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Strange noises from microphone

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Strange noises from microphone

Postby Ramirez » Tue Sep 19, 2017 12:18 pm

Hi all,

My AT4050 microphone has decided it now wants to be a synth. Have a listen: https://db.tt/hmajFHGqC0 (I've filtered out some major subsonic rumbles)

What's going on here? It seems that moisture triggers it - it's fine at a distance with instruments, but any breathing close to the mics triggers these noises, as well as a rhythmic clicking on occasion (I failed to make the clicking happen this time round). It's been in the same room for weeks, so there's been no sudden changes to it's environment.

Best to send it to Audio-Technica for a service?

Thanks,
Aled
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Re: Strange noises from microphone

Postby James Perrett » Tue Sep 19, 2017 2:12 pm

Probably a dirty capsule or contaminated circuit board. This is a fairly common problem with condenser mics. Do you leave it covered when not in use?
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Re: Strange noises from microphone

Postby Hugh Robjohns » Tue Sep 19, 2017 3:17 pm

I agree with James. The moisture in your breath is causing the capsule charge to leak away, and the usual reason for that is contamination on the capsule and diaphragm, typically from environmental smoke or from close singers without pop-screens. Professional cleaning of the capsule (or in extreme cases, replacement of the capsule) is the only long-term solution.

I hear what you say about the mic staying in the room, so condensation caused by changing room temperature isn't the issue, but it could be that the room has a very high humidity level, and that the extra moisture and warmth in the breath is enough to kick the mic over the edge.

Alternatively, (although more rarely in my experience) some mics have a protective (anti-moisture) lacquer on the high-impedance parts of the circuit board, and that can sometimes break down with similar effects. Again, replacement is the only long-term solution.

I think on balance from your descriptions I'd be minded to send the mic back to AT for a check-up.

H
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Re: Strange noises from microphone

Postby John Willett » Tue Sep 19, 2017 3:59 pm

What Hugh said. :thumbup:

If you use a mic. for vocals it really *is* advisable to use a pop filter - especially if you smoke.

Smoke particles can stay in the lungs and can contaminate a capsule even if you only smoke outside and then wait a while.

So a pop filter will halp protect the capsule from contaminents as well as protecting against plosives.

If you smoke, a foam pad pop filter often have removeable pads for easy cleaning.
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Re: Strange noises from microphone

Postby SimonZ » Tue Sep 19, 2017 4:39 pm

Just to add to Hugh's comments, this kind of thing usually gets exposed around this time of year as the weather turns colder.
Summer, microphone stays above the dew point overnight so no condensation.
Winter, mic gets cold at night, breath hits cold surfaces of capsule and you get condensation.

You may find that if you keep the mic from getting cold you will reduce the effect.
But ultimately the contamination needs to be removed.
Sometimes just a single tiny clothing fibre can cause this.
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Re: Strange noises from microphone

Postby Ramirez » Wed Sep 20, 2017 11:34 am

Thank you kind folk,

Off to AT it is then.

I don't smoke, and I don't use the mic all that often for vocals. It has, however, been left uncovered for a fair while. The mic is fairly old and has seen some use so a check-up would not be a bad thing. I recall it doing something similar a while ago, but as I don't use it so often on vocals it hasn't really been a problem.

A similar quick check on a Studio Projects B1 that's lying around the room for a while revealed something fairly similar, but much less drastic - breathing on it resulted in increased noise for a minute or so before settling down again. I don't think it would be cost effective to service this one, and it's not proving to be problematic in any case.

Thanks again,
Aed
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Re: Strange noises from microphone

Postby Ramirez » Tue Jan 15, 2019 6:43 pm

Well, it took me over a year to do anything about this...

Audio-Technica had a look and came back with a quote for a replacement capsule... almost £400!

For that money, I think I’d rather spend the extra £150 and get a new one, and keep the old one as it is as it seemed fine when not breathed on!

Would it be perhaps worth contacting Studiocare or the like to see if they could have a go at cleaning the capsule, or does the fact that AT suggested a complete capsule replacement suggest that it really is buggered?
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Re: Strange noises from microphone

Postby Janneman » Tue Jan 15, 2019 7:48 pm

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Re: Strange noises from microphone

Postby Ramirez » Wed Jan 16, 2019 12:04 am


Thanks Janneman, I may well contact them. I do wonder however that there must be a good reason AT quoted for a replacement capsule rather than a cleaning job.

Interesting video... I may try it on the Studio Projects mic, but I’m not risking the Audio-Technica!
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Re: Strange noises from microphone

Postby Sam Spoons » Wed Jan 16, 2019 1:50 am

Ramirez wrote:I do wonder however that there must be a good reason AT quoted for a replacement capsule rather than a cleaning job.

It may well be that Audio-Technica can't guarantee a result by cleaning and will opt to play safe. They know the replacement capsule will get your mic back to 'as new' performance every time. That doesn't mean that cleaning won't work, just that it involves more risk of damage or failure than the certainty of success a new component gives.
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Re: Strange noises from microphone

Postby MOF » Wed Jan 16, 2019 3:03 am

My experience of moisture in the mic’ is more a random frying sound on top of the wanted audio.
That was with detachable capsules on an AKG 451, a squirt of alcohol on the contact points usually solved it, I never heard what was on your audio file, perhaps that’s what happens in extremis.
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