Sound Distortion when there is heavy bass at DVinfo.net

Go Back   DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XH Series HDV Camcorders

Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


Reply
 
Thread Tools Search this Thread
Old October 13th, 2007, 12:58 AM   #1
New Boot
 
Join Date: Dec 2006
Location: suffolk
Posts: 18
Sound Distortion when there is heavy bass

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
Marko Grady is offline   Reply With Quote
Old October 13th, 2007, 02:09 AM   #2
Trustee
 
Join Date: Dec 2004
Location: Lipa City Batangas, Philippines
Posts: 1,110
Hi Marko. Are you using the attenuator? You need this to prevent preamp overload when the sound levels are gigh.

Richard
Richard Hunter is offline   Reply With Quote
Old October 13th, 2007, 05:24 AM   #3
Regular Crew
 
Join Date: Sep 2006
Location: Oslo, Norway
Posts: 106
Try turning on the low-cut filter, perhaps? That will eliminate any frequencies below 80Hz.
__________________
"Those who dream by day are cognizant of many things which escape those who dream only by night."
-- Edgar Allan Poe
Even Solberg is offline   Reply With Quote
Old October 13th, 2007, 09:19 AM   #4
Major Player
 
Join Date: May 2007
Location: Ireland
Posts: 579
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.
Ger Griffin is offline   Reply With Quote
Old October 13th, 2007, 03:06 PM   #5
Major Player
 
Join Date: Aug 2007
Location: Florida
Posts: 224
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.
Bryan Gilchrist is offline   Reply With Quote
Old October 13th, 2007, 03:53 PM   #6
Inner Circle
 
Join Date: Feb 2007
Location: Fairfield, Dunedin, New Zealand
Posts: 3,634
Images: 18
Hi Marko............

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.

Last edited by Chris Soucy; October 13th, 2007 at 04:12 PM. Reason: Addition
Chris Soucy is offline   Reply With Quote
Old October 14th, 2007, 02:18 AM   #7
Regular Crew
 
Join Date: Apr 2007
Location: Amersfoort, Netherlands
Posts: 85
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.
Winfried Dobbe is offline   Reply With Quote
Old October 15th, 2007, 05:11 AM   #8
Major Player
 
Join Date: May 2004
Location: Oxford, UK
Posts: 422
Quote:
Originally Posted by Winfried Dobbe View Post
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.)
__________________
Steam Age Pictures - videos in aid of railway preservation societies.
Mark Fry is offline   Reply With Quote
Old October 15th, 2007, 08:59 AM   #9
Wrangler
 
Join Date: Sep 2001
Location: Northern VA
Posts: 4,294
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.
__________________
dpalomaki@dspalomaki.com
Don Palomaki is offline   Reply With Quote
Old October 15th, 2007, 10:36 AM   #10
Regular Crew
 
Join Date: Apr 2007
Location: Amersfoort, Netherlands
Posts: 85
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)
Winfried Dobbe is offline   Reply With Quote
Old October 15th, 2007, 11:00 AM   #11
Major Player
 
Join Date: Mar 2007
Location: Canada
Posts: 294
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
Trish Kerr is offline   Reply With Quote
Old October 15th, 2007, 12:10 PM   #12
Wrangler
 
Join Date: Sep 2001
Location: Northern VA
Posts: 4,294
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.
__________________
dpalomaki@dspalomaki.com
Don Palomaki is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XH Series HDV Camcorders

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 07:31 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network