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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.
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.

post separation
Sennheiser HD800

HD800 kl

The Sennheiser HD800 doesn’t really belong here as it is well above the price of a budget headphone.
Still… It is an important headphone due to the driver concept.
Given the price range of today’s ‘flagships’ like Audeze LCD-4, Focal Utopia, HiFiman HE1000, Abyss AB1266, Sennheiser Orpheus HE-1060, Stax SR009 system the standard price isn’t absurd.
I got this one second hand for a reasonable price. 2nd hand prices will drop though with the new HD800S coming out. That one has more (percived) bass and somewhat less 6kHz treble peak.

Below the frequency response on a more flattering scale as previous measurements. Also note that the frequency response of the measurements spans 10Hz to 30kHz.
I think everything down to 10Hz is fairly accurate but above 10kHz is the no guarantee zone. The microphone used seems to top out at around 27kHz but don’t know how accurate absolute levels are. As the measurement setup is cheap … don’t bet on absolute accuracy. Ignore the ‘wiggles’ around 50-60Hz, they aren’t really there. A measurement error. This is true for all measurements on this website though. Left, Right

HD800 FR 30k

This is quite representatitive of how it sounds. Bass-shy though deep bass notes can still be heard but not as loud as it should. Quite accurate mids and BRIGHT.
Quite good channel matching.
Way too bright and because of it highly (overly) detailed and ‘spacious’ and ‘fast’ sounding. The large membrane, however, does not seem to do much above 20kHz though, compared to the HD650.
Below a comparison of the HD800 and HD650 (black driver but fitted with new pads)

HD800 vs HD600 new pads

The differences are obvious. The HD650 is warmer, has a bit more ‘presence’ in the area between 1kHz or 3kHz) or should I say the HD800 is lacking in that area.
The sharp rise and the peaks in the treble area make the HD800 sound so ‘thin’, ‘bright’ and ‘highly detailed’. Flat and ‘accurate’ the HD800 is absolutely NOT.
Notice how the HD650 is much flatter and accurate and has similar subbass and even better treble extension. Of course if most of the music you have is CD then everything above 20kHz is really moot.

Let’s do something naughty and zoom in in the dB scale a bit. The plot below has 2dB/division scale. It does seem strange to use such a scale BUT when you realise that a 1dB increase can heard (by trained listeners) and a -2dB change also then the plot below makes more sense. HD800 and HD650

HD800 vs HD650 new pads zoomed

Yes, the HD800 is relatively ‘bass-shy’, ‘bright’ and less accurate.
Recently I heard the Mr Speakers ETHER and compared that one to a (driven by Kameleon amplifier) HD650.  When doing the same comparison with the HD800 it is obvious the ETHER is MUCH more linear sounding and is the better buy for sure.
One of the features of the HD800 is comfort. It certainly doesn’t lack there, but the ETHER is better here too !
Maybe the similarly priced HD800S is closer to the ETHER.

In the HD650 article I also used white noise for frequency response measurements from 1kHz to 30kHz in a LINEAR frequency scale.
Below the FR response of the HD800.


As a comparison below the HD650 (with new pads)

Senn foam

Below the distortion plots of the HD800, left channel only, the right channel measures the same.DIST HD800L

The frequency range differs from the FR plots, these ones run from 30Hz to 30kHz. The distortion of these headphones, especially in the bass area is impressively low.
As a comparison below the distortion plot of the HD650 which has more distortion.
Around 40Hz there is a 40dB ‘distance’ between the signal and the 2nd and 3rd harmonics.
The HD800 does quite a bit better and shows a 46dB distance. At 1kHz the HD800 has a ‘distance’ of 58dB where the HD650 (no slouch in the distortion department either) has a distance of 53dB.
So the HD800 does perform better in the distortion department.

DIST new pads

Then there is also the waterfall plot or C.S.D. which is shown below and gives us some clues about ringing of the driver.

CSD HD800 newAt 6kHz (5.85kHz) and 10.5kHz resonances are visible. It’s not ringing very long though. Left and Right superimposed

Below a comparison between the HD650 and HD800. As can be seen the HD650 is not as ‘clean’ in the lower part of the FR (500Hz in this plot).
The HD800 is not ‘better’ though. The green part around 2kHz is higher in amplitude only so it seems as the HD800 is ‘better’ there. Likewise it would appear as though the HD650 is ‘better’ above 4kHz but again… this is only an ‘amplitude’ based difference. Both headphones do well in the CSD department.

CSD HD800 vs HD650

Below the spectrum plot of the HD800 (Right channel) the signal drops  down to -35dB fast all over the spectrum but takes a bit longer after that. No obvious problematic behaviour is shown here.

Spect HD800R

A way of looking at an impulse can also be done with a step signal. The plot below shows that after the initial step there is quite some ringing visible (8dB !) after the initial flank.
The sloping horizontal line indicates the subbass response is not that great and some LF roll-off is there.

Step HD800 R

Other interesting measurements are squarewave responses and needle pulses. These tell us something about the speed of membrane as well as how much they continue to vibrate after they are supposed to stop moving.
There are no software analysis in these squarewave plots and no sound cards involved either. Just a real squarewave and an oscilloscope so no digital filter ringing artefacts etc.

3 different measurements are made… They are explained HERE if you want mor info.
As above many comparisons are made to the HD650 below the plots will be no different.
On the left the HD800 with a 40Hz squarwave                          on the right the HD650.

40Hz SQR HD800

new pads 40Hz


Below the plots of a 440Hz squarewave.
On the left the HD800                          on the right the HD650.

440Hz HD800

new pads 440







The HD800 (on the left) isn’t really looking like the original applied squarewave. The HD650 (on the right) is much closer to the stimulus.

Below a 100μs needle pulse (choice over the usual 50μs is explained HERE).
On the left the HD800                     on the right the HD650

10us pulse HD800

new pads 100us








Here the differences between the HD800 (on the left) and HD650 (on the right) clearly start to show.
After an impulse the HD800’s bigger membane overshoots (the treble peaks) and has difficulties with stopping to vibrate.
The frequency it rings at is 5.85kHz (not surprisingly).
The HD650 is MUCH better damped and thus may sound a bit more ‘boring’ in the treble but actually is a much more accurate driver.

If you are on a budget and are still continuously haunted by the idea you need to upgrade from the HD600 or HD650 to an HD800 then above there may be some answers to your questions. To me, without doubt, the HD650 is technically the better headphone but if you prefer less ‘warmth’ and like a more ‘fierce’ treble the HD800 (when bought second hand) may be a nice break from the HD650. Personally I would recommend the ETHER over the HD800 given that they are in a similar price range when bought new.
Not a headphone for bass-heads for sure.

Have been playing around with the Kameleon amplifier and am trying to make a filter that improves bass response and lowers the 4-8kHz area.
The goal is more ‘body’ and to remove the ‘overly bright’ treble while not removing the detailed character.

Below the results of some playing around and are thus preliminary results. The filter may still be changed.
Right channel only stock HD800, HD800 via Kameleon

Kam vs stock

I also ‘removed’ the peak between 10k and 20k but this completely removed the detailed character of the headphone. That elevated treble is there for a reason… the 6kHz peak seems a by-product that is unwanted and gives it the ‘sharp’ edge.
So the >10kHz peak must stay. In fact I made it extend a little further so it doesn’t roll-off till about 24kHz.

Distortion is about the same. The bass distortion appears higher but it isn’t. The distance in dB between the signal (red trace) and the distortion products remain the same.Likewise for the treble distortion, which appears to have improved, is actually the same. The signal level is lower and thus also the harmonics. The distance between stimulus and harmonics is the same… and that’s what counts.

Kam DIST R HD800

Then there is the CSD which obviously changed as well.
Right and Left channel are superimposed.

CSD Kam HD800

Below the step response difference.
On the left the stock HD800, on the right via the Kameleon.

Reduced ringing and improved subbass response is obvious.

Then there is the square-wave and needle pulse response.
On the left the stock HD800, on the right via Kameleon amplifier.

HD800 sqr

Remember, scope plots are linear scale measurements (both in time and amplitude)  where all the other measurements are logarithmic (both in amplitude and frequency).
The 40Hz squarewave is improved. The 440Hz signal shows less ringing but also less ‘speed’.
The 100μs pulse doesn’t overshoot (which is the 6kHz ringing) but lacks in overall amplitude.

When you compare it to the HD650 (on Kameleon) it shows that the HD650 is actually the better ‘performing’ headphone (technically).

To me the sound has improved so much that I can finally listen to it and enjoy it. Still highly detailed and with ‘body’ now.
After much time with it and enjoying the sound the headphone seemed to ‘induce’ tinnitus. This doesn’t happen to me with other headphones.

Suspecting this is caused by the peak >10kHz some experiments were made using damping materials in front of the driver like felt and toilet paper. To reduce the upper peak 1 ply of toilet paper seemed to do the trick combined with the Kameleon amp.

Below a frequency plot of the HD800 via the Kameleon and the same combo with 1 ply of toilet paper.TP effect on Kameleon HD800

As can be seen the toilet paper is effective at lowering the upper treble.
It also lowers the treble extension as an unwanted side effect.
Will experiment with some felt as well in the future.

As suspected the ‘hyper details’ of the HD800 are ‘located’ in the upper treble. With the toilet paper I haven’t been able to envoke tinnitus so it does help with that BUT also reduces the detailed sound to ‘normal’ levels and somewhat narrows the overly wide stereo image.
It is much easier to listen to music with this small roll-off while retaining some of the finer qualities of this headphone.

Below the L and R frequency response of the HD800 on Kameleon and with 1ply of toilet paper between the driver and the dustcover.

Kameleon + TP FR

Looks nice accurate. Sounds accurate as well but less ‘splashy’… polite yet very open and dynamic.

Below the difference between stock and via Kameleon with toilet paper.

Kameleon + TP vs stock HD800

For completeness also the CSD of the stock and Kameleon + toilet paper

CSD Kameleon + TP vs stock

The squarewave and needle pulse response differs substantially between stock (left) and via Kameleon + toilet paper (right)

HD800 on Kameleon + toilet paper

When the 6kHz ringing would be solved (think resonator as in the newly released HD800S) it might be an even better headphone.

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