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Published: Oct-25-2017, updated Dec-14-2020

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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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Sennheiser HD800S


The Sennheiser HD800S is an open over-ear dynamic headphone. It is marketed next to the HD800 and not a replacement. The price of the HD800S is a lot higher though.
Not only because of the color and the absorber that lowers the 6kHz peak somewhat but also because of the extra (balanced) cable that comes with it.

Comfort of the HD800S is exactly the same as the HD800 which is very high.
Clamping force is very low and because the pads are very large and there is plenty of room in there for even the biggest ears you won’t get sweaty/hot ears.
There is a small chance, however, that depending on the shape/ size of the owners head seal may be broken resulting in less (sub)bass.

The connector is a LEMO-type 2-pin connector manufactured by ODU GmbH. This isn’t the cheapest connector around so when looking for a replacement cable be prepared to fork out quite a lot of cash.
Changing the cable is not a bad idea when you don’t like stiff, springy and long cables.

Also measured the HD800S 75th anniversary version which has a dark gold-ish color instead of the all black color of the regular HD800S.


Type: Over ear, open
Isolation: poor (open headphone)
Usage: Home, studio
Driver type: dynamic, ring driver
Pads: replaceable microfiber
Foldable: No
Headphone cup connector: proprietary ODU GmbH 2 pin connectors.
Cable entry: dual sided
Cable: 3m 6.3mm TRS +  balanced 4-pin XLR cable.
Driver size: 56mm, angled 10º
Inner Pad dimensions: depth font = 21mm, rear = 30mm, Width = 60mm, height = 75mm.
Max. power rating: 0.5W
Max. cont. input voltage: 12V rms
Max. drawn current: 40mA
Max. S.P.L.: 128dB
Impedance: 370 Ω (310Ω DC)
Efficiency: 101dB @ 1mW
Sensitivity: 105dB @1V
Weight: 380 g. (without the cable)
Clamping force: very low.
Accessories: 3m cable with 6.3 TRS connector, balanced cable with XLR4-connector, micro-fiber cleaning cloth, manual, USB flash drive

Sound description:

When I would have to give a very short description it would be this. A highly detailed and airy sound only lacking a bit in ‘body/grunt’ and subbass but not obviously missing bass.
To me the differences between the HD800 and HD800S aren’t that big. The HD800 is somewhat more ‘grating’ in the treble but that is really the only audible difference to me.
Most people claim it has more/less quality bass but to me it is the same. The HD800 does sound a bit less ‘warm’ because of the more elevated treble around 7kHz which ‘overpowers’ the sound in the HD800 way too much.
This is better in the HD800S but this one still is ‘overly’ trebly/bright and ‘hyper-detailed’ because of the ‘treble plateau’.|
There is a solution for this though. Imaging and stereo separation is top notch. With this I mean placement of instruments in the sound field and the ability to perceive them ‘separate’ and ‘realistic’ is excellent.
This is the strong point of this headphone, along with wearing comfort.
For music, other than classical, the HD800(S) needs some EQ in the treble and the lower bass. Even with the treble reduced the detail retrieval and ‘airy’ sound remains… just not overly hyped but just more realistic and less fatiguing.


Below the frequency response of the HD800S (Left, Right)

Below the measurements of the (brand new) HD800S 75YA. (Left, Right)Channel matching is excellent as should be expected in this price range.  Below 100Hz this headphone drops off very gradually. You can still hear deep rumbles but just not on an impressive level unless the recording has way too much lows in it.
Bass sounds ‘tight’ and very ‘dynamic’ and clean. Bass integrates seamlessly with the mids. Those mids are clear and articulate and have a decent presence.
From 100Hz to 1kHz the response is very flat and accurate.
The small dip from 1.5kHz to 5kHz may be a little less ‘deep’ in reality compared to the measurement  because the measurement rig does not have a pinna which does alter the response exactly in that area. Below in dotted green the perceived response.The treble response is elevated. The 6kHz peak is still 4dB too high (despite the absorber). The 10kHz peak even sticks out 10dB above the rest. The thing with the 10kHz peak is that HATS usually have a deep and narrow dip there. This means our ears will also have a narrow dip somewhere in this region. That 10kHz peak thus isn’t audible as a peak. The peak around 15kHz is too high to bother anyone and I suspect, along with the 10kHz emphasis is responsible for the excellent imaging (combined with ear-driver distance and angle).
This elevated treble is mostly responsible for the perceived high detail.
When this level is reduced by EQ one must be careful not to reduce the 10kHz part too much. That part is responsible for the fine detail reproduction and instrument ‘placement/localization’. When that level is reduced to the same level as the mids the headphone sounds ‘bland’ and lifeless.

Below the differences between the HD800 and HD800S. (Right channel only)

HD800 vs HD800S
The similarities are very obvious. The differences too.
From 10Hz to 1kHz the differences are negligible. The effect of the absorber is quite obvious. A reduction of about 5 dB is achieved. But ringing is also reduced which cannot be seen on this plot.
The reduction achieved by the SDR mod from ‘Sorrodje’ from tellementnomade.org is about the same and can be fitted in the HD800 with some guts and while voiding of the warranty.
This turns the HD800 in an HD800S but with better ‘measured bass performance’ than the HD800S as the distortion of the HD800 is slightly lower than that of the HD800S.

below the differenced between a demo HD800S (2016) and a new HD800S 75YA version.There are differences between the 2 headphones but are in the ‘range’ of product variations.

Seal can be an issue with closed-back headphones but is usually less of a problem for open headphones. Breaking the seal (improper fit on the head) usually means a loss of (sub)bass. Perfect seal, seal broken with thin armed glasses, seal broken with thick armed glasses and seal substantially broken by slightly lifting the bottom of the pads a few mm which can occur when not properly seated.

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 different output resistance amplifiers (0.2Ω, 10Ω, 33Ω and 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 (at 1kHz) as the low impedance amplifier. This way the plots are overlay-ed and it is easier to see how the tonal balance changes.

As can be seen the tonal balance changes just slightly on a very high resistance (120Ω) amplifier. when connected to a higher output resistance amplifier. You get about 1dB more lows. This can make the headphone sound slightly ‘fuller’. Lower bass is not boosted.
Output resistances below 33 Ohm have no effect at all.

Below the distortion plot of the HD800S : (only Right channel shown)

The distortion products are shown in dB.HD800S R dist

Below the same data but shown in a percentage scale instead of a dB scale.

Dist HD800S R percent

The distortion profile is typical for a dynamic driver. Higher 2nd harmonic distortion in the bass. Ignore the peaks at 50Hz and 100Hz, they aren’t there in reality but are caused by the measurement rig picking up some hum.
The distortion around 60Hz is around 1%
The measurement rig has a relatively high 2nd harmonic distortion so numbers below 0.2% (above 200Hz) will be there in reality. Distortion from 200Hz to 10kHz is very low.

Below the distortion plot of the HD800 (measured under better surrounding conditions).
Dist HD800 R percent

When comparing the two headphones it shows that the HD800S has slightly higher distortion levels below 100Hz. Particularly the 2nd order distortion.

Below the CSD of the HD800S (Left and Right channel are superimposed)The CSD shows a quite good response with no obvious and deal-breaking resonances or lingering. Small and short lived resonances can be seen at 6kHz and 10kHz though but doubt these are detrimental to the treble quality.

Below the HD800 CSD plots as a comparison.

As can be seen the absorber in the HD800S does a good job. Not only the amplitude of the 6kHz resonance is lower in the HD800S but the ringing is also much better damped/shorter lived. For the higher frequencies the absorber does not do anything.
The used ‘Helmholtz resonator’ seems to be perfectly tuned to the biggest ‘flaw’ of the HD800.

By lack of oscilloscope shots (not enough time to measure that) below a step response plot of the HD800S (Left, Right)

The fast impulse response of the HD800S is clearly seen as it reaches the 0dB line.
It is not really overshoot but the 6dB dip following the initial rise is a bit high.
What can be observed as well is that there is some ringing visible in a high frequency (10kHz). The gradual downwards slope is evidence of the slight slope in the bass/sub-bass.

Below the HD800 for comparative reasons.

Step HD800 R
What is obvious here is that the dip after the initial rise is deeper and that the resonance after it is lower in frequency (6kHz) and takes about twice as long long to die out.

below the step response of the HD660S.
step HD660S R

The step response clearly shows the lack of ‘bottom end’ as evidenced by the downwards sloping line. Headphones with a good sub-bass extension have a (close to) horizontal line after the initial rise. What can be seen is the superior initial rising flank which stops at 2dB below the 0dB line. On the other hand there is as good as no ringing seen at all.

A different plot is the spectrum plot. This basically is a CSD (Waterfall) plot but viewed from above where the level differences are colour coded instead of being in the vertical axis. Also the frequency range of the spectrum plot is wider (from 100Hz instead of 500Hz). The time span is also bigger in the spectrum plots and expired time is shown from below to top where in the CSD the time is shown from rear to front.

Below the spectrum plot of the HD800S 75YA (Left channel)

It shows the HD800S is well damped and even at low frequencies it shows a very fast decay.

passive filter

The treble peak of the original HD800 is already lowered using a resonator in the HD800S.
One can retrofit a similar DIY resonator into the HD800 but this requires some (not so difficult) ‘surgery’. The effect is similar to that of the HD800S.
To order this you can contact member ‘sorrodje’ at SBAF.

Even the HD800S still has some ‘sharpness’ in its sound though and while better than the HD800 already it still needs some EQ.
This can be done digitally (and correct for the bass at the same time) or to build (or buy) a passive filter that sits between the headphone amp and headphone cable. The schematic is shown below.

The effect of this filter is shown below. Stock HD800S and HD800S with passive filter.
It doesn’t look like this will make the difference but it does remove the remaining sharpness but leaves the overall sound completely as it is.


This headphone is top notch when it concerns fit, finish, looks and craftsmanship.
Tonal balance is bright and not bassy, overly detailed.
Instrument separation as well as dynamics and retrieval of the finer nuances is among the best of the TOTL headphones out there.

The elevated treble and slightly rolled off subbass are still downsides. The treble quality is better than that of the HD800.
Those that find the treble of the HD800S and HD800 SDR mod still a tad too sharp can use a passive filter to lower the (still present) boosted treble a bit.

Is it worth upgrading from the HD800 ?
When you like the tonal balance of the HD800 and are only looking for somewhat less ‘sharp’ treble and don’t mind the bass quality to be very slightly different then the HD800S may be an ‘upgrade’. When you are not afraid of some DIY and don’t need the balanced cable nor the black accents then the SDR mod is a better and cheaper idea or the passive filter which lowers the offending treble peak to desired levels.
A little bit less ‘romantic’ presentation perhaps then it might be worth ‘upgrading’.

When the lack of bass and elevated treble is something that you don’t particularly like but do like the other great assets of this headphone than the Kameleon or (software) EQ may be a way out.

Technically an excellent (maybe close to the being the best) headphone but to me a bit still a bit too bright and too ‘lean’. Fortunately there are fixes for this that do not affect the other excellent qualities.

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