Dealing with AGC? and audio options on cams at DVinfo.net

Luke McMillian · January 24th, 2006, 11:10 PM

Hi all,

I'm in a bit of a pickle, I'm buying a new camcorder and I've come down to either a consumer panasonic 3CCD (GS250) or one of the newer ones, waiting for a review), and Canon camcorders like the optura 60.

I have a Rode NTG-2 shot gun mic on order, with a boom pole, shockmount, hot shoe adapter to hold it on the cam, and a 1/8 to XLR. ( I realize the connection must be balanced, but that's what the store ordered in for me at $8, just to see how much noise etc it will pick up by being unbalanced.

I've heard when using a shot gun mic with a camcorder that has AGC it produces undesierable results, a wooshing sound or something. I was wondering how bad this sound is, is it really bad enough to fussing a lot over? If so I need a solution, I've got it down to this

a) Buy a canon camcorder that has more sophisticated manual audio options, such as ability to tun off AGC(if they do have that?) something to weaken the signal for the condenser shot gun mic, or do i need to worry about that? And use the simple 1/8 to xlr.( Altho low light issues reported from the cam concerned me)

b) Buy a Panasonic 3CCD of my choice, and use one of those beachtek adapters. I'm not sure if they can get rid of AGC, or weaken the signal coming from the cam, or balance it etc, and which model to get?

c) Buy a Panasonic 3CCD cam, get the good visuals with the cam, and invest in some kind of seperate audio recording unit. Not sure what to get, I've heard mini disc used, DAT recorders, and mixers. Basically I'd be looking for the cheapest possible solution to get good results. (Good thing is I know i could use this set up with a future cam, not sure what they use or will be used for high definition tho, cuz that'll be the next cam after this one.)Any model opinions?

d) Wait for reviews on the newer Panasonic cams and see if they have have manual audio adjustments that I need.

PV-GS180, PV-GS300, PV-GS500 (this was unsettling to read - Like all the Panasonic 3 CCD camcorders, the microphone jack will accept a low impedance, unbalanced microphone and provides plug-in power for electret (condenser) elements. There is no headphones jack. This will prove to be a difficult problem in using external microphones because their output level is too high and needs to be adjusted downward to avoid distortion. However, with no audio level adjustments like the GS500 and no headphones jack like the GS180, there is no way to monitor the effects of external level controls on the volume of recorded audio. Users will just have to use trial and error to find a compatible setting. Not cool, Panasonic.

or PV-GS29, PV-GS39, PV-GS59?

http://www.panasonic.com/consumer_e...2006/flash.asp?

So I've come to this lovely board again to ask for advice from you videographers. Please help, I'm going insane! haha What do you recomend, what cam, what audio equipment, etc?

thanks

Luke

Steve House · January 25th, 2006, 08:16 AM

Why do you keep saying you need to weaken the mic signal at the camera? When you feed a balanced mic to an unbalanced input through a properly wired simple adapter (which it remains to be seen if your $8 adapter is), you have might have a 50% reduction right there. Another problem with simple cable adapters is consumer cameras may supply a 5v mic power through the external mic jack - this is NOT the same thing as the 48v phantom power that many professional mics require and its presense can cause distortion and noise - a proper adapter will block it.

In any case, the problems with AGC generslly aren't caused by too strong a level from the mic anyway. The problem is sounds like speech aren't constant, there's periods of sound and periods of silence. The AGC tries to keep the signal constant - during sounds it reduces the gain and during silence it increases it. So when there's silence it's all the way up trying to hear something that isn't there. In fact it's so high that you hear hiss, etc. Then when the sound starts the gain is way too high and the AGC backs it down to the 'right' level. But this isn't instantaneous, it takes time - so the sound is loud and then fades down. Then when the sound stops it brings the gain back up and the hiss returns. Sounds pretty terrible IMHO and there's nothing you can do about it unless you can turn off AGC altogether. So the first and most important suggestion is: For serious work never buy a camera that doesn't let you defeat the AGC! The inability to defeat AGC should be an absolute deal-breaker for any camera under consideration.

Marco Leavitt · January 25th, 2006, 02:43 PM

As Steve notes, AGC is simply a bum deal. You can minimize clipping with a limiter, but it will still introduce all kinds of other crap into your soundtrack. If you're set on a Panasonic GS series camcorder (other than the GS400, which now seems hard to find), plan on double system sound. It's the best route anyway since the preamps on all consumer camcorders more or less suck. We're currently using an Optura 60 (yes, it does have manual audio controls) and the results are better than I would have expected, but nowhere near as good as even minidisc would be.

Luke McMillian · January 26th, 2006, 05:49 PM

Hey,

Thanks for the replies. I think I may opt for an external sound set up. What products should you recomend I buy? Do people usually buy a mini disc and a small mixer? What is the cheapest no hassle set up I can get decent results with? What specifics products should I buy? and is there anything else I need to be aware of, can i just make my own clapper board, is that fine?

Marco Leavitt · January 26th, 2006, 06:57 PM

It's all a matter of budget. I'd rather have a field mixer that had a limiter and record direct to camera (assuming it had manual controls), than just a minidisc. The minidisc technically sounds better, but in practical terms, the ability to control the sound with the mixer, and access to phantom power, will probably result in a better track, at least in our experience. Money for both (and crew to deal with the extra work), do it. I should say that recording double system sound is quite a bit more work. Lately we've been recording direct to camera just because we don't have enough crew. I hope to change that next month.

There's lots of other options than minidisc, or rather HiMD as the latest version is called. Most people are switching to a hard disc recorder of some sort. Lots of mixers at lots of different price points too. Those are topics in and of themselves. Do a search. Oh, and faced with the choice of the GS series which has excellent manual controls (but not for audio), and the Optura 60, which has manual audio but slightly awkward manual controls for exposure, we went with the Optura 60 and I'm glad of the decision every time I use it. I would never, ever, buy a camcorder that didn't have manual audio controls.

January 24th, 2006, 11:10 PM	#1
Luke McMillian Regular Crew Join Date: Dec 2005 Posts: 62	Dealing with AGC? and audio options on cams Hi all, I'm in a bit of a pickle, I'm buying a new camcorder and I've come down to either a consumer panasonic 3CCD (GS250) or one of the newer ones, waiting for a review), and Canon camcorders like the optura 60. I have a Rode NTG-2 shot gun mic on order, with a boom pole, shockmount, hot shoe adapter to hold it on the cam, and a 1/8 to XLR. ( I realize the connection must be balanced, but that's what the store ordered in for me at $8, just to see how much noise etc it will pick up by being unbalanced. I've heard when using a shot gun mic with a camcorder that has AGC it produces undesierable results, a wooshing sound or something. I was wondering how bad this sound is, is it really bad enough to fussing a lot over? If so I need a solution, I've got it down to this a) Buy a canon camcorder that has more sophisticated manual audio options, such as ability to tun off AGC(if they do have that?) something to weaken the signal for the condenser shot gun mic, or do i need to worry about that? And use the simple 1/8 to xlr.( Altho low light issues reported from the cam concerned me) b) Buy a Panasonic 3CCD of my choice, and use one of those beachtek adapters. I'm not sure if they can get rid of AGC, or weaken the signal coming from the cam, or balance it etc, and which model to get? c) Buy a Panasonic 3CCD cam, get the good visuals with the cam, and invest in some kind of seperate audio recording unit. Not sure what to get, I've heard mini disc used, DAT recorders, and mixers. Basically I'd be looking for the cheapest possible solution to get good results. (Good thing is I know i could use this set up with a future cam, not sure what they use or will be used for high definition tho, cuz that'll be the next cam after this one.)Any model opinions? d) Wait for reviews on the newer Panasonic cams and see if they have have manual audio adjustments that I need. PV-GS180, PV-GS300, PV-GS500 (this was unsettling to read - Like all the Panasonic 3 CCD camcorders, the microphone jack will accept a low impedance, unbalanced microphone and provides plug-in power for electret (condenser) elements. There is no headphones jack. This will prove to be a difficult problem in using external microphones because their output level is too high and needs to be adjusted downward to avoid distortion. However, with no audio level adjustments like the GS500 and no headphones jack like the GS180, there is no way to monitor the effects of external level controls on the volume of recorded audio. Users will just have to use trial and error to find a compatible setting. Not cool, Panasonic. or PV-GS29, PV-GS39, PV-GS59? http://www.panasonic.com/consumer_e...2006/flash.asp? So I've come to this lovely board again to ask for advice from you videographers. Please help, I'm going insane! haha What do you recomend, what cam, what audio equipment, etc? thanks Luke

January 25th, 2006, 08:16 AM	#2
Steve House Inner Circle Join Date: Mar 2005 Location: Hamilton, Ontario, Canada Posts: 5,742	Why do you keep saying you need to weaken the mic signal at the camera? When you feed a balanced mic to an unbalanced input through a properly wired simple adapter (which it remains to be seen if your $8 adapter is), you have might have a 50% reduction right there. Another problem with simple cable adapters is consumer cameras may supply a 5v mic power through the external mic jack - this is NOT the same thing as the 48v phantom power that many professional mics require and its presense can cause distortion and noise - a proper adapter will block it. In any case, the problems with AGC generslly aren't caused by too strong a level from the mic anyway. The problem is sounds like speech aren't constant, there's periods of sound and periods of silence. The AGC tries to keep the signal constant - during sounds it reduces the gain and during silence it increases it. So when there's silence it's all the way up trying to hear something that isn't there. In fact it's so high that you hear hiss, etc. Then when the sound starts the gain is way too high and the AGC backs it down to the 'right' level. But this isn't instantaneous, it takes time - so the sound is loud and then fades down. Then when the sound stops it brings the gain back up and the hiss returns. Sounds pretty terrible IMHO and there's nothing you can do about it unless you can turn off AGC altogether. So the first and most important suggestion is: For serious work never buy a camera that doesn't let you defeat the AGC! The inability to defeat AGC should be an absolute deal-breaker for any camera under consideration. __________________ Good news, Cousins! This week's chocolate ration is 15 grams! Last edited by Steve House; January 25th, 2006 at 04:11 PM.

January 25th, 2006, 02:43 PM	#3
Marco Leavitt Inner Circle Join Date: Jul 2002 Location: Albany, NY 12210 Posts: 2,652	As Steve notes, AGC is simply a bum deal. You can minimize clipping with a limiter, but it will still introduce all kinds of other crap into your soundtrack. If you're set on a Panasonic GS series camcorder (other than the GS400, which now seems hard to find), plan on double system sound. It's the best route anyway since the preamps on all consumer camcorders more or less suck. We're currently using an Optura 60 (yes, it does have manual audio controls) and the results are better than I would have expected, but nowhere near as good as even minidisc would be.

January 26th, 2006, 05:49 PM	#4
Luke McMillian Regular Crew Join Date: Dec 2005 Posts: 62	Hey, Thanks for the replies. I think I may opt for an external sound set up. What products should you recomend I buy? Do people usually buy a mini disc and a small mixer? What is the cheapest no hassle set up I can get decent results with? What specifics products should I buy? and is there anything else I need to be aware of, can i just make my own clapper board, is that fine?

January 26th, 2006, 06:57 PM	#5
Marco Leavitt Inner Circle Join Date: Jul 2002 Location: Albany, NY 12210 Posts: 2,652	It's all a matter of budget. I'd rather have a field mixer that had a limiter and record direct to camera (assuming it had manual controls), than just a minidisc. The minidisc technically sounds better, but in practical terms, the ability to control the sound with the mixer, and access to phantom power, will probably result in a better track, at least in our experience. Money for both (and crew to deal with the extra work), do it. I should say that recording double system sound is quite a bit more work. Lately we've been recording direct to camera just because we don't have enough crew. I hope to change that next month. There's lots of other options than minidisc, or rather HiMD as the latest version is called. Most people are switching to a hard disc recorder of some sort. Lots of mixers at lots of different price points too. Those are topics in and of themselves. Do a search. Oh, and faced with the choice of the GS series which has excellent manual controls (but not for audio), and the Optura 60, which has manual audio but slightly awkward manual controls for exposure, we went with the Optura 60 and I'm glad of the decision every time I use it. I would never, ever, buy a camcorder that didn't have manual audio controls.