I have been fighting "something" ill defined but I can hear and my wife very clearly, that is unpleasant is some recordings, played on some electronics on some speakers, for a good 10 years. I think I have finally cracked the code, so to speak.
Yesterday, I was able to make the symptom come and go based on which tweeter was in play, and which DAC I was using. Yes DAC.
The symptom is an upsetting "glare" for want of a better word. I tracked it down to a narrow frequency range, around 3100 Hz. Any recording engineer knows that band well. The good ones at least, which may be part of the problem. My theory is this being in the most sensitive part of our hearing, we may be genetically biased as it is the shrillness of a baby scream in distress. It is most evident on cymbals, trumpets, and soprano voices. Things strong in that band but have copious strong overtones. No, the problem is not simple EQ, though you can reduce it, doing so changes the balance even with a Q of 6 on the filter. Just cutting above 18K does not change the problem at all, so it is not solely the source. This problem is so clear as to be above small differences in level and EQ. Those we can hear too, but they are different.
The action I believe is upper harmonics exciting the tweeter breakup and the resulting IMD is down in the critical range. Likely all over but we seem to be sensitive to a narrow band. As they are not present in a CD due to being above the Nyquist limit, it is our playback chain.
I can make it more or less depending on the amplifier or DAC. I can make it decrease with a low pass filter on the tweeter. I can make it go away by switching to a tweeter better behaved above 18K. It may follow, the reason amps sound different is how they handle harmonics, dominant pole vs Miller compensation measurably changes this. DAC output filtering has many options as does the output buffer. Again measurable. Unfortunately, I can't afford the equipment to measure it. I can use my wife's hearing and to a lessor extent mine.
The key was getting some new Sennheiser headphones. I could hear NO difference in the DACS. My old Grado's I could. Well, they were not well behaved above 20K either. I could hear it in the speakers, 27TDFC or DXT vs XT-25. I have some old cheap VIfa domes that were far worse. XT-25's, DACs sounded the same. So it is interaction between source, through the playback electronics, and the transducer. That is my working theory. I swapped out the Parasound amp (biggest offender) for my old MOSFET, and swapped the Schiit Asgard internal DAC for the JDS AtomDAC+, another clear step. Now the speakers. So, ordering a pair of XT-25's and a set of CSS woofers today for a new build. ( If I had the budget, it would be Purifi and Scan Speak)
Cymbals a dead give away. Trumpets, and soprano voices. Maybe, after 45 years, I can crank up my Big Band and my better half does not leave the room.
Could this be why some prefer ribbon tweeters in spite of their higher HD? No breakup? I have always dismissed them as the are usually implemented way too bright and we don't have tone controls anymore. At least not in showrooms.
Yesterday, I was able to make the symptom come and go based on which tweeter was in play, and which DAC I was using. Yes DAC.
The symptom is an upsetting "glare" for want of a better word. I tracked it down to a narrow frequency range, around 3100 Hz. Any recording engineer knows that band well. The good ones at least, which may be part of the problem. My theory is this being in the most sensitive part of our hearing, we may be genetically biased as it is the shrillness of a baby scream in distress. It is most evident on cymbals, trumpets, and soprano voices. Things strong in that band but have copious strong overtones. No, the problem is not simple EQ, though you can reduce it, doing so changes the balance even with a Q of 6 on the filter. Just cutting above 18K does not change the problem at all, so it is not solely the source. This problem is so clear as to be above small differences in level and EQ. Those we can hear too, but they are different.
The action I believe is upper harmonics exciting the tweeter breakup and the resulting IMD is down in the critical range. Likely all over but we seem to be sensitive to a narrow band. As they are not present in a CD due to being above the Nyquist limit, it is our playback chain.
I can make it more or less depending on the amplifier or DAC. I can make it decrease with a low pass filter on the tweeter. I can make it go away by switching to a tweeter better behaved above 18K. It may follow, the reason amps sound different is how they handle harmonics, dominant pole vs Miller compensation measurably changes this. DAC output filtering has many options as does the output buffer. Again measurable. Unfortunately, I can't afford the equipment to measure it. I can use my wife's hearing and to a lessor extent mine.
The key was getting some new Sennheiser headphones. I could hear NO difference in the DACS. My old Grado's I could. Well, they were not well behaved above 20K either. I could hear it in the speakers, 27TDFC or DXT vs XT-25. I have some old cheap VIfa domes that were far worse. XT-25's, DACs sounded the same. So it is interaction between source, through the playback electronics, and the transducer. That is my working theory. I swapped out the Parasound amp (biggest offender) for my old MOSFET, and swapped the Schiit Asgard internal DAC for the JDS AtomDAC+, another clear step. Now the speakers. So, ordering a pair of XT-25's and a set of CSS woofers today for a new build. ( If I had the budget, it would be Purifi and Scan Speak)
Cymbals a dead give away. Trumpets, and soprano voices. Maybe, after 45 years, I can crank up my Big Band and my better half does not leave the room.
Could this be why some prefer ribbon tweeters in spite of their higher HD? No breakup? I have always dismissed them as the are usually implemented way too bright and we don't have tone controls anymore. At least not in showrooms.
Are you sure it's not just a simple case of a faulty tweeter(s) in your speakers? They get damaged/blown all the time when subjected to excessive power levels. Some of these tweeter faults can be pretty subtle. Could also be a faulty capacitor connecting the tweeter.
Nope, but good thought if it was just one set of speakers. I have been chasing this for 10 years and used many tweeters. It seems it is totally dependent on break-up behavior. I can go to a store and hear the same thing on different speakers. I originally blamed it solely on the amps. Did you notice I could hear the differences in DACS on my Grado's and not on the Sennheiser's? Did you notice I could make it better or worse depending on the electronics?
FWIW, I sold the Grados and sent the HD560's back. I like my old YH1's far better. The HD560's were not as "open ear" as I expected and they reflected too much of my blood flow sound back to me. You know, the "sound of the sea" when you hold a big shell to your ear? My Yamaha's don't. Sennheiser's are lower distortion and with a very small bit if EQ very very nice, except I can't stand the "hiss". I can listen to the the Yahammers with no eq.
There is another detail I hear in amplifiers, my go/no-go test. On a really clean classical guitar recording, "lessor" amps will put a metallic tint to the bass strings. Subtle, but I can hear it consistently. It does not matter if the amp is a good affordable one, or some uber ego reviewed in Stereophile monstrosity. Simple yes/no. The good news is, modern amps are most all better, so sounding more and more alike. 10 years ago I could differentiate about every one in the store. Last serious listen between three nice integrated, I could not tell them apart at all. About the biggest difference now is those with ****-poor power supplies that leave them lifeless. ( Rotel, are you listening? Put come caps in there!) I am not convinced on class D yet, but willing to give it another pass. After my speaker build maybe a Purifi based test. Fantastic specs, but only if that is what our silly brains think is music.
Another random thought. When CDs first came out, we blamed them for all kinds of ills. First generation well deserved, but it persisted. Digititus, and the such. Is it a coincidence, about that time we started getting tweeters with far more range and the more rigid domes came out? Sure, a super rigid ultra light dome extends the response, lower distortion, more consistent piston range, but the tradeoff is break-up. Often it's over 20 dB louder than the fundamentals! So, polycarb, to ceramic, aluminum, mag, and now Be, being progressively lighter and rigid. Progress? But gee, some old paper domes and good old doped silk can still sound sweeter even if less minute detail. Pick your evil? Was it really the CD's or the "improvements" in speakers that came about the same time? That, and early DACs sprayed IMD all over the place. My old Tanburg Facetts, ubiquitous 1 1/2 inch paper cone 49 cent tweeter, does not have the glare! By my wife's ears, the Vanderstein 2Ce and Martin Logans did not either, but about every speaker in a store ( mid 80's) did.
FWIW, I sold the Grados and sent the HD560's back. I like my old YH1's far better. The HD560's were not as "open ear" as I expected and they reflected too much of my blood flow sound back to me. You know, the "sound of the sea" when you hold a big shell to your ear? My Yamaha's don't. Sennheiser's are lower distortion and with a very small bit if EQ very very nice, except I can't stand the "hiss". I can listen to the the Yahammers with no eq.
There is another detail I hear in amplifiers, my go/no-go test. On a really clean classical guitar recording, "lessor" amps will put a metallic tint to the bass strings. Subtle, but I can hear it consistently. It does not matter if the amp is a good affordable one, or some uber ego reviewed in Stereophile monstrosity. Simple yes/no. The good news is, modern amps are most all better, so sounding more and more alike. 10 years ago I could differentiate about every one in the store. Last serious listen between three nice integrated, I could not tell them apart at all. About the biggest difference now is those with ****-poor power supplies that leave them lifeless. ( Rotel, are you listening? Put come caps in there!) I am not convinced on class D yet, but willing to give it another pass. After my speaker build maybe a Purifi based test. Fantastic specs, but only if that is what our silly brains think is music.
Another random thought. When CDs first came out, we blamed them for all kinds of ills. First generation well deserved, but it persisted. Digititus, and the such. Is it a coincidence, about that time we started getting tweeters with far more range and the more rigid domes came out? Sure, a super rigid ultra light dome extends the response, lower distortion, more consistent piston range, but the tradeoff is break-up. Often it's over 20 dB louder than the fundamentals! So, polycarb, to ceramic, aluminum, mag, and now Be, being progressively lighter and rigid. Progress? But gee, some old paper domes and good old doped silk can still sound sweeter even if less minute detail. Pick your evil? Was it really the CD's or the "improvements" in speakers that came about the same time? That, and early DACs sprayed IMD all over the place. My old Tanburg Facetts, ubiquitous 1 1/2 inch paper cone 49 cent tweeter, does not have the glare! By my wife's ears, the Vanderstein 2Ce and Martin Logans did not either, but about every speaker in a store ( mid 80's) did.
Can you list a few of the music tracks (songs) you use to readily identify the issue you have identified?
Chris
The Topping D30 pro and the internal Asgard AKM had this "glare" only through my speakers symptom I describe. My older Woldson also was not good, but it was a first generation and distortion was very high compared to today. My Focusrite is kind of in-between. Close enough if I was not listening for it, I might not notice it right off, but my wife does. Big time.
JDS Atom is much less. I don't know about all those micro detail, soundstage or pick your undefined subjective reviewer gobglty-gook term stuff in the reviews. Only this one issue. Other than that, all superb. I really wanted to like the Topping. Remote etc, but had other issues with it. *
Again, all the "new" ones sounded identical through the Sennheiser's. Very well behaved cans. ( used the Schiit amp for that. ) All sound fine with my old Yamaha's. Only the Grado's which are super detailed in finding faults did I hear the same as on my speakers.
Look at the specs on the Topping. Gad, it is hard to believe they can make a consumer market product like that! Even 10 years ago we would not believe the specs that good.
FWIW, I tested then with and without my LT medical grade USB filter and no audible difference. I don't think I had a problem, so no problem to filter out. All three DACS are well enough implemented as to not be a problem.
Billy Joel, 54 street. mostly the cymbals, but his voice some. Most any cymbals het harsh or just "off" if you know what a cymbal sounds like.
Oni Mitchel, Ladies of the Canyon. Her voice epically when she is overdubbed to the end. The slightest attempt at EQ on her voice it goes to hell quick.
Someone like Amanda McBroom or Nora Jones don't hit the fundamentals whose overtones seem to be the issue.
Harry James, The king James version. Trumpet when really on it. About any other trumpet, but Marcelles Baroque not so much. Buddy rich pushes his horn section harder to be slightly edgy, and that highlights the problem.
The Airplane 2400 Fulton St is a terrible recording, and it makes it worse.
Ang good classical guitar. Solo, I can hear the differences in the strings ( amps, not DAC) I am a fan of Bream, so I have a lot of his.
It is harder to hear with more complex recordings. Masking etc.
The opening applause on the Clapton unplugged is terrible, and this symptom makes it sound more terrible.
Fortunately 99% of my music sounds great and I could not tell one DAC from another. Now the Parasound 2125, I could hear that thing from across the street!
So, if you do not have this particular sensitivity, don't use my hearing as your DAC purchase guide, though the JDS for $109 is a heck of a deal if you don't need MQO-whatever 2000 bit giga Hz decoding. The topping does all that. For a $350, but is a pre and head amp too. I can't imagine a head amp cleaner than the Schiit audibly. The Schiit and Topping head amps I could not hear any difference, but the Schiit has more power if you need it. I am not a big headphones guy and will never have $5000 headphones to know if they magically bring out sounds that were probably not on the CD anyway.
* I had some dropouts. After power removed, it comes up in standby, and I could not get the SourceForge ASIO plugin into WMP to talk to it, but it could to my Focusrite. Only blame Topping for the dropouts. Never had them with any other DAC or since. My PC server is off-line with almost nothing else running.
JDS Atom is much less. I don't know about all those micro detail, soundstage or pick your undefined subjective reviewer gobglty-gook term stuff in the reviews. Only this one issue. Other than that, all superb. I really wanted to like the Topping. Remote etc, but had other issues with it. *
Again, all the "new" ones sounded identical through the Sennheiser's. Very well behaved cans. ( used the Schiit amp for that. ) All sound fine with my old Yamaha's. Only the Grado's which are super detailed in finding faults did I hear the same as on my speakers.
Look at the specs on the Topping. Gad, it is hard to believe they can make a consumer market product like that! Even 10 years ago we would not believe the specs that good.
FWIW, I tested then with and without my LT medical grade USB filter and no audible difference. I don't think I had a problem, so no problem to filter out. All three DACS are well enough implemented as to not be a problem.
Billy Joel, 54 street. mostly the cymbals, but his voice some. Most any cymbals het harsh or just "off" if you know what a cymbal sounds like.
Oni Mitchel, Ladies of the Canyon. Her voice epically when she is overdubbed to the end. The slightest attempt at EQ on her voice it goes to hell quick.
Someone like Amanda McBroom or Nora Jones don't hit the fundamentals whose overtones seem to be the issue.
Harry James, The king James version. Trumpet when really on it. About any other trumpet, but Marcelles Baroque not so much. Buddy rich pushes his horn section harder to be slightly edgy, and that highlights the problem.
The Airplane 2400 Fulton St is a terrible recording, and it makes it worse.
Ang good classical guitar. Solo, I can hear the differences in the strings ( amps, not DAC) I am a fan of Bream, so I have a lot of his.
It is harder to hear with more complex recordings. Masking etc.
The opening applause on the Clapton unplugged is terrible, and this symptom makes it sound more terrible.
Fortunately 99% of my music sounds great and I could not tell one DAC from another. Now the Parasound 2125, I could hear that thing from across the street!
So, if you do not have this particular sensitivity, don't use my hearing as your DAC purchase guide, though the JDS for $109 is a heck of a deal if you don't need MQO-whatever 2000 bit giga Hz decoding. The topping does all that. For a $350, but is a pre and head amp too. I can't imagine a head amp cleaner than the Schiit audibly. The Schiit and Topping head amps I could not hear any difference, but the Schiit has more power if you need it. I am not a big headphones guy and will never have $5000 headphones to know if they magically bring out sounds that were probably not on the CD anyway.
* I had some dropouts. After power removed, it comes up in standby, and I could not get the SourceForge ASIO plugin into WMP to talk to it, but it could to my Focusrite. Only blame Topping for the dropouts. Never had them with any other DAC or since. My PC server is off-line with almost nothing else running.
Have you tried getting rid of all the wall warts, SMPS, DC/DC converters, etc.? Those things can be a source of ugly noise that can get into the system. Also, dacs vary in their tolerance for USB noise from PCs, and and or ability to run cleanly off of USB power.
Otherwise, would it be correct to say all the dacs are sigma-delta types? (IIUC JDS Atom uses an AK4490). Some people have said they prefer the sound of AKM dacs over ESS, with the latter having a reputation for more of a 'bright' sound.
EDIT: I would also just note (as I often tend to do 🙂 ) that dacs can have audible aberrations that don't show up well in the kind of measurements featured at ASR. ESS explains about some of those things in the following links:
https://www.yumpu.com/en/document/read/23182504/noise-shaping-sigma-delta-dacs-ess-technology-inc ...some of the interesting stuff that your wife could possibly be hearing is discussed starting around page 44 of the presentation.
Some more info at: https://6moons.com/audioreviews2/resonessence/2.html
The power supply issue is another thing that doesn't always show up well on FFT type measurements, but it isn't really a fault of the dac chip (i.e. not something for ESS to say much about).
Otherwise, would it be correct to say all the dacs are sigma-delta types? (IIUC JDS Atom uses an AK4490). Some people have said they prefer the sound of AKM dacs over ESS, with the latter having a reputation for more of a 'bright' sound.
EDIT: I would also just note (as I often tend to do 🙂 ) that dacs can have audible aberrations that don't show up well in the kind of measurements featured at ASR. ESS explains about some of those things in the following links:
https://www.yumpu.com/en/document/read/23182504/noise-shaping-sigma-delta-dacs-ess-technology-inc ...some of the interesting stuff that your wife could possibly be hearing is discussed starting around page 44 of the presentation.
Some more info at: https://6moons.com/audioreviews2/resonessence/2.html
The power supply issue is another thing that doesn't always show up well on FFT type measurements, but it isn't really a fault of the dac chip (i.e. not something for ESS to say much about).
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Thanks for sharing. Certainly the ~3 kHz region is a sensitive one and I find a lot of recorded and reproduced music to be very shrill in that range. Shouldn't it be easy to measure a system in which you hear it, and one in which you do not? Like close miking the tweeter?
My experience is that all flagship DAC chips sound good if the output buffer section is up to the task. It's not the D/A, it's what follows.
If @tvrgeek can narrow down the glare he doesn't like to a cerain frequency range and to certain tweeters (or other gear) then it should be obvious in measurements. Maybe not easy to see in FR, but other measurements and analysis should reveal it, yeah?
Funny, I've owned both. Designed and built an ESS DAC from scratch that was for a commercial project that never took off. At RMAF it didn't go over great guns, most people found it too "soft." It certainly was gentle sounding to my ears. I suspect that we aren't used to that, our experience and expectation lies with a more edgy sound, be it analog or digital. Or maybe it was just too soft. 😉
My experience is that all flagship DAC chips sound good if the output buffer section is up to the task. It's not the D/A, it's what follows.
If @tvrgeek can narrow down the glare he doesn't like to a cerain frequency range and to certain tweeters (or other gear) then it should be obvious in measurements. Maybe not easy to see in FR, but other measurements and analysis should reveal it, yeah?
No idea on horn loading, but the XT-25 is a ring radiator. The only significance I place on it is it is very well behaved breakup. Basically none. It is as smooth or more than most tweeters with ferro fluid. If you look at the graphs, you will see the SB ring behave in a similar way, but has much higher distortion.
I would suspect CD's might exhibit the same as they are metal domes. Don't know, I don't need a PA system.
No, it does not show up in a simple frequency analysis. It does not show up with a pure tone.
I wish I had a mic, acquisition unit, and software that could measure to 30K and I believe it would show up, but I don't.
I wish I had a way to acquire a complex wave while it is being generated, time align it and look at the delta, but I do not.
Wall warts have nothing to do with it. Ironically the only one near my system is on the Atom DAC, the one that exhibits this less than the others. If you head over to ASR, and look at the bench measurements of all three products, you will see they executed their power very well. All three are premium performance, but not "ego premium audiofool" products.
I am not convinced any of the top line different DAC chips is any different. Actually, we are talking about three different, Cyrus, AKM and ESS. All the magic ephemeral descriptions I have seen reported I do not hear.
Please read my first post that I can now make it come and go at will. That is why I brought it up. I think I found the relationship.
Just this morning I unplugged a switcher power supply for my new streamer from the isolated/filtered power strip and put it directly on the wall to prevent it from polluting the rest of system. I could tell a difference, more calm, less funky detail.
Do you use snubbers on your linear power supplies, and use a line filter for your incoming AC?
The reason I am bringing it up is that strange effects of harmonics being picked up throughout the system can happen. It seemed that certain devices are more prone to this, but it happens less with cleaner power.
As Mark noted, if the offending DAC uses a dc-dc converter to achieve dual rail power for output op amps, that could be an explanation also.
Do you use snubbers on your linear power supplies, and use a line filter for your incoming AC?
The reason I am bringing it up is that strange effects of harmonics being picked up throughout the system can happen. It seemed that certain devices are more prone to this, but it happens less with cleaner power.
As Mark noted, if the offending DAC uses a dc-dc converter to achieve dual rail power for output op amps, that could be an explanation also.
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Please read my original post.
No I do not have a line filter in my sequencer. But a line filter does not change tweeter breakup.
My amp does happen to have a snubber in it. I do not know what is in the supply of the three DACs. The Schiit and JDS are linear. I do not know what was in the Topping.
But I can easily believe a poorly executer SMPS can cause hash a poorly designed LPS may not filter.
No I do not have a line filter in my sequencer. But a line filter does not change tweeter breakup.
My amp does happen to have a snubber in it. I do not know what is in the supply of the three DACs. The Schiit and JDS are linear. I do not know what was in the Topping.
But I can easily believe a poorly executer SMPS can cause hash a poorly designed LPS may not filter.
Watching. An interesting one, and the single most important reason I got rid of my old rig. Thank you for this effort!
Power supply noise can be ultrasonic. When it is it can break up tweeters.
Please don't get me wrong. I'm not saying I know what's causing the glare. What I am saying is that you have to do the experiments and or measurements before deciding what the problem can or can't be. Rationalizing that something shouldn't be a problem doesn't prove what is actually happening. Regarding SMPS, they can be made arbitrarily good but its not necessarily cheap or easy to do them well. The really good ones are usually too expensive to put in low cost consumer devices. With wall warts I have measured RF at mostly at 1MHz to 2Mhz as a common mode current on the ground line. Not hard for it to couple into differential mode and and cause audible problems. Not that humans can hear 1MHz directly, but the noise can get demodulated into the audio band or the ultrasonic region. The mechanisms by which that can happen are already known, there is nothing new here.
Please don't get me wrong. I'm not saying I know what's causing the glare. What I am saying is that you have to do the experiments and or measurements before deciding what the problem can or can't be. Rationalizing that something shouldn't be a problem doesn't prove what is actually happening. Regarding SMPS, they can be made arbitrarily good but its not necessarily cheap or easy to do them well. The really good ones are usually too expensive to put in low cost consumer devices. With wall warts I have measured RF at mostly at 1MHz to 2Mhz as a common mode current on the ground line. Not hard for it to couple into differential mode and and cause audible problems. Not that humans can hear 1MHz directly, but the noise can get demodulated into the audio band or the ultrasonic region. The mechanisms by which that can happen are already known, there is nothing new here.
I have a similar experience with the RME Adi-2 Pro. It has some sort of annoying sound compared to an old ebay CS4398 board with its opamp stage bypassed to transformer output. This sounds way better and more natural than the RME that has exemplary specs.
I agree with Pano, it is probably the output stage of the DAC.
I agree with Pano, it is probably the output stage of the DAC.
Output stage can cause problems too. There are various places to look for possible problems. Ultrasonic noise is less likely to be an output stage problem though. Sounding less real and breaking up tweeters are often two different issues.
Did you ever try the Peerless K010DTs from the 70s/80s, soft silk 1" domes? Still made by another manufacturer today? I used to use these, softer highs as you pointed out earlier, and maybe avoids the break-up of the stiffer metal domes?
I agree with @tvrgeek that out-of-band behaviour of tweeters must somehow alias rubbish into the audio band. Many tweeters have high Q peaks in the 26-32kHz region, way above my hearing yet I can't listen to a system that has such a beast.
Despite the ebullient praise for ring radiator tweeters when they first appeared, and no matter how well they 'measured', the ones I have heard either as individual components or in brand name high end systems, sounded quite unnatural to me when trying to reproduce ordinary natural acoustic sounds like hi-hat, cymbals, triangles, etc. I've never bothered with them since.
The 3kHz region is where the mechanical/acoustical hearing mechanism is most efficient, as reflected in the Fletcher Munson curve. As a consequence the anthropoid ear/brain auditory system has evolved to take advantage of this region of sensitivity. If acoustic energy in the octave centred on 3kHz is missing it becomes very difficult to distinguish between consonant sounds in speech like P T D G, etc, which is well known to severely impact speech intelligibility. I had a conversation with Dr David Griesinger in around 1999 where he attempted to explain to me how the same band provided the cues that allow, say, the individual violins in the first and second section of an orchestra to be differentiated. http://www.davidgriesinger.com
It doesn't help that most speaker systems have a crossover in this region and exacerbate the problem by having a power response hole around 3kHz, especially with 2nd, 3rd and higher order crossovers which make the power response hole even more pronounced.
Despite the ebullient praise for ring radiator tweeters when they first appeared, and no matter how well they 'measured', the ones I have heard either as individual components or in brand name high end systems, sounded quite unnatural to me when trying to reproduce ordinary natural acoustic sounds like hi-hat, cymbals, triangles, etc. I've never bothered with them since.
The 3kHz region is where the mechanical/acoustical hearing mechanism is most efficient, as reflected in the Fletcher Munson curve. As a consequence the anthropoid ear/brain auditory system has evolved to take advantage of this region of sensitivity. If acoustic energy in the octave centred on 3kHz is missing it becomes very difficult to distinguish between consonant sounds in speech like P T D G, etc, which is well known to severely impact speech intelligibility. I had a conversation with Dr David Griesinger in around 1999 where he attempted to explain to me how the same band provided the cues that allow, say, the individual violins in the first and second section of an orchestra to be differentiated. http://www.davidgriesinger.com
It doesn't help that most speaker systems have a crossover in this region and exacerbate the problem by having a power response hole around 3kHz, especially with 2nd, 3rd and higher order crossovers which make the power response hole even more pronounced.
Great post Johnmath! I think many speaker designers and enthusiasts overlook those F-M curves. Human hearing is not flat by any means as we know. That said, frequency response of the ears can vary from person to person (yet it is difficult to know that how you hear music may be a bit different from someone else). A simple physical aspect of this is the shape of the outer ear and how much it sticks out. If you take your fingers behind the ears and point them out just a little bit, you'll hear the tonality of most music change, suppose you were born that way, you'd never really know. So the 3 KHz region in combination with certain drivers, and/or crossovers and a person's hearing may account for the issue posted by Tvrgeek. I recently used the Dayton 2" dome reference mids RS52s which have a 3 db rise in this range and in certain music at higher amplitudes, certain instruments and vocals get a bit harsh.