Sound Distortion when there is heavy bass

[Marko Grady]

I keep getting sound distortion with heavy bass I have my camera set up so that the microphone is pretty low sound recording. I have a Rode NTG2.

Here is an example
http://youtube.com/watch?v=8Cwv3e3ynYM

[Richard Hunter]

Hi Marko. Are you using the attenuator? You need this to prevent preamp overload when the sound levels are gigh.

Richard

[Even Solberg]

Try turning on the low-cut filter, perhaps? That will eliminate any frequencies below 80Hz.

[Ger Griffin]

Marko thats some cool footage right there.

Beats weddings hands down!

But i do have this same problem with my weddings so let us
know what works.

[Bryan Gilchrist]

That actually seems like it's a problem with the microphone itself where the low end is causing problems with the diaphragm in the microphone...I don't know if cutting off your low end will help.

You may want to try using an external mic source or plug into the house's source if you can.

[Chris Soucy]

Great footage, that's what I call stamina............

As to your sound problem, from what I could see (the corners were a bit dark) it looks like that was shot in a concrete "box" (walls, ceiling, floor, pillars).

I think what we're hearing is the microphone picking up something the human ear/ brain (when in context) simply filters out - standing waves due to the low frequency, relatively small confined space and reflective nature of all the surfaces (I'm starting with the premise that it didn't sound like that to you when you were shooting?).

It almost sounds as if the mic is "bottoming out" with the LF pressure waves and distorting everything else in the process.

It really needs someone with a spectrum analyser/ waveform monitor to give this sound track a thorough scrute to confirm/ deny that this is, actually, what's going on.

If it is the mic "bottoming out" the only real answer is a different mic that can handle the dynamic range, especially at the bottom end. The Rode has a pretty good reputation as a "video" mic, this application requires something a bit more specialised (IMHO).

I would suggest (unless someone with experience of heavy duty bass music mics is about) you check out what "non video" mics are available, it's not a subect I'm at all versed in.

I could, of course, be completely wrong.


CS

PS. It would be really interesting is someone can confirm/ deny the above hypothesis. It has occured to me that an alternative to the above is that the mic is NOT bottoming out but that the O/P during the "standing waves" is overwhelming the pre amps in the camera. One way to prove that would be to run the mic through a good mixer before the camera and engage the limiter big time. Of course, if the above IS true, a different mic may just move the problem down the food chain and the mixer/ limiter may still be required to stop the signal smoking the pre - amps.

Yet another alternative would be to run the signal through a good graphic equaliser (before the camera) and trash the particular frequecy(ies) involved fairly comprehensively before they can do any damage down the line.

Whatever, I don't see any "magic bullet" to this, think it's going to take quite a bit of sleuthing.

[Winfried Dobbe]

Same mic, same problem during last wedding party. If you look at the specs, the NTG-1 has a larger dynamic range, so I should have bought that one.
Next time I'm going to try the low-cut filter, or if it doesn't work just use the built-in mic.

[Mark Fry]

Originally Posted by Winfried Dobbe

Same mic, same problem during last wedding party. If you look at the specs, the NTG-1 has a larger dynamic range, so I should have bought that one.
Next time I'm going to try the low-cut filter, or if it doesn't work just use the built-in mic.

NTG1 and NTG2 have identical specs when running on 48v phantom power, because they are essentially the same microphone. NTG2 has the option of battery power (standard 1.5v AA battery, IIRC), and with this power, the performance is a little different, understandably. If you are having quality problems when running with battery power, try using 48v phantom power instead. (The XH-A1 XLR sockets will provide this.)

[Don Palomaki]

As noted by others, If you do not have MIC ATT setting enabled, you are probably overloading the camcorder's mic preamp, which comes before the level control.

Using MIC ATT should avoid overloading the mic input amp (with associated clipping) on level peaks.

[Winfried Dobbe]

Quote: "NTG1 and NTG2 have identical specs when running on 48v phantom power".

Well that's not what Rode's website says:

NTG1:
Dynamic range din iec 651:
121 dB (per IEC651, IEC268-15)

NTG2:
Dynamic range din iec 651:
113 dB (per IEC651, IEC268-15)

[Trish Kerr]

Damn, I just bought the ntg2 thinking they were the same. The manual states 113dB

I used it for the first time on the weekend at a fund raising fashion show event and had to putt the ATT on as soon as the PA system kicked in with speeches and piped in music. As I hadn't pretested it I ended up going auto instead of manual as well and didn't put on high pass filter which i probably should have.

Do most go the manual route with ATT on in situations like these with piped in speaker music and talking? and highpass on or off?

And from reading here it looks like I should have went phantom power.

I also talked to the guy where I bought it and he said you should keep the foam on at all times - even indoors which I did but the manual states it's for outdoors.

trish

[Don Palomaki]

For most practical purposes, don't worry about the audio performances differences between the NTG-2 and the NTG-1.

There are differences, but they are mainly at the extremes of performance (i.e., painfully loud sounds). The key performance factors of signal to noise ratio, sensitivity, pick-up pattern, frequency response curve, and equivalent noise are the same.

There are some differences in output impedance (but not an issue with the XH-A1), maximum SPL (sound pressure level), and dynamic range. The difference in dynamic range is a direct result of the lower maximum SPL rating of the NTG-2, which is probably a by product of the limitations of the battery power option and corresponding lower current consumption that is available to provide output. The lower current has the effect of limiting the output level before distortion.

But for videography purposes, they can pickup equally soft sounds, will have about equal internal hiss levels, and provide the same output signal for the same acoustic input up to about 131 dB SPL. Beyond that sound level, the NTG-1 has the advantage - as long as phantom power is available.

As a point of reference, 131 dB SPL (the rating of the NTG-2) is about the threshold of pain - the sound pressure or sound pressure level beyond which sound becomes unbearable for a human listener - per some references on acoustics.