Help with history of AKG K160

Here's a little bit more about this model: http://20cheaddatebase.web.fc2.com/AKG/K160.html (Google can translate it into English.)

Basically the site seems to imply the K 160 was introduced in 1977 and discontinued in 1995 or 1996, although the translation may be inaccurate. There's also a price, 18 500 yen, about $220 today. I bought them for 15 euros off eBay.

First of all, I just love the funky AKG logo:

Sound-wise; man, these sound really muffled. Really muffled. My old K 141 sounds dark and smoky, but these are just something else. A thick blanket covering everything, and forget sparkle.

The AKG brochure says, "Powerful transducers for ... high energy bass," but there's not much bass to speak of either.

A lot of pictures I've seen on the internet have the driver grille visible through the holes in the pads, i.e. there is no foam in between. One picture, though, showed foam in there, so I thought I might add some in mine as well. The pads have a circular indentation inside, and the K 141 foam discs are almost the perfect size. This gives a little more bass and ties the sound together, much better. (What I wrote in the two paragraphs above was with the foams already in.)

Comfort is quite bad; a tight clamp and plastic pads (wouldn't even call them pleather). Still, I like the construction, very solid and minimal, although not a very typical AKG look.

What I really like about these phones, though, is that they seem to do human voices very well. Female vocals sound smooth, and I actually preferred them on the K 160 when I did a quick comparison against the K 271 S. Acoustic music seems quite nice, as does some lo-fi indie, like The Radio Dept's album Lesser Matters.

I do find that some EQ is in order, basically emphasizing the high frequencies by downplaying the mid and lower ones. Just way too muffled otherwise.

Nice cans.

Some of the screws on these phones were rusted pretty bad but I finally got them open.

Here's the rear end of the driver:

The construction is so delightfully no-frills. Simple plastic housing and not much in the way of empty space. Also, the back plates of the cups have some serious weight to them; the plastic is about 3 mm thick there.

The top of the driver is of some material that looks like cardboard to me:

It didn't occur to me to touch it to make sure, but it does indeed look like cardboard, which is a bit surprising. The driver capsule itself is glued(?) pretty solidly onto the front end of the cup.

I thought the phones had some nasty resonance going on, so I removed what little foam pieces there were in the cups, cut out two thin bits from a cotton pad and put them against the insides of the back plates. Helped with the resonance and the bass got a bit punchier, i.e. started existing. I'll get some blu-tack later and try that, too.

The cable has that strange German/Austrian würfel plug, i.e. a DIN with five pins in a cross pattern which, I believe, didn't take off in popularity after the 80s. The adapter plug looks DIY to the max, so I bought a new one; maybe that'll improve the sound and maybe it won't, but we'll see.

I still think these phones do vocals very well, as well as acoustic music. They're not immensely awesome or anything, and in fact they aren't that great overall, but for 15 euros it's not bad for those two things they do well.

I've been revisiting this headphone lately.

Going through the frequency range with SineGen, I noticed the K 160 are surprisingly free of peaks between 200 Hz and 7 kHz. Not ----------- flat, but no real peaks either. Above 7 kHz there's one notable peak at and around 9 kHz and two others at 11 kHz and 13 kHz – though my ears may not be the optimal measuring tool. (As I stated in earlier posts above, I've put some slight amount of cotton and blu-tack inside the cups, which helped eliminate a sort of echoing inside the cup.)

The soundstage is too small, but the default crossfeed DSP in foobar helps out tremendously.

The K 160 really are very inoffensive phones. Not sibilant in the least, though the sound is highly veiled. Bass has reasonable kick to it, doesn't sound flabby – but not much quantity to it either. Midrange is neat; human voices sound realistic and acoustic guitars are especially good. In fact (and I said this in the two previous posts above), simple acoustic music sounds surprisingly good – nothing sounds out of place or over/underemphasized.

If I switch on the vintage DT990s, the K 160 are brought to shame in just about everything (detail, soundstage, highs, bass...). Still, a curious and apparently not very common pair from AKG (and let's not forget the funky AKG logo on these).

More revisiting upon the K 160.

Here's the frequency response that I measured (ths is of the right channel):

Black line has 1/3 octave smoothing, light gray line is unsmoothed. I suspect the midrange hump is a bit exaggerated, but otherwise the graph is correct within reason.

I wrote in my last post that the K 160 is relatively flat until about 7 kHz, but the graph clearly combats that statement. The phones have that nice midrange hump, though the hump itself is smooth as I indicated. What I didn't note in my post is the absolutely massive drop-off at 1 kHz, which I do hear now. Explanation follows.

Here's the channel balance measurement (this is raw data, so don't take it as a frequency response graph):

Dark line is for the left channel, pink is for right. Blue line shows the absolute difference in dB between the two channels (the line is centered at -35 dB).

The black line there explains why I failed to grasp the 1 kHz dip in my last past. The K 160 has a very gross channel imbalance in that region; the left channel is neat while the right one does massive dipping (most likely aided by my having put a bit of blu-tack and cotton in the cups and not getting it symmetrical).

This is the impulse response for the right channel (this measurement is quite reliable, or should be):

Very light gray line indicates the signal.

So there you have it. AKG's mid-hump-backed K 160. Looking at that interesting triangle-based hump, I guess these phones were probably meant for monitoring people talking.