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-   -   What is the difference between a field mixer and a preamp (http://www.dvinfo.net/forum/all-things-audio/486986-what-difference-between-field-mixer-preamp.html)

Xin Jin November 3rd, 2010 06:04 PM

What is the difference between a field mixer and a preamp
 
Hi

I am wondering what the difference between a field mixer and a preamp (like juicedlink?) is? Do field mixers have preamps too?

I am going to shoot a film with either T2i or 5D2 (if I can get one with L lenses).
What is my best option for shooting one-way without having to sync video and audio in post? I once did sound for a friends short. There it was recorded with a shotgun going through a juicedlink cx-23something and into a h4n.
Although it allowed for mobility between camera and sound, I will probably not have so many people on set. I will also be filming in remote areas, where i wont have a giant crew, nor the time to instruct people on how to use all the stuff.

Thanks a lot, your help is much appreciated

Cheers Xin Jin
Vienna, Austria

Chris Barcellos November 3rd, 2010 11:56 PM

Since you are clearly stating that you have a limited crew available in what sounds like a remote situation, you have to become your own sound engineer, and try to design what you need. The fact that you came to this site shows that you are wanting to learn what to do.

Now essentially, the CX 231 is a mini mixer with its own preamps. However, its ability to amplify and get a strong clean signal to the camera is more limited . On top of that, the cameras you are using have their own automatic gain control that will usually push the gain to a fairly noisy level, even feeding from the CX231. The 5D now has adjustable gain, but feeding the 5D2 and still getting a decent recording is a real dance.

I have used an ENG 44, a $500 mixer, and fed the camera through a passive XLR adapter to my Canon 5D, with success. But in that situation, I had a sound guy on a boom monitoring the sound and at the same time we were recording to a separate but inexpensive Tascam DR07. We had decent results that way, and if the signal got fouled between the mixer and the camera, I still had a pretty clean signal on the separate recorder.

Recently though, I have moved to a new software Dual Eyes, which will automatically synch my video, by using my in camera mic recordings as a track to match and replace in a newly generated clip. It looks promising to me, in my first tests.

Good luck in your endeavor, and ignore those with those negative attitudes.... especially in getting them on your crew.

Bill Davis November 4th, 2010 01:55 AM

Xin Jin,

To answer your question specifically --

A MIXER is a device that receives multiple audio inputs and then sends those signals back out on a smaller number of outputs. A typical mixer might take 3 microphones and output the mixture of their sounds to one or two outputs. Mixers also typically allow for signal strength matching and may include tone controls such as the ability to cut or boost low frequencies, mid-range frequencies, or high frequencies.

Pre-amps are generally associated with VERY low level signals (phonograph needles, un-powered microphones, etc.) They are devices designed to take a VERY low level signal - and BOOST it's signal to the point where a standard amplification circuit can further amplify or otherwise control it.

Many field mixers have pre-amps. Some, however, are "passive" designs that can only lower signals - and as such can't work with the already very low signals being discussed here.

As to your final question area - no current DSLR cameras (definately including those you mention) are equipped to do a good job of recording audio without major compromise in sound quality.

That's why the tradition is to use "double system" sound - where the audio is recorded via a separate system and synced with the picture during the post-production process.

Yes, it's harder to pay attention to TWO separate systems during a shoot - but if you wish to take advantage of the exceptional visual capabilities of modern DSLRs - you're stuck with double system if you want a hope that the audio quality you record will come anywhere near matching the visual quality.

Hope that helps.

Chad Johnson November 5th, 2010 06:14 PM

"Mixer" is what video guys call preamps. If you're not driving speakers, like a power amp does, it's a preamp. Just call it a mixer and everyone will know what you mean.

On instrument amps (bass, guitar, keys) there are level knobs for all the channels and that's not called a mixer - it's called the preamp. The mixed/EQd signal goes to the power amp, which drives the speakers. Same for stereo components.

Shooting with a DSLR? Best to get the JuicedLink with the AGC defeating option. Still the camera audio is dubious, but if you don't want to record into a better recorder, you'll need the JuicedLink. Even with a recorder, a mixer is a good idea. Not the passive kind like Beachteck, but something active like the JuicedLink.

"What is my best option for shooting one-way without having to sync video and audio in post?" Use a video camera not a photo camera! LOL.

You still need someone to run boom don't you? Please don't tell us you're putting a mic on the camera.

Bill Davis November 6th, 2010 12:11 AM

"Mixer" is what video guys call Mixers.
"Pre-amps" are what video guys call Pre-Amps.

Even JuicedLink themselves are quite clear about these distinctions as is demonstrated by their very own web listings:
__
Audio: Preamps, Mixers, Etc : juicedLink, Unique and Trusted ...
juicedLink : Audio: Preamps, Mixers, Etc - Audio: Microphones / Accessories New Products About juicedLink Policies: Sales, Shipping, Etc Where to purchase .
Audio: Preamps, Mixers, Etc : juicedLink, Unique and Trusted Solutions for Audio and Video Production - Cached

While a product my include BOTH a pre-amp AND a mixer. There are also countless products that are one - the other - but NOT both.

If you are calling pre-amps - mixers - you're mis-speaking. (which happens a LOT in life to all of us, BTW)

In point of fact, terminology - particularly for recently developed and deployed technologies is always in flux. It's not just colloquial, it's often REGIONAL - with folks on the east coast having one term for a particular gizmo and folks on the west coast having a different term for the same thing.

That's why I'm appealing to everyone here to consider the terminology and language you learn and use as carefully as possible.

Also, please don't get fooled by thinking that the way you've personally solved equipment issues is the same way that everyone should. There are those working to different purposes, in different parts of the industry for whom a mic from Rode, for example, might be something to roll their eyes at. That doesn't mean it's not a good brand or mic in a particular use. It just means that they might have experience with 20 different mic brands and they ruled out Rode immediately, not based on it's performance or sound, but because NONE of the shops that they work with on a regular basis will offer service, support or have rental replacements for what they classify as a "consumer" piece of gear.

The factual reality might even be that a Rode NT-2 has 80% the functionality in a particular circumstance of, for example, a Shoeps CMIT5u mic at a fraction of the price. But in some situations pros find that that last 20% of extra performance is MORE than meaningful (and worth THOUSANDS OF DOLLARS extra spent) when their work is heard in 5.1 or 7.1 in a state of the art theatrical showing.

Sound is complex.

Sound equipment is likewise, complex.

Yes, there are newer, cheaper and often very useful replacements for what was once "top of the line" gear coming out all the time. It's not always easy to understand WHY things have developed the way they have when you're relatively new to your career. And it IS easy to transform satisfaction with a product that meets YOUR needs into an opinion that it will likely meet others' needs as well. But some times it won't. And usually because their needs DIFFER from yours.

Still, a rose by another name may, in fact, smell lovely, but a preamp STILL won't properly sum 3 mono mic signals into a stereo feed. Not without other circuitry in play.

Peace.

Richard Gooderick November 6th, 2010 03:00 AM

Quote:

Originally Posted by Xin Jin (Post 1584844)
What is my best option for shooting one-way without having to sync video and audio in post?

I would not worry about syncing in post. It is not difficult and it does not take very long. Particularly if you get someone to clap at the beginning of each take.

You don't need to use any software to do it either. Just match it up on the timeline using waveforms. Move one of the tracks in relation to the other until any echo disappears and you are in sync.

If you have just one other person on the set that should be a sound person.

Chad Johnson November 6th, 2010 02:58 PM

Though the mic list in this particular forum's signature is embarrassingly limited by budget, it in no way relates to my experience level, or is a complete list of my equipment. I use a combo preamp/mixer when feeding a mic's signal into a camera, yet it is sold as a "Mixer" and indeed video guys call it a "Mixer".

Peace.

Greg Kiger November 7th, 2010 07:14 PM

I am pretty sure Chris meant Plural Eyes which is a great little tool for syncing tool, well worth the minimal cost :)

Chris Barcellos November 7th, 2010 09:04 PM

Actually, I meant Dual Eyes.

Singular Software

Its a new product from Singular Software that is a stand alone version of Plural Eyes. I like the idea of being able to batch process a whole directory of video clips with a whole directory of audio clips. It does not have to be done on a time line in Vegas.

Chad Johnson November 8th, 2010 11:49 AM

Hey I like the looks of that Dual Eyes! I have neither Plural or Dual, and now I wonder which one is faster/easier. It looks like Dual makes new video clips with the good audio already on them. That's pretty sweet.

Chris Barcellos November 8th, 2010 12:20 PM

You can do it one of two ways. You can have it make audio clips that will match up exactly with the video clip, and is named so matching is easy, or you can have a new video clip generated with new sound replacing the old.

Xin Jin November 15th, 2010 07:43 AM

Thank you all so much for the detailed information. =)

Dave Stern November 23rd, 2010 12:51 AM

Quote:

Originally Posted by Chad Johnson (Post 1585993)
Hey I like the looks of that Dual Eyes! I have neither Plural or Dual, and now I wonder which one is faster/easier. It looks like Dual makes new video clips with the good audio already on them. That's pretty sweet.

I have the free version called cross-eyed! very easy to obtain, no download needed .. just stare at your monitor for many hours on end and you will automatically have it. and best of all, it's (in-)compatible with all NLE's!

oh, Xin, one thought so that my post isn't OT ... depending on how many mikes you are using and how many channels you are recording, you may want to take your 'main' mike and record it at two different levels (esp. if you are working alone)..this way you can have one with higher gain avail. when you need, and one with lower gain (volume) avail. if the sound gets too loud and blows out your higher gain channel, if you will want to focus on the video (just make sure you audio is recording all the time!) ... food for thought

Xin Jin November 23rd, 2010 06:15 AM

Hi Dave

my main mic would be a shotgun. How can I record it at two levels? Do I need two seperate recording devices or can it be recorded into one H4n? Sounds like a good advice, thanks.

Xin

Chad Johnson November 23rd, 2010 09:59 AM

Xin, I'm not sure about the H4N, but when going into a camera with one mic, you can have that signal go into both channels, and you set one level lower than the other as clip protection.


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