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generators - noise


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#1 claudio rietti

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Posted 13 February 2007 - 08:55 AM

what is generally considered to be an acceptable decibel level for shooting sync sound in regards to a generator at close proximity to the action. I've sourced out a 10K gennie at 70 dB. Seems to me that this is much to noisy for our purposes.

Thanks,
Claudio
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#2 claudio rietti

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Posted 13 February 2007 - 09:05 AM

Also, when would a 3-phase gennie be necessary?
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#3 Kevin Zanit

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Posted 13 February 2007 - 04:11 PM

"3-phase gennie be necessary"

When you need 3-phases . . .

The additional hot leg gives you more options as far as cable run and load balancing is concerned.

A far as noise level goes, I don't know the db figures, but most "movie quiet" generators are pretty quiet. That said, they can be too loud at times. You may find yourself parking it around a corner and needing to run a good amount of cable. Depends a lot on the location.
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#4 Brian Baker

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Posted 15 February 2007 - 10:08 PM

Aside from the need for a lot of power or to more evenly distribute power (as mentioned above), another reason you may need a 3 phase generator is for varying voltage levels.

Most (if not all?) 3 phase genies allow for voltage adjustments; weather it be in balancing small increments, or moving between 120v and 240v.

Also, on shoots where we were incapable of parking our genny far away, we'd build goal posts (speed rail across two Junior stands -- like tripe riser combos -- held by Big Ben / Cheeseboro clamps) and spring clamp several sound blankets to them.

Just be careful when using sound blankets not to cover the Gennie's vents.

Best,
BtB
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#5 Paul Bruening

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Posted 16 February 2007 - 03:23 PM

Other than blocking (hiding around building, walling with plywood, etc) or adding a car muffler to the unit you can high-pass filter some of that gennie grumbling out during shooting. Some mics have the filter built-in. You can also rent/buy the filters. If only a little of the noise makes it onto tape, you can turd polish some of it out in post. You can also mask some of it with other noise that seems appropriate to the situation during post. Situations don't always lend themselves to perfection during the shoot. A little of each of the techniques listed above, in various combinations, end up being needed.
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#6 Chris B. Cornell

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Posted 16 February 2007 - 03:33 PM

Is it not feasible to do a long power run? Power cable is a relatively low cost for rental, and a nice 3 phase genny will allow you to increase voltage to compensate for the line loss on your long power run.
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#7 chris kempinski

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Posted 16 February 2007 - 08:24 PM

We usually park our equiptment truck between our set and the gennie when we can't get far from set.


Chris
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#8 Mark Henderson

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Posted 16 February 2007 - 11:50 PM

From memory I believe...

0 db is silence
30 db is a whisper
40cb is a soft conversation
45-50 db is a conversation
55 is a loud conversation
60db is a loud radio
90 db is a lawnmower
110-120db is a jet

So I wouldn't want to record anywhere around 70db.

Mark
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