K181

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published: Jul-13-2014, edited: Feb-15-2021

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.

AKG K181

The AKG K181 is a ‘DJ’ headphone. This means it has decent isolation and the cups can fold away in all directions which makes it easy for travel. The 1.8m long cable is on the long side for portable usage though.
It is an on-ear with a fair amount of clamping force.
Because of its larger pads pressure is distributed better than the smaller on-ear headphones. The cable-joint is a bit flimsy.
While it is aimed at DJ work it really is more a ‘hifi headphone’ in the lower price range (around € 120.-) than one I would recommend for DJ-work.
You would want a more sturdy headphone there with less treble energy so you can play it louder.
It does have a higher power rating (3.5W) associated with DJ headphones, this way you can leave it around your neck and use it as ‘neckband speakers’ without blowing it up.
With a 42Ω impedance this means it can handle 12Vrms.

specifications:

Type: On-ear, closed
Usage: Home, Studio, Portable
Isolation: decent
Driver type: dynamic
Pads: replaceable, pleather
Pad dimensions: outer diameter: 90mm, inner diameter: 30mm, height: 10mm
Collapsible: the cups can swivel and fold flat
Headphone connector: 3-pin mini XLR
Cable entry: left sided.
Cable: 5m coiled with 3.5mm TRS and a 6.3mm adapter
Driver size: ø 50mm (partly covered by the pads)
Nom. power rating: 3.5W
Max. voltage: 12V
Max. current: 290mA
Max. S.P.L.: 133dB
Impedance: 42Ω
Efficiency: 98dB @ 1mW
Sensitivity: 112dB @ 1V
Weight: 280 g. (without the cable)
Colour: black
Clamping force: medium/high
Accessories: 6.3mm adapter, coiled cable, pouch

sound description

This headphone has slide switches on it, one is mono stereo but there is another slider called ‘Club’ and can be set to Small and Large, instead they should have named it ‘Flat’ and ‘Bass-boost’ because that’s what it does.
On the ‘small’ setting the headphone is surprisingly hifi-ish with a good tonal balance. On the ‘large’ setting it sounds boomy and bassy.
I would keep it on ‘small’ but with some (pop music) recordings that 6dB bass boost makes that music sound fuller without bloating the sound

measurements

Below the measured frequency response in ‘small’ setting. Some channel imbalance  but not very audible. left, right.
The frequency extension to both ends is very good and tonal balance is ‘neutral’. It doesn’t have the spiky treble associated with most AKG hifi headphones. Subbass extension is there but a smidgeon on the ‘lean’ side. Good for ‘hi-fi listening.

The ‘large’ setting boosts the bass and subbass. The increase between 100Hz and 200Hz is a bit too much though for hifi listening and makes the bass bloated and fat on well made recordings. It does have an appealing ‘warming’ of the sound of recordings that show very little bass. left, right

To show the effect of the slide switch below the two settings in one plot (right channel only) large, small. The slide switch seems to change something mechanical/acoustical inside (didn’t have a look inside). When I had these for measurements I should have come up with the idea of seeing if how the FR could be set to an in-between setting and get a bit a nice setting right between those two settings.

below distortion of the K181 in ‘small’ setting.Below the same plot but in percentage scale.Note only THD is shown. Distortion at 90dB SPL is very low over the entire audible range and reaching the measurement limit of the test rig.

Below the distortion of the K181 in ‘large’ setting.and below in percentage

Basically still low distortion but below 200Hz the distortion is higher because of the higher SPL.

The CSD (Waterfall) plot of the K181 in ‘small’ setting shows some slight ringing from 3.5kHz and up but doesn’t seem to mess up the sound that much. It isn’t completely ‘refined’ sounding but all the ‘components’ in the sound are present in a pleasant way. left, right

The CSD plot below is taken in the ‘large’ setting and shows a similar response from 4kHz and up but also shows more ringing below 700Hz though I have measured headphones that have even more ‘ringing’ in that area. The ‘club slider’ seems to change the damping of the driver.

Below the step response of the K181 in ‘small’ setting.Small higher frequency resonances. The higher 0-500μs part shows the bright character, the hardly sloping horizontal part shows the subbass extension is excellent.

Also the step response in ‘large’ setting below.The elevated part between 1ms and 5ms shows the boomy warmer character. Bass extension is great.

conclusion

In short a good (tonally balanced) sounding AKG headphone that is easy for travel but not the most comfortable one to use, certainly for longer listening sessions. Good isolation from sound around you. Only available second hand. Not particularly worthwhile to seek out unless one is a collector/horder.

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