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December 6th, 2005, 04:04 AM | #1 |
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getting good sound with a beachtek dxa-8 and oktava mk-012
I'm a film student, but I won't be taking "location sound" at school till next semester. In the meantime, I will be shooting another short, and would like to get better sound.
The gear I have is a beachtek dxa-8 and oktava mk-012. On the last short I shot, the sound was very inconsistent. The timbres of the voices seemed to be widely variable, as was the amount of background noise. Very often, there was a tremendous amount of background noise, so much so that I was surprised--I thought simply booming the mic and running it thru the adapter would really minimize the hiss. It is true that the mic was placed at variable distances from the actors depending on the setup. The sound was so noisy and inconsistent, it was hard cutting takes from different setups at editing time. Where did I go wrong, and what can I do to get better sound on my upcoming shoots? Fischer Spooner |
December 6th, 2005, 05:50 AM | #2 | |
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December 6th, 2005, 06:06 AM | #3 |
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The Beachtek only does two things.
1) Provide phantom power for the mic(s) 2) Provide a balanced interface to the mic. Depending on the type of mic you're using you've got to have phantom power or mic no work so 1) is pretty important if you're camera doesn't provide it. Running your mic lines balanced improves noise immunity, but only to induced noise in the cable. That's mostly mains interference (hum) and maybe Radio Frequency Interference (RFI). It almost certainly does nothing for hiss and definately has no affect at all on background noise. Hiss is noise from either the mic itself or the mic preamps, only two ways around this, better mic preamps and better mics or get more sound into the mic so you need less gain hence the noise is also reduced. Background noise (ambient noise) is a function of two things, mic to sound source distance and pickup pattern of the mic. Clearly reducing the mic to subject distance offers two advantages, that's why lapel mics are so widely used or if acceptable hand held mics, if you cannot use either of those then a hypercariod mic (shotgun) is the best solution. In a noisy environment nothing is perfect, that's why ADR is used so much. Assuming the mic you're using is up to the task then the other area needing attention is the mic preamp and the ones in almost all video camera are pretty pedestrian. You can either get around this by not using the camera to record audio and use a field recorder with good mic preamps or use a camera with line inputs and a GOOD external preamp. Most preamps are made for use with close micing, you need to look at gear made specifically for field recording, Sound Devices, HHB etc are the industry standard however as the market is small and everything has to be built to high standards costs are more than many DV cameras. |
December 6th, 2005, 06:33 AM | #4 |
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Bob, don't forget that the DXA-8 also is a preamp and limiter. The 6 is as you describe.
Fischer - is the camera a Sony? Manual audio settings are a must on the Sony need to be set around 20% (I assumed you would have done that, but just checking). There can be a slight hiss at anything above that on my VX2100 and unusable above about 40%. I have also heard some wierd variations when the battery voltage drops. I carry a VOM with me and any battery below 8.5v gets tossed. When it drops below 8v, you get crackle. |
December 6th, 2005, 08:24 AM | #5 |
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agree with george that this could be simple. the beachtek is a battery-sucking monster. change batteries frequently to keep consistent sound. always keep freshies close at hand.
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December 6th, 2005, 10:31 AM | #6 |
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Some additional things to check.
Where did you purchase the Oktava? Some of them work less reliably than others and pre-testing can help weed these out. The cardioid capsule for my Oktava has a very wide open pattern. As stated, a tested hypercardioid capsule from a vendor like The SoundRoom is very helpful for booming. Also make sure your capsule contacts and body threads are clean and securely tightened. This time of year moisture from condensation can cause additional mic noises. If the camera mic input gets changed from MIC Att to MIC, that obviously creates a huge difference, especially when you're using a preamp like the DXA-8. So keep close check for consistency on all your level settings throughout the chain. Location noise control is also very important. That's the cleanest way to reduce your ambient pickup, but obviously isn't always possible. As mentioned earlier try to keep a consistent close distance when booming. However you must also strike a balance here. In a particular scene you may not want to get as close as possible to one character if you know you can't get that close to another character that will be intercut. This is where ambient noise control and a directional mic can help. You can have more flexibility to work an extra foot away, getting consistent audio that is still clean. Remember to record ambient sound for each setup to use in editing for smoothing cut points. |
December 6th, 2005, 11:19 AM | #7 |
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And ALWAYS monitor ALL the sound with headphones. This will keep you from a world of hurt. Really, you shouldn't boom unless the boom operator can hear the mic. And either the op or you need to be responsible to assure that you are getting the sound you want, just as you do with monitoring picture.
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December 6th, 2005, 02:59 PM | #8 |
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The oktava is a hypercardiod from The Sound Room, in fact. What is the deal with pickup pattern? Is it there is a certain area of pickup in front of the mic, and the sound source should be in that area if possible? Jay, what is a "very wide open pattern" in your case?
- How does one have the boom op monitoring the sound if the camera is far away from the action? Fifty foot headphone cables? -It seems like it would be best to use the headphone jack coming out of the camera. The camera is a Sony. All the hiss comments were a bit intimidating at this time--I'll have to revisit them. - I was interested in the lav comments. I was listening to Soderbergh commentary on some dvd of his and he said booming was always better; because (according to these boards) the price of an oktava seems to produce audio that is so much better than similarly priced lavs, I decided to go the oktava route, but maybe I'm really missing something. |
December 6th, 2005, 04:48 PM | #9 | |
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50 foot headphone cards are not unheard of, but more commonly the boom operator has a small preamp/headphone amp on belt and his headphones plug in there. The camera operator also has headphones that plug into the camera and monitor the recording itself. More sophisticated arrangements feed the monitor output from the camera through a splitter with one going to the camera op and the other going back down that 50 foot extension cord in the form of a breakaway cable back to the boom operator and he can monitor either the feed from the mic and the return from the camera.
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December 6th, 2005, 05:00 PM | #10 |
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Sorry about the mixup over the Beachtek, after I posted I thought, oops, don't they do a version with pres in it and then got distracted, my bad.
Re headphones. Buy cheap fully enclosed ones. We've got a collection of expensive Sony and Sennheisers and they're pretty much useless with cameras, just not enough output from the cameras! We've been buying up cheapies off eBay, sold as DJ Headphones for around $20, we've had guys come back and buy 5 off us. They're at least 10dB more sensitive which makes for a huge difference when monitoring location sound. If we'd had these before at least one client would have avoided an audio disaster, she didn't realise the mic cable was unlugged as she could still 'hear' something, yeah right but not through the cans! Other option is a headphone amp, there's at least one around that'll bridge a mic feed, the boom operator puts this on his belt and the mic line runs through the amp. Only thing is of course again he's not hearing exactly what's going down on the tape but he can gauge how well he's positioning the mic. Better answer in my opinion is for the boom operator to have a field recorder, no long mic cables which can make for a safer shoot. One other tip re cans, don't plug them directly into a camera, make up a short lead with a 3.5mm minipin plug to go into the camera and a 1/4" socket on the other end. Use that between the cans and the camera. This way if you forget you're wearing the cans and walk away the thing comes unpugged, if you're wired direct into the camera almost certainly the force is lateral to the plug and it'll just jam in the socket. |
January 6th, 2006, 11:44 PM | #11 | |
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How can you tell that headphones would be 10dB louder than usual? I did a search on ebay for "dj headphones" and it returned 241 results. Are they the behrigner headphones, or the ones sold by usbestdeals? Both of those guys are cheaper $20. I love that someone professional is advising the use of $20 headphones. |
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January 7th, 2006, 10:41 PM | #12 | |
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The one I have now is worlds better. 3 to 3-1/2 hours nonstop while powering two mics. There is no crackling right up to the point where the audio suddenly dies. I think I could do two 2-hour gigs powering two mics if the battery rested between them.
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January 8th, 2006, 10:01 AM | #13 | |
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January 8th, 2006, 03:58 PM | #14 |
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Neither the price nor the performance sounds like you're talking about alkaline batteries. Am I wrong? Alkalines are worth the money.
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January 8th, 2006, 04:34 PM | #15 |
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Beachtek specifies that you use "a standard 9 volt alkaline battery".
The DXA-8, with phantom off, draws 35 ma (milliamps) from the battery. The cheap zinc carbon 9 volt batteries, no matter what they say on the battery, such as Super Heavy Duty, will only cause problems. I love my DXA-8, but I wish they would use AA's so that I could easily use high power, rechargable, NIMH batteries. I also wish that it had an external power supply input. I understand that there are NIMH (Nickel Metal Hydride) 9 Volt batteries and Lithium 9 Volt batteries. I fully believe that both of these will work well, but I have not personally used either in my DXA-8 (yet!).
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