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published: Jun-23-2018

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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 HD569


The Sennheiser HD569 is a closed over-ear dynamic headphone.
It retails for around € 150.- to € 200.- which can be considered cheap these days. Well…. affordable at least. Decent sounding closed headphones are not easy to find.

These are intended to be driven directly from phones and other portable devices.
They are lightweight and comfortable and look modern iwith their all black colour scheme.
The clamping force is dependent on the size of the head. Those with a wider/bigger than average head will find the clamping force high. For more average head sizes the clamping force is ‘medium’.
It comes with 2 detachable cables. One of which is 1.2m and has a 1-button remote control on it and a microphone with a 3.5mm TRRS plug. I did not find any info about compatibility with which phone as Apple and Android phones have different mic/remotes and are incompatible alas. The other one is 3m. long and has a 6.3mm plug.
The cables are microphonic so when the cable rubs against clothes this is audible in the left cup.
The headband is soft and comfortable and so are the suede pads. There is enough room for most ears but the pads do compress a lot so for some people their Pinnae may touch the drives. Height adjustment and tilt of the cups is large enough to suit most head sizes well.


Type: over ear, closed
Isolation: decent
Usage: home and portable
Driver type: dynamic
Pads: replaceable, suede
Foldable: No
Headphone cup connector: 2.5mm TRRS jack, locking.
Cable entry: single sided (left cup)
Cable: 3m cable with 6.3mm TRS Jack + 1.2m cable with 1 button remote control + mic. with 3.5mm TRRS jack (straight)
Inner Pad dimensions: depth = 20mm, Width = 45mm, height = 70mm, oval shaped
Driver size: 38mm
Max power rating: 0.5W
Max Input Voltage: 4 Vrms
Max drawn current: 125 mA rms
Max. S.P.L.: 127 dB
Impedance: 28 Ω
Efficiency: 100dB/1mW  (115dB/1V)
Weight: (around) 270 g.
Clamping force: medium to high (depends on head-size)
Accessories: 3m cable with 6.3mm TRS Jack + 1.2m cable with 1 button remote control + mic with 3.5mm TRRS Jack.

Sound description:

This headphone has deep lows and emphasized bass. For portable applications this may be a welcome asset. The bass has a ‘boomy’ character though which may put off those seeking ‘hi-fi’ sound.
The HD569 does sound quite dynamic/lively. The mids have a fairly ‘neutral-ish’ character to it. The treble is a bit ‘coarse’ as in not very ‘refined’. It is not ‘harsh’ nor ‘sharp’ or sibilant sounding though… just not very refined.
Music that is quite ‘busy’ (lots of instruments at the same time) becomes a bit ‘messy’ and it takes more ‘effort’ to distinguish all instruments. With better performing headphones this is much easier and all instruments are better ‘separated’.


Below the frequency response of the HD569 (Left, Right)

FR HD569


Channel matching is good.  Bass is elevated somewhat which is usually a good thing for portable usage. Mids are neutralish but lack some clarity due to the dip at around 3kHz.
from 4kHz to 10kHz the treble is back on proper levels again which mask the 3kHz dip somewhat.
Above 10kHz the treble is somewhat subdued but is extended to at least 30kHz.


Seal can be an issue with closed-back headphones. Breaking the seal (improper fit on the head) usually means a substantial loss of bass. The HD569 is not different than most other sealed headphones in this aspect. Perfect seal, with thin armed glasses on and with thick armed glasses.

seal loss


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 lower. To compensate for this the amplifier is cranked up to the same level (at 1kHz, 13dB in this case) as the low impedance amplifier. This way the plots are overlay-ed and it is easier to see how the tonal balance changes.

120 R

As can be seen the tonal balance changes just slightly with such a substantially higher output resistance. Just 1 dB more bass. This means that sources with output impedances till 30Ω or so can safely be used without the tonal balance changing audibly.

Below the distortion plot of the HD569: (Left channel shown)
Note that this headphone was measured at ears-unlimited-logo where  background noises were present in the demo room. As this is an open headphone distortion levels and spectrum plot performance may thus be better in reality than as shown on the plots.

The distortion products are shown in dB.


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

DIST HD569 L percent

The 2nd harmonic distortion in the bass area is quite low and remains under 0.5%. The 3rd harmonic distortion (which points to clipping alike behaviour) in the bass area is reaching 1%. These are levels that are just audible.
The measurement rig has a relatively high 2nd harmonic distortion so above 200Hz values will most likely be below 0.2% in reality.
Distortion from 200Hz to 10kHz is decent to good.

Below the CSD of the HD569 (Left and Right channel are superimposed)


The CSD shows a decent response. Around 5kHz there are some short lived resonances  but are probably not very audible in that part of the frequency range.

By lack of oscilloscope shots (not enough time to measure that) below a step response plot of the HD569 (Right channel)

step HD569R

The step response clearly shows the excellent subbass response as the horizontal trace barely sags. The plot also shows the driver is well damped as there are almost no resonances visible. The initial rise, however, does not reach the desired level indicating a lack of ‘speed’.


Those looking for a closed dynamic headphone that can be driven directly from a phone may well like this headphone. There are alternatives like the ATH-M50X for instance which also has a small lift in the lows.
The HD569 does have a short lead with a mic and one button remote on it (apple or Android ? I have no idea).
Even in Sennheisers own stable there are alternatives such as the HD598-CS and the bluetooth line as well.

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