Bill Davis
Forum Replies Created
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I’d never go on any shoot without black wrap in my kit.
I’d also never go on any shoot without my Gerber/Leatherman whatver multitool.So I can’t see the advantage of lugging a commercial dappleloris when I already have everything I need to make one to my exact specifications in less than 2 minutes.
FWIS
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Nope.
Echo is the primary sound followed by a reflection of that same sound – delayed in time.
Phase cancellation, by definition, is adding two copies of the SAME sound together with one of them delayed EXACTLY 180 degrees out of phase with the other.
That process has NO effect on sounds that are already naturally delayed like an echo. The echo is, by definition, a separate sound from the initial sound the echo resulted from.
As a technique, it’s valuable in something like balanced audio lines, where you have three wires, one carrying the signal, the other carrying nothing, the final wire the ground. Then when the CABLE picks up RF noise, you can take the whole signal – invert the phase – and mix the result back in – so that the NOISE picked up equally by BOTH conductors is cancelled out. But it only works because the noise you’re canceling is DIFFERENT from the signal you’re interested in passing.
The only way an echo is “different” is that it’s shifted in time. So the traditional way to TRY and compensate is to set up a gate so that you allow the primary attack of the word to pass through and then gate the circuit shut before the echo passes.
Often, that’s an “iffy” solution since you often get a mixture of the echos and the next wanted sounds in actual content.
There are also more sophisticated forensic audio tools that mathematically kill sounds below the threshold of amplitude of the initial attack sound.
But in reality, audio usually a lot like paint. Once you mix two of them together it’s pretty hard to “unmix” them. At least unless there’s something very distinct about the sounds you want to remove compared to the ones you want to keep.
Good luck.
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As always, I agree with what Mark says on principal.
My only quibble is that every time I’ve tried to use table mounted boundry mics such as PZMs – some knucklehead turns out to be a “table tapper” and clients get distracted trying to figure out who was playing the bass drum during the interview.
Boundry mics use the table top surface itself as an integral part of the process so they’re less efficient if there’s a tablecloth or if you try something clever like putting mouse pads under them to keep the mechanical noise transmission to a minimum.
The truth is, audio is complex, not intuitive, and a general pain in the ass.
Too bad it’s also the source of the vast majority of the useful information transmission in most videos.
Sigh.
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Hosa makes a cheap one that works just fine and is under $6.
Search: Hosa GLT-255 XLR Female to XLR Male Ground Lift Hum StopperOr you can just go to any Guitar Center and drop $20 on one.
The cost is insignificant compared to the danger of just cutting the third pin from a grounded plug.
Oh, and the point is that THIS outlet or THAT outlet and the state of it’s wiring may or may not put you in danger at any one point. But that’s NO guarantee that in six months you won’t find yourself in a hotel where they shaved a few thousand off the building costs by hiring idiots to wire things.
Then that extension cord, or equipment IBEC power cord, or whatever that you’ve happily been using for so long that you’ve totally forgotten that you snipped the ground prong off with your dykes – that’s the cable you’ll find yourself using – while standing on a piece of carpet where a recent champagne bucket spill has you a single sodden piece of shoe leather away from a world of hurt.
Sure, 120 probably won’t kill you. Unless you’re unlucky enough to grab something live and find that your arm and hand muscles have contracted under current and you simply CAN’T let it go.
I’m not so good with that concept.
Accidents have a name because they’re a universal human experience.
Cutting ground prongs ups the odds a LOT. Plus it puts a dangerous cable out into the world where someone who’s got NO clue is free to use it to power their home built kenetic metal sculpture.
Just say no to cutting ground pins and the world is a slightly better and safer place.
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Had to do exactly this about 6 months ago.
We re-configured a lecture room that had the modern “skinny table” group seating.
The room was relatively long and thin, so we set the camera position in the center of one of the short walls.
About six feet out from the other short wall, we created a simple chevron out of two of the tables.
Chairs were placed 5 and 5 behind the two tables.
The angle allowed us to ISO each group with it’s own camera.
I didn’t want to deal with the potential comb filtering of having 10 open mics, so I got 2 MKH 416 mics from the local rental house and using stands, sandbags, and boompoles, flew the two mics so that each mic was centered and pointed right at a group from just over camera range.
That gave me two balanced audio lines into the two inputs of the camera.
Worked out well, but we were going for a “focus group” type style and the fact that each person wasn’t individually mic’d added to the sense of a live recording.
If you’re trying to iso 10 people and have it sound like 10 distinct interviews, you’d probably need 10 lavs into a multi-track recording rig.
Good luck.
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Bob,
I’m sorry, but removing the ground pin from ANY AC plug is boneheadedly STUPID. And should NEVER, EVER be recommended by anyone.
Hums are inconvenient. Shocking/Injuring/Killing people on a set is VASTLY more inconvenient.
Safe ground lift adaptors are readily available. Yeah, they cost money. But noone doing sound or sound for video should practice without them.
Sorry to be harsh. But one mistake in this area could destroy your reputation and possibly bankrupt you both professionally and personally.
Ground pins have a FUNCTION. To keep people using electricity safe and healthy.
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Bob,
Probably not, but while tedious, it’s not particularly hard to figure out the TYPE of noise you’re facing.
Ground loop hum (common mode hum, more accurately) has a characterisitc sound. So does inductive RF noise. they’re similar since they can both be related to the 60hz carrier cycle of US alternating current. (our oveseas bretheren have their OWN set of sounds to understand) But over time you’ll learn to tell the diference. Ground loops tend to be stable in loudness regardless of what you move or do. Inductive RF will change depending on how the cables/antenna/lousy ground solder joint – changes.
Cel phone noise, however, tends to be totally different – not like ground related noise at all.
The key is learning basic step-by-step audio system problem solving – which is always the same. You start by identifying the signal inputs and outputs that are in use. Then you eliminate/decouple each signal in turn until you find the circuit that’s injecting the noise. Once you have the circuit isolated, you check every connection, device, power feed and cable involved in that circuit until changing something makes it go away.
If someone banged the Kino Flo and a cold solder joint cracked in the ground circuit, that doesn’t mean that brand or even that instrument sucks at ALL. It’s just an acknowledgment that over time, stuff happens to even the best of gear.
Our job is often to make it UN happen. So if your gut is telling you it’s the Kino, UNPLUG it. if the problem disappers, it’s something realate to the Kino. If the problem persists, move on.
Over time, you’ll learn the “sound” of various common problems, and that will shorten your problem solving time.
Also, you’ll learn that a lot of common mode grounding problems are caused by plugging different pieces of equipment into different AC feeds. Sometimes moving plug A from outlet A to outlet B will make everything go away. Or make things worse.
Welcome to audio. It’s NEVER boring!
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A security camera is like any other camera in one respect. It generates a picture. Sometimes, a fine picture that can hold it’s own against any other camera.
The issue is that security cameras are typically designed with features that are great for security applications but can be a problem when you’re using them for something else.
For example, most security cameras have auto-iris functions which is great for security as the sun moves across the sky – but terrible for something like a stage show where the lights are constantly changing.
Same with focus, zoom ability and a bunch of other aspects that with a manual camera you expect to control, but with a security camera you expect NOT to have control over.
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I’ll play.
Flew to San Diego to videotape a presentation at a convention of high level psychologists. The keynote speaker was a very nice and very accomplished woman who was debuting some new cutting edge research.
Room set up looked good when I arrived. The wall behind her was exterior windows but some smart soul had ordered a full wall of black velour pipe and drape so backlighting wasn’t going to be a problem. Then the folks brought in a set of really lovely light tan chinese folding screens across the stage that I just new was going to make a great neutral video background no matter what the speaker wore.
My client arrived and was delighted with the look of the stage. She went away to change into her speaking clothes and being a bit overweight, came back after choosing a slimming black silk suit with a juanty bright red scarf at the neck for a spot of color.
Of course, Murphy was waiting and less than a minute after I started rolling camera two stagehands came out and struck the Chinese screens.
Yep. Black silk suit against a black velvet drape.
The resulting video perfectly created the old Jay Leno “Beyondo” gag with a perfect floating head in a sea of nothing. Even her bright red scarf added the impression that the talking head had recently had a date with an executioner.
Sigh.
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You’re going to learn a LOT on your shoot.
For my money, the most important thing is to have RELIABLE communication between you and your cameras. Then make sure you are SPECIFIC when you give cameras their cues.
The typical rookie mistake is getting excited when looking at the monitor – pointing at it and shouting “PUSH IN” – which will likely result in both cameras suddenly pushing in.
You want measured commands that are crystal clear… like “Camera 1. Get Ready to push in on the drummer. OK, Camera 1 start your push. Dissolving to 1. Camera 1 you’re live. Camera 2, give me a medium two shot of the guitar and bass. Ready to Take 2. Take 2. Two is live. Camera 1 move to the marimba player…”
That leave nothing to chance and everyone knows what they’re supposed to be doing.
Also, understand that what you see on the monitor might be all that’s possible for your camera ops. I’ve seen a lot of newbie directors get caught up in their monitors and their “creative vision” and forget there’s a real human in a real world of limitations out there. “Camera 2 – I need you to go further right to clear the drummers face. Further. You’ve got to go further…” never realizing that poor camera 2 is at the edge of a riser and if they go further right, someone’s gonna have to call for an ambulance.
Finally, pray you have solid professional ClearCom type Com units, expect the loud music to make it hard for everyone to understand anything, And in fact in concert settings, it’s typical for the camera ops to disengage their mics so the com circuit doesn’t get blown out by stage sound. So don’t expect feedback from the ops – just be as CLEAR as possible when you give commands.
As to the creative, think of setting up shots that have both positive and negative space. Then during the cross fades, you can fill a negative space on one camera with something positive from the incoming shot.
I remember back in my early days as a camera op before I ever directed I was handheld op on-stage in a 4 camera live show featuring a blind pianist/singer, and just on the spur of the moment, I framed the pianist head lower left with a MASSIVE amount of negative space frame right where the grand piano lid and upright support made a nice vector up and away. The shot was pretty out of balance as a single. But the director saw it, and instantly got the second camera to shoot an enraptured listener in the crowd, composited the two shots with a half-dissolve and then held the damn thing for about 2 minutes.
I felt great about getting that shot, but unfortunately my angle had required me to crouch and my thighs hurt for about a week after that.
The real reason I tell that story is that the director came up to us after, demanded we all assemble back stage and then brought up that shot – and went off about how THAT was what he liked – “Give me more of that in the second half” he blurted – before punching out the tape and running off, presumably to impress the client.
After about 10 uncomfortable seconds of silence – and to my eternal gratitude – the woman on camera 2 finally said what was NEVER heard on com during the four days of the show. “nice shot 3”
Good shows are a team effort. Your real job as a director is not operating the equipment, it’s inspiring your team.
Have a great time.