-29-2016, 06:03 PM
 
Join Date: Feb 2016
Posts: 966
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 554 Post(s)
Liked: 331
Quote:
Originally Posted by kucharsk View Post
Or, subjectivists know amplifiers can sound wildly different and don't need an experiment to "prove" it.

Not to mention that suggested use of things like relays are going to negatively affect the sound, perhaps to the point where all amps will sound equivalently bad. In deference to AVS Forum, it would be like running BD and DVD through an analog switcher limited to 250 lines of resolution and trying to double blind which disc format was higher resolution, or comparing "Two Buck Chuck" and a fine vintage wine by sipping them out of dirty glassware.

The Porsche 911 comment is interesting, as though there are tests that can prove the difference in vehicles, if you gave a 911 to a Camry driver and told them to drive them in the same way they likely would not understand why one was 5x the price of the other, either.

While it's certainly a game of diminishing returns, subtle nuances in soundstage and instrument presentation might not be worth $50K or more to you, but to others with appropriate systems they might be.

What always amuses me is why the objectivists feel so obliged to prove the subjectivists wrong. If I have a stop and go commute and never get a car above 25 MPH, what different should it make to you whether I do it in a Ferrari or a Prius? Yet that desire to prove someone to prove the Ferrari driver an idiot isn't one that I'm aware of.
I get your points, but the use of bosch type relays over that of transistor, would not change the sound in any subjective or objective way.
Jady Jenkins is offline  
post #111 of 227 Old 02-29-2016, 06:04 PM
 
Join Date: Feb 2016
Posts: 966
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 554 Post(s)
Liked: 331
Quote:
Originally Posted by LFEer View Post
I don't know about others but I've never said or implied that all amps sound the same. Where do you get such notion from?
BTW, there is a simple way to silence the critics, show them the proof of what you claim. When I say proof, I don't mean opinion or speculation.
how to you show someone audio?
Jady Jenkins is offline  
post #112 of 227 Old 02-29-2016, 08:48 PM
AVS Forum Special Member
 
Join Date: Jan 2007
Posts: 2,630
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1331 Post(s)
Liked: 816
Quote:
Originally Posted by Jady Jenkins View Post
how to you show someone audio?
He said "show proof" not "show audio".
jaddie is offline  
post #113 of 227 Old 02-29-2016, 09:17 PM
 
LFEer's Avatar
 
Join Date: Jun 2013
Posts: 1,243
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 818 Post(s)
Liked: 532
Rough start for a newbie...
LFEer is offline  
post #114 of 227 Old 03-01-2016, 11:56 AM
 
Join Date: Feb 2016
Posts: 966
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 554 Post(s)
Liked: 331
Quote:
Originally Posted by jaddie View Post
He said "show proof" not "show audio".
Well you lost me.

We obviously cannot convince one another by hearing - at least not in an online text forum.

so the only other relevant sensory medium is sight. So I am wondering how you show someone audio proof. When you take the ears out of the ear-brain combination, and replace the ears with eyes, I'm not sure what such proof would look like. In fact, I don't think there's is an way to do so, outside of audio based demonstration / testing. the proof can at this point, only be found in the actual pudding - listening, not seeing. I would further argue that seeing often gets in the way of objective truth.

So the question how do you show someone audio proof - was really a rhetorical question, as the answer I thought to be obvious, you cannot.

So what I was / am really asking is what form of proof is he really looking for?

Good question - no?
Jady Jenkins is offline  
post #115 of 227 Old 03-01-2016, 12:08 PM
AVS Forum Special Member
 
Join Date: Jan 2007
Posts: 2,630
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1331 Post(s)
Liked: 816
Quote:
Originally Posted by Jady Jenkins View Post
Well you lost me.

We obviously cannot convince one another by hearing - at least not in an online text forum.

so the only other relevant sensory medium is sight. So I am wondering how you show someone audio proof. When you take the ears out of the ear-brain combination, and replace the ears with eyes, I'm not sure what such proof would look like. In fact, I don't think there's is an way to do so, outside of audio based demonstration / testing. the proof can at this point, only be found in the actual pudding - listening, not seeing. I would further argue that seeing often gets in the way of objective truth.

So the question how do you show someone audio proof - was really a rhetorical question, as the answer I thought to be obvious, you cannot.

So what I was / am really asking is what form of proof is he really looking for?

Good question - no?
"Show" in a request to "show proof" means to present. Proof could be in the form of an authoritative document, test results, etc., or a live demo, which would be hard to do for the entire forum, but the results could be presented.

You can always "show" (present) proof, if it exists.
jaddie is offline  
post #116 of 227 Old 03-01-2016, 12:15 PM
 
Join Date: Feb 2016
Posts: 966
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 554 Post(s)
Liked: 331
Quote:
Originally Posted by jaddie View Post
"Show" in a request to "show proof" means to present. Proof could be in the form of an authoritative document, test results, etc., or a live demo, which would be hard to do for the entire forum, but the results could be presented.

You can always "show" (present) proof, if it exists.
Thank you.

I wouldn't have considered such as being actual proof of much, but rather just another open door for more debate, such debate of the cited material itself and its author(s).

As an example, I posted a link to one of Toole more resent video recorded lectures, and you and other called into question his authority, when his credential don't get much better.

So I am still left wondering how anything outside of actual live demonstration would hold any real water.

But I do thank you for your direction.
Jady Jenkins is offline  
post #117 of 227 Old 03-01-2016, 12:28 PM
AVS Forum Special Member
 
Join Date: Jan 2007
Posts: 2,630
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1331 Post(s)
Liked: 816
Quote:
Originally Posted by Jady Jenkins View Post
Thank you.

I wouldn't have considered such as being actual proof of much, but rather just another open door for more debate, such debate of the cited material itself and its author(s).

As an example, I posted a link to one of Toole more resent video recorded lectures, and you and other called into question his authority, when his credential don't get much better.

So I am still left wondering how anything outside of actual live demonstration would hold any real water.

But I do thank you for your direction.
Live demos are not always reliable either, but properly done research is good. When we challenge something it's usually because of lack of properly done research or lack of experimental proof.
jaddie is offline  
post #118 of 227 Old 03-01-2016, 12:36 PM
 
Join Date: Feb 2016
Posts: 966
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 554 Post(s)
Liked: 331
Quote:
Originally Posted by jaddie View Post
Live demos are not always reliable either, but properly done research is good. When we challenge something it's usually because of lack of properly done research or lack of experimental proof.
I think I get what you're saying. If someone is posting their opinion they should say so, or otherwise at least make an attempt at offering up some supporting documents of some sort.

Seems like a lot of work, for a chat room, be it also seems worthwhile if something positive is achieved.

I'll do my best follow this outlined approach, please go easy on me, while I'm getting the hang of it. Its a little more work then I initial thought it would be.

Thanks again
Jady Jenkins is offline  
post #119 of 227 Old 03-01-2016, 12:50 PM
AVS Forum Special Member
 
Join Date: Jan 2007
Posts: 2,630
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1331 Post(s)
Liked: 816
Quote:
Originally Posted by Jady Jenkins View Post
I think I get what you're saying. If someone is posting their opinion they should say so, or otherwise at least make an attempt at offering up some supporting documents of some sort.

Seems like a lot of work, for a chat room, be it also seems worthwhile if something positive is achieved.

I'll do my best follow this outlined approach, please go easy on me, while I'm getting the hang of it. Its a little more work then I initial thought it would be.

Thanks again
These aren't really forum "rules", but since this is the AV Science forum, some of us value truth and accuracy. Not all, but some. Balance that against the fact that audio, as a general topic of interest, seems to be fraught with mythology and misinformation far more than most other topics, hobbies, and industries. We can theorize as to why elsewhere. But that means a whole lot of inaccurate information gets posted in a public forum, which in turn, propagates misinformation and myth, which doesn't seem to serve the greater good. Hence the corrections and requests for validation, especially where the laws of physics seem to be challenged.
jaddie is offline  
post #120 of 227 Old 03-01-2016, 01:04 PM
 
Join Date: Feb 2016
Posts: 966
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 554 Post(s)
Liked: 331
Quote:
Originally Posted by jaddie View Post
These aren't really forum "rules", but since this is the AV Science forum, some of us value truth and accuracy. Not all, but some. Balance that against the fact that audio, as a general topic of interest, seems to be fraught with mythology and misinformation far more than most other topics, hobbies, and industries. We can theorize as to why elsewhere. But that means a whole lot of inaccurate information gets posted in a public forum, which in turn, propagates misinformation and myth, which doesn't seem to serve the greater good. Hence the corrections and requests for validation, especially where the laws of physics seem to be challenged.
Thanks again: I'll do my best to fit in, although, I must say, these demands seem a little heavy, for me personally. And I am not necessarily sold on the idea that sonic outcomes can be proved or disproved, our even partially validated or invalidated, merely by text based debate, especially unmoderated debate. I do see how the basic's can be hammered down, and adhered to, no question, but as to outright challenge a person to prove / support there subjective impression(s) by the means that you have presented, well truthfully, that seems impractical, and not all that likely. But I may be absolutely incorrect, so I guess time will tell.
Jady Jenkins is offline  
Sponsored Links
Advertisement
 
Closed Thread Audio Theory, Setup, and Chat

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off