HPH-MT220
Published: Oct-10-2019, updated: Feb-27-2020
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.
HPH-MT220
The Yamaha HPH-MT220 is marketted as a professional Studio monitor headphone. It sold for around € 300.- after a while the price dropped to around € 170.-.
These came out in 2012 and are no longer in production (2019). The one reviewed here is 2nd hand and it is unknown how old it exactly is. It certainly had an enormous amount of hours on it as this headphone is pretty worn out, the pads and headband at least.
Unfortunately there are no spare parts available. Fitting different pads, most likely, will change the frequency response as well. Given the squarish shape alternative pads will be a bit more difficult to find.
As this is a closed headphone there is a decent attenuation. Not enough to drown out all outside noises when listening at a lower level.
The clamping force is higher than that of most hi-fi headphones but quite normal for studio monitoring headphones. These will stay on the head even when one is moving a lot. Not everyone will enjoy the clamping force for longer listening sessions.
The build quality of the headphone is and feels quite sturdy. The cups can swivel enough to the front and rear. The tilt of the cups is almost 180 degrees so the cups can turn outwards. The height of the headband has a large adjustment range (clicks in small steps) so think it will fit most headsizes. The headband creeks when adjusting but not when it is in normal use. The cups are easy to adjust.
It does not fold flat nor collaps for easier transport.
The pleather (fake leather) headband has started to flake so doesn’t look that great any more. There are no replacement parts alas.
The pads are made of the same pleather and will suffer the same fate. Also no original replacement parts available. On e-bay, Ali-express and Amazon can can find replacement pads. These may (or may not) change the tonal balance. The foam used in the pads is soft and made of fast memory foam. This ensures a good seal and comfort. The pads on this headphone clearly have seen the best days of their rather short life already. The bottom part is already missing some vinyl.
There is enough room in height (60mm) and width (40mm) to fit most ears. The depth of 19mm is enough for most ears. because the pads are quite soft and the claming force is a bit on the high side the pads will compress a few mm. The pads on this headphone are rather old so may compress slightly more than when new. When on the head the depth is reduced to about 15mm. This means for some people the inside may touch the ears. Some folks who are sensitive for this may want to look elsewhere.
The cable is fixed and is partly straight, close to the 3.5mm headphone plug it is coiled. The cable itself is quite thick and heavy in weight. As the cable is fixed you cannot use shorter or thinner aftermarkt cables.
When the coil is stretched the cable reaches 3.4m, when it is all coiled it is 1.2m. This is quite handy in the studio, less so at home or when using it in a portable setup.
The HPH-MT220 has a low impedance (37 Ohm) and high power rating (1.6W) so can play very loud.
specifications:
Type: On-ear, closed
Usage: Home, Studio, portable
Isolation: decent
Driver type: dynamic
Pads: replaceable, fast memory foam covered with pleather
Inner pad dimensions: Height: 60mm, width: 40mm, depth: 19mm
Collapsible: no
Headphone connector: fixed
Cable entry: left sided.
Cable: 1.2m – 3.4m straight + coiled terminated in 3.5mm TRS + screw-on 6.3mm adapter
Driver size: ø 45mm
Nom. power rating: 1.6W (1600mW)
Max. voltage: 7.7V
Max. current: 210mA
Max. S.P.L.: 131dB
Impedance: 37Ω
Efficiency: 99dB @ 1mW
Sensitivity: 113dB @ 1V
Weight: 340 g.(measured without cable), 419 gram with cable.
Colour: matte black with brushed aluminium accents
Clamping force: medium-high
Accessories: 6.3mm screw-on adapter.
Sound description:
The headphone has a ‘warm’ sound signature with elevated bass. The upper treble is sharp and accentuated. It has a dynamic sound with a sturdy ‘foundation’ in the lows.
Bass sounds full and tight and seamlessly integrates in the mids and is mildly accentuated.
It is lacking in clarity/presence in the mids. The mids are not subdued, just a lacking in detail and fidelity. Cymbals and instruments are a bit ‘coarse’ sounding, a bit ‘gritty’ and dynamic and the treble is over the top and ‘sharp’ .
Those looking for a smooth headphone for relaxed listening should definitely look elsewhere.
Those looking for a ‘studio’ type of sound will not be disappointed. Instruments ‘pop out’ and it is easy to separate instruments etc. The dynamic character reminds me of the OMTDOEH.
measurements:
Below the frequency response of the HPH-MT220 (Left, Right)
Channel matching is excellent. Bass extension is also very good (10Hz at 0dB). The bass response is basically flat from 20Hz to 300Hz.
From 300Hz upwards the mids drop about 5dB. From 1kHz upwards there is another gradual drop of about 5dB. As clarity is in the 2-4kHz region it is evident this is about 10dB below the bass. (-10dB is about half the perceived loudness).
From 4khz to about 7kHz the output is correct again. This more or less masks the lack of clarity by making the sound a bit ‘shriller’. From 7kHz to 14kHz there is a substantial peak (about+5dB opposite the mids) which is the reason for the splashy and ‘hard’ treble.
From about 16kHz the output drops fast. For studio usage this doesn’t really matter.
Those assuming it is beneficial to play anything above 44.1 kHz on these headphones should think again.
seal
As the seal of a headphone is of importance some experiments are done to see the effect.
(lots of) hair between the headphone and ear or an ear shape that does not allow a proper seal will affect the tonal balance.
Below: Perfect seal, a seal breach by (reading) glasses just above the skin and a substantial seal breach.
A seal breach isn’t really problematic at all. The tonal balance is hardly changed when listening to these headphones with or without glasses. Only a very slight loss of sub-lows (below 40Hz) is observed when the seal isn’t perfect. For a closed headphone this is pretty good performance.
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 (13dB at 1kHz) as the low impedance amplifier. This way the plots are overlay-ed and it is easier to show the tonal balance differences.
The impedance does rise somewhat around 45 Hz This means on a high output resistance (120Ω ) amplifier the lowest bass notes will be boosted about 1.5dB and upper treble will be lowered about 0.5dB (never mind the bump at 50Hz) it is mains being picked up.
Below the distortion measurements of the HPH-MT220 (Left channel)
Below the same distortion plot but with the vertical scale in percentages instead of level differences. 
The 3rd harmonic distortion is rather high for the lower frequencies. From 60Hz and up it drops below an acceptable 1% (acceptable for the lows). The 2nd harmonic distortion remains below 1% in the bass which is a decent from a 45mm driver at 90dB SPL.
The 2nd harmonic distortion is probably lower than 0.2% around 1kHz as limits of the test rig are around that level.
From 200Hz and up the distortion levels are quite good.
Below the CSD of the HPH-MT220. (Left and Right are superimposed)
The decay at 500Hz looks quite good. Some resonances are visible at 3kHz and 4kHz but are not long enough to be problematic. The treble peaks above 10kHz are clearly resonances. It might help explain the slightly ‘gritty’ cymbals.
Below the spectrum plot of the HPH-MT220 (Right channel). 
This plot looks quite good. The lower frequencies are decently damped.
There are no dealbreaking resonances which is somewhat of a testimony for the instruments being clearly distinguishable and the ‘dynamic’ sound.
The step response plot below (Left, Right)
This plot shows the emphasis is on the lower mids and bass. The horizontal line which hardly drops is evidence of the excellent subbass extension.
The rising part from 50μs to 1.5ms shows the lack of clarity. In an ideal situation the rising edge should reach almost 0dB and remain ‘flat’ to around 2ms.
Below the square-wave response of the HPH-MT220
The bass levels are accentuated as the measured signal is clearly higher than that of the applied signal. The sloping part of the 40Hz plot shows the good bass extension.
The 440Hz square-wave isn’t exactly a square-wave. The upwards tilt shows the emphasis on the lows.
The 100μs pulse (positive half of a 5kHz square-wave) as well as the 440Hz square-wave shows a lot of high frequency ringing above 10kHz. It is reasonably short lived though.
correction filter
A passive filter can be used to address the increase in bass and the upper treble part.
Below the schematic for the filter. 
Below the effect of this filter. stock versus filtered.
The green trace is measured with a passive correction filter. The elevated bass is lowered to a neutral level. The treble peak between 6khz and 12kHz is lowered to neutral levels.
Above 12kHz some elevation is still there. Removing that part as well removes the ‘sparkle’ and would make this headphone sound dull.
When one doesn’t want the bass levels lowered (by about 3dB) one can omit R1,R2,C1 and C2. The slightly elevated lows may well be appealing to some.
When you can’t make one yourself or don’t know anyone close to you who can, you can order a filter here if interested.
summary
The Yamaha HPH-MT220 is a heaphone that is well suited for studio usage. Very suited for monitoring purposes due to the decent isolation, high clamping force and tonal balance: not flat, slightly laid-back and high treble which highlights ‘details’.
I certainly wouldn’t want to mix on this headphone nor check the final result.
In hi-fi circles this headphone has also been popular.
The cable being fixed, long, heavy and curled is a downside for those wanting to use it portable. It would be suited for this task because of the slight bass emphasis and efficiency.
For hi-fi music enjoyment this headphone is less well suited unless one likes bigger bass, subdued clarity and feisty treble. A positive side would be the ‘dynamics’ and instrument separation (which is not the same as sound width or ‘head-stage’).
A relaxed listen with smooth treble it is not. Active listening (with EQ or filter) is one aspect it is fairly good at.
Not a real high flyer for hi-fi, good for studio usage/monitoring.
The high-ish clamping force is also something to take in consideration when using this to relax and listen to an album or so.
The original pads not being made available and headband pleather quality are clearly downsides.
DIY-Audio-Heaven 