AKG K371 Review (closed back headphone)

[Robbo99999]

Compared these to the HD600 very briefly the other night.
I think some other people mentioned the bass sounds a little disconnected and the treble isn't quite smooth (sounds like there are some peaks that come across a little unnatural) and I agree with that. The HD600 sounds considerably more linear with some sort of crazy magic in the midrange that just sounds right, for lack of a technical description. Although subbass is rolled off, I didn't find myself missing what the K371 offered in that area.
I wish I could explain the feeling of "natural" that the HD600 conveys. There'll be a technical explanation somewhere....just the right peaks in the FR, adhering to the appropriate targets....but it's crazy that a 24-year-old headphone can still go toe-to-toe with the most well-informed headphones we have today.

The K371 is great. Nothing (detail, transient response, timbre) felt lacking enough to bump it against anything under $1k. I know the measurements reflect this, but it was really cool to analyse the differences between the two. It helped me to appreciate both the HD600 and K371 even more.

Yeah, that's right, the HD600 is stunningly beautiful in the midrange even without EQ, it was the stand out feature for me (even though it's not my favourite headphone).

 

[Adahn]

The k371's one and only problem for me is the damn cable. Every little movement gets picked up and amplified right in your ear.

If anyone found a replacement cable that fixes this, please do share.

 

[Adahn]

The coiled cable is terrible, totally useless because of the microphonics. Other two that came with the cans are OK.

Didn't notice any difference between them tbh. All 3 equally microphonic, all 3 terrible.

 

[LTig]

I couldn't resist when I saw Thomanns offer to get the K371bt for €139 (down from €200):

• I wanted a better closed headphone than my worn down AKG K271 studio
• I wanted a BT headset.
  Yes, the K371bt has a built in microphone which works very good (had a short Teams call with my wife, and her voice sounded good to me as did mine to her). The only clue I have where it might be located is a tiny hole 2 cm above the micro USB port on the left side.
  All 3 supplied cables though have a standard 3.5mm connector for stereo headphones, so I think the microphone is not usable via Cable. Which may makes sense since it needs power for the builtin preamp which is powered when you switch on BT.

I EQ-ed it with my RME ADI-2 PRO fs as follows:

1. low shelf 40 Hz -2.0 dB Q=1.0 (I prefer a little less bass)
2. PEQ 180 Hz -2.0 dB Q=0.9 (made it sound clearer to me)
3. PEQ 2.2 kHz +1.5 dB Q=1.0 (like @amirm)
4. PEQ 3.9 kHz +4.0 dB Q=4.0 (like @amirm)
5. PEQ 6.8 kHz -3.0 dB Q=4.0 (like @amirm)

After this the sound is really very good, especially for a closed headphone. Deepest bass is outstanding.

 

[the_brunx]

My biggest complain about the new AKGs (made in China), is that unfortunately the build quality seems to have taken a nose dive compared to the older AKG models which were one of the most robust professional headphones imo. my K371 pair has a broken headband. and when I took off the earpads and looked at the silver drivers they have small deformation spots and when I played around with the ear-pads to see in detail how its made and seeing the white foam from behind, it all left me with a disappointed taste in my mouth it just look so cheap. I just cant see them stand the years of abuse which comes with most professional day to day work as the older ones did. but they do sound like a true reference closed back. Sadly its like AKG has gone the beats by dre type of build quality route since beats are the profit kings. even the headband design of these reminds me of beats by dre mixer

 

[the_brunx]

My brand new AkG juste broke. Second defect in one month, first one was the wired speaker that did not work. Not sure they will cover it this time again.
Advice: stay away from this!
View attachment 121748

That looks like the exact same spot mine was broken. I have the wired version though.

 

[markanini]

I blame AKG for thinking they could use a design that's sensitive to tolerances and corner cutting while contracting Chinese factories to manufacture it to a price.

 

[maty]

REVIEW / MEASUREMENTS: AKG K371 (closed-back, over-ear, dynamic driver) - An affordable, modern, standard studio headphone. (And on using the miniDSP [H]EARS rig.)

http://archimago.blogspot.com/2021/04/review-measurements-akg-k371closed-back.html

 

[LTig]

Didn't notice any difference between them tbh. All 3 equally microphonic, all 3 terrible.

Funny. On my K371bt the coiled is terribly microphonic, the short cable is better while the long cable is quite decent actually. Look and feel of the short and long cable is identical, the coiled cable is thinner and somewhat more (!) stiff which IMV is the cause of problem.

 

[Adahn]

Funny. On my K371bt the coiled is terribly microphonic, the short cable is better while the long cable is quite decent actually. Look and feel of the short and long cable is identical, the coiled cable is thinner and somewhat more (!) stiff which IMV is the cause of problem.

Could be different batches. The pair I got here is very recent, barely a couple months old. So, if anything, they're getting worse.

 

[LTig]

Could be different batches. The pair I got here is very recent, barely a couple months old. So, if anything, they're getting worse.

Mine are brand new, got them not two weeks ago.

 

[DivineCurrent]

Well, I have completely changed my mind about the K371 now. Really all I needed to do was EQ the 70 Hz region a little bit, and the bass is seriously good and linear. The slight dip at 70 Hz gives the impression of detached bass, so that was my main issue with them. And on top of that, I played around with the midrange and treble, and to be honest I prefer it to the Focal Elegia now. If anyone is interested, here is yet another EQ profile I came up with to better balance out the sound to my own ears, testing with sine sweeps and comparing to my other open back headphones:

Preamp: -3.7 dB
Filter: ON PK Fc 70 Hz Gain 2 dB Q 1.5
Filter: ON PK Fc 2300 Hz Gain -1.5 dB Q 2
Filter: ON PK Fc 7200 Hz Gain -2.5 dB Q 5
Filter: ON PK Fc 9500 Hz Gain -2 dB Q 5
Filter: ON HSC Fc 13500 Hz Gain 2.5 dB Q 0.8

 

[umbral]

This is a review and detailed measurements of the AKG K371 closed-back headphone. I purchased this last summer and it currently costs US $149 on Amazon including shipping.

Note: our company, Madrona Digital, carries various Harman brand products although not the AKG products.

The K371 is made out of plastic but has a nice finish which belies its cheap structure:

View attachment 107868

I especially like the feel of the pads. They are not huge but big enough to fit around my ears. Inside height of the pad is 2.51 inches. Inside width is 1.62 inches. With no depression, the pad depth to the driver is 0.8 inches. Outside diameter of the pad is 4 inches by 3 inches.

Three different cords are supplied which terminate into a 3-pin mini-XLR:

View attachment 107869

Let me warn you about something I hate about these headphones: the headband adjustment mechanism. It either gets stuck and doesn't move at all. Or all of a sudden moves a bunch of notches. I also see reports of the mechanism failing which means you have to send them back to Harman/AKG for repair (you pay shipping even under warranty).

Clamp pressure is a bit much especially if you wear glasses at first but gets better with some use. When I take them off, the pads are quite warm so likely in summer, they will not be comfortable if your room is not cool.

Note 1: The measurements you are about to see are preformed using standardized GRAS 45CA headphone measurement fixture. Headphone measurements require more interpretation than speaker tests and have more of a requirement for subjective testing as a result. In addition, comparison of measurements between different people doing it using different configurations requires fair bit of skill. So don't look for matching results. Focus on high level picture.

Getting the K371 seated did not require much work and indeed, measurements track some of the others I have seen using same fixture as I use.

AKG K371 Measurements
As usual we start with frequency response of K371. They are said to follow the Harman target. Let's see if that is the case:

View attachment 107870

This looks to be closest we have gotten to the target. Indeed in sub-bass where vast majority of headphones fall off, the K371 actually overachieves a bit. Then again the Harman fixture is a bit different than what the rest of us use so maybe in their fixture that was right on the money. Either way, during equalization and listening tests we will investigate this further.

Following down the curve, we have a dip around 3.8 to 3.9 kHz. It is a shame as past that the response envelop more or less follows our target.

We can subtract the response from the target and see the deviations:

View attachment 107871

Distortion is better than average:

View attachment 107872

The 94 dB line in blue shows extremely good performance. That keeps up even at 104 dBSPL.

Edit: forgot to include the absolute measurements:

View attachment 108584

Group delay gives us some clues to things going wrong with manifested in frequency response graph:
View attachment 107873

We get similar clues in impedance versus frequency:
View attachment 107874

This is a very sensitive headphone so don't need much horsepower to drive it:

View attachment 107875

AKG K371 Headphone Listening Tests & EQ
First impression was a very good response albeit, with a tad too much bass and a bit of exaggerated highs and harshness. You really had to listen to find these though. I also found the vocals to be a tiny bit recessed. Overall, you could listen to these headphones and be perfectly fine without any equalization.

But we, at least I, want perfection so let's apply a bit of touch up as instructed by the frequency response:
View attachment 107876

I first boosted the lower treble and while that opened the sound up and nicely increased detail, the sound became somewhat bright. So I went after one of the peaks at 6800 and pulled that down. That fixed most of that. I initially had the bass pulled down some as you see in Band 1 crossed out above. I turned that off as it nicely countered the slightly sharpness that was left. Once there, this headphone was absolutely delightful to listen to. I could only find the slightest amount of harshness left (which could be magnification of what is in the music).

It was such a pleasure to listen to music with deep bass with and without EQ and hear those notes resonate in my ear even at very modest playback levels. Tracks like
Nachtschwärmen, by Regen:Tropfen were stunning in their impulsive bass notes:

And so was the rest of the spectrum. Notes come from every end of spectrum at no time do you say, "oh, why is that too high or too low." It is all balanced to near perfection.

Spatially without EQ the experience is fine. My boost of the lower treble however helps a lot here to get very good "soundstage" and layering of instruments. Mind you, it is not crazy nice like that if Sennheiser HD800s and such but it is "correct" and satisfying.

Conclusions
Some of you have been asking, even demanding to see a headphone that does the job without EQ. Well, the AKG K371 is it. My equalizations of it are subtle (but worthwhile) so you could indeed live without it. I do however highly recommend that you deploy EQ if you can.

You could say I am rubber stamping the Harman research and approach to headphone tonality. But such was not the case. I went into this review critically and thinking hard about what rating to give the headphone. I almost notched it down one step to avoid accusation of bias. But at the end, the truth is the truth. Years of research by Harman has resulted in creating headphone tonality that matches what I dream about getting out of best speakers in the world. To the extent their research goes after that sound (tonality of a good speaker in the room), it is natural that Harman and I land in the same spot.

Note that my strong positive recommendation for AKG K371 is for sound only. Physically, this headphone may not do it for you. It may get too hot around your ears, and the adjustment mechanism may annoy you or break. I leave that to you to decide.

------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Thank you for this wonderful review.
Can anyone say what is the best method to use equalization for these headphone on Windows 10 ? Using what program ? What settings should i use ?
How can this equalization be made only to headphones and not the speakers ?

Thank you.

 

[LTig]

Thank you for this wonderful review.
Can anyone say what is the best method to use equalization for these headphone on Windows 10 ? Using what program ? What settings should i use ?
How can this equalization be made only to headphones and not the speakers ?

Thank you.

See here. For the settings see @amirm's settings in Roon or my settings in posting #349.

 

[Yorkshire Mouth]

A quick question.

I prefer velvet-feel earpads, and I see you can get some velour ones here:

https://www.brainwavzaudio.com/collections/oval-memory-foam-earpds/products/ath-m50x-velour-earpads

Are they likely to impact on the sound?

 

[Robbo99999]

A quick question.

I prefer velvet-feel earpads, and I see you can get some velour ones here:

https://www.brainwavzaudio.com/collections/oval-memory-foam-earpds/products/ath-m50x-velour-earpads

Are they likely to impact on the sound?

I think so, even worn pads vs new pads of the same pad design will show different frequency responses.....and certainly different pad designs & materials will change the frequency response....by how much and where is the question, and unless the headphone is measured with the different pads then you won't know. That's why I don't like using non-stock pads with headphones, because if you use different pads you can't rely on the measurements that are already out there for your headphone (eg Oratory/Crinacle/Amir).....and that therefore means you can't accurately EQ your headphone using those measurements. So I think it's best to use stock earpads and then EQ based on the available measurements.

 

[Jimbob54]

I think so, even worn pads vs new pads of the same pad design will show different frequency responses.....and certainly different pad designs & materials will change the frequency response....by how much and where is the question, and unless the headphone is measured with the different pads then you won't know. That's why I don't like using non-stock pads with headphones, because if you use different pads you can't rely on the measurements that are already out there for your headphone (eg Oratory/Crinacle/Amir).....and that therefore means you can't accurately EQ your headphone using those measurements. So I think it's best to use stock earpads and then EQ based on the available measurements.

IMHO the "harm" done by non stock pads to the FR and the ability to EQ based on accurate measurements pales into insignificance if the non stock pads make for a more comfortable experience.

 

[Robbo99999]

IMHO the "harm" done by non stock pads to the FR and the ability to EQ based on accurate measurements pales into insignificance if the non stock pads make for a more comfortable experience.

I've never found stock earpads a comfort problem on any of my headphones, so I can't really empathise with discomfort....it's true that some pads feel really nice as soon as you put them on, like my HE4XX, but then you forget about the initial feel as you wear them, as long as there's not some significant discomfort issue. For me getting the sound quality right is far more important than just a "nice" feel for the first few seconds after you've put them on. Changing the pads negates the measured frequency response, if that's not important to you, then fine, the person has to weigh up all the pros & cons.

 

[Yorkshire Mouth]

So I’m guessing an obvious question is this.

Someone must surely have measured a pair of phones with different pads (hopefully Amir).

What’s the ‘worst’ measured negative effect on sound? Has it ever been measured as completely screwing things up, or do the measurements usually onlyv show a small difference?

if a large difference has been measured, is there any correlation with they type if change made, for example dies the size make a bigger difference, or the material used?

 

[Robbo99999]

So I’m guessing an obvious question is this.

Someone must surely have measured a pair of phones with different pads (hopefully Amir).

What’s the ‘worst’ measured negative effect on sound? Has it ever been measured as completely screwing things up, or do the measurements usually onlyv show a small difference?

if a large difference has been measured, is there any correlation with they type if change made, for example dies the size make a bigger difference, or the material used?

Have a look over here:
https://www.reddit.com/r/oratory1990/wiki/index/list_of_presets
Oratory has measured at least one headphone with aftermarket pads. It's gonna come down to difference of the pad & the headphone measured, there is no "worst case" to speak of with any relevance.