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MartinTheMixer

Odd mic noise problem with audio samples

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Hello all, I have a noise I can't figure out. I first noticed it when I bumped my boom. It is with a condenser mic. It makes a "crunch,hiss noise". The sound noise only happens if you bump the boom, or if you take it off the boom, and bump it in your hand, same thing. I am really not familiar with the whole humidity noise problem, something I've never had to deal with. I have switched mixers, cables and mics, and it is still there. The noise probably lasts for 600 milliseconds. Any ideas? 

Sincerely, Martin 

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Hi Whit, thanks for your response. It doesn't matter whether it's on the pole or not and I think it's going to be a humidity issue, the problem originally started with a DPA 4017c, I also tried and Octava Mic, it does the same thing but the duration and pitch of the sound is a little different. Since the original post I tried a Sennheiser e945 lead singer mic, as I call it. It does NOT have that same problem and I also tried one of my Sanken Cubs and it does Not have the same problem. So, DPA Mic has that problem, Octava Mic has that problem, both have of course similar, but much different quality of build. Picture if you held the mic in your hand, and shake it on the downward shake as soon as it comes to a stop in your hand you here that noise. So I guess it's fair to say it doesn't come from moving the mic but rather the deceleration of that Mic.

Sincerely, Martin 

P.S. Is there some test to positively figure out if it's humidity? 

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You could try the "breath test" (gently). 

From Gearslutz: 

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"What you should try is the "humidity test" or "breath test" to see if their is enough dirt on the capsule to get it to collapse. You don't want to spit on the capsule but you want to speak into without a pop filter and breath on it a bit to get a very tiny amount of moisture on the capsule. If the capsule is in bad shape the moisture from your breath will trigger conductivity across the dirt and this will show up as horrible loud thundering or crackling and the signal will cut out. Now, the breath test may also cause a good capsule to shut off for a second or two as well, but you won't hear the horrible noises a bad capsule will make when its shutting off and coming back on again."

(jmikeperkins - 22nd December 2009, 08:49 PM)

-Mike

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Mike, Thanks. I'm having that situation with two mics. The One mic is new to me the other is not. I don't understand what's shaking it is doing, the mic works absolutely beautiful as long as you don't move it. Matter fact both mics do. I'm tired and I might be missing something obvious here.

Sincerely, Martin

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cineli   

Martin, did you check out the very low frequency influence ? With bumps or simple movements, many microphones like the DPA 4017C generates these low rumbles that can affect different kinds of electronic circuits or even transmitters. In what equipment do you plug your mikes ? I would personally try a high slope filter like the Schoeps LC60 (or equivalent) between the mike and anything else ! Just to say....

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Cineli, this is a crunch and then hiss sound. I'm plugging it into Nomads. I need to figure out how to get it into a computer and upload it, that's not really handy right now. Let me figure out how to do that. It's a  little crackling sound, then, shhhhhhh sound. I think that's accurate, and it's on 2 different mics. I'm baffled. I think my inexperience with humidity problems is at play here. Maybe?

Sincerely, Martin 

 

 

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cineli   

Martin, I totally understand that it is not a rumble noise, but you are speaking about a noise that occurs with two different mikes when you bump the body. This can be a case where the very high amplitude of the rumble can affect preamps, limiters, transmitters, etc...

Let me join Philip's answer: does it occur with other systems ? any kind ?

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Cineli, When you say does it occur with other systems you mean what exactly? And I don't really think it's so much a matter of when you bump the mic, it's when the mic comes to a halt after being bumped, the deceleration. I believe that's an accurate description. 

Someone tell me how humidity plays out and what that sounds like? When you get a mic thats too humid does it crackle just sitting still?

Sincerely, Martin 

1 minute ago, ramallo said:

I never have a humidity problem with any of my 4017, also working in the jungle (With a Nomad)

Ramallo, Thanks. I am perplexed. And I don't find myself there often. 

Sincerely, Martin 

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I had this on Maxx..is the hpf set to off or low setting , setting hpf to 90-100hz cured it....could be something similardit was LF distorting the a-d on input channel...richard 

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With90hzHP.mp3

DPAMicNoiseNOHPFILTER.mp3

1 hour ago, r.paterson said:

I had this on Maxx..is the hpf set to off or low setting , setting hpf to 90-100hz cured it....could be something similardit was LF distorting the a-d on input channel...richard 

 

1 hour ago, ramallo said:

Can you upload a recording with the noise?

 

1 hour ago, cineli said:

Martin, I totally understand that it is not a rumble noise, but you are speaking about a noise that occurs with two different mikes when you bump the body. This can be a case where the very high amplitude of the rumble can affect preamps, limiters, transmitters, etc...

Let me join Philip's answer: does it occur with other systems ? any kind ?

 

2 hours ago, Philip Perkins said:

Does this noise issue persist when you plug those mics into another system, like a mixer or other recorder?

 

4 hours ago, Whit Norris said:

What pole are you using and what mic are you using? 

Hi All and thanks for the help.The recordings I just uploaded are with 90 HZ HP turned on and turned off. I am taking the pole and swinging it really hard, then snatching it to a stop. The noise you hear is from the sudden deceleration.

I have never heard this before.

Sincerely, Martin

 

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cineli   

Martin, what I can hear on your recordings let me definitely think about a pb related to low rumbles. I don't know so much about the Nomad but I wouldn't be surprised if the HP filters (low slope ??) may be far away after the input in the audio chain. The very first stage may be affected by these rumbles. You need to try with a high slope filter between the 4017C and the Nomad input (Schoeps LC60). The other way would be to try with a B preamp that integrates a hidden 50Hz +18dB/oct (not speaking about the ring filters). If possible you can also try with the new MiniCMIT which integrates a fantastic +24dB/oct 70Hz. Good luck !

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Cineli, I just don't understand why I've never heard any of this before. And I don't understand why it's doing it on to 2 mics. The problem happens from sudden deceleration, I think. Your Nomad theory slope theory can only fit if Howy changed something in the Nomad. What are the theories why the handheld mic and the Cub don't experience that problem?

Sincerely, Martin 

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cineli   

Martin, all I can say is: what I hear and know let me think about a hard rumble issue, but maybe I'm wrong of course. The 4017C is well known to provide a high level of rumble that needs to be filtered. About Nomad, I had a look at characteristics (documentation) and I only found values of fcy cutoff but no indication of slope. It's also very difficult to know if filters are close to inputs or far away on the chain. On my opinion, most robust microphone filters are  very close to inputs, analog and high slope. A handheld mike doesn't have that high rumble level. What do you call the "Cub" ? Sanken one ? The CUB-01 has a real filtering below 100Hz. Another explanation could be the input impedance of the Nomad: around 1kohms which can be considered a bit low for some microphones in front of hard signals (rumbles).

In fact I would be interested to know how your 4017+Nomad would behave with the B preamp. Or 4017C + LC60 + Nomad, or ???MiniCMIT !

Good luck in your investigations !

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It does sound like momentary overloading caused by LF rumble.  The bit of static hiss you are hearing may possibly be the higher noise floor of the 2nd ADC in the Nomad.  It's rare that I can ever hear that in the Nomad, but it used to be i big problem for me in the TRX742.  Howy adjusted the timing a while back which made it much better.

What happens if you replace the Nomad with another non neverclip mixer?

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2 hours ago, Constantin said:


That's your files. Look at the header

OK, sure. So, what are we looking at? What is the purpose?

Sincerely, Martin 

2 hours ago, cineli said:

Martin, all I can say is: what I hear and know let me think about a hard rumble issue, but maybe I'm wrong of course. The 4017C is well known to provide a high level of rumble that needs to be filtered. About Nomad, I had a look at characteristics (documentation) and I only found values of fcy cutoff but no indication of slope. It's also very difficult to know if filters are close to inputs or far away on the chain. On my opinion, most robust microphone filters are  very close to inputs, analog and high slope. A handheld mike doesn't have that high rumble level. What do you call the "Cub" ? Sanken one ? The CUB-01 has a real filtering below 100Hz. Another explanation could be the input impedance of the Nomad: around 1kohms which can be considered a bit low for some microphones in front of hard signals (rumbles).

In fact I would be interested to know how your 4017+Nomad would behave with the B preamp. Or 4017C + LC60 + Nomad, or ???MiniCMIT !

Good luck in your investigations !

Cineli, I wondered the same thing about hooking up the B preamp. Last night , noise became much worse with it just sitting there you could hear the ocean roll loud. I should have recorded this, but I didn't because I was frustrated and just called it quits. That was with it just sitting still. When you say the handheld mic doesn't have that high rumble level, what do you mean? Why not? 

Thanks a bunch, Sincerely, Martin 

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cineli   

Martin, maybe Wandering Ear gives the exact reason (I don't know) but he's also convinced that rumbles may affect something in the input section.

Generally, handheld microphones are compensated for proximity effect, so it naturally filters low frequencies...a lot. Pressure microphones (omnidirectional) also have a much lower sensitivity to low frequency rumbles.

4017C (or 4018, 4011) gives a lot of rumbles, but other well-known "pressure-gradient" mikes are sooo sensitive (CCM8, MKH8040/50)

If you happen to make a test with B preamp or even C preamp + LC60, tell me about the result !

Philippe

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