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Old 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
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Old December 6th, 2005, 05:50 AM   #2
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Quote:
Originally Posted by Fischer Spooner
...
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.
...
Fischer Spooner
What capsule are you using on the Octava? Hypercardioids are your best bet for booming to reduce background sound creeping in. Hiss may be coming from having the gain in the camera too high and the mic level turned down at the Beach. Set the camea on manual, turn its gain controls about 3/4 or the way up, and adjust the level on the Beach until your average recording level is about -12db on the camera meters. As for the inconsistency, your last sentence is the most telling - try, try, try to keep the mic as close as possible to the talent AND at the same working distance from shot to shot. Lavs hidden on the talent is a good alternative to booming and gives you better results.
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Old 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.
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Old 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.
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Old 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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Old 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.
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Old 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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Old 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.
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Old December 6th, 2005, 04:48 PM   #9
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Quote:
Originally Posted by Fischer Spooner
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.
The hypercardioid pattern is quite directional and the mic should be pointed directly at the speaker's mouth for best pickup, and as close as you can get it to the talent without intruding into the shot. A "wide, open pattern" would mean that aim is not quite so critical. Of course that also means it picks up more background sounds coming from directions than that of the talent.

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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Old 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.
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Old January 6th, 2006, 11:44 PM   #11
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Quote:
Originally Posted by Bob Grant
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!
I've experienced the problems highlighted here.

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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Old January 7th, 2006, 10:41 PM   #12
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Quote:
Originally Posted by George Ellis
...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.
Be advised that there are unit to unit variations in this regard. The first DXA-8 that was delivered to me had a battery life I found unacceptable--about an hour and a half while supplying no phantom power--and a noisy battery death as you describe. That didn't sound quite right to BeachTek when I wrote to them about it and they offered an exchange. But it was new enough that B&H was willing to exhange it themselves.

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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Old January 8th, 2006, 10:01 AM   #13
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Originally Posted by Fred Retread
Be advised that there are unit to unit variations in this regard. The first DXA-8 that was delivered to me had a battery life I found unacceptable--about an hour and a half while supplying no phantom power--and a noisy battery death as you describe. That didn't sound quite right to BeachTek when I wrote to them about it and they offered an exchange. But it was new enough that B&H was willing to exhange it themselves.

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.
I remember reading this from you. The fact is that I think mine burns through a battery and dies a noisy death after maybe an hour or so. Since you can get two 9v batteries for 99 cents at the 99 cents store I wasn't worried so much about the cost as the pain factor. But thanks for letting me know. Hopefully I still have those receipts//
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Old 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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Old 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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