3.2 Sound (vs. K 340)
(19 Feb edit: Added a note to the end about the K 340 and velour pads.)
('Claimer: I'm comparing two vintage cans. As always, two or three decades of use has an effect on how a pair of headphones sound, so there's no guarantee that your pair would sound the same as mine.)
The K 340 was AKG's top of the line pair of headphones in the late 70s and early 80s. It's got an electret driver doing frequencies above 4 kHz and a regular dynamic unit for the lesser frequencies. Popularity for the K 340 on Head-Fi seems to have peaked around 2006/7.
The K 250 (echoing ideas from the rest of this thread, for those who haven't read it) is an odd duck, or whichever animal you prefer. AKG doesn't admit to ever having made them. Most people have never heard (of) them, most Head-Fiers who are into vintage haven't owned them, and half the people who think they have are confusing it with the Realistic Pro 50.
My source for this comparison was the Auzen Bravura (LME49720NA opamp). I believe the amp on it represents your decent, average headphone amp. Nothing fancy, nothing bad. 'Get it on a budget and be happy with its performance' kind of thing.
I'll start off by presenting notes that I took of specific songs while comparing these cans head-on. The notes contain some liberal figures of speech, but that's the nature of notes to begin with.
Carbon Based - Xerosis (electronica)
K 340: The soundstage feels 3d and layered: things in the background (behind), things in the middle and things in the foreground. The foreground seems more in focus. Makes an interesting effect with electronic music; multi-layered.
K 250: Soundstage is less interesting; sounds more matter-of-fact (instruments are presented to you for scrutiny, not for you to enjoy them with a beer in your hand). About as detailed as the K 340, but sounds more accurate.
Vintage DT990 (brought in for a guest appearance): Most detailed of the three. Soundstage not as 3d as on the K 340. Most aggressive sound of the three. Best of the bunch for this type of music (though the K 340 is pretty good too).
Ulver - Østenfor Sol Og Vestenfor Maane (acoustic)
K 250: Instruments seem to receive sharp focus individually. Vocals sound very natural. Soundstage is too small for this type of music (layered acoustic guitars).
K 340: Seems to be more about building a unified image of sound than to individually present the instruments. Song benefits from the larger soundstage – the instruments feel so well placed in the 3d stage that one could touch them. Vocals sound a bit less natural than on the K 250.
Some sections of this song seem a bit overlayered, with lots of vocals and guitars going off simultaneously. Both phones struggle a bit to image those passages, but the K 250 does a better job.
Agalloch - ...And The Great Cold Death Of The Earth (metal/acoustic)
I use this song often to test the PRaT of headphones. If the guitars at the beginning sound like the player is slightly overeager and playing slightly faster than the tempo of the song, I know the phones have good energy. With more laid-back phones, the playing sounds sluggish.
K 340. A bit sluggish. The soundstage feels over-separated between left and right – it's the nature of the song, but the K 340 emphasizes it too much. Imaging is less precise than on the K 250.
K 250: Good energy. Better imaging than on the K 340 – the K 250 seems to lift each instrument onto its own place, not mixing them at all, while the K 340 flattens that separation of individual instruments somewhat. I think I hear the K 250 giving the acoustic guitars a more natural sound, but I'm not totally sure; the K 340 offers them better body, but I think the K 250 has better timbre.
Taake - Nattestid Ser Porten Vid VII (metal)
K 250: Very good PRaT. Better highs (drums) than on the K 340; they sound more forward and present, while the K 340 has them veiled a bit; more detailed and quicker. Good imaging; the vocals are separated well from the wall-of-sound of the guitars.
K 340: Sound is dark and a bit boxy compared to the K 250. Not as energetic, not as good PRaT; but at the same time less sibilant.
This song sounds totally different depending on which pair of phones you choose. The K 340 has a dark, nasal quality to it, while the K 250 sounds a bit harsh in the treble but gives the song the aggressiveness I think it needs – not to mention the very good PRaT, again.
Russian Circles - Harper Lewis (post-rock)
I use this song to gauge the bass response.
K 250: Bass notes in drumming aren't as detailed as on the K 340; sounds like there's just one type of bass sound the drummer gets out of his kit.
K 340: Good bass texture to the drums, more detailed than the K 250; though there may be a bit of boominess.
I also wanted to test classical music, but I don't have my collection of classical anymore since I stopped listening some years ago. My best bet unfortunately was YouTube, where I was able to find some 720p samples of Anne-Sophie Mutter playing Vivaldi's Spring. The following notes are based on that:
I think the K 250 does the violin better than the K 340; sounds as if it has better dynamic range, more emotion. But I can't quite decide whether the K 250 renders the violin a bit too thin, lacking a bit of body. With many instruments playing at the same time, the K 250 separates them notably better than the K 340, which tries more to blend them into a single sound; the K 250 better retains each instrument's own character. Not sure if I'd specifically recommend either headphone for classical music, but the K 250 seems to do better based on this quick sampling of classical stuffs.
[Frequency response graphs]
These were measured by me, and are only indicative in nature. The lines have 1/3 octave smoothing. Black is K 250, pink is K 340.
You may find another (more reliable) measurement of the K 340 by Tyll
here – but I believe the pair measured was possibly bass-lite rather than my assumedly bass-heavy one.
The pair of K 340 in this post has had its cotton completely taken out. No other mods were done.
[Overall description of what we're up against]
The fundamental difference between the K 250 and the K 340 (or the pairs of them that I have) is this: the K 340 has a laid-back (or pushed-back), dark, slightly lush sound, with the listener reclining on their brown leather sofa; while the K 250 is about accuracy and clarity, with the listener alert at their console in the studio.
That's a difficult starting point for a comparison – I don't think these two cans were made for the same purpose. Regardless, I'll compare them (I've already started).
[Mids]
I've heard people say good things about the K 340 mids. It's a bit strange that they should have good mids, considering what the frequency graph looks like (my graph above is smoothed and so masks the many spikes in it, but see the other graph I linked to). But the K 340 shoot the graphs down and have good mids anyway. Likewise, the mids on the K 250 sound pretty good as well.
When you get down to it, I'm not sure how much difference there is in these two headphones when it comes to the mids. I hear a difference, a clear one, but I don't know how much of it is due to the fundamentally different characteristics of these headphones; the K 340 being a bit dark while the K 250 being a bit trebly. The mids seem quite similar when you subtract in your mind that difference.
Having said that, I think I like the mids on the K 250 a little bit more. But it's a difficult choice. The K 250 renders vocals better in my opinion, but I think they may sound a bit too lean. The K 340, on the other hand, gives vocals a bit more warmth, but muddles them up just that much. The K 250 sounds more natural, but that's just me.
[Bass]
The K 340 have bass; the K 250 don't. To simplify.
I think I own the bass-heavy version of K 340. They seem to extend a bit further than the pair that Tyll measured. I've taken out all the cotton from inside my pair, but I can still feel the bass hitting.
Listening to the song Harper Lewis (see above) on the K 340, I'm reminded a bit of the K 601. Those cans were awesome with this song. If I weren't a student, I'd have kept the K 601 just for this song. Really, really good bass on the K 601 for it, and the K 340 does it a bit similarly. The bass has good texture; I can hear and feel the varying acoustic shapes of the bass drum hits. I think it's not quite as snappy as I'd like, a little bloated, but just a little. And I don't think it's quite as good as the K 601, but similar.
The K 250, with that same song, just kinda don't do much with the bass drums. They almost ignore them. What they do is take the rest of the drums and give them very good snap – but since we're talking bass, no, the K 250 don't do much here. They're a lean pair of cans.
I'd like to say I prefer the K 340 for bass, but I'm not really a bass-head. I like a lean, accurate sound, which the K 250 give me. So I'll have to say I prefer the leanness of the K 250 over the more bassy K 340. But at the same time, the bass on my particular pair of K 340 is pretty good, so neither pair really loses here.
[Highs]
The K 250 are trebly, no doubt about that. But at the same time, I like its highs. They're relatively well detailed, and cymbals sound pretty good.
The K 340, on the other hand, is a bit dark as I've said (the pair that I have, in any case). It has pretty good and sparkly highs under the veil, but on the whole it sounds a bit ambiguous. Like there's good highs just trying to get out from under the veil, but can't. Cymbals sound very pleasing on the K 340 when they pass the veil.
I'm going to do something radical and take out the wild card. The vintage Beyerdynamic DT 990. This is the version made in the mid to late 1980s. I think it's got very good highs for being a dynamic headphone, and I don't think they're too far off the K 340 in terms of having real sparkle rather than the type of metallic pseudo-sparkle you usually get with dynamics of this level.
So, the K 250 and K 340 both have good highs. If you should like lots of treble (Grado types?), the K 250 is better; if you like veiled highs (Sennheiser types?), the K 340 is better. I prefer the vintage DT 990 for this, but like the K 250 highs over the K 340 ones, simply because they don't have a veil over them.
[Soundstage]
I'm pretty confident in saying that soundstaging is the best aspect of the K 340. They create a very nice sense of 3d space, which leads to some interesting layering effects in certain songs (the song by Carbon Based, for instance). But at the same time, it seems like this type of soundstage isn't so well suited for a wall-of-sound effect that I find (and like) a lot in metal. The soundstage's just too big (in three dimensions) to be filled with sound. (It's not that the soundstage is wide, just that it's got a relatively big volume due to the added depth.)
The K 250 has an interesting soundstage as well. They're semi-open phones (tiny holes at the back), and the soundstage seems a bit closed. Yet, at the same time, it feels airy. It's as if the instruments are placed so close around you not because it's a small soundstage, but because they simply are – because that was the natural way to place them. It seems rare that instruments collide into each other; they remain separated even when put onto this small stage. While I do think the soundstage is a bit too small, good imaging saves a lot and makes the soundstage work (for most things).
The K 340 has a better (and in fact very good) sense of 3d space, and for that I prefer it over the K 250. But, the side note again, if you like a forward sound, it won't make you happy at all.
[Imaging]
The strong point for the K 340 was its soundstage. The strong point for the K 250 is its imaging.
I need to hear an HD 800 to know what good imaging is, but until I do, I think the K 250 is the best I've heard. Instruments don't blur into each other, they don't seem confused as to where they should be, they're always crystal clear in their location. Different instruments laid on top of each other come out as clearly being two different things, and maintain their individual character.
The K 340 isn't much in the way of competition here. It has its good soundstage, but the imaging is just ok. Instruments are well-placed in three dimensions, but at the same time they run into each other a bit and seem a bit indistinct from each other.
I prefer the K 250.
[A quick word-let about wearing comfort]
The K 340 weigh too much, and the oval-shaped headband is strange. The K 250, on the other hand, are quite light and feel better (closer to normal AKG) on the head.
[Conclusion]
The K 250 seem to have been AKG's mid-level cans in the early 80s, based on the average type of box they came in (not much is really known about them). The K 340, on the other hand, came in a tall box and are built much heavier; they were top of the line.
In sound, however, the K 340 is a bit disappointing and the K 250 does better for itself.
I don't have the setup to get the most out of the K 340 for sure, and maybe I just have a lesser pair, but considering Tyll found the K 340 a bit off as well, I can't help but wonder... The K 340 used to be a big thing on Head-Fi, but the hype has apparently cooled down. Based on what I hear with my ears, they're not bad phones, but nothing truly amazing. Seemed to work best for electronica.
Why you might like the K 250:
+ neutral mids (and neutral bass, to some extent)
+ good energy and PRaT
+ good imaging
Why you might not like the K 250:
- lean bass
- small soundstage
- trebly
Why you might like the K 340:
+ bass seems well-textured
+ 3d soundstage
+ sparkly highs (when they happen)
Why you might not like the K 340:
- boring dynamics
- texture of sound on the whole is a bit dull
- slight boxy sound
(15 Feb edit: The pair of K 340 that I have benefit from a slight treble EQ, which helps lessen the boxy sound. With such EQ, they become more viable for enjoyable listening – but different pairs of K 340 seem to vary wildly in their sound, and you may find yours to be treble-heavy to begin with.)
(19 Feb edit: In this review, I found my particular K 340 too dark. I've now come to have found that by using velour pads instead of pleather makes the sound more alive, less veiled. The K 340 that way are still not as accurate or energetic as the K 250, but thoroughly best them in soundstaging, and, since the treble isn't so veiled anymore, have better highs.)
Edited by vid - 2/20/12 at 3:58am
You really want to get foam discs in there (or "Scheibe"s, as the 
