Need an inexpensive audio gain limiter
 

I'm shooting dog sports with a VX2100 and a Rode VideoMic. For my purposes, I'm happy with the audio quality, but occasionally there are drastically louder sounds (lots of applause, loud dog barking nearby) that inevitably clips at the audio level I need to use for the other 99% of the time (typically at Sony's default level).

The in-camera AGC will deal with the problem, but tends to overkill the rest of my audio (what's that person behind you saying? Let me give you a little audio boost and find out!). So I'm wondering if there's an inexpensive device I can add between my mic and camera to compress the loudest sounds coming off the mic? Or do I have to go to an XLR adapter to add a gain limiter?

Thanks for the help.

-Terence

Terence,

I found some software at:
http://innig.net/software/au/gainshaper/
it's a plugin for sound applications that looks promising since you are able to control the limiter up or down manually in post instead of setting an audio clip in production. I haven't tried it so I cannot speak from experience.

Hi Terrence,

You are definately on the right track, it is much easier to deal with audio peaks before they get recorded on the camera.

There are devices that will do what you want, but most compressors are designed as stand alone processors and as such are usually designed with line level interfaces. This means you would need to pre-amp the microphone level signal to line level before going to the compressor. They are not usually designed to be run on battery either, so mains power would probably be required. I do see two on B&H's site that take mic in, but Behringer isn't a brand that most people like to recommend (I'm one of them...) and there is still the issue of power.

I would suggest looking into an ENG mixer like the Sound Devices MixPre or 302, or the PSC DV ProMix 1. They will take your microphone signal, amplify and limit it, then hand off a line level signal you can put into your camera with a small adapter. They are all "portably" small and run off of batteries. A mixer will also give you the benefits of an XLR input adapter box and is usually easier to adjust levels "on the fly" than twiddling on the camera itself.

Check out some of the sponsor sites and look for a -10db attenuator. I think thats what you're looking for.
I just have never seen any that work with the mic in question as its a mini connection. All I've ever seen or own are xlr connects.
Fix it before post not after if you can-after theres a good chance it can't be fixed.

Don

Not familiar with a 2100 but a GL2 will let you manually set one channel to record significantly lower than another. Assuming you can do the same, I'd set the left channel to your normal levels and set the right so that it wouldn't be max'ed on the louder segments.

Once it's clipped it's clipped and there's not much you can do to fix it in post. It's crucial to avoid overloading the camera's audio inputs as well as the rest of its electronics going to the tape. Problem is, you can clip at the input with too strong a signal even before it gets to the audio circuitry and the camera's level controls with the result that the levels are fine going to tape and yet the signal itself is still clipping. The best way to avoid that is to feed the camera with a field mixer that incorporates a limiter along with careful gain staging.

The camera mounted Beachtek DXA-FX has limiters (but XLR inputs and 3.5mm outputs) and should be suitable for a VX2100? It will mean investing in XLR mics though. Might be worth investigating?

Totally agree it's better to catch those peaks BEFORE you record them and overload the tape. Once clipped, no amount of post processing can recover them - only mask them.

Take a look at the Soundevices Mix pre. It has a really good sound, limiters and small enoughto wear on your belt.
You can sometimes ind one used on ebay. Since thes ar usually owned by sound mixers, a used one would probably have been well cared for.
http://www.bhphotovideo.com/bnh/cont...goryNavigation

Bruce S. yarock
www.yarock.com

a cheap solution:
I really like my Presonus Limiters...12 preset selections of varying attack and release....2 are true limiters, the rest are compressors af various flavors....and they're $99 per channel. I do live music videos for local musicians. You think lead vocalists don't have egos? Vocal dynamics either clip or aren't loud enough to discern over the background instrumentals. Solution? Brick wall limiter between their patch bay and my mixer works like a dream.

Thanks everyone for chiming in. It sounds like my hope of a simple little in-line device I can buy at Radio Shack is delusional (hey, there has to be something I need that doesn't chew up my profit margin).

Bill: I couldn't figure out what you're using from the Presonus web site -- can you describe it more? It sounds like they're probably line-level, but otherwise the brick wall limiter sounds like exactly what I'm looking for.

I suspect this may be my best option. They make a similar (and cheaper) adapter for the VX2100 which also has a aux mini input, but it doesn't have the limiters. But I think I could use a mini-to-XLR converter and postpone the mic upgrade. I wish the battery life was a bit longer, though. The Beachtek web site claims 10 hours typical, which is right on the borderline for a day of shooting for me.


-Terence

Unless you get your audio under control, you won't have any profit to worry about. Get a ENG-44 mixer from SignVideo.

Regards,

Ty Ford

I think the underlying problem here is not going to be fixed by mixers, limiters or the best micorphones money can buy.
It's a simple question of mic placement. The dogs barking is way louder than the speech, sure limiters will stop the barking from clipping, but what happens to the speech, it's gone for as long as they're barking. The only answer is to get he mic closer (much closer I suspect) to the wanted source and further from the unwanted.

I'd advise against using a wired shotgun around dog shows and the like. We've used a 416 with a Senny SKP 100 transmitter plugged into it and a matching receiver on the camera. Pressed the better half into service as a boom operator and it worked a treat. The same kit would work with the Rode shotgun. The biggest issue is you need another person to handle getting the mic in close, that could be an issue if you're trying to avoid people knowing they're being recorded but the lack of a cable helps and you can hold a mic so it's not too obvious and still get good pickup.

Presonus Comp16. I put mine between the mic output and the pre-amp input. Balance and unbalanced connections, phantom power.

Thanks Bill. That comes pretty close, and the price is certainly right, but it looks a little too power-hungry (16W, almost 4x as hungry as my camera) to make it work on-camera. So I guess I'll have to bite the bullet for the Beachtek. I read a comment somewhere about spending more money on batteries than on the equipment, and at one 9V per day I can see how that's going to add up....

-Terence

I would agree with Ty Ford. Most people want to get by with minimal investment into sound, after all, this is video. But, IMHO, bad sound can ruin the greatest picture. If you've spent a couple of thousand on a nice camera, a few hundred or so for good audio is a bargain. The pre-amp with a limiter may be the best solution for a one man op. Rob Wilson and Bob Grant gave great advice that will also help improve you audio and may alleviate the need for a separate limiter, though I would put all the advice together and get the best audio you can. Your VX2100 produces great pictures, but viewers will still think it's from a cheap camcorder if the sound seems cheap.