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published: Sep-29-2018, updated: Jun-16-2019

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NO SMOOTHING is applied to the shown plots. Most measurement sites have some smoothing applied which ‘irons flat’ sharp peaks and ‘wiggles’. I do not use smoothing because some info about sound quality is lost when plots are smoothed.

Aside from a small correction of the microphone itself also some correction in the lowest frequencies is applied to the plots to compensate for the perceived loss of bass when using headphones. This is described HERE in more detail.
A ‘horizontal‘ frequency response curve on the shown frequency response plots on this website thus indicates a perceived ‘flat’ tonal signature.

ALL measurements are made with a good SEAL on a flatbed measurement rig.
The shape of your head, bone structure, pad size, pad ‘softness,  (compliance), hair or no hair and or wearing glasses may (drastically) change the frequency response of some headphones, so… your personal experience may differ substantially from these plots.

Frequency response (tonal balance) is the most sound-determining aspect of headphones. A horizontal line shows audible neutral response in the plots on this website. Deviations in different severities at different frequency bands have an effect on the sound character.
The bigger the deviation the stronger the effect.

Below an aid to help determining the sound character of headphones with relation to the frequency response.


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The NAD VISO HP50 is a closed over ear headphone. NAD is mostly known for their audio equipment. They also have 3 headphones in their assortment. The cheaper HP30, the wireless noise cancelling HP70, the HP20 In-Ear and the HP50.
It comes with 2 cables. One of them has a 3-button remote in it but is only suited for Apple products, the other one has no mic in it. It also comes with a soft carrying bag and a small but very handy pouch which contains an airplane and a 6.3mm adapter.

The headphone has a stylish look and feel. The earcups are fingerprint magnets and due to the high-gloss finish are likely to show scratches quite well.
The HP50 has cable entries on both sides of the headphone but the cable is single entry so the headphone only needs to be connected on one side using a straight 3.5mm TRRS jack. On the other side of the cable an angled 3.5mm TRS jack. The connectors are nickel plated. The cords are silicone and are flat and a bit springy and are pretty ‘tangle-free’.
Alas,  the cable is somewhat microphonic. In quiet moments you can hear the cable rubbing against clothes. While playing music this is no issue.

The adjustability of the HP50 is not very big but just big enough to suit most headsizes.
It’s headband is padded with foam and vinyl covered. The pads are made of leather? and feel soft. Memory foam is used in the pads. The depth of the pads may be a bit small for some. 18mm while not compressed will be a bit too little for some and your Pinna may touch the driver baffle.
While the pads are comfortable they can seal quite good. A medium clamping force ensures this. The ears do get warm pretty soon due to the small and fully sealed ‘chamber’. People with larger heads or ears than average may have seal issues on the bottom side of the pads due to the limited tilt of the earcups and or inner pad dimensions not being big enough.

Because of the very low power rating it isn’t wise to connect the HP50 to more powerfull amps.


Type: Over ear, closed
Usage: Home, Portable
Isolation: decent
Driver type: dynamic
Pads: replaceable, leather (at least it does not look like pleather)
Inner Pad dimensions: depth = 18mm, height 65mm, width 34mm
Collapsible: No but folds flat for easier transport
Headphone connector: 3.5mm TRRS socket, non locking.
Cable entry: single sided but can be inserted in either cup.
Cable: 1.2m terminated in angled 3.5mm TRS jack + 1.2m headset cable with microphone and 3-button remote (apple) with an angled 3.5mm TRRS plug.
Driver size: ø 40mm
Nom. power rating: 0.03W (30mW)
Max. voltage: 1V
Max. current: 30mA
Max. S.P.L.: 115dB
Impedance: 32 Ω
Efficiency: 100dB/1mW (115dB/1V)
Weight: 256 g.
Colour options: black, white, red
Clamping force: medium
Accessories: 1.2m terminated in angled 3.5mm TRS jack + 1.2m headset cable with microphone and 3-button remote (apple) with an angled 3.5mm TRRS plug. 6.3mm adapter, carrying bag, handy pouch for accesories.

Sound description:

When a good seal is reached the sound is immediatly impressive, even when driven just from a phone. The sound is ‘full’ as in speaker-alike. Bass is deep and ‘rich’. Not muddy but does have some ‘fat-tisch’ character to it.
It has a very pleasant sound which is never harsh or shrill and sounds distortion free.
The overall sound is not neutral as in analytic and ‘open’ but ‘warm/full’.
It does not sound compressed but is pleasantly ‘dynamic’ and ‘open’.
Stereo image is a bit on the ‘narrow’ side.
It is laid-back, yet has just enough treble to not make it dark. It does lack a bit in ‘air’
It can play pretty loud and still sounds good. My personal preference is a bit closer to ‘flat’ but the mild bass boost and mild roll-off is very tastefully done and closer to ‘neutral’ than say the Meze 99 for instance.
The tonal character is agreeable with a lot (if not almost all) types of music. This is a very good thing as people with a varying taste in music will most likely not feel the need to swap headphones.
There are no obviously audible dips nor peaks that annoy me after a while.
No bloated bass, no harsh mids, no piercing treble. But alas also less ‘clarity/presence’ and ‘air’. With a lot of pop music this isn’t a disadvantage though but helps in making the music more ‘musical’ (as in less ‘clinical’)
The treble is pleasant and silky but is somewhat lacking in ‘extension’ which can be heard on cymbals etc.
For this headphone to sound full and warm it needs a perfect seal between the pads and skin all around. Breaking the seal just slightly (glasses, hair) results in less bass/warmth and fullness. The tonal balance changes for full to ‘neutral’ with a small seal breech to bass-shy and midrangy/bright when the seal is broken a bit more (thicker armed glasses). More on this seal issue below.
This headphone sounds excellent at lower listening levels b.t.w. due to its ’tilt’ and how the hearing works.


Below the frequency response of the VISO HP50 (Left, Right)FR HP50

Channel matching is decent. Bass is well extended and flat to below 10Hz. The small lift around 120Hz and subsequent sloping response to 2kHz. Due to the drivers being small and not angled there is very little Pinna activation. This means that the ‘dip’ between 1kHz and 5kHz is a few dB less ‘deep’ than shown in the plot (measured without a Pinna).
Because of this the downward ‘slope’ from 150Hz to 4kHz gives it a warm/full sound. As the slope is gentle and ‘linear’ without sudden dips and peaks the sound is still realistic.
The dip peak between 5kHz and 9kHz is on a neutral level so despite the sound being ‘warm’ there is a very good amount  (and quality) of treble.
Above 16kHz the drivers drop off quickly. This is one of the indicators for lack of ‘air’.
The treble is of good quality and even though it looks rolled-off it does not sound rolled-off. Something to consider when listening to hi-res recordings. There isn’t much ‘life’ beyond 16kHz yet it does not lack ‘air’.


Getting a good seal is important for closed headphones. The soft leather earpads (cushions) help with getting a good seal. However, wearing glasses that sit above the skin or hair between pads the head will affect bass response. For the HP50 is good seal is essential as can be seen belowglasses seal
Only the Right channel is shown. Perfect seal, wearing glasses with ‘thin’ arms, wearing glasses with ‘thick’ arms, bottom part of the pad slightly lifted so loss of seal.
As can be seen the bass (extension) suffers when seal is broken.

output resistance / damping-factor

As this is a dynamic headphone the frequency response might be amplifier output resistance dependent when certain higher output resistance amplifiers are used.
To test this the headphone is measured via a low impedance amplifier (0.2Ω) and a high impedance amplifier (120Ω).
On a higher output resistance amplifier the output level will be considerably lower. To compensate for this the amplifier is cranked up to the same level (12dB at 1kHz) as the low impedance amplifier. This way the plots are overlay-ed and it is easier to show the tonal balance differences.R120 (-12.3dB)As can be seen the tonal balance does not change when driven from higher output resistance of (some) desktop ampifiers. So no need to worry when your phone has a few Ohm output resistance, not even when your amplifier ahs 120 Ohm output resistance.

The NAD VISO HP50 is not the only headphone with a ‘warm/full’ sound. There are headphones like the MH40 and Meze 99 Classic which also have a similar ‘effect’.comp MH40-meze99-HP50What is evident from the plot above is that the MH40 and Meze 99 Classics are bassier and the response is not sloping as smoothly as the HP50.  Also the amount of treble on the MH40 and Meze are substantially subdued compared to the HP50.
The HP50 is a more realistic sounding headphone compared to these 2 ‘warm/bassy’ headphones.

The uncrowned king of ‘warmth’ is the AudioQuest NightHawk. It has much more presence around 400Hz and drops off fast in an unnatural way to 1kHz. The HP50 is much more linear and doesn’t have the wooly-ness and ‘congestion’ the NightHawk shows.
Treble of the NH has much better extension though but is a bit more subdued.
The Sony MDR-1A also has a warm-ish character but is more ‘bassy’ in nature. The MDR-1A has about the same treble extension as the HP50 but less in quantity and quality

comp HP50-NH-MDR1A

Below the distortion measurements of the HP50 (Right channel)dist HP50R

Below the same distortion plot but with the vertical scale in percentages instead of level differences. dist HP50R percentThe distortion in the bass is very low, certainly for such a small (40mm) dynamic driver. Most likely the 2nd harmonic distortion above 100Hz is lower than 0.5%. The limit of my measurement rig is reached. Around 4kHz there is a small peak of around 0.3% which is still more than decent.
Overall the distortion is impressively low. The sound of this headphone is very clean and smooth which is also seen in the measurements.

Below the CSD of the HP50 (Left and Right are superimposed)The CSD shows there are 2 small and short lived resonances around 6kHz and 8kHz. These are short lived and don’t appear to be problematic. The lower frequencies are quite well damped.

Below the spectrum plot of the HP50 (Left channel) which doesn’t show any alarming issues at all. The bass around 150Hz is boosted somewhat and lingers on slightly longer than desirable for ‘tight’ bass. The HP50 driver is well damped above 400Hz.spectr HP50R

The step response plot below shows some short lived ringing. The initial rise does not reach the 0dB line and the ‘dip’ after the initial rise is indicative for the lack of  ‘detailing’ and ‘attack’.
(Sub)bass extension and overall tonality is great given the horizontal trace hardly drops.
The ‘hump’ in this plot is indicative for the ‘warmth’  in the sound.step HP50R

Squarewave and impulse response

Below the 40Hz, 440Hz and 100μs impulse response oscilloscope plots.


In the 40Hz plot (on the left) the signal follows the applied signal very well showing the excellent bass response and extension. (with a perfect seal).
The 440Hz plot shows the ‘warmth’ of this headphone. The mids are not ‘accurate’ and have relatively a too small amount of upper mids (the rising edge not reaching the stimulus).
The needle pulse also shows the HP50 is not reaching the applied signal level (about -5dB). The double peak shows the membrane does not ‘stop’ directly after the stimulus is gone but ‘lengthens’ the signal a bit. Could be a cup reflection as well. After that first ‘bounce’ the membrane seems very well damped as there are very little and short lived resonances visible.
These plots also show the ‘warm’ tonal balance of this headphone but do not show ringing or problematic areas.


Below the difference in response is shown when using the Kameleon HP50 module. Original HP50, via KameleonFR HP50 Kameleon vs stock

Clarity and treble extension. Treble response is more ‘even’. Less warm and Bassy as a result. Maybe interesting for those that want a bit more clarity.

passive filter

Fortunately a very similar effect can also be obtained using a passive filter.
Below the results using the passive filter vs stock.stock HP50 vs filtered HP50 7dB level corrected
As can be seen you get more ‘clarity’ and a bit more even treble. Of course this takes away the ‘overly warmth’ and bassy character so would possibly only be interesting for those who wish it had more clarity and less warmth.

The plot above does not show the actual working of the filter as a passive filter can only attenuate and not amplify. It does show the audible effect though.
Below the actual effect of the filter.stock HP50 vs filtered HP50
The filter attenuates the lower frequencies and lowers the treble ‘peak’. The lows are attenuated by almost 7dB so the overall loudness is quite a bit (about 5dB) lower.
This means the efficiency of 115dB/V is effectively lowerd to about 110dB/V which still is quite high.
For those that like to build one themselves below the schematic diagram.filter schematic


 Problems I encountered …

  1. The first problem I encountered was getting a good seal. In order to get a good seal I had to extend the cups a bit further than would have been the case for a proper seating. When extended a bit and wearing the headband a bit more forward on the head I can get a good seal. Without a good seal the loudness ‘varies’ when moving the head as well as tonal (an L-R) image shift.
  2. The next problem I encountered was the left driver being blown up by the square-wave test. Obviously the max. power rating was reached. Have had the same issue with the Takstar Pro 82. Both have a very low power rating (30mW) as are quite a few other Chinese drivers. These are intended for usage with phones or low power BT or NC headphones. Something to be aware off. Luckily there are original drivers for sale on Ali-express (which indeed are genuine !) so problem solved but did cost
    € 22.- (for 2 drivers).
  3. After selling it onwards the new owner mentioned 1 channel did not work any more. So… refunded him and paid for return shipping…
    Turns out there is a very thin and extremely stiff 3 wire cable in the headband. It cannot be replaced as I cannot find such wire anywhere. It has to be stiff otherwise the when sliding the cups inwards (to put it in its pouch) the wire would not go in the cups.
    Well… that wire broke internally. 2 of the 3 wires were broken. This wire has to be in the headband to enable the feature that one can use a single entry headphone cable and plug it in the left or right cup. That feature thus no longer works. The headphone now needs a dual entry cable with 3.5mm TRS jacks to work.
    I can live with that. Have to buy a new headphone cable (add € ….) with the correct connectors and… cannot use the supplied cables any more.
    However, I don’t think I am the only one that may have encountered this issue.
    It may even be the reason why the original drivers (in baffle) are up for sale.. not repairable headband cable broken perhaps ?


The NAD VISO HP50 is a very ‘pleasant’ sounding headphone. Those that feel the more analytic and ‘clear’ sounding headphones are too ‘bright’ and are looking for a slight warm ’tilt’ in the sound reproduction but find the above mentioned other ‘warm/bassy’ alternatives a bit ‘overdone’ and too dark or missing treble really should give this headphone a listen.
There isn’t much in the sound I fault or find objectionable and is one of the very few ‘warm’ headphones I could actually live with and aren’t ‘overdone’.
Is this my favorite headphone ? No, but is the best ‘warm-ish’ tilted headphone I have heard in this price range. The ‘warmth can easily be ‘removed’ using tone controls or EQ where it reacts to in a good way.
Personally I prefer a bit less ‘warmth’ and want a bit more clarity, which can be achieved using tone controls.

That said… the well extended bass, the pleasant, dynamic, open and just detailed enough sound are definitely strong points.
The fact that the ‘warmth tilt’ is gradual and ‘linear’ makes instruments and voices sound realistic yet ‘warm’ without other ‘colorations’ to the sound which may annoy after a while. Have not experienced listening fatigue with this headphone yet but crave for a bit more clarity with quite a few recordings.
Also the ‘warm’ tilt becomes ‘neutral’ at lower listening levels (due to the way the hearing works) which makes the headphone excellent for listening at lower SPL levels.

Are there things to complain about ? Well yes there are.
The power rating is one of them but as long as it is connected to low power devices this is a non-issue.
The downsides it has to me are the issues with getting a good seal which results in either loudness variations when moving the head around and bass roll-off when a perfect seal is not obtained. The pads have to touch the skin all around.
The limited ’tilt’ of the cups and ‘room for the ears’ may be an issue for some people.
After a while finnicking with height adjustment and getting it to sit correctly on my head I am able to get a consistent seal and good sound.
Personally, I am using it with some EQ and like it a lot.
Another downside is the microphonic cable. You can hear the cable running against clothes.
Add to that the headband wire may eventually stop working and you have a few reasons not to buy it.

In short: When the issues above are something one can live with and/or aren’t present the HP50 is a ‘warm’ tilted headphone that will be agreeable for most people.
It’s warm tilt tastefully and well executed !
When a warm tilt, i.e. speaker in room alike without the sound coming in front of you, is what you are looking for with realistic (i.e. not boosted) bass is your goal and EQ is something you don’t like/want give this headphone a chance. Excellent tonality at lower listening levels.
At its MSRP it may be a tad expensive for what it is (around € 300.-) . Sometimes these can also be bought (new in box) for around € 150.- I cannot fault its sound that much.

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