heath's full (DV mode) audio review at DVinfo.net

Heath McKnight · August 22nd, 2003, 01:25 AM

Just taped, well, my friend taped, 90 minutes worth of DV mode interviews of me for my DVD (plug plug). I was outside in South Florida (nice day, surprisingly) with bugs making noise, an airport to the east (small), I-95 to the west (not as busy since it was a Saturday), a guy trimming bushes loudly to the north and me talking, and I was shocked:

The audio didn't do any funky things that would make it screw up the first word out of my mouth. Unfortunately, the audio sounded like I was in a can. It sounded in a can when my friend interviewed inside my apartment with no sound (fans, fridge and A/C were off, etc.). Huh...No strange hiss under it, like on my old XL-1, but still....Then again, I bet it's easier to fix the canned sound than a hiss. Even a pro audio guy had problems with ice cream cooler sound in the re-mix of my film for DVD, but managed to make it a HECK of a lot better!

Anyway, does anyone think the audio will sound different in HD mode? I'm guessing not. Also, my friend had the camera in manual mode, but the exposure wheel wasn't locked. I barely saw any adjustments at all when my shadowed face would pop up in front of a well lit out door scene. Weird...Maybe it's more manual than I thought...

heath

Steve Mullen · August 22nd, 2003, 05:44 AM

"in a can" struck a chord with me. Everything I shot with the camcorder's mic sounded great. Bujt when i shot with Dynamic mic connected by XLR it too sounded like the mic was in "a can."

I figured it was a matching problem between the very hi-output Dynamic mic. But now I'm beginning to wonder!

Sounds like we need everone to run some audio checks!!!

Heath McKnight · August 22nd, 2003, 03:26 PM

Yes, plugging in a microphone, I believe, is causing this horrible canned (but no XL-1 hiss, a plus in my book) sound. Any ideas how I can fix this in post?

Now I have to buy a DAT recorder? No money coming in yet, and still I have to spend MORE money...

heath

Gints Klimanis · August 22nd, 2003, 03:45 PM

The canned sound is often due to a number of resonances.
Have you tried other microphones in a store?

Since you're trying to fix existing sound, it may be possible to
identify the resonances and reduce them. Try to find files of
of pink or white noise. Play it through a speaker (flat EQ, please) in a heavily carpeted room and use the same dynamic microphone to record it. The noise has a smooth spectrum.
You are looking to identify bumps in the spectrum. Use a frequency analyzer, such as that found in CoolEdit or SoundForge,
to identify the height and width of the humps. Then, apply equalization to remove these humps. Parametric equalizers are good for this job, and you may need several. You will set the center frequency to the middle of the hump, the gain to the negative of the height of the hump. The Q or bandwidth setting may be a rough. If your parametric EQ uses bandwidth, just estimate the width of the hump at -3 decibels on each side of the peak. If your EQ needs a Q setting, convert your measured bandwidth -> Q = center frequency / bandwidth . Tweak the equalizers until the humps in your rerecorded noise file disappear.
Then, apply these equalizer to your recorded audio. This method works on the steady state response of a system, so while it will probably help, it will not remove all of the "in a can" time-domain effects. Basically, you may be dealing with a very short echo from a feedback path. If so, you may have a TON of resonances.

Heath McKnight · August 22nd, 2003, 04:10 PM

Thanks for the tips and advice! I'll try some other microphones.

heath

Lynne Whelden · August 22nd, 2003, 08:47 PM

Not that it matters since you've since sold the camera, but it sounds like an impedance mis-match. Either that or you forgot that the XLR input is not balanced and you ran too much mic cord (greater than 6') and started picking up interference from outside electrical sources.

Heath McKnight · August 22nd, 2003, 09:11 PM

<<<-- Originally posted by Lynne Whelden : Not that it matters since you've since sold the camera, but it sounds like an impedance mis-match. Either that or you forgot that the XLR input is not balanced and you ran too much mic cord (greater than 6') and started picking up interference from outside electrical sources. -->>>

Not sold yet.

Did it wireless for one, with a 6 foot long lav for the other.

heath

August 22nd, 2003, 01:25 AM	#1
Heath McKnight MPS Digital Studios Join Date: Apr 2003 Location: Palm Beach County, Florida Posts: 8,531	heath's full (DV mode) audio review Just taped, well, my friend taped, 90 minutes worth of DV mode interviews of me for my DVD (plug plug). I was outside in South Florida (nice day, surprisingly) with bugs making noise, an airport to the east (small), I-95 to the west (not as busy since it was a Saturday), a guy trimming bushes loudly to the north and me talking, and I was shocked: The audio didn't do any funky things that would make it screw up the first word out of my mouth. Unfortunately, the audio sounded like I was in a can. It sounded in a can when my friend interviewed inside my apartment with no sound (fans, fridge and A/C were off, etc.). Huh...No strange hiss under it, like on my old XL-1, but still....Then again, I bet it's easier to fix the canned sound than a hiss. Even a pro audio guy had problems with ice cream cooler sound in the re-mix of my film for DVD, but managed to make it a HECK of a lot better! Anyway, does anyone think the audio will sound different in HD mode? I'm guessing not. Also, my friend had the camera in manual mode, but the exposure wheel wasn't locked. I barely saw any adjustments at all when my shadowed face would pop up in front of a well lit out door scene. Weird...Maybe it's more manual than I thought... heath __________________ My Final Cut Pro X blog

August 22nd, 2003, 05:44 AM	#2
Steve Mullen HDV Cinema Join Date: Feb 2003 Location: Las Vegas Posts: 4,007	"in a can" struck a chord with me. Everything I shot with the camcorder's mic sounded great. Bujt when i shot with Dynamic mic connected by XLR it too sounded like the mic was in "a can." I figured it was a matching problem between the very hi-output Dynamic mic. But now I'm beginning to wonder! Sounds like we need everone to run some audio checks!!! __________________ Switcher's Quick Guide to the Avid Media Composer >>> http://home.mindspring.com/~d-v-c

August 22nd, 2003, 03:26 PM	#3
Heath McKnight MPS Digital Studios Join Date: Apr 2003 Location: Palm Beach County, Florida Posts: 8,531	Yes, plugging in a microphone, I believe, is causing this horrible canned (but no XL-1 hiss, a plus in my book) sound. Any ideas how I can fix this in post? Now I have to buy a DAT recorder? No money coming in yet, and still I have to spend MORE money... heath __________________ My Final Cut Pro X blog

August 22nd, 2003, 04:10 PM	#5
Heath McKnight MPS Digital Studios Join Date: Apr 2003 Location: Palm Beach County, Florida Posts: 8,531	Thanks for the tips and advice! I'll try some other microphones. heath __________________ My Final Cut Pro X blog

August 22nd, 2003, 09:11 PM	#7
Heath McKnight MPS Digital Studios Join Date: Apr 2003 Location: Palm Beach County, Florida Posts: 8,531	<<<-- Originally posted by Lynne Whelden : Not that it matters since you've since sold the camera, but it sounds like an impedance mis-match. Either that or you forgot that the XLR input is not balanced and you ran too much mic cord (greater than 6') and started picking up interference from outside electrical sources. -->>> Not sold yet. Did it wireless for one, with a 6 foot long lav for the other. heath __________________ My Final Cut Pro X blog

August 22nd, 2003, 03:45 PM	#4
Gints Klimanis Inner Circle Join Date: Jun 2003 Location: San Jose, CA Posts: 2,222	The canned sound is often due to a number of resonances. Have you tried other microphones in a store? Since you're trying to fix existing sound, it may be possible to identify the resonances and reduce them. Try to find files of of pink or white noise. Play it through a speaker (flat EQ, please) in a heavily carpeted room and use the same dynamic microphone to record it. The noise has a smooth spectrum. You are looking to identify bumps in the spectrum. Use a frequency analyzer, such as that found in CoolEdit or SoundForge, to identify the height and width of the humps. Then, apply equalization to remove these humps. Parametric equalizers are good for this job, and you may need several. You will set the center frequency to the middle of the hump, the gain to the negative of the height of the hump. The Q or bandwidth setting may be a rough. If your parametric EQ uses bandwidth, just estimate the width of the hump at -3 decibels on each side of the peak. If your EQ needs a Q setting, convert your measured bandwidth -> Q = center frequency / bandwidth . Tweak the equalizers until the humps in your rerecorded noise file disappear. Then, apply these equalizer to your recorded audio. This method works on the steady state response of a system, so while it will probably help, it will not remove all of the "in a can" time-domain effects. Basically, you may be dealing with a very short echo from a feedback path. If so, you may have a TON of resonances.

August 22nd, 2003, 08:47 PM	#6
Lynne Whelden Major Player Join Date: Feb 2003 Location: williamsport, pa Posts: 604	Not that it matters since you've since sold the camera, but it sounds like an impedance mis-match. Either that or you forgot that the XLR input is not balanced and you ran too much mic cord (greater than 6') and started picking up interference from outside electrical sources.