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AKG K240 55 Ohm Review (Headphone)

PuX

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I have a new old stock pair (bought it like 25 years after it was made, had to replace the foam), K240S is indeed not even close.

quite likely it is heavily dependent on the amp though - at 600 Ohm it's a difficult headphone to drive and without a proper amp the sound will probably be bass light or have other frequency differences etc.
 

Blank Verse

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I have a new old stock pair (bought it like 25 years after it was made, had to replace the foam), K240S is indeed not even close.

quite likely it is heavily dependent on the amp though - at 600 Ohm it's a difficult headphone to drive and without a proper amp the sound will probably be bass light or have other frequency differences etc.
It's funny you talk about the amp requirements for the K240M, because it really is relatively easy to drive in my direct experience. There is a legend that it needs a nuclear reactor to be powered and it is simply not true. I just got a few comments in a Youtube video of a famous reviewer censored because I told him he was incorrect, it is a very sensitive matter and many people become offended.

I am listening to it right now from a mid 2000s Sigmatel DAC mp3 player that runs off an AAA battery and I can't notice any differences between this source and my O2/DAC. At the O2/DAC, 10:00 on low gain gets me enough power, more than this would be bad for long listening sessions.

I think some portable sources might not be a good match for the K240M and would sound dull, but the headphones are not really too hard to drive unamped if you find the right portable source. They are around 93dB/mW, not too bad.

The HD600 is much more sensitive and people claim the HD600 needs an amp also, which is even more nonsense.
 

Joe Smith

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Yeah, easy to drive with a decent amp, but just not good-sounding. So many other better options out there.
 

PuX

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It's funny you talk about the amp requirements for the K240M, because it really is relatively easy to drive in my direct experience.
you don't mean for it to become loud, right?

because that's not the objective and could be done with portable sources, but the sound still wouldn't be right.

I might try it with some other source, like a laptop just to see if it's horrible or not.

The HD600 is much more sensitive and people claim the HD600 needs an amp also, which is even more nonsense.
maybe it sounds fine without one, but the benefit from a good amp is still there.
 

Blank Verse

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you don't mean for it to become loud, right?

because that's not the objective and could be done with portable sources, but the sound still wouldn't be right.

I might try it with some other source, like a laptop just to see if it's horrible or not.
I am sure there are plenty of portable sources that will give a really bad result if you combine them with the K240 Monitor, I am just saying that this is not necessarily the case. The power requirements to make a headphone like the K240 Monitor sound well are vastly overrated.

How much power do you think you need to drive a 600 ohm 94dB/mW headphone like the K240 Monitor to 100 dB (which is louder than I can listen to)? There is enough energy in a rechargeable AAA nimH battery to power a headphone like that under those conditions for about 100 hours, except that most of the power is lost in the wire, the mp3 circuits, and due to the internal resistance of the battery. But in reality the amount of energy needed to power a headphone like that to reasonable levels is miniscule.

maybe it sounds fine without one, but the benefit from a good amp is still there.
What benefit would that be? I can guarantee you that if you do an A/B blind test between a good portable source (even a battery operated mp3 player) and a transparent amp like the O2, the results would be statistically insignificant. This is all a myth in my experience.
 

PuX

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How much power do you think you need to drive a 600 ohm 94dB/mW headphone like the K240 Monitor to 100 dB (which is louder than I can listen to)? There is enough energy in a rechargeable AAA nimH battery to power a headphone like that under those conditions for about 100 hours, except that most of the power is lost in the wire, the mp3 circuits, and due to the internal resistance of the battery. But in reality the amount of energy needed to power a headphone like that to reasonable levels is miniscule.
really depends on the implementation.
look at USB dongles. they are wildly different in terms of power output. so making a good portable amp is of course possible. O2 that you mentioned is sort of portable by the way, you could use it with batteries.

What benefit would that be? I can guarantee you that if you do an A/B blind test between a good portable source (even a battery operated mp3 player) and a transparent amp like the O2, the results would be statistically insignificant. This is all a myth in my experience.
O2 is good but not amazing by today standards (100db of SINAD).
if you take one of the top level DACs from 2020-2021, pair it with an amp of the same level, you will get ~20db more than with O2 in terms of SINAD.
or a few more bits of information.
if your music is 16 bit, the benefit is low. with well recorded 24 bit music, this extra 20db of SINAD gives you a chance of getting more musical information.
 

Cbdb2

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really depends on the implementation.
look at USB dongles. they are wildly different in terms of power output. so making a good portable amp is of course possible. O2 that you mentioned is sort of portable by the way, you could use it with batteries.


O2 is good but not amazing by today standards (100db of SINAD).
if you take one of the top level DACs from 2020-2021, pair it with an amp of the same level, you will get ~20db more than with O2 in terms of SINAD.
or a few more bits of information.
if your music is 16 bit, the benefit is low. with well recorded 24 bit music, this extra 20db of SINAD gives you a chance of getting more musical information.

Information thats not audible. Prove otherwise.
 

PuX

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Information thats not audible. Prove otherwise.
I can never understand people who dislike the idea that audio equipment can be meaningfully improved.
why would they come here? the whole point of these reviews is to show in hard umbers that some of the products perform better than others.
whether you can guess 10 times of 10 which is better by ear is irrelevant. some can't tell coke and pepsi apart, that's their problem.
 

Andretti60

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F70E000F-3018-4781-A910-6BDD71B86BD1.jpeg
I found this forum looking for a review of this headphones.
The AGK K40 was the first piece of audio equipment I bought with my own money, saving all my allowance, in the late seventies, at that time AKG was making professional mic and only two headphones model, the small K40 and the K240 that were worth a fortune. I was so happy with my tiny K40 that I used for more than a decade, until I finally bought the original K240mkii in the early 90s when they were still made in Austria, I think I paid almost 300US$ for them.
They still remain my reference headphones, they still work great, no injuries at all (they were really well made) only the tiny piece of metal with the AKG logo from the side got unglued (I should still have it in one of my drawers, never minded put it back). Other than that, the leather and the foam is still the original, cable and connector have survived years of abuse.
Since then I bought countless headphones, but they still remain my favorite, personal feelings are in play here.
 

600_OHM

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There is a "trick" to know about the K240 current models (not super sextet vintage). It wasn't designed for sonic-accuracy, but has more to do with ear-protection and desensitization as a general purpose monitor (not final mixer or anything like that).

Aside from frequency response characteristics, there is a weird timing (group delay difference possibly - dunno) purposely added to "chop off the leading edge of high-energy spikes", and also etch or dither the high end to enable long term monitoring. That is, so you don't end up in the desensitize and turn up the volume loop over and over.

So, things like gunshots, and especially metallic strikes are toned down and dithered. Or somebody plugging in a hot guitar into the board slowly and your cans are on. Stuff like that.

For rock music, you'll notice if you listen carefully, the initial "strike" of a cymbal is muted or gone. All you hear is the cymbal "ring". And that ring is dithered so all cymbals sound the same. Strikes on the drums themselves are also muted. Funny to watch and listen. Everybody seems like a jazz musician using brushes.

Classical - you'll never hear the initial strike of the triangle. Only a weak muted ring being struck by a child's energy. Again, most cymbals all sound the same dithered.

Test track: Try listening to Procul-Harem's "Whiskey Train" at a rocking (but not dangerous) level, where they are striking what seems to be cowbells and glass bottles. If you aren't listening with K240's, chances are you won't make it to the end, or if you do, be unable to hold a conversation afterwards. :)

So I believe this timing trick to mute the leading edge of strikes, along with dithering, is what allows the unit to be worn for seriously long periods of time. But that doesn't make for good advertising - we're protecting your ears.

So not my daily drivers, but I do use them occasionally for an entertainment factor, to hunt down little things I might miss with more accurate cans!
 

600_OHM

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Visually, I found this graph from years ago about the group delay differences between Left and Right. I saw a similiar link in an earlier post, so if this isn't cool, let me know. It is for the MKII which is merely a slightly different color, and velour pads and coiled cord as an addition.

Pads? I prefer the velour just to take some of that overblown mid-bass hump off without eq'ing it.

It's the only set of cans where the group delay goes in opposite directions right from the very start. Is this what is chopping off the high-energy transients? I'm no expert, so this is just a guess. Weird that I ONLY see this on the K240.


Personally, I wouldn't waste time trying to EQ or fix the K240. It has it's own groove baked in, I think on purpose, not due to poor quality. Still, I only wear them to have a good laugh, or hunt down lost notes or weird little noises in tracks burned into the soul.
 

solderdude

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Neither Amir nor Rtings nor me measured a weirdly or substantially deviating group delay (in any of the AKG). Also not between L and R.
gd-k240.png

For rock music, you'll notice if you listen carefully, the initial "strike" of a cymbal is muted or gone. All you hear is the cymbal "ring". And that ring is dithered so all cymbals sound the same. Strikes on the drums themselves are also muted. Funny to watch and listen. Everybody seems like a jazz musician using brushes.

Yes... the recessed 1-6 kHz region is the reason for the 'muted' sounds. The coarse (not dithered) treble is caused by the emphasis from 6 to 10kHz.

These semi-open headphones are intended for monitoring/tracking only. Not for mixing, production, reproduction. A (cheap) tool in a studio.
 

600_OHM

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Ah, look below 20 hz (not that it would be at all audible). There seems to be something beyond just frequency response hiding that initial strike say of a cymbal going from tick-crash to just crash.

These were designed back in the days when people always said "needs more cowbell!" :) Hence the ultimate test-track of Procul-Harum's "Whiskey Train" and being able to have a conversation afterwards..
 

Jimbob54

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There is a "trick" to know about the K240 current models (not super sextet vintage). It wasn't designed for sonic-accuracy, but has more to do with ear-protection and desensitization as a general purpose monitor (not final mixer or anything like that).

Aside from frequency response characteristics, there is a weird timing (group delay difference possibly - dunno) purposely added to "chop off the leading edge of high-energy spikes", and also etch or dither the high end to enable long term monitoring. That is, so you don't end up in the desensitize and turn up the volume loop over and over.

So, things like gunshots, and especially metallic strikes are toned down and dithered. Or somebody plugging in a hot guitar into the board slowly and your cans are on. Stuff like that.

For rock music, you'll notice if you listen carefully, the initial "strike" of a cymbal is muted or gone. All you hear is the cymbal "ring". And that ring is dithered so all cymbals sound the same. Strikes on the drums themselves are also muted. Funny to watch and listen. Everybody seems like a jazz musician using brushes.

Classical - you'll never hear the initial strike of the triangle. Only a weak muted ring being struck by a child's energy. Again, most cymbals all sound the same dithered.

Test track: Try listening to Procul-Harem's "Whiskey Train" at a rocking (but not dangerous) level, where they are striking what seems to be cowbells and glass bottles. If you aren't listening with K240's, chances are you won't make it to the end, or if you do, be unable to hold a conversation afterwards. :)

So I believe this timing trick to mute the leading edge of strikes, along with dithering, is what allows the unit to be worn for seriously long periods of time. But that doesn't make for good advertising - we're protecting your ears.

So not my daily drivers, but I do use them occasionally for an entertainment factor, to hunt down little things I might miss with more accurate cans!
By what mechanism do you think they do this transient chopping? Or are they just a bit dull in the high end?
 

600_OHM

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I have to find an old old reference I had. Somebody said that there is a brain-trick going on to protect your ears that involved group-delay being different in each ear at the beginning. So things like gunshots, hot-mics, drumstick tips, triangle/cowbell strikes miss that initial strike.

Seems to match what I hear. I've used them for a long time, but always knew "something just isn't right" and it wasn't about frequency response per-se.

So when I saw that other chart with the group delay going in opposite directions (apparently at practically dc levels, not audio) and seemingly only for the K240, it put what I was hearing into perspective.

But solderdude is probably right. That other chart, or my misunderstanding of it could be in doubt.
 

solderdude

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Ah, look below 20 hz (not that it would be at all audible). There seems to be something beyond just frequency response hiding that initial strike say of a cymbal going from tick-crash to just crash.

Below 14Hz is inaudible anyway.
All you effects you mentioned is (limited and wonky) frequency response related.
Somebody said that there is a brain-trick going on to protect your ears that involved group-delay being different in each ear at the beginning.

Group delay between L and R is quite normal. Frequencies below 14Hz are not present in recordings anyway and the wavelength is incredibly long there anyway.

No group delay issues... only FR.
 

nyxnyxnyx

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What are the differences between the current K240 versus the old Sextett/gold ring vintage K240?
Simply put, if audio quality is concerned, which one performs better?
 

solderdude

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Differences in impedance (600 ohm vs 55 ohm) and frequency response are the main differences.
The only thing they really have in common is the name and looks.
 
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