At the intersection of philosophy, psychology and scientific analysis we find Paul Barton's standout creation: the VISO HP50's by NAD. These headphones represent homogenous mixture of technical excellence and a logical approach to human perception. Paul Barton's willingness to take strides forward in development based upon his decades of research on the subjects of loud speakers and audio perception presents an exciting opportunity for those who own headphones he has produced. By implementing a bleeding edge target curve (a curve that appears to largely parallel the findings of Harman researcher Dr. Sean Olive) Barton has given listeners an opportunity to literally listen to the future of the headphone design.
To understanding what the HP50's were intended to accomplish is vitally important as it sets the tone for this entire review. The earth-shattering fact is that the HP50's were DESIGNED TO SOUND GOOD. As patronizing as that statement might have sounded, it is worth noting that these headphones are not pursuing perfect flatness, they are not attempting to match the HD800's for ultra-articulate treble response, and they are not trying to match Ultrasone for being pure crazy (Only kidding... I know they work hard on their product and people enjoy their headphones...). Paul Barton lets the concept that there are known preferences in how loudspeakers sound, and the fact a lot of music is mastered for speaker playback guide him to create a headphone that aspires above all else to deliver a listening experience that is pleasing to the human ear.
Now, before your mind begins to fill with thoughts of headphones that color sound like a sugar-filled three year-old colors on walls, realize that what has been achieved in the development of the HP50's more closely resembles the fine colors and strokes of a master painter. Some of the finest works of art, such as frescoes in the Sistine Chapel, do not appear photo-realistic, yet we do not think of them “falling short” of the medium of painting because they don't look like photographs. Rather we realize that the artist may use their knowledge of physical appearance and human psychology to craft an image that is even more pleasing to the eye than a photograph would be. Just as there are certain measurements and ratios that must be present for a painting to look appealing there are certain ratios and measurements that have been proven to sound pleasing through headphones. Additionally, in a similar way to how a painter uses his understanding of perspective and the human mind to add substance to their masterpiece, so too does Paul Barton's approach to headphone design consider the variable of subjective perception when creating a target EQ. Together these core elements construct the framework for our how we will analyze the NAD VISO HP50 headphones.
The technical measuring-stick will be SanjiWatsuki's set of criteria for flagship-level headphones. While these grading points might be controversial for some, they accomplish the task of giving us a general benchmark for the sonic capabilities of a pair of headphones.
1. Bass linearity of +-5 dB from 20hz to 100hz.
The HP50's exhibit VERY flat bass response that lies within a 5db spread of amplitude. This bests the requirement handily by sustaining a linear bass response that is twice as tight as is demanded for a flagship. PASS
2. 100dB distortion should not exceed 0.8% beyond the sub-bass frequencies.
3. 100dB distortion should not exceed 1% at 30hz.
Distortion is incredibly low for dynamic drivers and is a non-issue at every point within the audio spectrum.
PASS and PASS.
4. Frequency response curve should be very smooth with any resonances being very minor -- no major dips.
Smooth for broad patches, but there is a dip at 6K and a definite fall-off after 10K. FAIL
5. Very small to absolutely no dip at 70hz-150hz.
Studying SanjiWatsuki's commentary reveals that the very small dip at 107hz is nothing to be concerned about. PASS
6. Air-level treble should be no more than -15dB relative to the mid-range.
There is no question that air-level treble does roll off and that this does impact their sound.
Technically the HP50's FAIL... However, the question then becomes: do these cans fail this specification by design? Paul Barton has used a target EQ that intentionally rolls of the treble and creates a very natural listening experience that is less fatiguing than would be experienced with a more elevated upper range. This creates a sound signature that is quite enjoyable, but may not please those who are addicted to the sound of violins slicing through their skulls. All sarcasm aside, I encourage the reader not to dismiss these headphones because of this attribute, as the HP50's are still capable of producing a well detailed sound. Paul Barton reasons that when speakers are used in an ideal setting the treble is attenuated by the room, thus naturally rolling-off the highs and creating a pleasing listening experience.
7. No "wiggle" in the impedance graph.
The HP50's have a fairly smooth impedance graph. There is a small bump between 5K and 6K but it is only slight and SanjiWatsuki passes other cans that have a similar minor deviance. The kind of variance is nowhere near what is seen on an impedance graph for something like the Fostex TH-900's. PASS
8. Nearly perfect channel balance.
Channels are matched very well. PASS
9. The headphone is open or semi-open.
Before I heard the HP50's I would have been more willing to ascent to this criterion blindly but having listened to the NAD's there is a clear and striking difference in their soundstage as compared with a typical closed headphone. When I listen to something like the Beyerdynamic dt770's I can hear the tonality that the plastic rear enclosure is imparting to the music. Interestingly, the enclosure on the HP50's does not impart a perceived change to the timbre of the audio. When this is combined with a large soundstage it firmly challenges conventional thought regarding what can be accomplished with a closed headphone. Of all the criterion found here, this is the most subjective and it ignores practical questions regarding whether insulation from other sounds or openness to room acoustics is preferable. Ultimately, I am going to side with Tyll Hertsen on this point and disregard it as a testing credential.
Total Score: 6/8
The technical successes of the HP50's far outweigh their shortcomings. While I will not make unwarranted extrapolations based upon these numbers I will let these figures stand as a testament to the competence of the HP50's to stand on their own as excellent performers at and above their price point.
For perceptual analysis I am going to review a set of songs I am very familiar with and comment on how these cans perform at rendering that audio. Because it is extremely unlikely that we listen to the same music (I have varied taste... :P) I will provide a link for the audio to facilitate a better understanding of what I am describing. In the spirit of both not having very high-end gear and representing the average consumer/audio-enthusiast I will be playing lossless files directly out of my ipod classic for each sample.
“Unfolding”, By Jerry Douglass on the CD, Glide.
This jazz piece features resonator guitar, drums, bowed and plucked upright bass, violin, and electric guitar. The recording is of fantastic quality with an attention to properly using stereo to create separation between instruments. It is vital that I communicate how cohesive this song sounds on the HP50's. There is fantastic separation with a sense of exactness to where instruments are placed within the soundscape. Drums sound very realistic with cymbal crashes sounding tight and not at all splashy. Jerry Douglas' resonator guitar has an articulate tone that conveys the talent of the musician using a metal slide on metal strings. The details are not masked in order to create an illusion of clean playing, rather they are exposed with the details revealing the subtleties of the musician's technique. The violin is well placed and carries no un-natural harshness I would associate with an unbalanced EQ. Both the violin and bowed bass convey the sound of the musician moving the bow across the strings. Low notes on the bass are not inflated but retain the weight of the massive instrument that is producing them. When plucked you can hear the details of how the bass is being played as well as the notes that are being produced. The tonality of the electric guitar is exquisite and integrates into the mix very effectively.
“I'm Not Ashamed” by Steve Camp on the CD, Taking Heaven by Storm.
There are certain songs that just show off what a headphone is capable of. This is most definitely one of those songs for the HP50's. The bass is thumping good and hard while retaining texture and not overwhelming the other aspects of the song. The saxophone on this track is absolutely amazing as it is replicated with such detail that you can close your eyes and imagine its player directly in front of you (the imaging is that good). Vocals are clear and fall properly within the mix. The main vocal does not suffer from a sense of being withdrawn and the background vocals are presented very well tonally and spatially. Every element just works wonderfully together on this song. With so much going on constantly on this track the ability of these cans to articulate the position of each component is put to the test. Not for a moment is there an impression of muddiness or a suffocatingly cramped presentation. That is not to say that they sound as good as a top-tier open headphone in terms of spaciousness, but they deliver a very satisfying presentation with a wonderful musicality.
“Over Hill” by Howard Shore on the CD, The Hobbit: An Unexpected Journey.
This track is chosen not because it is a favorite within my collection but because it provides a very high quality symphonic recording that can serve as an appropriate means of measuring the performance of the HP50's. The soundstage most definitely expands outside of my head yet retains a specificity in relation to instrument placement that creates a enveloping and cohesive sound. Strings are very accurately portrayed with a detailed, strident-free presentation that is very easy to listen to for long periods of time. The horns and woodwinds have a sweetness to them that avoids the trap of an artificial presentation. When challenged with a harder hitting, modern soundtrack like Hans Zimmer's Inception, these cans rise to the occasion and provide the best listening experience I have had for those tracks since I saw the film in theaters... all three times.
By creating the NAD VISO HP50 Paul Barton has added a potent weapon in his ongoing battle. This fight is not waged so much against other headphone manufacturers, as it is a positive struggle for progress and innovation that extends beyond mere production and seeks to provide an ever-better answer to the simple yet profound question: What sounds good? Time will tell if the future sounds like the HP50's, but my hope is that you will find immense enjoyment in finding out for yourself by purchasing a pair of these fantastic headphones.
Please ask me any questions you might have and let me know if you appreciate the review.
Information obtained from Innerfidelity has been used with Tyll Hertsens' gracious consent. I strongly encourage you to check out his review of the HP50's.
•NAD VISO HP50 Measurements: http://www.innerfidelity.com/images/NADVISOHP50.pdf
•Tyll's original article about headphone response: http://www.innerfidelity.com/content/harman-researchers-make-important-headway-understanding-headphone-response
•An extensive interview with Paul Barton about sound design: http://www.hometheaterhifi.com/video-coverage/video-coverage/designing-better-headphones-with-paul-barton.html
•SanjiWatsuki's analysis of flagship headphones: https://docs.google.com/presentation/d/1wi8M-HSeK0JF33P-5ypydQjQ4OshRQhvWM0IX2h0NQ8/edit?pli=1#slide=id.p
•Tyll's take on SanjiWatsuki's criteria: http://www.innerfidelity.com/content/one-enthusiasts-take-top-line-headphones-state-flagships