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AKG K60 Vintage Headphone Review

Rate this headphone:

  • 1. Poor (headless panther)

    Votes: 123 92.5%
  • 2. Not terrible (postman panther)

    Votes: 5 3.8%
  • 3. Fine (happy panther)

    Votes: 1 0.8%
  • 4. Great (golfing panther)

    Votes: 4 3.0%

  • Total voters
    133

amirm

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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.
AKG K60 Vintage headphone review.jpg

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:

AKG K60 Vintage headphone advertising.jpg


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:
AKG K60 Vintage Headphone Frequency Response Measurement.png

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:
AKG K60 Vintage Headphone relative THD Measurement.png


Take caution in looking at absolute distortion levels when the response is not flat:
AKG K60 Vintage Headphone THD Measurement.png


Group delay is bizarre:

AKG K60 Vintage Group Delay Measurement.png


Impedance is quite high:
AKG K60 Vintage Headphone Impedance Measurement.png


Sensitivity is slightly better than average:
Best vintage headphone review 2024.png



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.

------------
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/
 

Attachments

  • AKG K60.zip
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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.
 
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

Code:
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

AKG K60 APO EQ Flat@HF 96000Hz.png
 

Attachments

  • AKG K60 APO EQ Flat@HF 96000Hz.txt
    412 bytes · Views: 34
Last edited:
Weren't the extremely heavy but popular Koss Pro 4AA 'phones from this period similar in mid to upper balance (maybe there was more low bass in this latter though)?
Yes, they were awful, weren’t they? Headcrushers, I used to call them! I’d like to see the brilliant original Sennheiser HD414 alongside the AKG as I’m pretty sure I got mine in about 1971.
 
Massdrop 99 Noir:
Massdrop 99 Noir Dashboard.png
 
As soon as I saw the graph, the phrase came to mind, “What are you listening to?”
 
Yes, they were awful, weren’t they? Headcrushers, I used to call them! I’d like to see the brilliant original Sennheiser HD414 alongside the AKG as I’m pretty sure I got mine in about 1971.
HD414 from the same time period. These were quite comfortable though. (target = horizontal line)

hd414-fr.png


and a Roelofs from the same time period:
fr-dh-09s.png


and a 2015 (€ 5.-) headphone below
pulse.png
 
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..)
 
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