[Citizen13469]

Hello all, first post..
 
I recently picked up a pair of K550 factory refurbished phones and thought they had potential. I generally liked the overall signature, but as many others report I found the bass light. I ALSO was not overly impressed with the sound stage. I spent about a week fidgeting with them, putting cord in the earcups, using the rubber band trick trying to get a good seal holding them closed etc. Eventually I felt they were pretty good and was somewhat happy.
 
It should be noted that I own the Sony MA900, Beyer DT770, Sennheiser Momentum, Sennheiser Amperior and Shure SRH940. For home listening with open backed phones I am completely happy with the Sony MA900's (got these after returning a pair of Senn HD598's, the Sony were just nicer to my ears). I've also auditioned lower to mid level Grado's the HD650 etc.
 
Anyway, back to the K550's. After seeing a few threads during the week about possible different versions of the K550 or the product line having quality control or silent upgrades I ordered a pair of new 551's. They've been sitting here unopened for 3 days. Basically I thought there is no way there could be that much variability and was skeptical of people saying so. So I didn't open them.
 
After fidgeting more with the 550's, tonight I opened the 551's and immediately noticed they sound quite a bit better than the 550's I have. I have had to do zero fidgeting to get a seal etc. Just plopped them on my head and they sound a lot better. Bass is greatly improved and highs sweeter.
 
I now believe that AKG has either quality control issues or has silently updated these phones. This would sort of explain the widely varying opinions on these cans having no bass or other tonal issues. I now am more inclined to think that getting a seal and fit issues are LESS of the problem and that the issue really is something with quality control of the components.
 
Has anyone else had a couple of pairs and encountered such a drastic difference in them? One last thing, playing all audio thru Fiio X3, flac files typically. Home system for Reference is Tannoy System 10 DMT II's and also Yamaha MSP 10's to give you an idea of the type of sound I "like".
 
Thanks. 

 

[ProtegeManiac]

It's possible that the K551 has different/more dampening material/volume inside the earcups. Or, the headband material may be different. Both bass (lack thereof) and fit on smaller heads have been raised about the K550, and AKG could have done both tweaks. From a business standpoint however the headband tweak makes more sense - it will not only help the fit, but the sound also (since, ideally, the sound will be its best/truest to the drivers' capabilities when the fit is at its best also).
 
 
BTW I did get to test them back-to-back, albeit briefly, last November at the local Hi-Fi show (what I really wanted to test was both on the X3 vs my SGS3), and didn't notice any difference. Then again I never had any issues with the K550's fit, so it might be possible that in your case that might be it - did your fidgeting with them involve bending the headband?