K361

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Published: Apr-30-2020, updated: May-21-2020

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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.

descriptors2

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AKG K361

OLYMPUS DIGITAL CAMERA

The AKG K361 is a closed headphone with a 50mm dynamic titanium coated driver. It is available in black with very dark grey accents. The MSRP is around €149.- but retail price (2020) is between €85.- and €100.-

The headband can easily adjust over a wide enough 32mm range and is padded with a soft rubbery feeling part resting on the head.
L and R markings are located on the inside of the headband. A give away for the left cup is the cable entry as well. It is exactly the same as the K371 in this aspect.

The straight 1.2m and 3m cables aren’t thin, but also not ‘audiophile thick’. The K361 doesn’t come with the 3m coiled cable that is included with the 371. The cables are quite microphonic. One can hear the cable rubbing against clothes in the left ear cup even when listening at background levels. The cables have a locking 2.5mm TRS on the headphone side and a goldplated 3.5mm TRS with a gold plated screw-on 6.3mm adapter.
The thing that baffles me is why the cable connector is quite long and pointing towards the shoulders as well. Because of this the microphony of the cable is much worse than when the connector were shorter or pointing forward.
The 2 different cables that come with it ensures this headphone can be used in portable conditions (no mic/remote) and home and studio applications. This saves you from having to buy more or different cables.
As the headphone itself has a 2.5mm TRS connector this headphone can NOT be used with balanced amps. Nor is this possible with adapters.

Given the high efficiency (114dB/V) a high output power is not needed and is easily driven well even from a phone.
The low impedance 34Ω (measured, 32Ω specified) also is good for portable equipment but less suited for high output impedance OTL tube amplifiers.

The pads are large enough in inner heigth of 60mm and 40mm width and have a decent depth (19 mm once on the head) so most ears will fit. The pads are pleather (fake leather) with very soft memory foam inside. This creates a good seal which is essential for good sound (bass extension). The clamping force is very good between low and medium and quite comfortable even for longer periods. The K361 stays put and doesn’t move around when moving (your head) around.

This headphone is quite comfortable and can be worn for long periods without getting too ‘hot’ on the ears. The headphone is light in weight.
The weight of the K361 is slightly lower than that of the K371. The reason for this is the lighter connector (3.5mm TRS) versus the mini XLR and the added weights in the right cup of the K371 which are not present in the K361 resulting in 35 gram less weight.extra weightsThis is not the only difference with the K371 though. More on this at the bottom of this page.

The headphone feels and is quite sturdy. The mechanism for adjusting the ear cups is quite simple but works quite well. On both sides the cups can rotate to the back of the head so you can keep it on your head while listening to one cup. Handy for in the studio or having a short conversation.
Both cups can rotate all the way into the headband making them smaller when taking them along. The cups cannot fold flat but as they aren’t very wide this is not a big problem. It looks like some thought went into the design yet the mechanics of it are simple and effective.

specifications:

Type: On-ear, closed
Usage: Home, Studio, Portable
Isolation: lower frequencies are not attenuated much, higher frequencies are.
Driver type: dynamic
Pads: replaceable, pleather with soft memory foam
Inner pad dimensions: height: 60mm, width: 40mm, depth: 20mm
Collapsible: the cups can swivel backward (handy or DJ/musician) but not fold flat
Headphone connector: locking 2.5mm TRS jack.
Cable entry: left sided.
Cable: 3m + 1.2m with 3.5mm TRS and a 6.3mm screw-on adapter
Driver size: ø 50mm (membrane = ø 43mm)
Nom. power rating: not specified, assumed 200mW
Max. voltage: 2.6V
Max. current: 75mA
Max. S.P.L.: 122dB
Impedance: 34Ω (measured)
Efficiency: 99dB/1mW (114dB/1V)
Weight: 220 g.
Colour: black
Clamping force: medium/low
Accessories: screw-on 6.3mm adapter, 2 cables, pouch

Sound description:

The AKG K361 has a neutral tonal balance. This means all instruments sound ‘natural’ or at least are at the right level. This does not mean all people will perceive it this way.
Those that want to use this headphone as a monitor or even to check their mix on a headphone can use this headphone and get good results.
Is this the perfect headphone ? No it also lacks here and there a bit and while tonally correct it isn’t a real high flyer when it comes to finer details and smoothness in the treble. The treble is a bit ‘coarse’ in the K361. It is not sibilant, elevated or subdued. It just isn’t really smooth and lacks ‘small details’ The K361 is coarser sounding in the treble compared to the K371. The K371 is a bit more ‘hifi’ comparatively.
Bass is on the correct level (so NOT for bassheads !) and sounds quite good providing you have a good seal. Mids sound ‘open’ and ‘forward’. There is no cuppy sound and the bass and mids are integrated nicely. Those preferring ‘laid-back’ sound should look elsewhere.
The upper treble and highs is not the K361’s trong point. It certainly isn’t performing poorly though. There is decent clarity but you can hear there is a drop in clarity when comparing it to say a HD600. Treble is not over the top.  There is less ‘air’ and ‘detail’ compared to the K371. The K361 doesn’t do many things wrong here, it just doesn’t excel and while an excellent choice for monitoring it is less suitable for hi-fi. The K371 is a bit better overall. No sibilance nor shouty sound and treble is at the correct level. Just not super refined.
Those looking for a closed headphone with a neutral sound should definitely audition the K361 and perhaps the slightly better sounding K371.

measurements:

Below the frequency response of the K361 (Left, Right)FR stockFrom 20Hz to 2kHz the response is fairly very even and ‘flat’. The sub-bass is very well extended to even below 10Hz.
There is some imbalance between L and R drivers between 200Hz and 1kHz but is small and not audible to me.
There is an audible dip around 4kHz. This results in a slight lack of detail in female voices and some instruments. This can be beneficial with some pop recordings as it will take off the ‘edge’.
The treble response (as opposed to the smooth bass/mids) with its dips and (fairly well damped) peaks is responsible for the ‘coarseness’ in the treble.
Treble extension is excellent and the driver reaches at least 24kHz which is higher than most other headphones in this price class.

Below some comparisons with other headphones.

The K371 vs the K361K361 vs K371The extra subbass boost in the K371 is quite measurable. Do note that 30Hz is about the lowest frequency one can actually hear and can be present in recordings.
Also the treble level is higher in the K371 but also a bit ‘jagged’ just like the K361.
The biggest difference is in the 8kHz region. These drivers are clearly ‘related’.

Below the K361 vs the HD600which is often hailed as being one of the most neutral but bass-light and a bit ‘too hot’ in the 3kHz area.K361 vs HD600Here we can see that the K361 has better bass extension and the ‘hot’ area around 3kHz is not present in the K361. However, the treble response of the HD600 is much smoother.
Indeed the HD600 lacks in subbass but the treble quality of the HD600 is measurably and audible ‘better’. Of course the HD600 is an open headphone where the K361 is closed.

Below the K361 vs the somewhat higher priced Beyerdynamic Custom One Pro in ‘bass setting 2K361 vs COP-2
These perform similar in several aspects. The COP lacks the 5kHz emphasis and instead has a dip there. The COP extends to 20kHz. Upper mids on the COP are a bit more ‘laid-back’, the K361 treble is not as good as that of the COP.

Another closed headphone in a similar price class is the NAD VISO HP50 vs K361K361 vs HP50
Here the HP50 also shows good bass extension. The small bump between 100Hz and 300Hz , however, makes the bass of the HP50 a bit ‘wooly’. The K361 clearly performs better.  Mids of the HP50 have a warm ’tilt’ and lack in clarity where the K361 is more neutral. Treble of the HP50 sounds a bit ‘smoother’ eventhough the measurements do not seem to support this. Treble extension/’air’ of the K361 is better.

Another closed headphone with a small form factor and which is populat is the Meze 99 Classic(Neo) below compared to the K361K361 vs 99 Cl.
The boosted lows and even more lacking upper mids make the Meze 99 much warmer/bassier and more laid back. Treble quality of the Meze is better (smoother) than the K361.

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, thick armed glasses and a big seal breach.sealA small seal breach isn’t really problematic at all. The tonal balance is hardly changed when listening to these headphones with or without thin armed glasses. Only when there is a more substantial seal breach or thicker armed glasses are used one will notice lower bass notes are subdued.
It is thus important to get a good seal with these headphones. The very soft and supple pads will ensure a good seal in most circumstances.

 

Below the distortion measurements of the K361 (Right channel)dist R

Below the same distortion plot as above but with the vertical scale in percentages instead of level differences. dist R percent

To get a sense of what level of distortion is audible below a plot showing audibility thresholds when listening to music or 2nd and 3rd harmonic distortion dist audibility limits

The distortion in the bass is quite low, 1% is very good for a dynamic driver. Above 150Hz the distortion remains below 0.5%. The elephant in the room is visible around 4-5kHz where there are some resonance issues. This is also seen in the CSD below.
The 2nd harmonic distortion is probably lower than 0.3% around 1kHz as limits of the test rig are around that level.

Below the CSD of the K361. (Left and Right are superimposed) CSD K361The narrow treble peaks (6kHz, 9kHz 11khz, 15kHz and 22kHz) are resonances. This also points toward some less refined treble.

Below the spectrum plot of the K361 (Right channel). spetr K361 R
This plot looks quite good. The lower frequencies are fairly well damped.
Around 1kHz there is a little lingering. Also see the small ripple in the FR plot, it seems happy to vibrate at that frequency at very low levels. I don’t think this is detrimental to the sound.

The step response plot below  (Left, Right)step K361The excellent bass extension and tonal accuracy is clearly shown in this plot. The horizontal line is barely sloping indicating excellent bass extension. No large resonances.
The membrane isn’t reaching 0dB so impulse response is slightly lower than desirable.

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 (12.5dB 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 12-5dBThe headphone does not react to higher output resistances other than in level (12.5dB). There is hardly any difference.
The output resistance of the used source/amplifier has NO practical influence on the sound/frequency response/tonal balance.
Sometimes people feel that headphones driven from 120Ω source (Damping factor of 0.25 !) results in less damping and thus the membrane not stopping as fast anymore.
Below the CSD (stops below 500Hz) where the red part is the behaviour from 0.2Ω and the green via 120Ω resistor. As shown below it doesn’t change anything significantly.

CSD 120 Ohm

Below the spectrum plot (CSD but colorcoded, different time and frequency scale) shows there is a small difference in the lower frequencies. One would expect to see the best damping to be from the lowest amp resistance but much to my surprise the plot with the ‘faster’ decay is when driven from 120Ω.spectrIn short, this headphone can also be driven from amplifiers with a higher output resistance.

driver experiments

The drivers themselves seem to be the same for K371 and K361. Perhaps more carefully matched/selected and a bit more sub-bassy in the K371.
The baffle is what differs between these headphones as well as the front damping.

K371 vs K361 baffleThe K371 has open (not covered) holes around. Some of the smaller holes are covered with acoustic paper. Also the baffle ports are bigger and paper covered.
The K361 has its bigger holes covered with black acoustic paper and a fine nylon mesh covering the paper and smaller holes. The porting differs as well. There are 4 small holes covered with the same nylon mesh that covers the driver. The K371 baffle is screwed down by 6 screws, the K361 with 4.
The rear side of the driver itself appears to be the same.OLYMPUS DIGITAL CAMERAThe outer plastic edge of the driver is 50mm, the membrane itself is 43mm in diameter.

Curious whether or not the K361 can be turned into a cheaper version of the K371 (but without the mini-XLR) means I had to do some potentially irreversible modifications given the fact that the mesh and paper filter-ring are stuck onto the baffle with some adhesive.

The nylon mesh can be removed and when removed very carefully can be put back. The glue sticks onto the mesh. When this is removed there is a paper sticker glued on the baffle with the same glue material, when carefully pried loose and pulled of gently the material can be put back in place. The black paper is denser than the white acoustic paper. Below the difference between the stock K361 and with the mesh & paper ring removed.R paper ring + mesh removedBetween 70Hz and 1kHz the output is increased a bit. Effectively lowering the bass to the same level as the mids. Also the treble between 6kHz and 8kHz is increased by 5dB.
Above 8kHz nothing much changed but relatively to the rest of the spectrum the output is lowered a bit.

To see and hear if the K371 sound can be re-created with the K361 I made a ring of 1 ply of a 3-ply toilet paper of roughly the same size as the ring on the K371. I expect the paper to be quite similar to the paper used on the K371, possibly the toilet paper is damping somewhat less though. Some small glue droplets were positioned on the baffle. This way the paper can be stuck on the baffle. It doesn’t look nice and the porting in the baffle isn’t exactly the same but below the result.K371 vs mod K361 baffleThe end result is a somewhat improved upper treble. The sub-bass boost of the K371 is not present but the treble response is closer. freq stock vs modifResponse of the modified driver is still 0dB at 30Hz, at 18Hz it is -3dB. The extra energy in the 6-8kHz range gives the sound a bit more detail and improved treble quality. Very close, if not the same as that of the K371.

Below the distortion plots of the original K361 and the same driver but with the damping scheme of the K371.dist stock vs modifThe damping materials in front of the stock K361 driver is higher than with the modified driver. Here we can see that lower frequencies have lower 2nd and 3rd harmonic distortion. However, at 4kHz the distortion is higher again.

summary

The K361 is a very neutral/realistic and dynamic sounding headphone. In its price class (street prices from €85.- to €120.-) this may well be the most neutral sounding closed headphone giving the DT250-250 a run for the money.
This headphone is excellent for monitoring and even checking a final mix in a studio.
The cups that can swivel backwards can be handy in a studio.
It is also very well suited for portable usage but misses a mic/remote so more suited for personal music enjoyment than phone usage.
While this is a closed headphone there is not much isolation from low frequency noises.
On a plane/bus the isolation will not be enough. Higher frequencies are well attenuated though so in a home or studio situation you get a decent isolation from outside noises.
For lower budget ‘hi-fi’ music enjoyment this headphone sounds decent, the K371 is a better choice for this.
No it doesn’t sound really refined and ‘relaxed’ but sounds good for ‘active’ listening even at higher SPL. This is NOT a basshead headphone for those that are wondering but is well extended to both sides of the audible spetrum.

Comfort is quite good. It is light weight and clamping force is low.
The pads are replaceable which may well be needed after a while as the pads are pleather. It feels somewhat different from most other pleather pads, these have a rubbery feel to them. Maybe longevity is better than the typical pleather
When one has a wider than average head it may be difficult to get a good seal.

The 2 supplied cables are handy and makes this headphone quite universal without having to buy (sometimes expensive) aftermarket cables.
The cables are microphonic, so when the cables rub against your clothes you can hear this contact sound in the left cup.

For around €100.- this headphone is amazing value. For €150.- this headphone is still affordable and a good reference headphone, certainly considering this is a closed headphone without any hint of typical ‘closed headphone’ coloration in the sound.
Highly recommended for sure.

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