AKG K271 Review (Closed Back Headphone)

[solderdude]

Yep, I have the ISK's and they are unusably bright

Indeed like most Superluxes. Can be EQ'ed. Toilet paper also helps.

 

[Maxicut]

Indeed like most Superluxes. Can be EQ'ed. Toilet paper also helps.

Nah, really high distortion as well. I EQ'd them & the distortion went through the roof. Binned.

 

[Thomas_A]

I find these thin sounding due to lack of bass. There is an older version of the K271 that sounded and measured much better out of the box though.

 

[GWolfman]

Thanks, as always.

 

[restorer-john]

@amirm The headphones you have pictured say "Made in Austria".

I was under the impression all current AKGs are made in China and have been for a number of years after Harman shut the Austrian facilities. So this pair is rather old and may not be representative of the current production?

 

[amirm]

Your guess is as good as mine...

 

[Thomas_A]

@amirm The headphones you have pictured say "Made in Austria".

I was under the impression all current AKGs are made in China and have been for a number of years Harman shut the Austrian facilities. So this pair is rather old and may not be representative of the current production?

Good spot. My unit says made in China. And it does not sound ok, IMO.

 

[restorer-john]

Good spot. My unit says made in China. And it does not sound ok, IMO.

You could send (if you are in the US) them to @amirm and he may be able to run a few tests to see what, if anything, is different between older Austrian and newer Chinese manufacture.

 

[Maxicut]

@amirm The headphones you have pictured say "Made in Austria".

I was under the impression all current AKGs are made in China and have been for a number of years Harman shut the Austrian facilities. So this pair is rather old and may not be representative of the current production?

They've been made in China for at least 3-years

 

[restorer-john]

They've been made in China for at least 3-years

I believe the Austrian factory was shuttered in mid 2017.

 

[Thomas_A]

You could send (if you are in the US) them to @amirm and he may be able to run a few tests to see what, if anything, is different between older Austrian and newer Chinese manufacture.

Not in the US, but I will send them as one-way ticket, since they only collect dust. I may send a sleeper as well while I am at it. Later during summer.

 

[Fritz-Kola_Enthusiast]

You should buy a bicycle and with the saved money better audio equipment.

Imagine having to drive 50km to work on a frickin bike... yikes....

 

[renaudrenaud]

Imagine having to drive 50km to work on a frickin bike... yikes....

I've done this during years.

 

[Robbo99999]

Strange, to me the measurements of this headphone is worse in both frequency response & distortion than the K7XX that was reviewed yesterday, yet the listening tests saved this K271. I am surprised, because I would think in the listening tests that Amir wouldn't listen at louder than 94dB at 1kHz (in terms of the actual musical content at that point) when listening to music, which doesn't look bad on the 94dB blue line of the K7XX when looking at the graph below:

Yet, the bass distortion on this K271 in this review right here is "off-the-scale" in comparison to that of the K7XX, and it's the bass area that you EQ up by a large amount (so more representative of actual usage), even in Amir's listening tests, so I find a bit of a mismatch between the distortion measurements of the two headphones and their respective listening test impressions from Amir - and yes it's harder to detect distortion in bass (but still). K271 showing lots of distortion in bass & some mids:

Amir's listening impression is Amir's listening impression, just seems a mismatch with the distortion plots for the points I mentioned. Hmmm.
(I wouldn't buy this headphone over the K7XX judging from the measurements, and to be honest neither would I from the review as a whole)

 

[PuX]

I understand if you buy them new, you get two sets of pads. The sample I have only came with the "leather" one:

I believe these are the same as default ones on K240S, so maybe you can try to measure the basic frequency response of K240S with these pads? some people were having doubts because of different earpads (me included).
I am 99% sure K240S and K271 are the same in terms of technical design and the main difference is K240S is semi-open, while K271 is closed. this should influence the sound, but not that much.

you get the second set of pads (velour) only with MKII model. regular K271 is exactly the same but has 1 set of pads, pleather.

I was under the impression all current AKGs are made in China and have been for a number of years after Harman shut the Austrian facilities. So this pair is rather old and may not be representative of the current production?

they never announced any changes besides moving the factory, so should be the same.
there were some slight differences on some models, like K702 from China had no dimples in the headband.
would be good to see if this is true in measurements to confirm.

 

[m8o]

I am going to recommend the AKG K271.

... with all that distortion?
May want to consider moving that threshold line of acceptability. (or a slope or curve)

 

[Blumlein 88]

You could send (if you are in the US) them to @amirm and he may be able to run a few tests to see what, if anything, is different between older Austrian and newer Chinese manufacture.

That would be an excellent and highly informative comparison to make. I hope someone sends one in and makes it happen.

 

[_thelaughingman]

These have so much distortion at the low end when listening to a track that has heavy kick drum or a taiko drum. Listening to Battle Drums by Joe Hisaishi highlights that distortion.
The build quality is very cheap and the earcup foams are terrible, there is no cushioning on it.

 

[Maiky76]

This is a review and detailed measurements of the AKG K271 MKII closed back headphone. It is on kind loan from a member and costs US $118 on Amazon including prime shipping.

I understand if you buy them new, you get two sets of pads. The sample I have only came with the "leather" one:

View attachment 139343

The headphone is ultra light and feels quite plasticky. You certainly don't get a feeling that you bought something of value. The pads are quite shallow (maybe they are worn?) to the tune of 16 mm, the lowest I have measured on any over the ear headphone. As such, they pushed the artificial ear lobes on my fixture and my own ear. I did not mind it much though. As mentioned, they are extremely light:

View attachment 139344

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements even if performed with the same fixtures as mine, differ in end results. Protocols vary such as headband pressure and averaging (which I don't do). As you will see, I confirm the approximate accuracy of the measurements using Equalization and listening tests. Ultimately headphone measurements are less exact than speakers mostly in bass and above a few kilohertz so keep that in mind as you read these tests. If you think you have an exact idea of a headphone performance, you are likely wrong!

The K271 has a self-adjusting mechanism which makes it hard to put high pressure on the test fixture. I could see some air gaps when I fit it there and observed high variability in bass performance. So be mindful of this when you see the follow on measurements.

AKG K271 ohm Measurements
Let's start with our usual frequency response measurements:

View attachment 139345

At first blush, this looks scary bad. But when you look past the kinks here and there, the compliance with our target curve in the critical range of 200 Hz to 3 kHz is quite good! Below that we have messy bass response but that could be due to measurement error as evidenced by green channel doing better (which I could confirm visually to be the case). At the highest frequencies we have a bit of excess energy but not much.

Here is our relative frequency response measurement:

View attachment 139346

The relative distortion graph looks really bad in bass because the response is dropping while distortion is increasing there:

View attachment 139347
View attachment 139348

Maybe the super light weight of this headphone and not so tight fit on the fixture is causing its body to resonate or something. We will circle back to this (sort of) when we perform our listening tests.

Group delay just confirms there are point frequency issues in this design:
View attachment 139349

Of note, there is no fuzziness in mid frequencies yet as you will read in the subjective section, there is very good spatial effects.

Impedance is on the low side and somewhat variable:

View attachment 139350

Sensitivity is a bit better than average:
View attachment 139351

Combined with lowish impedance, you should be able to drive the K271 with portable devices.

AKG K271 Listening Tests
While not perfect, out of the box tonality was close to what I expected to hear. My reference tracks immediately sounded (almost) right. Some equalization with substantial boost in bass transformed this headphone's performance:

View attachment 139352

Wow or wow! This thing has incredible bass now and very nice spatiality. I ran the tests yesterday and today I am still listening to them! Track after track sounds wonderful.

As to bass distortion, I can't hear it unless I blast it and then it starts to rattle and such. But at any reasonable level, it sounds very clean counter to the measurements.

Was just listening to the track, Je Suis Une Fleure, from the album Best Kept Secretes Part 2 by Shigeru Umebayashi makes you think you have died and gone to heaven:

Conclusions
What is the old saying? Don't judge a book by its cover? So is the story of AKG K271. Out of the box it is mostly fine but not exciting. Add some EQ and this headphone transforms into jewel, something that is hard to find in closed back headphones. The large cups provide for very nice spatial effects. Combine this with the low price and you have a winner here.

I am going to recommend the AKG K271. With equalization, it almost earns a golfing panther! I would give it such if I was not worried about you all chasing me out of town that such a cheap headphone with seemingly messy measurements would achieve such.

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Hi,

Here are some thoughts about the EQ.
Notes about the EQ design:

• The average L/R is used to calculate the score.
• The resolution is 12 points per octave interpolated from the raw data (provided by @amirm)
• A Genetic Algorithm is used to optimize the EQ.
• The EQ Score is designed to MAXIMIZE the Score WHILE fitting the Harman target curve with a fixed complexity.
  This will avoid weird results if one only optimizes for the Score.
  It will probably flatten the Error regression doing so, the tonal balance should be more neutral.
• The EQs are starting point and may require tuning (certainly at LF).
• The range above 10kHz is usually not EQed unless smooth enough to do so.
• I am using PEQ (PK) as from my experience the definition is more consistent across different DSP/platform implementations than shelves.
• With some HP/amp combo the boosts and preamp gain need to be carefully considered to avoid issues

Poor L/R match.

I have generated one EQ, the APO config file is attached.

Score no EQ: 50.5
Score Armirm: 59.3
Score with EQ: 103.6

AKG K271 APO EQ Flat@HF 96000Hz
July082021-115100

Preamp: -11.6 dB

Filter 1: ON PK Fc 24.35 Hz Gain 6.97 dB Q 0.26
Filter 2: ON PK Fc 70.19 Hz Gain 6.72 dB Q 1.28
Filter 3: ON PK Fc 626.70 Hz Gain -2.59 dB Q 4.99
Filter 4: ON PK Fc 1775.70 Hz Gain -3.09 dB Q 3.23
Filter 5: ON PK Fc 2182.64 Hz Gain 4.00 dB Q 4.04
Filter 6: ON PK Fc 5124.45 Hz Gain 6.45 dB Q 1.18
Filter 7: ON PK Fc 8517.12 Hz Gain -4.68 dB Q 3.73

 

[amirm]

... with all that distortion?

These don't seal on the fixture and so some of that could be low frequency ambient noise. At higher frequencies, distortion is actually extremely low:

Look at the 1 KHz+ at 94 dBSPL. It hugs the zero line. That is where our hearing is most sensitive.