AKG K371 Review (closed back headphone)

[markanini]

Amusingly to some extent the mentioned HD600 are close match to Harman, barring the bass shelf. Many highly-regarded headphones which came out back before 2012 seem to be Harman-compliant to a higher extent than can be incidental (SRH840). Might be that Harman guys just put the idea into proper research and done the work to formalize it.

Besides Occam's razor, the stats provide some compelling evidence for this. https://github.com/jaakkopasanen/AutoEq/blob/master/results/RANKING.md Many headphones that are a close match to Harman were released before 2012, when the Harman target was introduced. I'm wearing a pair of Shure SRH440 right now. Introduced 2004, eight years before the first Harman paper, has a ultra high preference score of 95: https://www.dropbox.com/s/wq2c7tdt6kodkl1/Shure SRH440.pdf?dl=0

 

[solderdude]

I'm wearing a pair of Shure SRH440 right now. Introduced 2004, eight years before the first Harman paper, has a ultra high preference score of 95:

The SRH440A scores only 60.

 

[Feelas]

Besides Occam's razor, the stats provide some compelling evidence for this. https://github.com/jaakkopasanen/AutoEq/blob/master/results/RANKING.md Many headphones that are a close match to Harman were released before 2012, when the Harman target was introduced. I'm wearing a pair of Shure SRH440 right now. Introduced 2004, eight years before the first Harman paper, has a ultra high preference score of 95: https://www.dropbox.com/s/wq2c7tdt6kodkl1/Shure SRH440.pdf?dl=0

Apart from that, it's actually kind of mind-boggling that Sennheiser's HE-1 (the modern-day Orpheus) are Harman-voiced. Why would they choose this voicing does actually make sense, seeing HD600/HD650 response being in the same ballpark with typical bass issues of open-backed designs.

I'm seriously wondering whether in 10 years we won't be looking back at Harman as the "dead-end which looked promising".

 

[Robbo99999]

Apart from that, it's actually kind of mind-boggling that Sennheiser's HE-1 (the modern-day Orpheus) are Harman-voiced. Why would they choose this voicing does actually make sense, seeing HD600/HD650 response being in the same ballpark with typical bass issues of open-backed designs.

I'm seriously wondering whether in 10 years we won't be looking back at Harman as the "dead-end which looked promising".

I think in order to improve on the Harman Curve then another study would have to be done that was even more representative of the population, and maybe based on an initial Target Curve from a more anatomically accurate average mannequin and ear..........if that's possible, I suppose it is, but someone would have to determine what that would be and have it manufactured, and then carry out the study again. But all of that could be eclipsed in the future by personalised Target Curves & DSP based on head/face/ear scans perhaps to simulate accurately what Impulcifier and Smyth Realiser currently achieve, but with a lot greater convenience/speed and lower cost. I think the second option is the most likely, I'd be kinda surprised if Harman or anyone else redo the study and publically release the research and target curves again based on mannequin heads/ears. So I reckon we have Harman until the second option I was talking about becomes mainstream or properly workable...... (re good/fantastic results....speaker simulation in headphones).....if it ever does.

 

[nyxnyxnyx]

I think it's still hard to say what target is "right" and "truthful" because a pair of headphones does not solely rely just on FR.
I think about it this way: there are headphones perceived as great and "natural-sounding" by both amateurs and pros, musicians and what-else-you-name-it but the thing is between those headphones, there are both non-Harman compliant and Harman-compliant ones so I fail to see how it's just the FR target dictating everything else. And that's how I feel about the 371 because based on the names behind the product, the famed FR target, and other good selling points I thought it would sound way more amazing.

Another point is back when Amir measured and reviewed hd800 (or hd800s, I don't remember). He said he can't pin-point the exact factor that made the soundstage....hd800. The industry has already advanced a lot and debunked quite a great deal of nonsense but I'm still open to consider that maybe we haven't fully discovered and understood everything yet.

 

[Feelas]

I think in order to improve on the Harman Curve then another study would have to be done that was even more representative of the population, and maybe based on an initial Target Curve from a more anatomically accurate average mannequin and ear..........if that's possible, I suppose it is, but someone would have to determine what that would be and have it manufactured, and then carry out the study again. But all of that could be eclipsed in the future by personalised Target Curves & DSP based on head/face/ear scans perhaps to simulate accurately what Impulcifier and Smyth Realiser currently achieve, but with a lot greater convenience/speed and lower cost. I think the second option is the most likely, I'd be kinda surprised if Harman or anyone else redo the study and publically release the research and target curves again based on mannequin heads/ears. So I reckon we have Harman until the second option I was talking about becomes mainstream or properly workable...... (re good/fantastic results....speaker simulation in headphones).....if it ever does.

I wonder whether this discussion doesn't now necessitate a separate thread, lol.

Arriving at a "more anatomically accurave manequin and ear" could as well be better as to prepare different manequins for different population variants and then selling differently tuned models for a specific demographic. I believe that investing in easily available in-ear mics (perhaps even exposing the calibration mics in IEMs to be used independently by software) would be better in a longer timespan. Remember that there was Nuraloop with dynamic ear canal measurements for tweaks and also some developments. Simply put, feedback systems w/ dynamic calibration are the only way to go. Static calibration & tuning should go away.

As for the Impulficer, static speakers emulation is the best we can have without physical head tracking module, as I believe it is an integral part of Smyth's Realizer. Seems we're stuck paying a few thousand bucks to perceive 3D sound on headphones. Sad state of affairs...

... at least until someone works out on how to integrate dynamic mixing of sound into Jaakko's Impulcifer with some kind of freeware TrackIR-compatible simulation (like Freetrack), because that is essentially a well-known head-tracker for webcams (even cheap consumer ones) based on an IR filter and a really cheap DIY IR-based headset clip-on or a cap with diodes. I've used a DIY made by my dad to play around with Flight Simulator 2004 like ten years ago and it DOES work really well. Would sound reasonable to consider that Smyth is getting HRTFs of various angles for all of the speakers and then working with these. I don't know whether it would be easy to accomplish, but modern video games have very considerable soundspace simulation models. After all, it might be a matter of convolving channels w/ proper HRTF & then downmixing to stereo, but hey - I'm not a matter expert here.

I think it's still hard to say what target is "right" and "truthful" because a pair of headphones does not solely rely just on FR.
I think about it this way: there are headphones perceived as great and "natural-sounding" by both amateurs and pros, musicians and what-else-you-name-it but the thing is between those headphones, there are both non-Harman compliant and Harman-compliant ones so I fail to see how it's just the FR target dictating everything else.

Take what I write with a pinch of salt, since I'm not a certified sounds expert, nor a Masters/PhD in the matter.

The sound does depend mostly (and very importantly) on the FR, since it is the direct and complete (many other factors can be inferred from FR) measure of linear performance of a device. The working theory around ASR is that high-Q (narrow in frequency) high-energy peaks might be the reason of varying "details-resolving" performance between various headphones. Masking phenomena are known for like what, over 30 years now? That's why I brought upon the FR's smoothness.
THD & group delay are measures of non-linear performance aspects of headphones. THD is already low in modern headphones. THD was explicitly neglected in Harman's limitations of 2013 study. Fit issues end up being FR & THD issues. Also linking a study from 2014 on correlation of non-linear distortion vs listener preference. I didn't read that one before, but it's interesting to see that two-tone IMD on headphones can go up to 20%!

When bringing pro-audio market into the equation, remember that they *might* consider just buying anything that doesn't break after dropping it 2 meters high, the rest can be fixed in EQ to some extent if you need, as digital EQ is available everywhere. For monitoring, EQ-ing is very often not necessary (given that monitoring is a relatively narrow-band exercise) and mixing is done on speakers anyways, thus the context of recommendations & reviews is EXTREMELY important.

Whether impact of earpad size, depth & distance from ears has been extensively assessed in studies would be a good thing to research, as some have brought upon how HD800's have legendary soundstaging performance might be connected with their unique and unusual way of fitting the ears - this is the pair used in Smyth Realizer demos, maybe not without reason... Also, a disregarded but VERY important parameter is the L/R matching quality - very small deviations can cause sound localization issues (see https://www.mdpi.com/2076-3417/6/4/117); this work also brings previous works which connect FR with proper front/back spatial perception (see section 6.2, paragraph 3 on "front-back confusion").

Theory I subscribe to, which I don't remember seeing in full form (probably personal compilation of some papers), is that mismatch between one's HRTF and headphones FR is one of the crucial factors on how a pair will be perceived. Get a high mismatch between the headphones vs. HRTF of your daily life and see the disaster happening. Seems that VR-related studies like this one touch on this subject. Using headphones with a "wrong" FR should be similar to using a non-personalized HRTF (from a different person).

 

[SpaceMonkey]

Ordered K371 for the fun of it. They arrived and sounded weird. For some reason everytime I listen to them the soundstage would go to the left ear. Tested my hearing with HD600 and others. Hearing ok. So started suspecting phase inversion in one of the channels. measured on my highly unscientific stand where I obtained very similar measurements for both channels but phase in the right channel was inverted. Took a track, opened it in audacity and inverted one of the channels and listened on k371. Boom, soundstage was correct again.
So these are going back to Amazon.

P.S. These do sound nice but soo boomy for me at times. I just dont feel like playing the QC roulette to see if next ones are fine (as I was oblivious to the whole K371/K361 QC drama). Sigh.

 

[Feelas]

Ordered K371 for the fun of it. They arrived and sounded weird. For some reason everytime I listen to them the soundstage would go to the left ear. Tested my hearing with HD600 and others. Hearing ok. So started suspecting phase inversion in one of the channels. measured on my highly unscientific stand where I obtained very similar measurements for both channels but phase in the right channel was inverted. Took a track, opened it in audacity and inverted one of the channels and listened on k371. Boom, soundstage was correct again.
So these are going back to Amazon.

P.S. These do sound nice but soo boomy for me at times. I just dont feel like playing the QC roulette to see if next ones are fine (as I was oblivious to the whole K371/K361 QC drama). Sigh.

Wondering whether these are just from the old QC issues period or if there is a new one happening...

 

[markanini]

Wondering whether these are just from the old QC issues period or if there is a new one happening...

Yeah, I haven't heard of anyone getting an out of phase set yet, chances are your replacement would be correct. I sold mine because of fit issues. In @SpaceMonkey's case I'd just get a replacement and take advantage of the 30 day return policy.

 

[SpaceMonkey]

Wondering whether these are just from the old QC issues period or if there is a new one happening...

Pretty sure that some nice chinese lady just mixed up wires during soldering. Can't even blame her, soldering is tiring.

Actual responses are very similar for both channels, although distortion is slightly different. Not the crappy FRs k371s that the guy from Wheeze Tech posted on youtube.

 

[SpaceMonkey]

Yeah, I haven't heard of anyone getting an out of phase set yet, chances are your replacement would be correct. I sold mine because of fit issues. In @SpaceMonkey's case I'd just get a replacement and take advantage of the 30 day return policy.

I tried measuring my hd600 and k240df i have and they are just identical between channels. Even hd410, which is like 30-40 yo measure identical. My experimentation fire just burned out on k371s

 

[Robbo99999]

I think it's still hard to say what target is "right" and "truthful" because a pair of headphones does not solely rely just on FR.
I think about it this way: there are headphones perceived as great and "natural-sounding" by both amateurs and pros, musicians and what-else-you-name-it but the thing is between those headphones, there are both non-Harman compliant and Harman-compliant ones so I fail to see how it's just the FR target dictating everything else. And that's how I feel about the 371 because based on the names behind the product, the famed FR target, and other good selling points I thought it would sound way more amazing.

Another point is back when Amir measured and reviewed hd800 (or hd800s, I don't remember). He said he can't pin-point the exact factor that made the soundstage....hd800. The industry has already advanced a lot and debunked quite a great deal of nonsense but I'm still open to consider that maybe we haven't fully discovered and understood everything yet.

Well, the K371 does have a pretty big ommission in the frequency response from 3.3-4.8kHz:

I can imagine it lacking some pizazz when used at stock!

 

[nyxnyxnyx]

Well, the K371 does have a pretty big ommission in the frequency response from 3.3-4.8kHz:
View attachment 223513
I can imagine it lacking some pizazz when used at stock!

I did try to EQ it to oratory's target and some other minor adjustments people suggested on forums... I say 371 sound pretty nice both EQ or not.

 

[Robbo99999]

I did try to EQ it to oratory's target and some other minor adjustments people suggested on forums... I say 371 sound pretty nice both EQ or not.

Oratory EQ doesn't fully correct that dip though, still looks pretty significant even after EQ:

AKG K371.pdf

Shared with Dropbox

www.dropbox.com

I think that's enough that it wouldn't "sound amazing" - as you say you didn't think they sounded amazing. The soundstage variable and also how well they seal on your head is another variable that could throw a spanner in the works.....also unit to unit variation, I don't know how much the K371 varies between units. I mean I still think that the K371 can be a solid headphone if it fits you properly, just I wouldn't expect it to sound amazing.

 

[nyxnyxnyx]

Oratory EQ doesn't fully correct that dip though, still looks pretty significant even after EQ:

AKG K371.pdf

Shared with Dropbox

www.dropbox.com

I think that's enough that it wouldn't "sound amazing" - as you say you didn't think they sounded amazing. The soundstage variable and also how well they seal on your head is another variable that could throw a spanner in the works.....also unit to unit variation, I don't know how much the K371 varies between units. I mean I still think that the K371 can be a solid headphone if it fits you properly, just I wouldn't expect it to sound amazing.

IIRC I did try EQ it to oratory, ASR and another person's target. Then made some minor adjustments here and there out of curiosity and personalization. Not sure if I ever truly hit the the target perfectly because I don't have any headphones measurement kits.

Seal was no problem to me, it fits on my head very nice. It did not sound amazing and in the beginning I didn't expect it to, but after reading so many comments and remarks I think I did let my expectation run a bit wild, seeing how it's the most recommended closed-back headphones not just at this price range (~$200). I did say soundstage is a tad boxy and separation is not good but in all fairness I also experience that with many other closed-back headphones, from cheap to ridiculously expensive. My uneducated guess is it is one of the limitations of closed-back designs, especially the ones with small and/or narrow cups (that might also do not have proper internal damping).

I haven't tried pads swapping though, the original pads were comfy enough for me to not think about it.

 

[Robbo99999]

IIRC I did try EQ it to oratory, ASR and another person's target. Then made some minor adjustments here and there out of curiosity and personalization. Not sure if I ever truly hit the the target perfectly because I don't have any headphones measurement kits.

Seal was no problem to me, it fits on my head very nice. It did not sound amazing and in the beginning I didn't expect it to, but after reading so many comments and remarks I think I did let my expectation run a bit wild, seeing how it's the most recommended closed-back headphones not just at this price range (~$200). I did say soundstage is a tad boxy and separation is not good but in all fairness I also experience that with many other closed-back headphones, from cheap to ridiculously expensive. My uneducated guess is it is one of the limitations of closed-back designs, especially the ones with small and/or narrow cups (that might also do not have proper internal damping).

I haven't tried pads swapping though, the original pads were comfy enough for me to not think about it.

Closed backs do have a reputation for generally worse soundstage than open backs. I only have one closed back headphone (NAD HP50) to compare that theory, and 3 open backed headphones, and my soundstage representation from best to worst is K702 / HD560s / HE4XX / HP50 / HD600 - so the closed back didn't come last, the HD600 did, but neither did it rate highly for me on soundstage.....so there still could be something in the theory that closed back headphones generally have a worse soundstage than open backs. When I think of good closed back headphones though, I think of DCA Closed X & DCA Stealth, that's what I have in my mind based on what I've seen. If I could somehow get a cracking deal on a DCA Closed X I might get one, but it's not high on my priority list (& the Stealth is too expensive).

 

[Feelas]

I did say soundstage is a tad boxy and separation is not good but in all fairness I also experience that with many other closed-back headphones, from cheap to ridiculously expensive. My uneducated guess is it is one of the limitations of closed-back designs, especially the ones with small and/or narrow cups (that might also do not have proper internal damping).

I've got an idea here, actually - try to listen for a few hours on a tad lower volume than usual with the said closed-backs. Without proper volume matching it's hard to do a good soundstage assessment and it's oftentimes it's much easier to go overboard with closed designs. Saying from experience, depth & wideness is very much volume-bound. You'll also have a much better experience with 371's bass response when played at lower volumes (Phon curves do their thing).

Anyhow, a fun experiment to pull off, just to tune out to a lower volume for some days and see what happens then.

It's important to remember that FR is a static parameter, but our perception of it is dynamic and volume-dependent. And that's the reason why speaker calibration is done at standarized sound levels. Since Phons affect how we perceive loudness, the perceived dynamics (and potentially soundstage depth and wideness, since it depends on relative differences in volume apart from the time differences) might also be different at various listening levels. One more reason that one cannot really rely on subjective gear reviews.

 

[nyxnyxnyx]

Closed backs do have a reputation for generally worse soundstage than open backs. I only have one closed back headphone (NAD HP50) to compare that theory, and 3 open backed headphones, and my soundstage representation from best to worst is K702 / HD560s / HE4XX / HP50 / HD600 - so the closed back didn't come last, the HD600 did, but neither did it rate highly for me on soundstage.....so there still could be something in the theory that closed back headphones generally have a worse soundstage than open backs. When I think of good closed back headphones though, I think of DCA Closed X & DCA Stealth, that's what I have in my mind based on what I've seen. If I could somehow get a cracking deal on a DCA Closed X I might get one, but it's not high on my priority list (& the Stealth is too expensive).

I've tried a fair share of closed-backs and open-backs, imo I think you are right with the presumption. The lack of airiness and space to properly reproduce staging is my guess on why many close-backs suffer in this aspect. For open-backs I've only found the "egg-shell design" models from Hifiman like HE1000, the HD800/800s and Stax 007/009 to have truly spectacular soundstage and separation. The rest I may not remember clear enough right now, or they just aren't as good.
Right now I want to try close-backs from DCA/Mr.Speaker (his old models) and the D9200 from Denon. I've heard good things about them but unfortunately they're not popular in my area and there are no local dealers.

 

[nyxnyxnyx]

I've got an idea here, actually - try to listen for a few hours on a tad lower volume than usual with the said closed-backs. Without proper volume matching it's hard to do a good soundstage assessment and it's oftentimes it's much easier to go overboard with closed designs. Saying from experience, depth & wideness is very much volume-bound. You'll also have a much better experience with 371's bass response when played at lower volumes (Phon curves do their thing).

Anyhow, a fun experiment to pull off, just to tune out to a lower volume for some days and see what happens then.

I actually tried it at times. I like to mess with volume levels with some headphones to sort of feel a better grip of them, and to figure out if I want to EQ something more or less.

With headphones that have a 'boxy' soundstage, imo it does help to listen on lower volume and/or listen to music with fewer instruments, and generally well-recorded tracks. In my span with the 371 I enjoyed them with slow jazz and typical 'audiophiles' vocal. When I listen to those genre at moderate volume I felt like the shortcoming(s) of those headphones was well hidden.

Edit: I also think it has to do with the FR of those headphones too. One time I did cut the upper-bass area of 371 by 3-4dB or something and it felt a little more spacious and a tad leaner overall. I think the older AKG headphones had a reputation for being clear-sounding and spacious because they basically didn't have much bass, but I might be completely off the hook here.

 

[Feelas]

Edit: I also think it has to do with the FR of those headphones too. One time I did cut the upper-bass area of 371 by 3-4dB or something and it felt a little more spacious and a tad leaner overall. I think the older AKG headphones had a reputation for being clear-sounding and spacious because they basically didn't have much bass, but I might be completely off the hook here.

I think that cutting upper bass (what freq exactly?) like this might as well cause the music's dynamics to expand, since mid/treble/bass difference goes up. Did you compensate for the missing loudness from the cut range when checking this? In any case, there is this widely known connection between brightness and spaciousness and since there is no way to measure objectively, it cannot really be discussed whether it really yields a better soundstage or just a perception bias. K6xx and K7xx have also done some shenaningans in the general treble range (apart from lack of bass), which might've also contributed.