Broken microphones?

[Prof_Rikk]

Hello everybody!

As my first post here, I'm gonna tell you a quite strange fact, hoping that you can help.

I've been using for some years (when I was living in Italy) 2 AKG C2000B microphones, together with a Behringer Eurorack MX602 mixer, and never had a problem.
This September I decided to bring them over to London (via airplane), packed all the stuff with the original package (really good in shock absorption!) plus some bubblewrap, and put it in my hand luggage (and of course I handled it really carefully!).

Now the problem: once I got to London, I started getting an awful noise, ranging from about 110 to 8000Hz. Initially I thought it was the recorder (Tascam DP01-FX), but it wasn't. Then I thought it could have been some sort of electrical interference, but it wasn't.

Turns out it's the microphones. Both of them. Same noise.



Question 1: do you think they may have been damaged at the security controls (metal detector)? How could it be possible???

Question 2: any chance of getting them fixed? Would it be worth it or would it be better to buy new ones?

Question 3: if you think I should get new ones, would you advise AKG C4500B-BC or C4000B (my budget is around 500GBP) to record mainly pipe organ, small orchestras and choirs (all live recording)?



Thank you very much for helping me, and apologies for bothering you!

 

[Prof_Rikk]

Whooops, sorry I posted the thread twice!

 

[lpdeluxe]

Check out the Behringer with other mics: it may be the mixer, since the problem affects both microphones.

 

[Prof_Rikk]

I have checked the microphones separately with the mixer and with the recording machine (which has got phantom power), and the problem is exactly the same.
Yesterday I borrowed from a friend an AKG C1000 mic and tried it, and it didn't give any problem at all...

 

[Prof_Rikk]

...no more help?

 

[MartinKantola]

Interesting case... Been transporting microphones through the metal detectors a lot without any problems. The other thing to consider is the increased air pressure during the flight. Capsules should be able to handle this, but...

Can you visually check the diaphragms somehow? Try to see if they are still flat as mirrors with the help of a bright light.

Another possible cause is lots of humidity, but London is not that bad, is it?

Martin

 

[billisa]

Now the problem: once I got to London, I started getting an awful noise, ranging from about 110 to 8000Hz. Initially I thought it was the recorder (Tascam DP01-FX), but it wasn't.

This may be a long-shot, but this sounds an awful lot like humidity or microscopic condensation on the diaghragm...

Try putting one of the mics near a 100 watt light-bulb for an hour to really dry it out. Then see if the sound clears up.

 

[lpdeluxe]

This may be a long-shot, but this sounds an awful lot like humidity or microscopic condensation on the diaghragm...

Try putting one of the mics near a 100 watt light-bulb for an hour to really dry it out. Then see if the sound clears up.

How about a hair dryer?

 

[TyphoidHippo]

How about a hair dryer?

That's a joke, right? If it's not a joke - that won't hurt it? Seems, to me, at least, like that could definitely harm a condenser diaphragm...

edit: Are you from....Nacogdoches?! I can't believe it...I'm not the only person here?!

 

[beatbug]

Not to hijack your thread Prof Rik but I have an EV767 N/D for live vocals that crapped out last week after about 4 yrs. Seems to have lost all bottom. I think I'll send it to EV and see what the cost of repair is. Why not see if AKG can fix your mics if the cost is reasonable?

 

[MartinKantola]

How about a hair dryer?

No, please be careful with your mikes... Putting them in a sealed plastic bag with some silica gel could do the trick without damage...

Martin

 

[billisa]

No, please be careful with your mikes... Putting them in a sealed plastic bag with some silica gel could do the trick without damage...

Martin

The light-bulb trick does work without blowing air into the capsule, a-la the hairdryer technique.

But, yes, I store all of my meager collection of condensors in glass jars with silica gel packets. Of course travelling necessetates a different approach...

 

[Prof_Rikk]

Thank you all, guys!

I've always been keeping some silica gel together with the mics, but at this point I'm wondring how long it would last before it has to be replaced... maybe after all it's just humidity?

I'll check the diaphragms and try with some more silica and lightbulb!

Thanks again, I'll keep you posted on progress!

 

[lpdeluxe]

Well, it looks as though my hair dryer idea was shot down (I've never actually tried it, which is why I put a question mark on my suggestion).

I'm in humid East Texas, and I've not had a problem with my condensers. Knock on wood....

 

[billisa]

Well, it looks as though my hair dryer idea was shot down (I've never actually tried it, which is why I put a question mark on my suggestion).

I'm in humid East Texas, and I've not had a problem with my condensers. Knock on wood....

I think the hairdryer could easily work, but for the possibility of blowing contaminants into the delicate capsule...

 

[MartinKantola]

So what happened?

Martin

 

[Prof_Rikk]

Well, I've bought some new silica gel and put one of the two mics in a jar with it, kept it there until today, and tried to record something.

Surprise, surprise, it still sounds really crap!

Shall I commit seppuku?

I think I'll go for 2 new AKG C4500BC.
I guess they should be ok to record pipe organs.

Any better recommendation?




Btw thank you guys for your help and support. It's great to know that there is always somebody out there ready to offer help and advice. God bless!

 

[dgatwood]

Is this a pink noise sound like a hiss but warmer?

 

[Prof_Rikk]

Well I don't have any idea what a pink noise is, but it sounds mainly as a low A (110Hz roughly).
I've tried to filter it (90 to 130Hz) but was left with more (softer) noises up to 8Khz.

At this point I think I should throw away my mics and buy new ones...

 

[dgatwood]

Well I don't have any idea what a pink noise is, but it sounds mainly as a low A (110Hz roughly).
I've tried to filter it (90 to 130Hz) but was left with more (softer) noises up to 8Khz.

If it were a little lower, I'd say you were hearing the first harmonic of the 50Hz line frequency. If a mic hums, it is usually caused by a disconnected ground somewhere... possibly something as simple as a loose screw or set screw preventing the body of the microphone from making adequate contact with the grille, the jacket of the mic connector on the bottom of the mic, etc.