[mosi]

Somehow I can't quite get if my DT990 might be damaged or if this is by design.

I just found that with at least one track the bass seems to be distorting slightly at pretty loud volumes.
Its most clearly audible at the track Madonna - Mother and Father somewhere where there is just the baseline playing. It sounds like a very tiny membrane "flapping" in sync with the bass beats. The rest of the tracks I tried over the last several hours play perfectly fine and show no audible distortion.

My Ety's also don't show this but its present with the 990's from another source so that basically rules the source and amp out of the equation. It seems to go away when I cup my hands over the outer grill of the phones, essentially stopping them from breating.

Maybe its an unlucky combination of frequency and volume or something like that. The track sure is bass-heavy.

Did anyone else experience something like that with some can?

PS: the alarm clock on madonna's confessions on a dancefloor album -can- give you some sort of heart attack if unexpected...

greetings
mosi

 

[Shahrose]

no, i had that problem too, it turned out to be a hair in the driver. makes a rattling noise that sounds like distortion, like a piece of paper is hitting the driver as it undergoes excursion from heavy bass passages. gotta open and clean. search "grado grattle" and there are many threads on removing such a hair.

this is quite common in the dt990/dt770.

 

[b0dhi]

Are you using an EQ to boost the bass? If not, it's extremely unlikely that you're pushing the drivers too much.

 

[mosi]

Thanks alot for the tip. It made things a bit better but not completely removed the problem.
I'm not using any EQ in the chain currently, the regular bass-hump on the 990's is enough for me.

I followed the steps outlined in here by ericj and needed to pry the black retaining ring up to get under the foam. There were also like two or three hairs lying flat all over the place on both sides.

For the right earcup however things didn't improve much.
I was about to write that I can't go any deeper from there when suddenly one of the driver units gently fell out of the casing onto my hand. Gotta love those "oh... " moments.
After having the right driver unit out of its cup the effect is still present so it has to be something in the driver itself apparently. I tried breathing into the driver unit from both sides to blow stuff away from the diaphragm but that didn't help either.

I wonder what to do now

 

[mosi]

This must be my lucky day. I just had a closer look at the thing and noticed that after another round of really breathing hard into the driver a hair was sticking from one of the tiny holes. I even needed pliers to pull the person out there since it seemed to be stuck to something in there.
I just ran another test on a volume close to mind numbing and can't make out any more of the rattling noises from either sides now.

Its really astonishing how deep a hair can enter into a headphone given like 1.5 years of time.

Again, thanks alot for the advice!

 

[Shahrose]

np