Katz's Corner Episode 17: Perfecting Perfection

Continuous Improvement
Hi again, fellow headphone investigators! The article I had originally planned to be Episode #15 was shelved and replaced by #16: The Smoking Gun. Since then, the LCD-4s which I reviewed have been replaced by Audeze because at some point they were damaged—no one knows where or how.

Regarding the Focal controversy, I personally disagree with Tyll's decision to keep the Focal Utopias on the wall of fame, since no one seems to be able to find a current-production unit with the warmer, more neutral characteristics that had earned it a place on the wall in the first place. As well, I would like Audeze to send Tyll four or five current samples of the LCD-4, to confirm manufacturing consistency. But I do applaud his tentative placement of the LCD-4 on the wall. I've discussed the issue of Audeze's manufacturing with Tyll and with Sankar from Audeze and I feel confident that their quality control is excellent. They put every headphone through careful measurements in a test jig. Things just sometimes happen at the bleeding edge where we audiophiles tend to live. Every LCD-4 is practically custom made, there may not be any in inventory at a given moment.

Bob's Philosophy of Sonic Neutrality
Today I'd like to discuss what I mean by sonic perfection or sonic neutrality. Most audiophiles have observed that excellent playback systems of different manufacturers can sound radically different! Even the most accurate loudspeakers are subtly voiced and are different sounding. But how can there be more than one "right"? Philosophically speaking, two different-sounding playback systems can't both be "right": one of them must be correct and the other must be incorrect! Or maybe both are wrong!

Obviously there are systems which sound more "right" than others and no reproduction system is perfect. Plus, our tastes vary in loudspeakers and headphones. Some of us tolerate certain anomalies more than others. With correction, a loudspeaker can measure extremely flat, with the anomalies greatly reduced, but we have to use good, transparent correction or the cure can sound worse than the disease. And we have to understand how to interpret our measurements and know something about psychoacoustics. Many "automatic" correction systems sound horrid and far worse than no correction at all.

The Chicken and the Egg
We acknowledge that the stereo recording process is imperfect and recordings are only a semblance of reality. You can't fit a 100 piece orchestra in your living room. Nevertheless, we adapt, we can at least compare reproduced tonality to the sounds we know in real life.

We use recordings to judge our loudspeakers. We use loudspeakers to judge our recordings. That is the ultimate chicken and egg problem! Dr. Floyd Toole calls this "the circle of confusion." Recordings vary so much in tonality that it's difficult for us to decide which is the right recording to judge the correctness of a loudspeaker or headphone. And here's a rub: How can any reviewer make a judgment about a transducer without knowing what a recording is supposed to sound like? Some reviewers and consumers may leap to conclusions about a playback system without knowledge of what a recording is supposed to sound like.

As readers of audio reviews, we like to see the reviewer's reactions to a bunch of recordings that we are familiar with. The only problem is that the recordings we think we know have been colored by our memory of what they sound like on our own playback systems, and our own systems are inaccurate, in varying degrees! When we visit a friend's house and listen to recordings we are familiar with, we sometimes negatively react when it sounds different from our own reproduction system, but we neglect the fact that we tend to like what we are familiar with. What if our own familiar system is at fault and the other system is telling the truth?

You'd think that only recording engineers who were present at the session could judge a transducer. As an audiophile recording engineer for decades, I'm very familiar with the sound of my own best recordings, which I've heard on numerous playback systems. I know how I made these recordings, and where all the bodies are buried!1 I also use familiar recordings made by other engineers which sound excellent on my reference playback system, to avoid the "not invented here" syndrome. Being familiar with a recording does help, but it is not essential as we shall see.

The first step in identifying whether a system is accurate is to listen to a wide variety of recordings on the playback system, loudspeaker or headphone, and take very careful notes of the tonal anomalies you think you hear. If every single recording that you listen to produces a similar tonal anomaly, then it's probably safe to conclude that the transducer (or perhaps the power amplifier or converter or even the cables) is the cause of the issue. But what should you conclude if only some recordings produce the anomaly and others do not?

A lot of the time, recordings themselves are at fault. The bass range is particularly difficult to control and so recording and mixing engineers struggle with uneven bass in their control rooms as much as us music listeners. The classic case is the common popular music mixing practice of using a Yamaha NS-10 loudspeaker on top of a console: That's an acoustic nightmare! As a mastering engineer, I usually can tell a recording was mixed with desktop NS-10s by the heavy bass drum and the weak bass instrument. Often my job as mastering engineer is to fix problems caused by poor monitoring during the recording or mixing session. Many transducers are hyped at the high end to give a kind of "hi-fi impression" and a false sense of transparency. But sibilance and cymbals are not exaggerated in real life.

My best reference for tonal accuracy is of course the tonality of real life and the many acoustic recordings I and others have made that try to approach real life. I also subscribe to the principle that the most accurate loudspeaker or headphone system is the one which reproduces the widest set of reference recordings without requiring EQ. That's how I came up with this bell curve (Fig 17-1):

KatzCorner_Ep17_Graph_BellCurve

Fig 17-1: Bob's Bell Curve of Transducer Accuracy

A loudspeaker or headphone that only sounds good with a small subset of recordings or that satisfies fewer listeners must be less accurate than one which successfully reproduces a greater portion of reference recordings. Audio expert Dr. Floyd Toole has demonstrated that averaging all the different consumer speakers (some bright, some with too much bass or midrange, etc.) one ends up with a very flat curve, which is empirical proof that mastering with an extremely accurate and flat playback system yields a product that sounds correct on more systems. So if you want the best translation, pick a loudspeaker with the flattest response. Likewise, if you are looking for accuracy, pick the headphone that successfully reproduces the widest variety of good recordings.

Unlike loudspeakers, headphones should not measure flat and so we use a correction curve like the Harman curve promoted by Tyll. If we subtract the correction from the measured response we should get a flat line. Assuming that the correction curve is also correct! I use a modified curve, with slightly less bass boost than Tyll advises and I've tweaked the upper midrange/treble boost until the corrected headphones closely resemble my reference speakers. But I agree with the general shape proposed by Tyll and Sean Olive.

Another challenge is how to pick your reference recordings. I advise you pick a group of at least 20 fine recordings that you love, ranging from, say, brightest to dullest: always play these recordings when evaluating headphones. If your headphones reproduce a large quantity of reference recordings without exhibiting common tonal anomalies, then it's a fair shake to say they are accurate.

One recording may not have enough information in a particular frequency range to excite an anomaly. In episodes 13 and 14 we did nail down some clear anomalies with both the Focal and the Audeze, "family resemblances" that are common to a given headphone within a large set of good recordings. For example, I found some warm recordings which do not excite the sibilance range, so the sibilance anomalies in the Focal were not always excited. However, all six listeners felt a large portion of the reference recordings to sound far more sibilant on the Focals than on the Audeze or the loudspeakers. Conversely, the consensus of all six listeners is that the LCD-4 is probably boosting the sub bass a bit, warming up the lower midrange and is a little bit weak in the extreme treble. However, in upcoming episode 18, you'll find that the latest iteration of the LCD-4 is even more tonally neutral and does not have any obvious bass boost. I truly believe Audeze is trying to get to sonic neutrality.

Bob's Headphone Evaluation Method
To sum up, here's my approach to reviewing headphones:

a) If a large portion of a set of high quality recordings exhibits a certain anomaly when auditioning transducer #1 but not when auditioning transducer #2, then we can conclude transducer #1 is probably less accurate in that frequency range. The key here is to listen to a large number of good recordings in different genres and recording styles.

b) If the reference loudspeaker system does not reveal the anomaly on the recording in question, but it is audible on headphone #1 and not on headphone #2, then we conclude that headphone #1 is more accurate compared with the loudspeakers.

c) Adding some more expert listeners gives us a lot more data points, as in Episode 14.

So our best shot is to combine methods a and b, and if possible c. In addition, if we are very familiar with a recording and have heard it on a large number of systems, we can give increased weight to that recording. All this takes us closer to a very accurate subjective judgment of headphones' sonic neutrality.

You say tom-ay-toes
Recently a post at Head-case criticized my use of the terminology "lower treble" to describe the range circa 10 kHz. The fact is that there is no standardized vocabulary of defining a given frequency range. Where does "the upper midrange" lie? Is it 5 kHz-centered? That's where it is for me. For some, the "upper midrange" is around 2 kHz. While I try to be consistent in my terminology my dilemma is that there aren't enough terms to precisely describe all the frequency ranges that interest me.

How do you label the ranges 250-500 Hz, 1-2 kHz, 4-6 kHz, 8-10 kHz, and above 10 kHz? I like to call the frequencies above 13 kHz or so the "air frequencies", for example, because they are above the traditional high treble. Some people lump 4-9 kHz into one range that they may call "upper-upper midrange" or "lower treble". In my book, "Mastering Audio: The Art and the Science", I have a chart of frequency ranges and we discover that there are overlaps and differences in how people describe those ranges. So to be less ambiguous I ought to use the exact frequency range values in question. But I like to write enjoyable language so I sprinkle my vocabulary with words instead of numbers! Just remember that when we differ in the frequency language, neither of us is wrong.

If leaping to conclusions was an Olympic event, audiophiles would get the gold medal. I placed one little adjective in front of the name of the O2 amplifier that incensed another Head-Case participant, although my previous reviews made it clear how I place the O2 amp in the pantheon. (It's a lightweight. It gained its "fame" by semi-marketing more than by its sonic performance. But it is an inexpensive reference that many people know, and it was important to note that it failed to drive the LCD-4 with anything approaching good sound.) Another Head-Case participant criticized my discussion of the left-right Focal sample drivers being off in sensitivity by 1 dB. He said, "at least run a frequency sweep to verify." Frequency sweep is actually a poor way to judge left-right balance: Have you ever tried to evaluate 5 kHz sensitivity by ear using a sine wave? It's not a pleasant thought. Besides, individual frequencies sometimes shift with nodes that exist in the cans, but if the octave band is balanced in the center, then the balance is probably fine.

I've been around the block a few times and am well aware of these issues. If the complainer had read the entire paragraph he would notice that I did play mono pink noise. After level balancing, the pink noise imaged narrowly in the center at all main frequencies, certainly well enough for me to conclude that the two Focal drivers were well matched in level and frequency response after a simple level correction. So, folks, please be a little more tolerant—before you gossip in "the Internets", ask me about it. Trust first and verify. I always strive to be better; communication is better than criticizing someone on line.

Bob's Reference Loudspeakers and Room
In order to judge headphones against loudspeakers, we must use an accurate set of loudspeakers. In Studio A I master recordings which are going to be enjoyed by the public. My goal is to produce masters that sound good everywhere: meaning that they translate to the car, clubs, Hi-Fi, small systems, and audiophile systems. By inference, when my masters translate to a lot of playback systems, the more accurate my mastering loudspeaker.

The power to this room is a 100-amp dedicated service, divided into 5 20-amp 120 volt circuits, each home run back to the distribution/breaker box in the room. That forms a central point and minimizes loop area. The circuits are protected by Surge-X series protectors with EMI and RFI filtering. There are no MOVs on this circuit, which can contaminate the power by leakage current. I analyzed the line voltage with an FFT analyzer, line to neutral and line to ground. After the new power installation, the power line was about 20 dB quieter! This has resulted in a cleaner and quieter audio. Also, I now have more audio headroom: the dedicated AC power does not sag on peaks, and so delivers 4 dB more output level from the power amps before clipping compared to the regular house wiring! The main power amplifiers are two ATSAH 500 by Acoustic Imagery, each which deliver 700 watts continuous into 4 ohms and much more on short peaks. In addition to two 1500 watt subwoofer amplifiers.

My room has been trapped with both active and passive traps. The reverberation time versus frequency is very even. The loudspeakers have been corrected through FIR processing to produce an astoundingly linear frequency, phase and impulse response. This translates to a transparent, impacting, musical and accurate playback. Here's the frequency response curve of the left and right channel at the listening position (Fig 17-2), before and after correction, measured with Acourate software by Audio Vero. It's corrected to my preferred "target", which is flat from 20 Hz to 1 kHz, and a little more than 6 dB down at 20 kHz. This target sounds neither too bright nor too dull using a set of reference recordings. It helps deal with the natural rolloff with distance in the air. As you can see, compared to that target, my system is remarkably flat. It extends down to -3 dB near 15 Hz. It does not exaggerate cymbals or sibilance, a fake "hi-fi" attribute that I abhor—I downgrade headphones or loudspeakers that exhibit those anomalies. Unfortunately, a lot of headphones that get high marks have an exaggerated high end. That seems to be the trend, and I don't like it. My advice: Don't be seduced by the treble unless it sounds natural.

KatzCorner_Ep17_Graph_SystemFR

Fig. 17-2: Dynaudio plus JL subs. Left front /Right front amplitude response before correction (brown/blue). After correction (red/green). The "before" curve has been offset 5 dB for clarity.

The step response of this loudspeaker system is just as astounding (fig 17-3):

KatzCorner_Ep17_Graph_SystemStep

Fig 17-3: Dynaudio Step response, left front channel. Before correction (red). After correction (brown)

Take a look at the red curve (before correction): We notice a distinct positive-going initial pulse (which is the tweeter), followed by a negative "recovery" (the midrange driver) after which the signal returns to positive and eventually decays to zero. The initial up/down/up of the impulse takes about a ms to complete. By contrast, after correction, the step response (brown) is a single distinct, short positive pulse which smoothly decays to zero in about a ms. This is a remarkable achievement: The loudspeaker has been converted into a nearly perfect "single point" source by the magic of DSP phase and time correction.

About eight feet tall, the two loudspeakers produce a coherent planar wavefront. Bass energy moves your pants leg; you can feel it. All the partials arrive at the listener's ear at about the same time. Sonically, this translates to an impressive transient response, a very coherent image, and a big soundstage with holographic depth. The snap of a snare drum sounds very realistic. All genres of well-recorded music sound impacting, real, and natural in this room. A very pleasant experience, indeed and an excellent reference to compare against headphones. Those are my tools. In the next episode we'll put them to work.

1 For those who are not familiar with Bob's work, his discography can be found at tinyurl.com/bobkatz. Bob's recordings have been used as references at high-fi shows worldwide. Several have been judged "Records to Die For" and "Recording of the Month" in Stereophile magazine. Three of his albums have earned Grammy® awards.

COMMENTS
castleofargh's picture

"If leaping to conclusions was an Olympic event, audiophiles would get the gold medal."

add to that the concept of passing fidelity judgement by ear without even thinking about getting a proper reference first, and you've explained why I have massive trust issues ^_^.

I've noticed that many audiophiles insist on fidelity all the time and buy fancy gris-gris with dubious specs to solve problems they usually don't have. also in the name fidelity(while never measuring a thing). but when it comes to calibrating speakers, for some reason most people I talk to didn't bother. or worst, think they don't need to. so of course the next step of using them as reference to EQ the headphone for themselves might be troublesome. :\
I'm guessing half are scared by the idea of having to RTFM if they get gears to measure something. and the other half is probably just stuck in the stone age with ideas like "EQ degrades audio, I want the real sound unaltered". which unlike puppies, is a silliness nobody finds cute.
but the end result is the same, I'd be amazed if 10% of the people reading this blog have done any sort of objective calibration on their speakers.
I'd love to be wrong about that though.

pro tip/auto-trolling of the day: calibrating speakers doesn't work so good if somebody moves them every week to clean behind while you're out... I spent a full month wondering what I was doing wrong or if "burn in" was really something massive I shouldn't have neglected. but then one day the right speaker wasn't even pretending to be pointed toward me, and I used all I learned watching Sherlock Holmes to deduce that it probably wasn't burn in. ^_^

Bob Katz's picture

Tyll forgot to include the link in the article: tinyurl.com/bobkatz

pbarach's picture

1. Please put the missing hyperlink to Bob's discography in the footnote
2. Bob, please share what recordings you use to assess headphones!

Interesting article. Thanks!

Martin.'s picture

Yes, please!

Bob Katz's picture

Dear Pharoah: I'm sorry, I haven't put together a list of my reference recordings for consumption here yet. I promise I will in due time. In the meantime, I think you'll find a great deal of my favorite references used in each of my blogs here at Innerfidelity. For better or worse, many of these recordings are now unobtainable. And I also use a lot of recordings which are not in the popular domain because as we all know, a lot of popular recordings are far from "audiophile quality". But a few, a few are exemplary.

One great example of an exemplary popular recording is Ray Charles: Genius Loves Company, the anniversary edition. I advise you to purchase the HD tracks 2496 version because it's just superb. A great demonstration by engineer/producer Al Schmidt that you don't have to hype a recording to make a great one that everyone can enjoy. It sounds wonderfully correct on my system and translates well to all kinds of systems... a perfect example of my bell curve principle at work.

Hope this helps,

Bob

br777's picture

You just described my audio philosophy exactly. I often pondered writing something like this but you did much better than I could. You covered all the bases. Great job! This should be mandatory reading for anyone who calls themselves an audiophile, or even if they dont.

detlev24's picture

Interesting article; thank you.

"My goal is to produce masters that sound good everywhere: meaning that they translate to the car, clubs, Hi-Fi, small systems, and audiophile systems. By inference, when my masters translate to a lot of playback systems, the more accurate my mastering loudspeaker."

Question: Is it even possible to produce a master that sounds good everywhere? To my understanding it would rather be a master that aims for an average amongst what would translate as the optimum for cars, clubs, Hi-Fi, small systems, and audiophile systems. Consequently, there would still be space for improvement if aiming for a specific setup, e.g., an accurate listening environment.

Bob Katz's picture

The key word here is "translation". When I master a pop recording, it will translate to clubs,high fi systems, cars and ipods. Yes, there are some clubs with hyper-exaggerated woofers, but consider the bell curve from my article to apply to recordings as well as to loudspeaker systems. If I make a recording that sounds great on accurate speakers, it will translate to the widest variety of systems. Conversely, if you try to adjust the EQ so it will sound "more right" in the car, it will sound wrong on a lot of other systems. There was a time when I was concerned about the bass when played on 24" woofers in some clubs, but I found that when my system was adjusted to be extended, impacting, and flat down to 15 Hz, my recordings would still translate to those giant, misadjusted club woofers.

Similarly, if I tried to turn up the bass so that it sounds more "impacting" on the Macbook Pro speakers (which is not even possible), they would not translate anywhere else. So that's the key: Translation.

I hope this helps!

wiinippongamer's picture

Closest to perfect fidelity would be anechoic flat speakers with low distortion, playing back a pre-mastered recording from an also flat-FR, low-distortion microphone. It's pretty simple.

However, due to large variations in recording equipment over the decades, aswell as gear used by the mastering guy and his personal preference + band input, etc. It's impossible to get one transducer that sounds great with all recordings, unless you apply modifications to the recording itself.

detlev24's picture

I guess that would be done via 'convolution'?

AudioVero (producer of 'Acourate') and Sonarworks seem to offer capable consumer software for this purpose. Nevertheless, I prefer to have a listening environment that is as acourate as practicable [for a specific setup]. The downside; one constantly is searching for great [re-]releases, since most mass-market music will not be fully enjoyable.

wiinippongamer's picture

That isn't practical if you want to apply a different one per-album or even per-piece. A decent graphic equalizer goes most of the way of what you can do to improve an already-mastered recording. Pretty much the main reason interactive equalizers exist.

Bob Katz's picture

Yes, it's true that it's impossible to get one transducer that sounds great with all recordings, unless you EQ. However, my masters which are designed to sound great on the most accurate system, will translate to a wider variety of transducers and so you will need less EQ with a good, translatable master, when using any loudspeaker or headphone.

There are ugly-sounding, bright, harsh pop recordings. You all know them. They sound "acceptable" on cheap systems because the cheap systems hide the high end hype. But that doesn't mean that you have to hype the high end in mastering in order to sound right on a cheap system. I've learned that is not necessary and self-defeating. The only reason the myth that you have to hype the high end perpetuates is because when A&R hear a master in the making that does not sound like the current crop, they get nervous and ask you to turn the high end up. But it's self-defeating, these bright and harsh, clipped recordings sound worse on the radio and worse in streaming as well. If I get caught having to make one (and I've had to make my share, because the customer is the boss) I've observed that they don't sound as good everywhere and they don't translate to the widest variety of playback systems.

Scientist1's picture

Audeze headphones have a terrible design. They are uncomfortable and mine fell apart after a few weeks.

The O2’s performance is excellent. This is not debatable. It can also drive the LCD-4’s to 120 dB according to basic math. If you cannot get good sound out of the LCD-4 with the O2, then you cannot get good sound out of the LCD-4 with an accurate amplifier.

tinyaudio's picture

go ahead and argue with Bob Katz about sound.

Scientist1's picture

Yup, I'll argue with anyone who obviously full of shit.

detlev24's picture
castleofargh's picture

I doubt power is the issue, but just taking Tyll's readings on the LCD4 and for the O2 under ideal conditions we'd end up somewhere around 113dB before distorting seriously.
still very reasonable but I for example like to set 115dB as my reference when I estimate my needs. I know I almost never listen at 90dB SPL, but it's like a worst case scenario package in case all the little approximations and habits end up pushing in the same wrong direction.

here we don't know the gain setting used, or the output of the DAC when both can be relevant. we know Bob is using EQ so that's a few more dB gone to the wind that the amp will have to compensate for.
I know I use relaygain all the time for listening comfort, that's some serious dent into maximum loudness depending on the song.
maybe he likes to listen pretty loud from time to time? maybe it's one of those "synergy" stuff, where we say synergy like we'd say "God did it", anytime we don't really know what is causing the difference with the other amp.

I don't dismiss the subjective bias, but I also don't reject the possibility that under his specific conditions the result wasn't great.

now is there a way to get low disto and fairly good measurements into the LCD4 with an O2, I have no reason to see why not. but I can't make any claim about subjective preferences. ^_^

Bob Katz's picture

Clearly, Scientist1, your ears and mine do not agree.

kais's picture

Looking at the measurement of your reference speaker system the curve looks a bit like following a theory too tightly. The transition between the linear and sloped down part looks too abrupt. I would expect this to sound like a tiny boost in the 1.5 kHz region, as a natural transition would not have this little corner there.
2nd I have a question about the measurement:
Which microphone was used and how was it positioned/angled in relation to the speakers?
I am aiming on the fact that usually measurement microphones due to their physical dimensions are not omnidirectional in the upper two octaves of the audio band.

Bob Katz's picture

All I can say is that my loudspekaer target curve works for me as well as a lot of other users I'm aware of with this target curve. Have you actually listened to this curve?

The test microphone is a specially calibrated Josephson C550. It was positioned vertically. But you're not asking all the necessary questions: What was the FFT window which was used? What kind of smoothing was used to make the measurement? For that you'll have to read up on Acourate and how it performs its measurements. Every measurement system is a bit different, and Acourate uses the precepts developed by Jim Johnston and others which use a continuously-narrowing FFT window from 20 Hz to 20 kHz. The window is near anechoic at 20 kHz, to correspond with the ear's psychoacoustic response, which listens primarily to the direct sound at high frequencies. In addition, Acourate performs thousands of transient simulations to psychoacoustically ignore inaudible issues which many other systems measure incorrectly.

The omnidirectionality, or more correclty the off-axis response of the microphone is not as important as having a known small diameter and being aware of the rolloff that would result off axis. By pointing the microphone upward, it has an even response to all horizontal angles, which is far more linear than if you point it at the front, where even a 1/8" diaphragm will exhibit some HF rolloff with increased off-axis angle. What this means is that even if you use a larger diaphragm omni (which I would not advise) but if you point it upwards, then you will get a predictable and dealable rolloff. I arrived at my near -6 d
B at 20 kHz HF response and the 1 kHz hinge point empirically, by listening to many good recordings, and arriving at a measured HF rolloff that placed the brightest and dullest of the recordings at acceptable extremes and the majority of the recordings' HF response sounding just right.

Hope this helps!

Martin.'s picture

I enjoy the fact that you flat out disagree with Tyll because I feel it makes this site more comprehensive. Also, great to see that you take the time to reply to everyone's comment. You obviously have tons of expertise and recognition, yet you take the time to answer to every comment. Thank you!

tyan's picture

My main use of headphones have been to create music whilst on the move or at work (I have some hours of free time there). Contrary to what I've read others claim I find that most headphones have more midrange detail than speakers. Even the NAD HP50 which sticks close to the Harman curve has a bit of that (I own them). For the time being I'm using the Philips Fidelio X2, but I'm curious about the PM3 that you recommended Bob. Do they fit around your ears? They look kinda smallish..

Bob Katz's picture

I'd like to think I have average size ears. The Pm3s sit on them and totally cover the pinna within the cavity and the earlobe sticks out a couple of mm below the PM3 earcup. No one who has tried them so far has complained their ears are too large for them. Try to get a trial purchase from Oppo and return them if you wish. Keep in my that a 1/2 to 1 dB boost, curved up from 1 kHz to +1 at 25k or higher seems to be beneficial to the PM3s. A small sacrifice requirement if you will for such a detailed and neutral headphone at its price/performance point, in my opinion. Can you listen to these with pleasure without EQ? I think so.

tyan's picture

Edit: Did a second reading of your posts about the PM3 and found your comment about their fit. I'm gonna give them a shot!

Martin.'s picture

I have owned the fidelio x2, own the oppo pm-3, and tried the NAD VISO HP 50. They will fit much comfier around your ear than any of those other two. I have like 69mm ears, but they are comfortable enough for me. Of all of the above, I would say the x2 were the most comfortable on the ears, but my head isn't so big and they would slide down.

tyan's picture

Thanks for the info Martin. Yeah the Fidelio is really comfy.

Bob Katz's picture

The target curve you choose is going to depend on the response of your reference microphone. In the end it's going to take a little time to adjust to your sensitivities and preferences, but in the end you will be rewarded. Here are some tips and comments:

Recordings do vary, the variables include the engineer, mike placement, what monitors the engineer used for his or her reference, etc. But I feel the average of all "good" recordings will be "flat" by definition. If the listener can find the center line of all those good recordings, then he will create a target curve that will maximize the number of recordings that will be acceptable to listening without having to apply any EQ. That increases our enjoyment of a good sound system.

A related issue is that the monitoring quality many years ago was inferior to what is available today, consequently, many older recordings are much brighter than today's recordings. The tendency today (for better or worse) has drifted towards brighter monitors than many years ago. So if you look at the trend over 40 years or more, recordings have been getting warmer and less bright so that they sound good on these brighter loudspeakers.

My answer is to try to pick 20 to 50 good recordings that range from brightest to dullest and find the center. This determines your target rolloff. The problem of course is what is your definition of "good recording". I think it is potentially an iterative process. I've spent hours determining my target curve and occasionally refine it by 0.1 dB.

If you start with unequalized bright monitors and pick "good" recordings you will tend to pick dull recordings as your references before you even equalize the monitors! So there is room for "sharing" a list of good recordings and getting opinions from listeners as to whether they fit within their judgment of "close to the center" of their target curve.

But I think your target will come out well in the end as you go through the adventure of equalizing your monitors. If you don't discover MORE acceptable recordings after making your target curve, then your curve must not be in the center of their range from brightest to dullest. Because in principle, your list of "good" recordings should expand after you make your target curve. So ask yourself, did my list of "good recordings" expand after equalization? That's a good sign that the target curve is right in the middle. If my list of "good recordings" shrunk then my target curve must be bad.

I also pick the very brightest recording in my reference list and the very dullest and listen to them with the new target curve and if they are both acceptable then my target must be very good.

What do you all you think?

dirac28's picture

Absolutely agree! It's the only way to get a target curve that fits most recordings. Unfortunately there is no 100% studio standard so you can only try to get a curve that is in the middle of the curves that the studios use. Tonal perfection is only possible if you listen to the recording in the studio where the recording was made. With the same loudspeakers in the same room!

Concerning headphones one should also choose one that fits most recordings. But with headphones it's harder to buy something that was recommended because of the personal HRTF. A headphone that is completely neutral for one person can be problematic for another one. With headphones it's a very personal choice and i think the individual HRTF is one of the most important factors why opinions differ so much especially when we talk about peaks and dips of the high frequencies.

Bob Katz's picture

I'd like to see a database comparing audiophile's reactions to different headphones, to see if the personal HRTF is really as important a factor as Dirac says it is.

raj1234's picture

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