AKG K60 Vintage Headphone Review

[GXAlan]

The paper has this graph:
View attachment 373778

Further, they show another huge resonance starting around 5 kHz would explain why that response is pulled down as well

Interestingly, there is a 5 kHz dip in the ML5909 in the digital mode where Harman can go all out with DSP using their internal knowledge rather than the published smoothed curve. I wonder if that is intentional?

That photo of the “in ear” mic is super cool.
It really shows that as measurement gear gets better, you can design better headphones.

Some people like tubes, no one says that the K60 is *better* than a modern headphone. Just an interesting one.

The same is true with speakers. As we got better measuring tools, we get better performing products.

 

[InfiniteJester]

I suspect that new algorithms that personalize the audio for your HRTF, your room, your head movements, the music you are listening to and so on in real time will soon make what we regard now as excellent no much better than these "vintage" headphones.

 

[LTig]

[..] The headphones that were around 60 years ago simply weren't that great sounding. At least not the ones I know of from that time period.
Many of them were just some small 8ohm radio speakers (often even paper cone) in an enclosure with plastic pads with foam in them.
Only Sennheiser was really being 'novel' with their foam on-ears. [..]

I had a fair bunch of Sennheisers in my "career":

• My father bought a HD 414 in the 70ies. I didn't like it after a while (no bass, mid centric)
• When I had enough money I bought a HD 424 which wasn't as shouty.
• In 1979 I bought the HD430 (which I still own) which had more bass and smoother treble.
• In 1994 a auditioned a HD-580 precision of a colleague. It sounded so real with organ music I thought that the speakers ware running in parallel, so I bought one as well.
• In 2014 the cable of the HD-580 got connection problems (it was the 2nd cable) so I checked new headphones and ended up with a HD800, due to it having the same deep bass like the AKG K812 and a very wide soundstage (However after @amirm tested the AKG K371 I stumbled over a cheap brand new AKG K371bt (same price as the non-bt) and realized that its deep bass betters the HD800 significantly - all without EQ).

So I think the mid centric sound profile of the K60 was rather the norm in its time. Also most people at that time had small bass anemic speakers at home and wouldn't know how bass sounds in the first place.

 

[restorer-john]

So I think the mid centric sound profile of the K60 was rather the norm in its time. Also most people at that time had small bass anemic speakers at home and wouldn't know how bass sounds in the first place.

I have quite a decent collection of vintage headphones and you're correct- most have a squawky sound to them. Not even one comes close to a modern AKG in any respect. They look awesome, but most sound like complete ass.

People need to consider the only small drivers available in quantity and low enough price to produce headphones mainly originated from the pocket transistor radio segment and variations of that.

Most medium cost headphones sold in the mid 70s were based around paper/mylar coned 2-1/4" alnico magnet based derivatives. Only a few companies went the path of building specific drivers based on some sort of research. The big Japanese companies produced some at the tops of their ranges which were reasonable, but I've never heard anything built in the 1970s I could live with other than as a prop alongside a vintage piece.

These AKGs reviewed are truly hideous, looking like half an aviation headset and half a Marconi operator look. But cool for a collection I guess. And great to see them reviewed in 2024. I highly doubt there is anything much wrong with the drivers themselves. Sure, any foam inside or used as damping will have turned to dust, but sometimes you find a pair that has defied the odds and looks like new.

 

[temujin44]

perfect for podcasts!

 

[solderdude]

I had a fair bunch of Sennheisers in my "career":

• My father bought a HD 414 in the 70ies. I didn't like it after a while (no bass, mid centric)
• When I had enough money I bought a HD 424 which wasn't as shouty.
• In 1979 I bought the HD430 (which I still own) which had more bass and smoother treble.
• In 1994 a auditioned a HD-580 precision of a colleague. It sounded so real with organ music I thought that the speakers ware running in parallel, so I bought one as well.
• In 2014 the cable of the HD-580 got connection problems (it was the 2nd cable) so I checked new headphones and ended up with a HD800, due to it having the same deep bass like the AKG K812 and a very wide soundstage (However after @amirm tested the AKG K371 I stumbled over a cheap brand new AKG K371bt (same price as the non-bt) and realized that its deep bass betters the HD800 significantly - all without EQ).

So I think the mid centric sound profile of the K60 was rather the norm in its time. Also most people at that time had small bass anemic speakers at home and wouldn't know how bass sounds in the first place.

The HD430 indeed was again an increase in sound quality/tonality:

The HD580 is indeed a step in the good direction of another order:

The connections were indeed an issue but only a small jewelers screwdriver is needed to fix that for the next 10 years or so.

Not much progress from there though HD600 and HD650 just were slight variations on the HD580, more cosmetic than sound quality

When you want to upgrade from the K371 the new HD620S should be on your list.

Just like with Sennheiser, AKG also only did small steps in the good direction after the K400.
The K500/501/601/701/702 were not really big steps anymore but rather refinements. Mostly in better bass extension and slight changes in the top end.
Of course those are the most difficult areas to improve upon (low bass and treble).. mids are relatively easy to get right ... and yet.. some headphones still manage to not do that right.

 

[Bob101]

requires a new category above '1' poor in the poll.
One could call it '0' awful.

That said, most headphones of that era probably did not measure well compared to today's standards.

Mould

 

[restorer-john]

The K500/501/601/701/702 were not really big steps anymore but rather refinements.

Massive difference between the K500/501 and the K601/701/702. I have them here. The K500 was awesome back in the day when I compared it to Sony MDR CD-333/555/777, but they are all long gone due to pad rot (back when only original pads were available and cost a fortune from Sony).

 

[uwotm8]

the AKG K371

I hope yours are still good. Mine K361 earpads pleather torn apart after less than a year. Worst pleather so far I ever dealt with.
Q701 I owned in ~2014-2020 were just another league in both sound quality (if equalized - out of box tune is very specific) and build.
K361 sound is acceptable if you buy these with typical Harman 50% discount for like under $70 (and needs EQ as well but they sound cheap regardless). Hype train went crazy with these.

 

[LTig]

I hope yours are still good. Mine K361 earpads pleather torn apart after less than a year. Worst pleather so far I ever dealt with.

My K371bt earpads pleather started to rot this year.

 

[Vict0r]

Okay, these didn't age well, but look at them! I think they look amazing!

 

[PuX]

K371bt

it may sound strange but the BT editions are not really similar to actual K371.

I have K371 and K361BT.
the pads on K361BT disintegrated in ~1 year, the glue is a weak point, the seams come apart.
but K371 is fine so far.
also they sound different and feel different, the materials and moulds are not the same. cup size/depth as well.

 

[Robbo99999]

Ha, that's a funky *ss frequency response! One of the craziest!

 

[Robbo99999]

Here are some thoughts about the EQ.
Please report your findings, positive or negative!

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 (and other constrains) with a fixed complexity.
  This will avoid weird results if one only optimizes for the Score, start your journey here or there.
  There is a presentation by S. Olive here.
  It will probably flatten the Error regression doing so, the tonal balance should be therefore more neutral.
• The EQs are starting point and may require tuning (certainly at LF and maybe at HF).
• The range around and 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 (loss of Dynamic range) need to be carefully considered to avoid issues with, amongst other things, too low a Max SPL or damaging your device. You have beed warned.
• Not all units of the same product are made equal. The EQ is based on the measurements of a single unit. YMMV with regard to the very unit you are trying this EQ on.
• I sometimes use variations of the Harman curve for some reasons. See rational here and here
• NOTE: the score then calculated is not comparable to the scores derived from the default Harman target curve if not otherwise noted.

Vintage!
Not great L/R match.

I have generated one EQ, the APO config file is attached.
Score no EQ: -5.2
Score with EQ: 85.5

AKG K60 APO EQ Flat@HF 96000Hz
June072024-170645

Preamp: -10.00 dB

Filter 1: ON PK Fc 47.5 Hz Gain 7.46 dB Q 0.79
Filter 2: ON PK Fc 76.7 Hz Gain 11.42 dB Q 1.12
Filter 3: ON PK Fc 111.7 Hz Gain -15.76 dB Q 1.52
Filter 4: ON PK Fc 287.0 Hz Gain -12.13 dB Q 0.76
Filter 5: ON PK Fc 1142.5 Hz Gain 8.36 dB Q 1.34
Filter 6: ON PK Fc 4160.4 Hz Gain 5.73 dB Q 1.22
Filter 7: ON PK Fc 6192.6 Hz Gain -6.69 dB Q 5.00

View attachment 373642

Just NO, stop it!

 

[Robbo99999]

I suspect that new algorithms that personalize the audio for your HRTF, your room, your head movements, the music you are listening to and so on in real time will soon make what we regard now as excellent no much better than these "vintage" headphones.

I hope so!

 

[Bruce Morgen]

View attachment 373632
View attachment 373634
View attachment 373633

When I was -- very infrequently -- attending sessions at Atlantic's studios in NYC, the headphones given to the musicians were uniformly crappy off-brand junk. IOW, back in day headphone SQ was not a consideration for the performers, even at famous recording venues -- those 'phones were just there to keep everything synchronized.

 

[ElJaimito]

I have a pair of 1970's Koss Pro 4AA in a drawer somewhere (as well as 5s). Truly awful sound for something supposed to be Professional (but very well made). We are lucky nowadays.

 

[bullshoy55]

Considering how there was not much in terms of measurement equipment available during the development of this headphone, they're actually surprisingly close.

(They're not close *at all*, but imagine having to come up with a speaker design for headphones without being able to use an ear simulator during development..)

I think the brain is an ear simulator.

 

[solderdude]

I think the brain is an ear simulator.

Please explain further .... what is your train of thought here ?

 

[Sean Olive]

This is a review, listening tests and detailed measurements of the AKG K60, circa 1970s, new old stock headphone review. It is on kind loan from a member and costs US $170.
View attachment 373622
I am stunned how fresh, new and clean this headphone is! It feels like you have gone back in time. Owner sent this to me as AKG Vienna was supposed to have built this based on research:

View attachment 373623

Sounds kind of like how Harman researched headphone preference. Let's see where they got.

AKG K60 Headphone Measurements
They say a picture is worth a 1000 words:
View attachment 373624
I guess their research told them the main thing we care about is 100 to 500 Hz which considering that is vocal range, maybe that makes sense.

I am ignoring the bass distortion as that is high due to lack of output:
View attachment 373626

Take caution in looking at absolute distortion levels when the response is not flat:
View attachment 373627

Group delay is bizarre:

View attachment 373628

Impedance is quite high:
View attachment 373629

Sensitivity is slightly better than average:
View attachment 373630


AKG K60 Listening Tests
Listening to my first track, produced the muffled, "closed in a box" sound that you would expect. Interestingly, it was not annoying. It was a clean midrange response.

Conclusions
We have come a long way as far as knowing what a good headphone could be. Clearly a lot of bad ideas were going around decades back, even with good intentions in research and design.

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

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HD414 from the same time period. These were quite comfortable though. (target = horizontal line)

and a Roelofs from the same time period:

and a 2015 (€ 5.-) headphone below

The science behind it is strongly featured in the advertising as "humanized" listening where they measured the headphone placed on humans using a probe mic inserted in the cup. But apparently they didn't bother to carefully ask the humans how it sounded?