Field Production Mixer

Re: Field Production Mixer

tghats good for indoar ac powere or studio situation - try to do it rain and snow and you will find yourself with out the tool , the real life( and location recording) is to hard for this equipment - thats why the cooper cost 15 large( of corse if every one was buying it like makie uit probably was falling down)
 
Re: Field Production Mixer

I am going to puchase an XL2 soon. However, the XL2 lacks line-level inputs. It accepts mic-level only.

What does this mean for me as it applies to a field production mixer? Will the Sound Devices Mixpre still be a good idea? The way I understand the sound connection will be:

Microphone > Mixer's XLR mic-level inputs > XLR mic-level outputs > Canon XL2

But it doesn't look like the Mixpre has mic-level outputs, just line-level outputs. I don't want to use any more equipment aside from the mixer and camera so no attenuaters.

Dave, can you tell me if the Mixpre has mic-level outputs?

I'm not sure if I understand everything Matt is talking about - are you guys refering to using a mixer panel usually found in editing suites?

What do you think about using a Behringer UB1622FX-PRO or even a Behringer MXB1002 as a mixer? They are definitely a lot cheaper although less robust.

Thanks for the help and advice, guys.
 
Re: Field Production Mixer

CMS,

You have described the ideal signal path for the XL2.  You could go line it but then you would have to use an unbalanced conection off your mixer.  If this is a run of just a few feet, it really isn’t a problem, however if it is much longer it could be as you have a much greater chance of introducing noise.  For the record balanced cables can also introduce noise, it’s just much areder to do so.  As far as I know, the Sound Devices Mixpre only has balanced XLR line level outputs.  But maybe Dave can correct me on that.

The biggest problem I have with the audio discussions I’ve seen is that they are always talking about the ideal, which is great!  BUT…  Sometimes we can’t have or afford the ideal.  For every other aspect of indie filmmaking we talk about the ideal but then we also talk about how to “make do”, because many of us can’t do it any other way, due to budget restrictions, yet these low/no budget filmmakers still get amazing results.  Lighting is a perfect example of this.  If everyone here could afford an Arri lightkit with all the lights they would want/need, there would be no discussion of work lights or homemade Chinese lanterns.  But not everyone can afford the lights they would want, so they learn to make do with what they can afford.  But because they have a camera and a vision, they’re comfortable experimenting with this, maybe because it isn’t so foreign to them.  For some reason these same folks are uncomfortable experimenting with guerilla audio solutions – and they shouldn’t be.  Audio is really no different.  That’s why I make some of the suggestions I do, NOT because they are the ideal (which I hopefully make clear) but because they are guerilla techniques for getting good sound on a budget.  Look every piece of equipment has it’s purpose, and in an ideal world we would all own all of them so that we always had the optimal piece of kit for the circumstances we found ourselves in.  If you can afford to work that way, that’s great!!!  All, I’m suggesting is that for those who can’t afford it, there may be some other, more cost effect, if less ideal, solutions.

The basics for recording video are no different if you are recording a cooking show for cable as they are if you are recording an indie film.  The details that you set up, such as lighting, staging and your camera settings will be different, but the essence of capturing the image on tape remains the same.  At its simplest, recording audio is the same whether you are recording dialog for a film, the New York Philharmonic or your local garage band.

We are trying to capture the clearest most present sound while at the same time avoiding as much noise as possible.  This is called having a high (or good) signal-to-noise ratio).  Let’s think of this in terms of light.  If we want to capture a scene visually and the circumstances are visually optimal (there’s plenty of soft light, say) we don’t have a problem.  We just point the camera, adjust the iris so that we don’t get too much light (visual distortion) press record and capture the image.  (I’m keeping this simple for purposes of example)  Now, if there isn’t enough light, we have two choices.  We can increase the amount of light, or we can increase the gain setting on the camera.  Both work, but increasing the amount of available light is better because it’s clean, whereas if we increase the gain setting on the camera we generate digital noise in the signal.

All of this is the same with audio.  If our signal is good and loud, we adjust our level so that we don’t get to much volume (just like too much light which will result in audio distortion or “clipping” ) and just record it.  If the signal is weak (not enough light) then we have two basic choices, we can increase the signal (get our actors to speak more loudly) or we can increase the gain.  However just as with your camera, the more you increase the gain, the greater the potential for introducing digital noise.  This is where it starts to get more complicated (in a way).  Better gear gives you better results in the signal-to-noise department.  That’s why audio folks argue over preamps – which ones give the best SNR.  But also, every, or most every, preamp colors the sound a bit, so you have to determine which pre you like based on clarity and coloration – just like a camera.  The DVX and the XL2 are both fine visual capture devices, but they look different.  Well, two different mic pres can both be great pres but they will sound different, what you choose is a matter of $$ and preference.  And then there is resolution.  If you had your druthers in capturing images you would either choose 35mm film or CineAlt video because it has the best resolution/look.  Well in audio, you would ideally capture 32 bit floating point at 196k.  But this is an ideal.  DVD compression is limited to 48k and CD compression is limited to 44.1k.  I don’t know too many people who claim to hear a difference above 48k sampling rate.  I don’t know anyone who says they can hear a difference between 92k and 196k.  But maybe there are.  Now if you want your head to spin, get over to an audio board and join a discussion on what’s more important, bit depth or sampling rate…

Anyway, so we’ve settled on a mic, and a mic pre, whether it is the pre in our camera or an external one and we’re capturing the audio at the best setting that our recording device can handle.  Why do we need a mixer or compressor or anything else?  Well, a mixer can “mix” multiple input sources.  But for an indie film you probably wont be recording with too many sources, but even if you are only using one, as I mentioned before, a mixer is handy for two reasons.  First, it allows someone else to be in charge of sound, second it allows that person to constantly work the level (gain) control.  In a studio this would be refered to as “riding the fader” on a film set the audio tech would refer to this as “riding the gain”.  What are we talking about here?  Well, unlike light, audio tends to fluctuate quite a bit – it gets progressively louder and softer.  Or one conversation might be louder than a previous conversation.  This is fine and a certain amount of fluxuation is desired (called “dynamic range”) however we still want our signal to be “hot” (clear and present with high SNR).  Audio guys differ, but for dialog figure you want your audio signal to peak, or ideally remain at, between -12.0db and -6.0db.  Music engineers typically go for -3.0db, but for a dialog track this is unnecessary and might be cutting things to close for comfort.  To keep the signal this hot the audio tech will lower or increase the gain (just as the boom man might move the boom within limitations) to maintain the signal level.  These constant, minute adjustments are why it is good to have an audio tech working with a mixer.

Now what about a limiter.  Well, just as visual images can distort if they exceed the 100IRE, an audio signal will distort if it goes beyond.  0.0db.  As I said before, where with analog signals this produced a pleasing distortion (the reason may folks prefer LPs to CDs) in the digital world you just get a very, very ugly sound.  Basically a limiter works by cutting off any signal that goes over whatever threshold you set it at.  So, if you set your threshold at -3.00db then any signal hotter than that will be “clipped” or not recorded.  This is good because you avoid the ugly sound we talked about, but bad because you have lost information (audio) which you will either have to live without or replace. A compressor works a little differently.  A compressor compresses the signal above a certain threshold, effectively riding the gain on any audio above your setting.  So, if you set your threshold at -3.0db and your compression ratio at say 3:1 then every sound over your threshold will be reduced in volume (compressed) by a ratio of three to one, thereby keeping all of your information without distorting.  This was a simplified explanation but it tells you what you need to know.  You can also use compression to make an overall soundrack louder.  By limiting the dynamic range of a piece of audio (making the difference between the softest parts and the loudest parts very small) we can then increase the volume of the over all track because our peaks wont exceed our threshold.  When I talk about transparent, or soft-knee compression, that basically just means that you won’t notice that any compression has been applied.  This is the more common type, although some folks in music will use (overuse) compression to achieve a noticeable effect.  

There are so many options available today for capturing and working with sound it is really incredible.  10 years ago, I would have needed well over $100,000 worth of equipment and a dedicated studio to do what I now do in a spare bedroom with a G5, some software and a few pieces of affordable outboard gear.  Anyone here who has a computer capable of being and NLE can also set it up as a DAW (digital audio workstation) capable of manipulating audio in post.  Once you start doing that, guerrilla techniques become much more viable.   I would recommend any low/no budget guys to get over to a large chain music store with a pro-audio department and experiment.  You don’t have to buy anything, just talk to the guys, play with the gear, and research on the net.  You’ll be amazed at what you can do for relatively little money.

Again, if you have all the money in the world, disregard my posts or tell me that you have all the money in the world and I’ll offer an appropriate solution.  But if you’re a guerilla out there trying to do the best you can on a budget, don’t let audio be some mystical craft that you have to spend a fortune on – cause it aint so.

Matt

EDIT: In this post I made some comparisons to light and video, two things I am new to. I did this to try and be helpful with my analogy. If I made mistakes along those lines I appologize. Please take this post in the spirit in which it was intended.
 
Re: Field Production Mixer

That was quite a post! :o

Yes, the MixPre only has line out.
 
Re: Field Production Mixer

Sorry. :-[

I've reread it a bunch of times and still feel like I wasn't clear enough either in what I was trying to explain or why I was trying to explain it - plus way too many typos.

Matt
 
Re: Field Production Mixer

And Dave, just to be clear. My advice regarding the Fostex was for using it instead of the MixPre. You don't have to record to it, you can simplly use it as a battery operated preamp/mixer unit and rout the signal straight to the DVX for recording, which, incidently, is EXACTLY what the MixPre does. Now if you say that the pres in the MixPre are WAY better than those in the Fostex, I'll give you the benefit of the doubt (hell for the price they should be) but I would want to hear them myself first before I justified the cost.

Matt
 
Re: Field Production Mixer

Oleg,

Yes, you're right. Although it you're setting up a waveform monitor and such, or using DVRack to monitor and record your video, you could just as easily set up a small board or use a laptop running Logic, Nuendo or Protools to monitor and record your audio - it is no different. What if it rains or snows? Well, we worked under a tent. Maybe that wont work, maybe you need a portable solution. Maybe you're going to record two women jogging through the park and your audio guys and video guys are going to jog/move along with them. Well then it won't work then either - you're right. But if your filming the typical indie short/wedding/comercial/industrial/studio/or usual location footage, it will work just fine.

Matt
 
Re: Field Production Mixer

Thanks for the indepth and highly informative post, Matt!

I understand every one of your points, and appreciate the time you took to explain the basics of audio for us. Audio is an area I'm unsure about, but your explanations helped out a lot especially on limiters and compressors, which until now has always been an unclear topic for me.

Essentially, I want to ensure I have the best audio possible for my low budget, and because of the price, I'm certain I'll have to resort to guerilla tactics at some point.

Fortunately, I can afford a mixer of some kind, under $800 preferably, and would like to purchase one, even though I could get by with the camcorder's audio alone. I want to get a mixer because I can't afford a dedicated sound recorder now, and would like the benefit of having to avoid the camera's internal preamps. I learned from reading Jay Rose's columns over at DV magazine and on the DV.com website that most camcorder preamps are substandard, including those found on the Canon XL1, Canon GL2, JVC GY-DV300U, and Sony DSR-PD150. The AG-DVX100 was the only exception, but even then, I understand that many productions can benefit from having a mixer if you can afford the cost. Register on DV.com and search for Jay Rose's article "DV Camera Audio: Real Numbers, Real Recommendations," along with a side column he wrote for the AG-DVX100 (search for AG-DVX100 and audio).

Another reason I would like a mixer other than avoiding the camcorder's internal preamps is because I will have a dedicated sound person, although he too comes from a music/DJ background. I want to give him and whoever is holding the boom the opportunity to monitor sound properly.

So far I purchased a Lightwave boompole, Audio Technica shockmount, Sony MDR-7506 headphones, and an Audio Technica 4073a shotgun microphone.

Thanks, again!

Charles
 
Re: Field Production Mixer

Your last comment hit an important issue for you...boom person monitoring the sound.
IF you have a person mixing AND another person booming then you can use an AC powered board set up somewhere and be OK, if you can send a feed back to the boom operator from the board. Some boards can easily acomplish this and others are more difficult to wire for that.
IF you have ONE sound person then the sound mixer/boom operator must wear the mixer. It is the only practical way to boom, mix and send to camera.
I have a 'bag' setup. My sound person wears it and is tethered to me with a 20' ENG cable. this cable sends stereo to camera and also has a return feed from camera to mixer. Good field mixers have a matrix to select whether you listen directly to the mixer or listen to the return feed from camera. Good mixers use both. Listen to the camera return to make sure it is going there. Also listen to the mixer because it is a cleaner feed than the noisy return from most cameras like the DVX.
The bag is also set up with 2 wireless RX and a boom pole. We use any number of combinations of wireless and boom, depending on the situation. I do a lot of walking/talking work for the networks and this rig is the only way to go.
Again, if you can send a return to a dedicated boom operator from a fixed position then the other mixer options are acceptable. They are just limited in their flexability.
Also, I don't think the headphone matrix for monitoring the camera is a part of the mixers you are considering. I have jerry rigged a setup for my Mackie 1402 that suffices but it's not a standard part.
 
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