CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS

Lobby => Headphone Measurements => Topic started by: Marvey on July 14, 2013, 07:12:02 PM

Title: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Marvey on July 14, 2013, 07:12:02 PM
AKG K550 Revisited

Background (about one year ago):
Today:
Moral of Story:
(http://www.changstar.com/index.php?action=dlattach;topic=1053.0;attach=3516;image)

^ Yeah - pretty good, huh? Compare to RD's #2 AKG550 (http://www.changstar.com/index.php/topic,373.0.html)
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Marvey on July 14, 2013, 07:28:46 PM
CSDs

I don't know what's up with the L driver ringing at 3k. Don't hear anything deleterious, but it could be something loose. (took rig apart and L measurement several times)
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: munch on July 14, 2013, 09:24:35 PM
other than strange matching at like 2k? ish? that looks pretty goshing good.
any idea if the K551 sounds the same and has less unit-unit variance? that would make these an OK rec I think?
as I assuuuume the K550 is discontinued because of K551?
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Deep Funk on July 14, 2013, 09:35:36 PM
You have found the tasty chocolate in the box.

Impressive frequency response...
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: CEE TEE on July 14, 2013, 10:20:04 PM
Thanks for measuring these, purrin.  I do not plug them into amps, just enjoy them occasionally out of an iDevice.  Two other pairs of K550 that I have heard could easily get annoying for us with that weird peak.  These don't have the same issue the other two did and I like the sound sig.  Very interesting to see the Left side ringing.  Will have to see later if I can pick that out.  (Glad it's on the left rather than the right as I probably attenuate HF in my left ear a bit.)
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: AstralStorm on July 14, 2013, 11:01:47 PM
I concur, there are at least three kinds of AKG K550s, I've had both tried in the same shop, which is ran by an AKG fan.

1) Subbass dropped bright shrill one, not really broken but terrible.
2) Subbass dropped but not ringy.
3) One that sounds almost exactly like a good Beyerdynamic DT 1350.

The one here is the third kind, the one in the former thread presumably the first?
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Rabbit on July 15, 2013, 02:25:58 PM
I have found that the K550 works better from 120 ohms output impedance. I know that many think that the effect is very subtle but it does seem more 'natural' in the treble region when the output impedance is higher.

At near zero, I find it a little on the thin, edgy side but put in some resistance and it takes that sharp edge down a tad.

Astralstorm, with those three 'versions' of sound you were getting, were they all produced recently or were any of them the first batch? There are always stories about headphones being quietly modded or whatever, but to have three versions of the same headphone seems to show up poor quality control if they were made around the same time.

Especially seeing the ringing that Purrin has seen in the left cup but not the right.
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Marvey on July 15, 2013, 04:25:19 PM
Samples I've heard:
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Rabbit on July 15, 2013, 06:33:48 PM
Samples I've heard:
  • HeadRoom: Absolutely horrible. Will destroy your hearing.
  • RD #1: Only heard the modded version, which was still horrible. I assume when unmodded - as horrible as the HeadRoom K550.
  • RD #2: Slightly better than the above, but still horrible.
  • CT: Pretty good.

Yes, it's very weird. Looks like the same problem that the Beyer DT1350 seems to have. ie: quality control. Or else, it has been quietly 'developing' as a headphone. (I doubt that though since once they're designed, the companies tend to leave well alone unless there's a real problem)

Mine is one of the first out in the UK. Tomorrow, I'll have a new one so I'll compare the two.

I have my amp set at 100 ohms out and that seems to calm the sting in the top. (It's a valve amp as well)  It still has its lively top end, but not as 'stabbing'.  No bloom on mens' voices and yet it shows some really very deep bass on some recordings too. (So no hump in the mid bass to colour mens' voices)

I guess the K550 is on its way out since it's now being sold quite cheap over here in the UK but if they are so variable, you're not guaranteed a good one.

Mine doesn't seem bad in spite of being one of the first over here.

I tend to have to wear it quite 'high slung' in order to ensure a good seal as well. Higher than my other headphones anyway - so that the bottom of my earlobes are just touching the inside of the pads - I find I get a robust bass in that position.

I wonder whether the CT one is a more recently made headphone?
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: CEE TEE on July 15, 2013, 07:56:44 PM
I believe it was made around the same time, I have had it for about the same time as the RD ones. 
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Rabbit on July 16, 2013, 10:09:34 AM
I compared mine with a new one directly today. There ARE subtle differences, but it could be the pads. The new pads are slightly more full.

The result is the NEW one has a slightly less rounded sound. My old one is more mellow.

I'm not over fussed about the question of burn in (although I have heard things with some headphones, not all) but it could be down to pad thickness perhaps?

The new one seems to lack bass and is edgy. If I turn up, the bass appears, but the sound is too edgy but the old one goes up more comfortably so you feel that there is a better bass.

So, I'll whack the new one with sound for a day or two in order to see whether the treble calms (allowing me to develop more bass) or whether the bass actually forms better after a while......

It's not a massive difference and I'm not able to exactly pinpoint what's different, but there is a difference.
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: donunus on July 16, 2013, 10:54:04 AM
You were probably one of the lucky ones that got a good one in the first place Rabbit
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Rabbit on July 16, 2013, 03:14:54 PM
You were probably one of the lucky ones that got a good one in the first place Rabbit

Yes, could be. One difference is the pad thickness though. The older ones are slightly thinner and that could affect the bottom end.

Or ..... they do actually vary!!
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: jupitreas on July 16, 2013, 03:59:41 PM
It is such a shame that there are these production variances with the K550 as I still consider them to be the most comfortable and best looking headphones I've had... The pair I had was probably one of the better ones as I did not experience ear-piercing ringing and the bass was very good, although the sound was a little 'zazzy', to use Tyll's vocabulary. I eventually got rid of them because they are just too big and delicate to be used as portables and I bought a HD600 at a bargain price at the time (making the closed circumarual AKG redundant for listening at home).

As most of you probably know, the K550 is the first headphone by AKG that was not manufactured in Austria and they instead chose to outsource it to a Chinese OEM. I'm guessing this must be the reason for the poor quality control and I'd buy a "made in Austria" K550 in a heartbeat if AKG decided to move production there (perhaps K552?). I think I'd even sell the HD600 to pay for it.
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: DaveBSC on July 17, 2013, 01:03:09 AM
FWIW, Tyll seems to significantly prefer the K267 to the 550.
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Maxvla on July 17, 2013, 06:58:16 AM
The pair I heard at Austin 2013 sounded very good. Reminded me of a cheap HD800. Refined and smooth, detailed but not that detailed. Good soundstage but not as good center imaging. A can I could honestly settle for if I had to cut back. I heard it through my X-Sabre and unbalanced out from BHA-1.
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Solderdude on July 17, 2013, 07:34:14 AM

Yes, could be. One difference is the pad thickness though. The older ones are slightly thinner and that could affect the bottom end.

Or ..... they do actually vary!!

Did you..

A: swap pads between the 2 and see (hear actually) if the sonic signature swaps along with the pads.
B: apply more 'clamping force' on the bass-light version to see if it is a 'seal' problem.
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Rabbit on July 17, 2013, 10:43:14 AM
I didn't swap the pads but I did the 'pressure' test. Fact is they both warm up slightly with pressure. So the new ones sounded more like the first with pressure and the first got even warmer with pressure.

My gut feeling is that it was a pad thing.
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: funkmeister on July 18, 2013, 04:48:13 AM
As most of you probably know, the K550 is the first headphone by AKG that was not manufactured in Austria and they instead chose to outsource it to a Chinese OEM. I'm guessing this must be the reason for the poor quality control and I'd buy a "made in Austria" K550 in a heartbeat if AKG decided to move production there (perhaps K552?). I think I'd even sell the HD600 to pay for it.

The K272HD was being made in China before the K550 was even announced. I know because I bought one a couple of years ago. The label said "Made in P.R.C." My K171 Mk II was made in Austria and I love it for voice work but the K142HD I have for casual listening was made in China as well.
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: roBernd on July 18, 2013, 09:30:23 AM
actually, several other headphones were manufactured in China before the release of the K550. Several low-fi AKGs as well as the K601 (later production)
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: wildstar on July 18, 2013, 11:36:06 AM
Earbuds are headphones too (K315)!
(http://i.imgur.com/XSUYISw.jpg)
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Solderdude on January 26, 2014, 10:30:52 AM
Here is the K550 that was sent in for K551 modifications.

(http://diyaudioheaven.files.wordpress.com/2014/01/k550-stock.png?w=614&h=324)

CSD...

(http://diyaudioheaven.files.wordpress.com/2013/12/k550-csd-r.png?w=614&h=317)
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Solderdude on January 26, 2014, 09:28:05 PM
With the mods as described in the K551 article:

(http://diyaudioheaven.files.wordpress.com/2014/01/k550-modified-version.png?w=996)

I smuggled a bit and used 1/12th smoothing on this plot  ;)
More importantly it sounds excellent !
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: funkmeister on January 28, 2014, 11:56:58 PM
Wow... I guess driver matching has become less critical over at AKG. It doesn't look too bad but I still expected better.

The mods look great, though.
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Solderdude on February 04, 2014, 08:09:25 PM
Got another K550 in.

(http://i837.photobucket.com/albums/zz296/solderdude/k550davestock_zpsc1a8e2c7.png) (http://s837.photobucket.com/user/solderdude/media/k550davestock_zpsc1a8e2c7.png.html)

AKG needs to work on their quality control  ::).
3dB level difference in the mids and the behaviour above 3kHz differs considerably.
The differences with this one are even bigger than those of my K551 and the other K550 that was sent in.

Will have to check if the differences between L and R in the mids aren't due to leakage of the cable entry in the left cup.  :-S
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: CEE TEE on February 04, 2014, 08:54:57 PM
^I have heard three pairs and two were more annoying in that area.  I'm going to spend some time with mine and consider doing the mods!
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Solderdude on February 05, 2014, 02:19:55 PM
Modified !

(http://i837.photobucket.com/albums/zz296/solderdude/K550modifiedL-R_zpsdae95720.png) (http://s837.photobucket.com/user/solderdude/media/K550modifiedL-R_zpsdae95720.png.html)

This one came with a solid silver headphone cable (VERY microphonic and stiff)
It was open anyway to paly with the resistor values in the filter (22 Ohm in this one) so soldered (thin) copper wires to the drivers as well and routed them through the sheath and soldered a plug to it.
This way I could leave the headphone on the test rig and simply change the plug in the amp.
Results below:
(http://i837.photobucket.com/albums/zz296/solderdude/k550davelsilver-copper_zps6546fc97.png) (http://s837.photobucket.com/user/solderdude/media/k550davelsilver-copper_zps6546fc97.png.html)

This was the left stock driver, blue = silver wire, orange = copper wire,
The reason you see only one trace (the blue one) is because they measure the same.

(P.S. don't mind the Ohm scale on the right I forgot to remove it as it serves no purpose here)
Title: Re: AKG K550 Revisited - A WTF moment which may finally stop the arguing
Post by: Deep Funk on February 05, 2014, 03:21:34 PM
The spike looks scary.