[meatling]

Hi all,

a couple days ago I bought a new, shrink-wrapped K 701. Just today, after checking a few bass sounds with my synth I began suspecting that not all is well with these cans.

I then tried a sine sweep (20-60 Hz @ -1 dBFS) and confirmed that there's a kinda buzzing sound emanating from the right driver, which definitely isn't part of the signal. For demonstration purposes (when possibly returning the cans to the store where I bought them) I tried this with a tiny iRiver MP3 player, and voila, even this puny gadget can apparently drive the K 701's speakers to the point of breaking up. NB, the iRiver sports 12 mW per channel, and the K 701's rated input power is 200 mW.

Now I remember that I've had the same problem many years ago with an ancestor of those cans, I think it was the K 500 if memory serves. Back then it was the Yamaha SY77 Synthesizer that had me scurrying back to the dealer with those phones.

And I'm beginning to wonder, are my new 701 broken, or is it more likely that AKG headphones simply aren't made for Rock & Pop where they might encounter more bass than, say, from a string quartet?

Thanks for reading and for your opinions.

 

[JaZZ]

No, that's not normal. But you may check if there's some debris on the membrane. Remove the pad (by turning it counterclockwise) and the inner foam to have a look at it. It's also possible that something's sticking in the foam and touching the membrane.

If the problem isn't solvable that way, bring/send it back for an exchange!


BTW, welcome to Head-Fi!

.

 

[MCC]

Both my HFI-680 and HD-595 had a similar problem out of the box. The Ultrasones had a bit of loose plastic behind the driver and the Sennheisers had a defective driver. If you do take it apart be careful so that you can exchange them if needed.

 

[jcx]

if the voice coil isn't properly centered you can also get rub - sometimes break in can relax mechcanical stress or just wear off high spots of glue/varnish and it could go away

very low frequency drive can cause over excursion and the voice coil former can simply bottom out - if its different on one driver then you have a case for return/replacement to get better matched/aligned drivers

 

[meatling]

Thanks for your comments, and for the welcome

I looked like JaZZ recommended, but it's as clean as a whistle. Also, wouldn't it have to buzz all the time if there were debris in the case, by and large independent of pitch?

It doesn't do that. It happens only with bass, and actually I couldn't positively reproduce the phenomenon with pre-recorded music. Like I said, I noticed when playing bass lines myself, directly from the synthesizer.

I never had any such problems with my beyer DT770 Pro, but then again I suspected I don't hear all the detail with those headphones: That was the reason to get the AKG in the first place.

I will definitely return this 701 to the store. I'm just not sure whether to try the same again.

 

[ffrr]

Quote:

Originally Posted by meatling /img/forum/go_quote.gif Thanks for your comments, and for the welcome I looked like JaZZ recommended, but it's as clean as a whistle. Also, wouldn't it have to buzz all the time if there were debris in the case, by and large independent of pitch? It doesn't do that. It happens only with bass, and actually I couldn't positively reproduce the phenomenon with pre-recorded music. Like I said, I noticed when playing bass lines myself, directly from the synthesizer. I never had any such problems with my beyer DT770 Pro, but then again I suspected I don't hear all the detail with those headphones: That was the reason to get the AKG in the first place. I will definitely return this 701 to the store. I'm just not sure whether to try the same again.

eh, every manufacturer has issues from time to time. Stories like yours are rare. Give em another shot. You won't be sorry.

 

[Mr.Sneis]

The internal soldering on the k701 is a little spotty in my experience, it's likely a bad joint somewhere.