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Where is this "wind" coming from?...

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Anonymous
September 21, 2005 9:36:29 AM

Archived from groups: rec.audio.pro (More info?)

Hello.

First of all, this is my first time here so please excuse me if I'm in
the wrong place asking the wrong questions...

Secondly, I'm *not* experienced in - or knowledgeable about - pro
recording so I'll keep things simple.

I have a regular need to make high quality recordings of (spoken)
dialogues.

The equipment I have purchased (over the last 18 months) to do this
consists of:

1. a Marantz PMD 670 recording unit (compact flash)
2. a small Behringer UB1002 mixer (hooked up to the Marantz)
3. 2 Rode NT3 microphones (which run into the mixer)
4. XLR cables (x 2) (which connect the mics to the mixer)
5. a double cable with regular stereo "jacks" (to connect the mixer to
the line ins on the Marantz unit.)
5. Sony headphones

As regards set up, that's it in a nutshell.

The problem is this: sometimes, I get absolutely pristine recordings -
perfectly pure and without distortion (at least none that my amateur
ear is capable of hearing).

Then, randomly - but frequently - I get what I would describe as "wind"
in the background. It's *very* noticeable and renders my recordings
unusable. (Apart from being very audible, it causes the rec levels on
my Marantz to "shimmer", as if I was carrying out my recordings on a
beach with wind hitting the mics.)

I have plugged my headphones into the mixer (rather than the recorder)
and have even taken my recording unit out of the equation altogether
and have still had this noise. Consequently, I'm inclined to think it's
either the mics or xlr cables or mixer...

I hired a different mixer - also a Behringer (UB1204FX-PRO) - and am
still getting the noise. As usual, it's sporadic. It just comes and
goes.

Now, about the mics. They can take batteries but can operate on phantom
power, too. I've tried with and without batteries. Still, I can't
figure out or solve the problem.

Can anyone point me in the right direction? I'm going nuts, slowly but
surely...

Thanks a lot,

Hugh

More about : wind coming

Anonymous
September 21, 2005 9:50:05 AM

Archived from groups: rec.audio.pro (More info?)

It's definitely not the acoustical environment. I've moved location
several times to try and resolve the issue...

I'll try those dummy loads. Next job is to lay my hands on them
somewhere...

Hugh
Related resources
Anonymous
September 21, 2005 12:19:16 PM

Archived from groups: rec.audio.pro (More info?)

<hugh.nagle@gmail.com> wrote in message
news:1127306188.962798.142800@o13g2000cwo.googlegroups.com...
> Hello.
>
> First of all, this is my first time here so please excuse me if I'm in
> the wrong place asking the wrong questions...
>
> Secondly, I'm *not* experienced in - or knowledgeable about - pro
> recording so I'll keep things simple.
>
> I have a regular need to make high quality recordings of (spoken)
> dialogues.
>
> The equipment I have purchased (over the last 18 months) to do this
> consists of:
>
> 1. a Marantz PMD 670 recording unit (compact flash)
> 2. a small Behringer UB1002 mixer (hooked up to the Marantz)
> 3. 2 Rode NT3 microphones (which run into the mixer)
> 4. XLR cables (x 2) (which connect the mics to the mixer)
> 5. a double cable with regular stereo "jacks" (to connect the mixer to
> the line ins on the Marantz unit.)
> 5. Sony headphones
>
> As regards set up, that's it in a nutshell.
>
> The problem is this: sometimes, I get absolutely pristine recordings -
> perfectly pure and without distortion (at least none that my amateur
> ear is capable of hearing).
>
> Then, randomly - but frequently - I get what I would describe as "wind"
> in the background. It's *very* noticeable and renders my recordings
> unusable. (Apart from being very audible, it causes the rec levels on
> my Marantz to "shimmer", as if I was carrying out my recordings on a
> beach with wind hitting the mics.)
>
> I have plugged my headphones into the mixer (rather than the recorder)
> and have even taken my recording unit out of the equation altogether
> and have still had this noise. Consequently, I'm inclined to think it's
> either the mics or xlr cables or mixer...
>
> I hired a different mixer - also a Behringer (UB1204FX-PRO) - and am
> still getting the noise. As usual, it's sporadic. It just comes and
> goes.
>
> Now, about the mics. They can take batteries but can operate on phantom
> power, too. I've tried with and without batteries. Still, I can't
> figure out or solve the problem.
>
> Can anyone point me in the right direction? I'm going nuts, slowly but
> surely...
>
> Thanks a lot,
>
> Hugh

While your putting together those dummy loads, can you post an MP3 somewhere
so we can listen to the problem?

Steve King
Anonymous
September 21, 2005 12:43:04 PM

Archived from groups: rec.audio.pro (More info?)

After the last hour I spent, maybe I can shed more light...

Having rented the second mixer but ending up with the same noise, I
returned that mixer to the rental shop just now.

I brought along my two Rode mics. The guy in the shop plugged in one
mic into his own setup (in his shop). His first reaction was "Wow!
These mics are incredibly sensitive!..." That mic he plugged in
appeared to be working ok. He spoke into the mic - "testing, one, two,
three...", etc.

Then he plugged in the second mic. Straight away, there was that "wind"
sound.... He then plugged back in the first mic and, on closer
listening, the "wind" was blowing there, too, although less strongly...

He wasn't a very techy guy himself and suggested I call back on Monday
when his techy employee would be back from wherever.

It seems to me that I have two extremely sensitive mics. Is it possible
that this is, in fact, my "problem" and that it isn't a problem at all
if I offset the sensitivity on my mixer? How do I do that?...

By the way, a couple of you have mentioned my acoustic environment.
It's a big room (not ideal with some too-reflective surfaces, thus
creating an echo). There's no air conditioner or anything like that -
I'm in Ireland! - no need for those here.

As for input gain, attenuators, etc, I never fiddle with any of that -
I nearly always leave everything "flat". My most adventurous forays
include turning up the treble a little on a man with a "bassy" voice
and the bass on a female with a "treble" voice. I just need the very
basics in my recordings at the moment which, as I said before, consist
of dialogues in the main.

So, is there a quick fix for (very) high sensitivity mics? The guy in
the shop also said something about impedance... Any suggestions?

Hugh
Anonymous
September 21, 2005 12:43:49 PM

Archived from groups: rec.audio.pro (More info?)

<hugh.nagle@gmail.com> wrote in message
news:1127306188.962798.142800@o13g2000cwo.googlegroups.com
> Hello.
>
> First of all, this is my first time here so please excuse
> me if I'm in the wrong place asking the wrong questions...
>
> Secondly, I'm *not* experienced in - or knowledgeable
> about - pro recording so I'll keep things simple.
>
> I have a regular need to make high quality recordings of
> (spoken) dialogues.
>
> The equipment I have purchased (over the last 18 months)
> to do this consists of:
>
> 1. a Marantz PMD 670 recording unit (compact flash)
> 2. a small Behringer UB1002 mixer (hooked up to the
> Marantz)
> 3. 2 Rode NT3 microphones (which run into the mixer)
> 4. XLR cables (x 2) (which connect the mics to the mixer)
> 5. a double cable with regular stereo "jacks" (to connect
> the mixer to the line ins on the Marantz unit.)
> 5. Sony headphones
>
> As regards set up, that's it in a nutshell.
>
> The problem is this: sometimes, I get absolutely pristine
> recordings - perfectly pure and without distortion (at
> least none that my amateur ear is capable of hearing).
>
> Then, randomly - but frequently - I get what I would
> describe as "wind" in the background. It's *very*
> noticeable and renders my recordings unusable. (Apart
> from being very audible, it causes the rec levels on my
> Marantz to "shimmer", as if I was carrying out my
> recordings on a beach with wind hitting the mics.)

Try replacing the mics with dummy loads. These are simply
XLR plugs with 150 ohm resistors soldered from pin 2 to pin
3. Make a recording and see if the "wind" is still there.
If it isn't, then you have probably isolated the problem to
the mics and the acoustical environment. If it is still
there, remove equipment piece by piece working backward
towards the recorder.
Anonymous
September 21, 2005 1:10:24 PM

Archived from groups: rec.audio.pro (More info?)

<hugh.nagle@gmail.com> wrote in message
news:1127307005.435749.283840@g44g2000cwa.googlegroups.com
> It's definitely not the acoustical environment. I've
> moved location several times to try and resolve the
> issue...
>
> I'll try those dummy loads. Next job is to lay my hands
> on them somewhere...

Really, all you need is one dummy load if the problem is in
both channels.

I think you can still get the 2 parts required for a
credible dummy load from Radio Shack for about $5. Solder
much?
Anonymous
September 21, 2005 3:59:24 PM

Archived from groups: rec.audio.pro (More info?)

<hugh.nagle@gmail.com> wrote in message
news:1127317384.048123.243720@o13g2000cwo.googlegroups.com


> It seems to me that I have two extremely sensitive mics.

Spec-wise they seem to be in the range one might expect for
condenser mics.

> Is it possible that this is, in fact, my "problem" and
> that it isn't a problem at all if I offset the
> sensitivity on my mixer? How do I do that?...

Turn the gain down.

> By the way, a couple of you have mentioned my acoustic
> environment. It's a big room (not ideal with some
> too-reflective surfaces, thus creating an echo). There's
> no air conditioner or anything like that - I'm in
> Ireland! - no need for those here.

Big room
Temperature differences due to changing day
Drafts

> As for input gain, attenuators, etc, I never fiddle with
> any of that - I nearly always leave everything "flat"

12 o'clock is not always the right answer for a mic channel
trim.

I presume that you are hooking the output of your MXB1002 to
the line inputs of your Marantz, right?

I notice that the line inputs of the Marantz are speced at
300 mv, which is more consumer than audio production
standard.

IOW, if you are going to interface the output of a MXB1002
to your Marantz, the gain controls on your Marantz need to
be reduced.


In the end, noise levels need to be judged in the context of
a real-world signal. There's nothing in this world that is
noise-free if you turn all the gain controls up and do the
moral equivalent of putting your ear next to the
loudpspeaker.

IOW, when you set the levels to record a typical musical
performance or some spoken word, do you hear hiss?
Anonymous
September 21, 2005 4:08:09 PM

Archived from groups: rec.audio.pro (More info?)

<hugh.nagle@gmail.com> wrote in message
news:1127317384.048123.243720@o13g2000cwo.googlegroups.com...
> After the last hour I spent, maybe I can shed more light...
>
> Having rented the second mixer but ending up with the same noise, I
> returned that mixer to the rental shop just now.
>
> I brought along my two Rode mics. The guy in the shop plugged in one
> mic into his own setup (in his shop). His first reaction was "Wow!
> These mics are incredibly sensitive!..." That mic he plugged in
> appeared to be working ok. He spoke into the mic - "testing, one, two,
> three...", etc.
>
> Then he plugged in the second mic. Straight away, there was that "wind"
> sound.... He then plugged back in the first mic and, on closer
> listening, the "wind" was blowing there, too, although less strongly...
>
> He wasn't a very techy guy himself and suggested I call back on Monday
> when his techy employee would be back from wherever.
>
> It seems to me that I have two extremely sensitive mics. Is it possible
> that this is, in fact, my "problem" and that it isn't a problem at all
> if I offset the sensitivity on my mixer? How do I do that?...
>
> By the way, a couple of you have mentioned my acoustic environment.
> It's a big room (not ideal with some too-reflective surfaces, thus
> creating an echo). There's no air conditioner or anything like that -
> I'm in Ireland! - no need for those here.
>
> As for input gain, attenuators, etc, I never fiddle with any of that -

go ahead and fiddle... that what they are there for

> I nearly always leave everything "flat". My most adventurous forays
> include turning up the treble a little on a man with a "bassy" voice
> and the bass on a female with a "treble" voice. I just need the very
> basics in my recordings at the moment which, as I said before, consist
> of dialogues in the main.
>
> So, is there a quick fix for (very) high sensitivity mics? The guy in
> the shop also said something about impedance... Any suggestions?

all microphones will give you a whooshy sound if you amplify them to that
point.

reduce the gain to only what is needed.

i sounds to me like your 2 microphones are not mached. perhaps one is
damaged.
Anonymous
September 21, 2005 6:39:58 PM

Archived from groups: rec.audio.pro (More info?)

<hugh.nagle@gmail.com> wrote in message
news:1127311835.029458.43620@g43g2000cwa.googlegroups.com...
>2 clips, one good, one bad, are at this link:
>
> http://www.pluspublications.com/pages/audioClips.htm
>
> Hugh
>

Sounds like an acoustical borne noise to me. Since the levels were so
different it could just be ambient noise. If both recordings where made with
the same chain then it's due to user error (operation/setup). Sounds like
you need a shockmount too.
Anonymous
September 21, 2005 6:48:24 PM

Archived from groups: rec.audio.pro (More info?)

You may have a noisy board level component somewhere. It
happens to even new equipment. A resistor, transistor/chip,
etc., maybe even a cold solder joint, maybe a slightly
oxidized connection somewhere. In troubleshooting some of my
own equipment over the years, I've occasionally found a
component will warm/cool and be the source of the kind of
sound on your clip.

Eliminate one piece at a time. The dummy loads are a good
first start. When you troubleshoot, be sure to use "known
good" substitutes at each point.

It can be frustrating, but approach it in a scientific way,
and you'll find it, or at least narrow it down to a
component that you can have looked at by someone else if
your electronic repair skills aren't up to it.

Good luck.


TM




hugh.nagle@gmail.com wrote:
>
> 2 clips, one good, one bad, are at this link:
>
> http://www.pluspublications.com/pages/audioClips.htm
Anonymous
September 21, 2005 7:49:20 PM

Archived from groups: rec.audio.pro (More info?)

<hugh.nagle@gmail.com> wrote in message
news:1127311835.029458.43620@g43g2000cwa.googlegroups.com...
> 2 clips, one good, one bad, are at this link:
>
> http://www.pluspublications.com/pages/audioClips.htm

Using the "Noise reduction" analyzer in Goldwave, I can see that the volume
level between say 200 and 300Hz is -50dB in the file without noise,
but -70dB in the file with noise.

So I'd guess the signal level in the file with noise was 20dB lower than the
file without noise; but the automatic level control in the PMD670 boosted
the recording level to compensate (also boosting any noise present.).

I zoomed in on the wave files with an audio editor (Goldwave). If you zoom
in far enough on a part with no speech - about a quarter of a second - you
can see the file with noise has a -20db signal at about 50Hz, together with
harmonics.

Tim
Anonymous
September 21, 2005 7:49:21 PM

Archived from groups: rec.audio.pro (More info?)

"Tim Martin" <tim2718281@ntlworld.com> wrote in message
news:4ifYe.11797$ws4.3467@newsfe5-win.ntli.net
> <hugh.nagle@gmail.com> wrote in message
> news:1127311835.029458.43620@g43g2000cwa.googlegroups.com...
>> 2 clips, one good, one bad, are at this link:
>>
>> http://www.pluspublications.com/pages/audioClips.htm
>
> Using the "Noise reduction" analyzer in Goldwave, I can
> see that the volume level between say 200 and 300Hz is
> -50dB in the file without noise,
> but -70dB in the file with noise.
>
> So I'd guess the signal level in the file with noise was
> 20dB lower than the file without noise; but the automatic
> level control in the PMD670 boosted the recording level
> to compensate (also boosting any noise present.).

Making recordings with automatic level control on makes
analysis just about impossible.

Any possibility of recordings with automatic level control
"off"?

As a rule, automatic level control should *never* be used
for serious recording.
Anonymous
September 21, 2005 7:52:52 PM

Archived from groups: rec.audio.pro (More info?)

On Wed, 21 Sep 2005 14:48:24 GMT, T Maki wrote:

> You may have a noisy board level component somewhere. It
> happens to even new equipment. A resistor, transistor/chip,
> etc., maybe even a cold solder joint, maybe a slightly
> oxidized connection somewhere. In troubleshooting some of my
> own equipment over the years, I've occasionally found a
> component will warm/cool and be the source of the kind of
> sound on your clip.
>
> Eliminate one piece at a time. The dummy loads are a good
> first start. When you troubleshoot, be sure to use "known
> good" substitutes at each point.
>
> It can be frustrating, but approach it in a scientific way,
> and you'll find it, or at least narrow it down to a
> component that you can have looked at by someone else if
> your electronic repair skills aren't up to it.
>
> Good luck.
>
>
> TM
>
>
If the noise were confined to a single channel, I would agree. But it is on
both, so the source must be somehow shared. It could be that the acoustic
environment is somehow different - artists further from the mic, air
conditioning on or off for example. Or it might be that the gain plan of
the chain is somehow different - attenuators switched into the mic, input
gain settings changed, perhaps.

d
Anonymous
September 21, 2005 10:10:19 PM

Archived from groups: rec.audio.pro (More info?)

Don Pearce wrote:
>
> >
> If the noise were confined to a single channel, I would agree. But it is on
> both, so the source must be somehow shared.

True. I hear the files as mono, so there's no telling. If
both inputs are panned center, now the signal is "shared".

We don't know exactly how OP has set up his system. If he's
panning to center, he needs to test again with both sources
panned hard to the sides, and give another listen.

I do not believe this to be an oversensitive microphone, or
gain too high. There appear to be no other discernible signs
of those conditions. There could be a noise problem in one
of the microphones, and separating the signal(s) is one way
to find it.

OP says he has the noise even using another mixer. The
liklihood that another mixer picked at random would exhibit
exactly the same problem is low.

I'm betting on a defective microphone - possibly a cable,
but not likely. In my experience, cables don't make this
kind of noise. I've had condenser mics act this way - mostly
my body-worn elements with wireless systems. That's usually
a drop of sweat or other moisture. In this case, that's
probably outrulable. Moisture would have dried up after a
time. Possibly a cap or resistor in the mic output circuit.
Maybe even a capsule polarizing problem.

I'd investigate the microphones a little further. I'm not
familiar with the construction of these mics, but can the
body be separated from the capsule by unscrewing them? I've
had 81s and 451s act this way, and a little mechanical
cleaning of a contact solved the problem.



TM
Anonymous
September 22, 2005 12:06:43 AM

Archived from groups: rec.audio.pro (More info?)

Hugh Nagle wrote:

> 2 clips, one good, one bad, are at this link:
>
> http://www.pluspublications.com/pages/audioClips.htm

Hugh, thanks for providing the link to your recordings.

That particular noise is the sound of either excessive humidity, a bad
transistor, or a marginal solder joint. Since you have no air conditioning
and are in Ireland, I'd bet on humidity. Moisture can especially be a
problem if you move the mics from an air conditioned environment (such as a
car or office) to a humid non-air conditioned location. Just as eye glasses
may fog, so do the mics. It is not due to the difference in level between
the two recordings.

You might try positioning the noisy mic several inches above a light bulb
for a few minutes and see if the noise goes away.

Jeff Jasper
www.jeffjasper.com
Anonymous
September 22, 2005 12:53:19 AM

Archived from groups: rec.audio.pro (More info?)

Tim Martin wrote:
> <hugh.nagle@gmail.com> wrote in message
> news:1127311835.029458.43620@g43g2000cwa.googlegroups.com...
>
>>2 clips, one good, one bad, are at this link:
>>
>>http://www.pluspublications.com/pages/audioClips.htm
>
>
> Using the "Noise reduction" analyzer in Goldwave, I can see that the volume
> level between say 200 and 300Hz is -50dB in the file without noise,
> but -70dB in the file with noise.
>
> So I'd guess the signal level in the file with noise was 20dB lower than the
> file without noise; but the automatic level control in the PMD670 boosted
> the recording level to compensate (also boosting any noise present.).
>
> I zoomed in on the wave files with an audio editor (Goldwave). If you zoom
> in far enough on a part with no speech - about a quarter of a second - you
> can see the file with noise has a -20db signal at about 50Hz, together with
> harmonics.
>
> Tim
>

I pretty much agree with Tim, though I viewed it slightly differently.

I noticed that the noise floor has the same spectral content in both
recordings but is quite a bit higher in the "windy" recording. The noise
is your garden variety pink (1/f) type noise that is present in every
electrical circuit. It is amplified considerably more in the "windy"
recording. It gives that distinctive rumbling sound because most of its
energy is at very low frequencies.

If (as Tim and others have surmised) the recordings were made with auto
gain control engaged, the difference could be due to varying distance
between the mic and the speakers. Alternatively, the speakers might just
be speaking more loudly in the good recording, requiring less amplification.

I can suggest two possible cures:
1. Make sure the speakers are close to the mic at all times, or
2. Insert a high-pass filter to attenuate the very low frequency noise.
Anonymous
September 22, 2005 6:47:04 AM

Archived from groups: rec.audio.pro (More info?)

Arny Krueger <arnyk@hotpop.com> wrote:

> I think you can still get the 2 parts required for a
> credible dummy load from Radio Shack for about $5. Solder
> much?

I guess you haven't been to Radio Shack in a few years. Try finding
someone there who knows what a resistor is! And as for actually selling
you one....

Rob R.
Anonymous
September 22, 2005 6:47:05 AM

Archived from groups: rec.audio.pro (More info?)

"Rob Reedijk" <reedijk@hera.med.utoronto.ca> wrote in message
news:D gt5v8$4jf$1@news1.chem.utoronto.ca...
> Arny Krueger <arnyk@hotpop.com> wrote:
>
> > I think you can still get the 2 parts required for a
> > credible dummy load from Radio Shack for about $5. Solder
> > much?
>
> I guess you haven't been to Radio Shack in a few years. Try finding
> someone there who knows what a resistor is! And as for actually selling
> you one....
>
> Rob R.

psst: they are hiding in the drawers now. but only one or 2 pieces... if you
have several stores in town it helps to know all the locations.
Anonymous
September 22, 2005 7:36:50 AM

Archived from groups: rec.audio.pro (More info?)

Thank you all so much for your help. I've learned a lot.

I think, despite all the recommendations you have made, that the
problem was with the mics - *both* of them, though one to a lesser
degree.

(Jeff, I don't think humidity was an issue. I'm working in a dry, new
building, without major fluctuations in temperature or humidity.)

I spoke to a tech support guy working for Rode in California. He
listening intently to what I described and was very helpful. He
wondered if the "capsule" in one, or both, mics was defective. He spoke
to me about a lot of things - uniform power supply, phantom power,
gain, attenuation, etc.

After a 20-minute conversation, he himself was inclined to think there
was a problem with the mics.

BTW, a few of you wondered if I was using Auto Level Control: I wasn't,
and haven't ever, though it is possible on my recorder. In any case, I
had taken the recorder out of the loop and was getting the "wind"
phenomenon coming back to me through the phones plugged into the
mixer(s).

Finally, I should say that I was very inconsistent about the way I
prepared the two audio clips above - I wanted to post them quickly to
give you an idea. I think I may have run a normalise filter on the
"windy" one (but not on the "pure" one) which explains the difference
in levels. To be honest, at this stage, I'm not quite sure exactly what
I've done, and when. There have been so many frustrating recordings!...

Right now, I'm on the verge of sending the mics back to Rode. They'll
fix them (or replace them) free of charge. I've got to pay the shipping
though...

Thanks again to you all, for your help.

Hugh
Anonymous
September 22, 2005 10:50:48 AM

Archived from groups: rec.audio.pro (More info?)

"Rob Reedijk" <reedijk@hera.med.utoronto.ca> wrote in
message news:D gt5v8$4jf$1@news1.chem.utoronto.ca
> Arny Krueger <arnyk@hotpop.com> wrote:
>
>> I think you can still get the 2 parts required for a
>> credible dummy load from Radio Shack for about $5. Solder
>> much?
>
> I guess you haven't been to Radio Shack in a few years.

There is a RS store about 300' from my front door.

Due to poor planning on my part, I often pay their
exhorbitant prices for average or worse parts when I should
mail order good parts for low prices.

> Try finding someone there who knows what a resistor is!

They still have the resistors and XLR connectors in those
fancy new drawer units they put in about a year ago.

> And as for actually selling you one....

Been there, done that.
!