Heavy Noise boom Problem :(

N

nyquist-x

Active member
Hi Guys!

I´m seeking for some help regarding this issue:

Right now I´m using a Fostex FR2LE with an Oktava Mk012c with hyper cap and a Rode SM4 shockmount (picture attached) with rode boompole, canare cables and neutrik connectors.

p36579.jpg


I´m having some trouble when I swing the pole slightly, it´s extremly delicated... I know that the terrible distortion is because the mic it´s overloading the FR2 preamps, but, I can´t figure out why it´s so sensitive. I guess that it´s the shockmount (not good enough?)

I attached an audioclip to point my problem properly.

Best Regards.
Fernando
 

Attachments

From looking at the waveform, the most likely cause appears to be mechanical shock (vs. wind noise, etc.) Is the shock mount suspension "bottoming out"? Is it cable-slap along the pole somewhere? Can you have someone look closely at the mic and pole while you reproduce the phenomenon?
 
IMO that example sounds like something thumps the mic body itself overloading the preamp.

Easily and unobtrusively done when you're new, check the way you cable it up and once you set up, shake the boom to hear any loose bits. Cheers.
 
You might also consider replacing the rubber mounts with the K-Tek KSUS mounts... I picked up a pair for my old Audio-Technica shockmount & like them much better than the original bands. They hold the mic much more firmly:


at8415.jpg



I still think the Rycote Invision shockmount is the best bet for the money ($62 @ B&H)... The "Lyres" keep the mic very stable. I use the for the AKG C393B hyper or the Rode NTG-1 short shotgun. The INV-7 has the adjustable Lyres, so you can use it with a number of different mics.

041107_inv-7_empty_jpg_380x380_q85.jpg
 
If the noise is happening during a steady swing, then it's not the suspension, but wind noise, which the sound I heard on the clip could certainly be. You didn't mention what type of wind protection you are using. Are you using foam, fur, zep, or anything?

Glen Trew
 
Glen Trew said:
If the noise is happening during a steady swing, then it's not the suspension, but wind noise, which the sound I heard on the clip could certainly be. You didn't mention what type of wind protection you are using. Are you using foam, fur, zep, or anything?

Glen Trew
Click to expand...

That was my first guess, too. But I looked at the waveform and there is no large low-frequency component as in wind-noise cases. The noise looked very much like a sharp mechanical shock.
 
It may very well not be wind noise. However, the Octava is VERY susceptible to wind noise - even indoors on a boom. Not unreasonable to use both a baby ball gag and windjammer all the time with those mics.
 
tflak said:
It may very well not be wind noise. However, the Octava is VERY susceptible to wind noise - even indoors on a boom. Not unreasonable to use both a baby ball gag and windjammer all the time with those mics.
Click to expand...

Very true. That was going to be my initial response until I looked at the waveform. I've seen several really strange low-frequency anomalies from things a bizarre as someone slamming a door or a conductor delivering a downbeat. But there was no real LF component in the posted sample. It seems far more likely to be mechanical vs. airborne.

But is is always a good idea to at least use a foam windscreen at all times. If for no other reason, it keeps the actors safe from lacerations caused by accidental collisions with the boom mic. :-)
 
responses

responses

Well Guys! Thanks for all the data, I´ll be more precise in my description.

The Oktava had a Foam (it came with the mic). It was indoor, with zero breeze or wind and that was a steady shot. Of course that there´s a chance that it´s just my bad handling.. but that bad?!

John, both are great ideas to improve the handling. I just recorded a video of the setup and showing when the mic does this noise, I´ll upload it tomorrow (I´ve to sync the audio from the FR2LE to the video, and convert to a smaller file).

If I grab the pole and move it around, there´s no noise except if I move it to quicky (wind), but If I suddently release one hand off the pole, or grab the pole with two hands while recording, the noise it´s there and it´s very very noticeable.

Thanks to all for your help!
Fernando
 
The sound heard is not low freq rumble, but harmonics and crackling caused by low freq overload. Wind noise can be as low as a few cycles per second. These fundamentals would never be heard, but the noise they create can sound just like the clip in the original post.

If the noise happens "when swinging the pole slightly" as the original post says, I'm betting it's wind noise. A small solid foam teardrop windscreen does very little to help with wind noise on a cardioid mic.

I agree that the Lyre suspension isolates much better than the Rode suspension in the original photograph, but I doubt that the Rode suspension is responsible for the noise in the original post. If the problem is not wind noise, but is handling noise, I would suspect that the cable is too tight from the mic to the pole, which would be a problem with any suspension. But even then, "swinging the pole slightly" would not cause handling noise, so I'm still betting that the problem is caused from wind while panning the pole.

The hyper wind-sensitive Sennheiser 8040 has exactly the same tendencies with even very slight panning of the pole, even with its included foam windscreen. In the case of the Sennheiser, the only devices I've found to control wind are the Schoeps B5D hollow foam teardrop (see photo of this rig at the bottom of this article: http://www.trewaudio.com/news/200902/hannah_montana/ ) and, for outdoor use, the new Rycote extended ball gag, which can be seen here: http://www.trewaudio.com/audioflow/2009/11/06/rycote-does-it-again/

Glen Trew
 
Video

Video

Well guys, all your info was so helpful. Here´s a video of me recording the noise last night (3am :) ) synced with the audio from the FR2LE. Of course, I would never work like that, it just an exagerated demostration to see when the noise appears.

http://www.postmedia.com.ar/varios/Fer/Boompole_noise_mail.mov

(sorry for the link, I can´t upload it here because it´s size)

To notice: windows were closed, no wind and no breeze. You will here by the end a little snaps sound, that was the cable hanging hitting the floor :)

Please, send me your opinions.

Best Regards.
Fernando
 
It is clearly NOT wind noise since the video shows many instances of the noise when the microphone was not moving at all. This confirms my theory that the problem is mechanical and not acoustic.

Time for some differential diagnosis. First unwrap the cable and let it just hang to the ground and try the same experiment to product the sound. Then try it with the boom pole all the way collapsed (and with various sections extended individually) etc, etc.
 
videos

videos

Sure, I will record some examples tonight, I´ll post them tomorrow!

Thanks for the response.

Best Regards.
Fernando
 
stupid question, but do you have a low freq cut on?
That and a not so great suspension...
and you're going to get that.

Depending on the speed of your meters, those low freq thumps could be clipping your camera
and you don't even know it.

Not saying this is it for sure, but an area to explore.
 
LowCut

LowCut

Hi Rippie!

The lowcut filter was deactivated. but when On it´s the same sound with less low freq content-

Best Regards.
Fernando
 
nyquist-x said:
The lowcut filter was deactivated. but when On it´s the same sound with less low freq content-
Click to expand...

Looking at the waveform, I didn't even see any remnant artifacts of an initial LF hit (as from an acoustic source). After looking at many of these you can kinda tell from the waveform if there was a LF cause, even if most of the LF was filtered out. It looks completely mechanical, and indirect (i.e. not something directly hitting the mic, but maybe conveyed through the cable or the suspension, etc.)
 
You have a bad connection somewhere I would guess. Capsule could be loose, dirty XLR pins, broken wire that's mostly making contact? Poss the XLR housing isn't locked on? It could be straight mechanical but I doubt it unless it's the capsule. The hand taps for one thing wouldn't be that loud with a straight mechanical. I would first make sure all the things that should be tight are. The little locking screws on the XLR and the mic body (remember they often "unscrew" to tighten. Make sure the capsule is on tight and the contacts are all clean. Then I would swap out the cable. After that I would suspect a damaged mic. I have heard/ seen this before and it was always a bad connection amplifying the mechanical noise. Well there was one time that the diaphragm was loose in the capsule, but it had a more floppy sound.
 
clues

clues

Hi Glen and Richard! Thanks for all the responses.

Today I recorded some shots on a residential area, here in B.A. I had the opportunity to check this problem. We recorded with a sennheiser MKH60-48P straight to a Sony Z1, I took the Fostex FR2LE and the Oktava with me to try some experiments.

I used my rode boompole and the rode sm4 shockmount all the time.

First of all, I tested the cables with the Mk60, everything went fine, next, the Oktava connected to the Z1, smooth with no problems at all... so It´s gotta be the Fostex recorder. I connected the Senn to the FR2le, good response, a little more sensitive to handling than the Z1, adding a little pops and cracks (from overloading the input stage). Then I connected the Oktava, and those pops and cracks were awful, literally. So, I decided to tweak the trim pot a little down, and level the recording level to -18dB, then those ugly noises disappear, not completly, but now they´re not noticeable. I also changed the recording type from Stereo to Mono (I was using only 1 channel).

So, I think that It was a mix of problems, a very sensitive mic with too high input level.

If you think of any other thing.. please comment.

I want to thank you all for the fast lighting responses, this forum teach me a lot everyday.

Best Regards.
Fernando

pd. sorry for the long post.
 
it's a mechanical thing of waves, created by tapping on the boompole that let "shake" the capsule inside the mice.... Would be my thought.

Or a bad cable, or the connector of the mic that's bad....
 
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