Levels, and headphones, and batteries, oh my!

[Robert Martens]

Okay, so I've been putting off asking this for a few hours now, worried both that my explanation would be too cumbersome, and that I'd be yelled at for not searching first. Well, I'm just gonna have to go ahead and be cumbersome, and for all the searching I've done, I can't put together an answer to my questions. Maybe I'm just stupid, I don't know.

Here's the deal.

I was recently chosen to help Hal Wolin and company on their movie, "A Couple Days in Vegas". I've just finished helping them shoot auditions, and will soon be doing rehearsals; I'm currently handling both camera work and audio. The thought is that as we get into actual production, the responsibilities of audio will be offloaded to others--hopefully others who know more than I do--something I'm very happy with. Don't get me wrong, I understand and respect the power of audio, and what it's worth to do it right, and I wish desperately to get a handle on such things, but I can't. Try as I might, I'm a total screwup when it comes to audio. Unfortunately (for myself AND the final product), I'm stuck trying to grasp this stuff for the time being.

The auditions were, and the rehearsals will be, shot in a small audition space in Manhattan. About ten by fifteen feet, with nine or ten foot ceilings. I think. I'm no judge of distance. It's not terribly well suited for this purpose, as the only thing they've got on the walls is some "soundproofing" material that's totally useless. It's packing foam, really; it certainly LOOKS like the echo-absorption stuff, but it doesn't actually work, and it sure as heck does nothing to stop sound from coming in or going out of the room. But even the genuine "eggcrate"-lookin' material isn't meant to do that. The tracks we record, as I understand it, are echoey.

But that's a minor consideration, in the end: they ARE just auditions, and the sound needn't be theatrical release quality. No, what I can't grasp are the more basic things involved here. There's no one around to operate a boom, no boom pole to stick the boom mic on ("He bought a shotgun without a boom pole?! What the frig is wrong with this guy?"), and no room for the guy to walk around even if we had him, so we're using two wireless mics. One's a Sony of some sort, I'm not sure which, that's theirs, the other is my Sennheiser Evolution 100. The package I bought came with the EK100 bodypack receiver, SK100 bodypack transmitter, ME-2 lavalier, and SKP100 plug-on transmitter.

I've got the receiver mounted on a Bracket 1 (couldn't afford the cozy little box when I got it, so it's just clipped on right now), plugged directly into my VX2000's mini jack. Yeah, I know, the output of this receiver is balanced, I should be plugging it into the balanced mini jack on my DXA-4, but that's been damaged, and is out of the equation (to speak the truth, the damage is my own fault, and I'm too embarrassed to send it in for repair. Same with my camera and my laptop; I like to punish myself for being an ass by breaking my most expensive stuff).

The first round of auditions I recorded--they had actually done some already, these were just the first I was there for--were too soft, and barely audible. I made sure to set my camera's audio control so it got nice and close to the 0dBFS mark on the peaks without actually clipping, and it sounded fine to MY ears through the headphones they let me borrow (I'm gonna get some 7506s ASAP), but the result was almost useless. I remembered, only after the fact of course, that the receiver has its OWN volume control, and for my second round of auditions, I tried adjusting it. Yet I couldn't figure out if I did it right because I had THREE volume controls to worry about: the one on the receiver, the one in camera, and the one on the headphone cable (this was a cheap pair of cans, only purchased at the last minute to make sure I was recording SOMETHING on tape). I had the little bars in the LCD screen on the receiver spending most of their time at the one half to three quarters mark, with occasional peaks on loud words going up toward the top, and I did the same with my camera's control, even though I had to turn it down almost completely. There was still some crackling every now and then, but I believe that was the headphones themselves. I have yet to hear the results, as they are the ones reviewing the tapes. Should I have insisted on listening to the tapes at the end of the day? Probably, but it was late and I was tired.

"So what the hell are you asking?", you say. I'll give you a list:

1.) Exactly how does one properly, accurately adjust the levels of a wireless mic setup like this?

2.) Should I have the VX2000's switch set to "line" instead of "mic"? I realized, after arriving and setting up, that I didn't know which was correct. I tried both, and "mic" was the only one I got a signal on, so I assumed it was right, but now I'm thinking maybe I simply did something wrong. Again.

3.) What's the deal with batteries for this stuff? I know you're supposed to put a fresh one in each device at the start of each day, and I'm fine with that. I can afford to get a few boxes of nine volts. But I don't know how long they usually last, or whether I'm supposed to switch the units off between auditions. Sometimes it's a ten to fifteen minute wait, sometimes we go out for an hour and grab something to eat. Should the things be on the whole time?

3b.) As a side note to the above, can anyone tell me the official, electrical reason you're not supposed to leave batteries inside of things? I always hear "never put your camera/mics away with the batteries inside", and I follow the advice, but I've never understood exactly why.


If anyone can provide me with answers to those questions, that'd be great, and if anyone can provide some more general, overall advice for my particular situation, that'd be even...greater.

No idea what I'm doin'.

[Troy Tiscareno]

First, the G2 receiver sends out an unbalanced signal, but that's no problem since the cam's input is unbalanced anyway and you're using a very short cable that doesn't cause problems that balancing fixes.

Second, the G2 receiver comes from the factory with the output level cranked way up to (IIRC) +10 or +12 db. If it isn't adjusted down, it will overdrive the input circuit on the cam and cause the crackling distortion you heard. Go into the menu on the receiver, scroll to the "AF Out" setting, and change it to around -12 dB (that's a good starting point, anyway; you may need to adjust a bit up or down).

Now, with the receiver plugged directly into the cam, you'll need to adjust the audio input level on the cam. Start by going into the Menu and switching the Audio to Manual instead of Auto. Then, adjust the level so that the bars are close to, but not going into the red, with the loudest sounds. You never, ever want the peaks to actually hit the red, as digital audio has a "hard ceiling", which means that anything that actually hits the red will be distorting.

Ideally, the camera's input level setting will be around 2/3 of the way up or a bit more. If you have it more than 3/4 of the way up, then adjust the G2 receiver's output down a bit more and try adjusting the cam again. If the cam's level is less than half way up, then adjust the G2 receiver's output up a bit. The idea is to be getting the right audio levels with the camera's input somewhere between 2/3 and 3/4 of the way up. You'll have less circuit noise/hiss in this range, while having plenty of "headroom", so that you don't overdrive the circuit.

If you can, as each actor gets ready to audition, have them talk loudly so that you can adjust the peak levels on the cam. If you set the input on someone with a loud voice and leave it there, the next person may have a soft voice that's too quiet on tape, and vice versa. If you can afford the 30 seconds or so per actor, you'll be able to fine-tune and get the best audio. Ideally, you won't adjust the levels during the actual taping, but if you find that the audio really IS too quiet or too loud (clipping/distortion), then it's better to adjust it than to let it continue to be bad.

The key thing to understand is that the camera has the "master" volume, meaning it is the device who's level matters most. The other devices (your G2 receiver, or your BeachTek) need to be level-adjusted to suit the cam, not vice versa. If you can keep the cam's level somewhere around the sweet spot, and match the other devices to that, you'll generally get good audio. Once you understand that, you'll find that actually *doing* it isn't so tough.

-Troy

[Robert Martens]

Appreciate the advice, Troy, thanks! Met again with the guys yesterday (only got home at five o'clock this morning), turns out the audio was "fine" on the most recent auditions; seems I did something right. Your tips can only help more.

Coupla things, though:

-Not sure how much difference it makes, but I don't have the "G2" model transmitter/receiver. I have the earlier model, which doesn't seem to have any particular designation beside "ew100".

-Pardon the stupid question, but if it's sending out an unbalanced signal, why do they include a three conductor mini-to-mini cable? It's got two separate plastic rings, and three separate metal contact areas (the tip, ring, and sleeve). Does that just mean it's stereo, and not necessarily balanced?

[David Ennis]

Robert,

Actually the mini jack on the DXA-4 is unbalanced.

My guess is that if you test for continuity between the tip and the ring section of the free end of your cable with the other end plugged into the receiver, you'll find that they're shorted together by the receiver's jack. This would apply the mono signal to both channels of the cam if you plug directly into it, and would still apply it to the left channel when plugged into the BeachTek.

The same thing could be accomplished with a mono jack at the receiver and a cable wired for mono to stereo, but the setup they're using is more error proof for the user.

I love Troy's explanation of the "sweet spot." I've never seen the heirarchy of audio level settings expressed more clearly. It should be posted as a sticky somewhere rather than buried in this thread.

[Robert Martens]

Oh, it is? I wasn't aware of that. So, it's just there as a convenience, to prevent you from having to repeatedly unplug the unit from the camera when you want to plug something else in?

[David Ennis]

More than a convenience. It's there to provide a 1/8" input to the left channel while still allowing an XLR input to the right. Usually whatever you plug into it would be close enough not to need balanced cable, such as a lav receiver or a cam mounted shotgun.

[K. Forman]

I did auditions in a small suite, about the same size as yor room. All I did, was set up my GL1 on a tripod, and run the s-vid out to a vcr and monitor. The on cam mic was actually well suited this time, as it always picks up my voice behind it.

The vhs came out fine. It wasn't cinematic, but as you said, it is just rehersals and auditions.

[Troy Tiscareno]

<<<-- Originally posted by Fred Retread : Robert,
I love Troy's explanation of the "sweet spot." I've never seen the heirarchy of audio level settings expressed more clearly. It should be posted as a sticky somewhere rather than buried in this thread. -->>>

Thanks; I'm glad it made sense (sometimes it's hard to know). I have an audio engineering background, so while I'm struggling to overcome my mediocracy with video, I've got the audio part down pretty well. Signal flow and gain structure is a part of my very being at this point, ya know?

Robert,

As far as you having the older model, I understand that the adjustments are very similar.

Fred is correct in that there is only signal on pins 2 (hot) and 1 (ground) on the 3-pin XLR connector that comes from the receiver. That's not a problem, though, because the cable run is so short that the advantages of a balanced line are moot. If you were going to plug a 50' mic cable between the receiver and the camera, THEN the fact that it wasn't balanced would be a problem.

-Troy