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Old February 7th, 2012, 10:15 AM   #1
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A Crazy Idea, is it workable ?

Hi All,

I am new to this field and sound recording is not really something i have done a lot,
i have a Rode for my on camera mic and use a Zoom H4N for the ambient sound recordings .

My main focus area is wildlife.

Here is the idea i thought of using the Zoom H4N with a Parabolic Dish ****

The Zoom H4N is very decent recorder and with a parabolic dish it may be able to get to record better in terms of nature sounds .

Has any one ever had a setup with the Zoom H4N with such a dish before

Has anyone got suggestions of how to make this setup

You folks are into Audio very deep and may be able to think how this works, being new to audio recording i am unable to think this out.

Let me know what you folks think of this idea and is it workable.
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Old February 7th, 2012, 10:42 AM   #2
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Re: A Crazy Idea, is it workable ?

There is no fundamental reason it should not work. I would say go for it.

Remember that the Zoom H4n has two built-in microphones which point in opposite directions. So you will need to select ONE of them and position it so that the microphone is aimed at the center of the reflector. The sound from the other microphone/channel will be of no significant value.

A custom way of mounting the H4n will be required so it is positioned properly (sideways and at an angle) in front of the reflector. And in a position which puts the selected microphone at the focal point of the dish.

You will likely still need wind protection (foam and probably furry on top of it) unless you are in a dead calm.

Any handling noise will be recorded and maybe even amplified by the reflector. This includes noise from turning the recorded on/off, noise from adjusting levels, noise from headphone cable, etc.

Unless you are leaving it unattended, it is always better to monitor what you are recording. And of course monitoring is mandatory for locating the H4n at the focal point, and for initial aiming the dish.
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Old February 7th, 2012, 11:16 AM   #3
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Re: A Crazy Idea, is it workable ?

Richard,

It didnt strike me that i will have to use only one mic of the zoom H4N now that will get me the second mic redundant . i thought i can use both the mics as with both i make good sound recording with nature.

Now thats a drawback.

i looked a parabolic dish on the Wildeye site Parabolic Reflectors for Sound Recording however i do not think this can take the weight of the zoomh4n mounted in middle with a custom fabricated attachment.
Thats why i think it should be some other Parabolic dish which can take the weight , the second issue is of making the whole rig holdable in hand or would it be needed on a tripod.

i would be using a furry cover on the zoomh4n , are you suggesting using one on the complete Dish
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Old February 7th, 2012, 02:52 PM   #4
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Re: A Crazy Idea, is it workable ?

A common parabolic reflector "dish" has only one focus point. Unless you place the microphone at EXACTLY that focus point, you get almost no benefit from the reflector, and more likely just a bad "hollow" sound.

It might be possible to design a parabolic reflector with TWO focus points, but...
1) The microphones on the H4 are still pointing in the wrong directions. They must both be pointed towards the reflector.
2) You would be reduced to practically a monaural signal into both of the microphones anyway because of the small diameter of the dish relative to the wavelengths of sound. So there would be almost no practical benefit even if you went to all that trouble.

Note that there are parabolic reflector satellite antennas which have multiple points of focus. But the LNB antenna horns are pointed directly at the dish, and the wavelengths of satellite signals are many orders of magnitude smaller than sound waves.

https://encrypted-tbn1.google.com/im...pPfjH8FUSWflkQ

It should not be difficult to create a mounting bracket for an H4n to hold it in just the right place in the focus point of any parabolic reflector. Of course it will be more sturdy than something meant to hold a tiny microphone. On the internet you can find many pictures of parabolic dish reflectors for microphones. Larger reflectors (or higher wind) would likely require use of a tripod.

The smaller you make the diameter of the reflector, the less low frequency response you will get. There are many websites that discuss low frequency pickup vs. parabola diameter.

Unless the wind is causing the reflector itself to make noise, you need protection only on the microphone head.
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Old February 7th, 2012, 05:03 PM   #5
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Re: A Crazy Idea, is it workable ?

Hi, Vishal................

I think you're making a rod for your own back with the current design of the sound system.

Personally, I'd use a lav in the dish, connected to one channel of the H4 "off dish", and for the second channel a wireless system with a omni/ shotgun/ insert mic type here (take your pick) positioned wherever you like within range of the wireless system.

You get two channels, one pin pointed, the other more wide, do a suitable mix, it will sound great.

You can use cable for the second mic, but that could be one heck of a lot of cable to trip over.

Just my thoughts.


CS
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Old February 8th, 2012, 10:26 AM   #6
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Re: A Crazy Idea, is it workable ?

I know this may already be obvious, but be aware that the LF response of the dish system is limited by the size of the dish. For bird calls, general nature "rustling" and the like, a modest-sized dish will probably work fine. But anything below 250 Hz or so starts to require a fairly large dish.
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Old February 9th, 2012, 02:40 AM   #7
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Re: A Crazy Idea, is it workable ?

Hey Thanks folks for the suggestions.

I think that from the things i have read that making a Parabolic dish recording device with a zoom H4N would be more of a overhead and may have restrictive capabilities.

Has then any one used
Zoom H4N + 2 Shot gun mics may be ROde connected to the zoom H4n via the xlr ports.

may be the 2 shotgun mounted at the top of a handy pole and the zoom h4n mounted a foot below that with 120 degree wide setting .

I know i am imagining too much and am pathatic at physics, however has anyone used such a setup and any pictures of your sound recording setup.

do let me know

vishal
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Old February 9th, 2012, 03:20 AM   #8
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Re: A Crazy Idea, is it workable ?

Most wildlife sounds are actually recorded in mono as closeup sound and stereo general ambience may be added in post to give a general soundstage.

Your recorder with it's on board mic's will be OK for general stereo ambience but to get close up sound you will need a specialist mic.

The pro's tend to use long shotguns such as the sennheiser 815 or 816 and at a push a rode NTG1/2 or a 416 or AT 875r will get a more focussed sound than the stereo on board mic's but to get that real close effects takes a lot of time and planning and may involve rigging microphones some distance from your recording position. A parabolic dish can also be useful but needs setting up properly and the correct mic in place at it's focus point.

A good friend of mine is Chris Watson and you may wish to have a look at his web site and blogs to get more info: | Chris Watson |
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Old February 9th, 2012, 04:04 AM   #9
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Re: A Crazy Idea, is it workable ?

There are loads of old second hand satellite dishes around, and if they have the LNB arm attached, you know where the focal point is, so you can just try it and see. Being mono is not remotely a problem, and stereo imaging at a distance isn't really possible from a narrow beam angle anyway. Imagine you are maybe 20 mtrs away, your dish is probably going to be so narrow that the 'illuminated' spot is quite small, so small accurate alignment is a must. Left and right within that very small area is not going to produce any meaningful separation, and if the sound source moves about within the frame so much that you need it to go left and right, then panning the mono dish with a bit of normal wide stereo ambience will work better. Sports TV use dishes quite often.

Broadcast Product Front Page

I had a bit of fun with two obsolete 2m sat dishes on tripod bases. We set them up a couple of hundred metres apart, and then by sticking your ear to the lnb 'hole', you could talk in a normal level voice to the person the other end - weird!
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Old February 9th, 2012, 04:34 AM   #10
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Re: A Crazy Idea, is it workable ?

I would be interested to hear what tone an old sat disk has, the dedicated audio ones tend to be smooth plastic so a perforated old SKY dish will be interesting and will also pick-up sound from behind the dish!
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Old February 9th, 2012, 05:36 AM   #11
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Re: A Crazy Idea, is it workable ?

At one stage I thought of trying a parabolic reflector for nature recordings but decided that the equipment would have to be too bulky to be practical for my purposes. There are also potential problems with frequency responses that may spoil your recordings. These problems are related to the diameter and focal length of the reflector.
I just did a Google “parabolic reflectors for sound” search and got 378,000 references. You may be interested in,
Parabolic Stereo

Instead of a parabola I currently have a sensitive microphone with very low self-noise so that I can use a high gain setting. With this set-up I can record sounds that I cannot hear but I have to use an intricate suspension system to reduce handling noise picked up by the high gain.
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Old February 9th, 2012, 08:02 AM   #12
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Re: A Crazy Idea, is it workable ?

Note that there is an online forum specifically dedicated to recording nature sounds. I have to believe that this topic has been discussed before over there and may even be a FAQ. naturerecordists : E-Mail group of individuals interested i They have favorite microphones with very low self-noise.

Parabolic dish reflectors are not wide-band devices. Their low frequency performance is limited by the diameter of the dish relative to the wavelength of sound. Not unlike the similar phenomenon with "shotgun" microphones where the low frequency directionality depends to a large extent on their length.

Satellite receiver dishes (DirecTV, Dish Network in the US, et.al.) are rather shallow and make up only a small segment of the parabolic curve. They also typically have asymmetrical profiles with the LNB feedhorn offset. I would expect that their performance may not be as good at audio wavelengths as more complete profiles.

The major satellite providers use several adjacent satellites to support services with "500 channels" for their couch-potato special customers. The shape of the parabola is modified to cover a wider profile of two or three satellites, but they are spaced at only 2-3 degrees apart. That is many miles/km out at the Clark Belt in outer space at an altitude of 22,000 miles, but essentially nothing for "stereo" purposes down here on the surface of the planet.

Reflectors made of mesh (expanded or perforated metal) are only effective at frequencies determined by the particular pattern. Expanded metal 3-10 meter BUD (big ugly dish) antennas were popular for the C-band in earlier times of more primitive satellite technology. They presented less of a "sail" profile to be blown away by the wind or to collect snow. But they are useless (transparent) for the higher-frequency Ku-band DBS (direct-broadcast satellites) that are used in modern times.

And at the other end of the spectrum, expanded metal reflectors are effectively transparent at audio frequencies and useless for parabolic reflector purposes. Metal screen forms a good barrier (reflector) to radio frequencies. We commonly make "Faraday cages" out of copper screen. But you can hear (and see) right through them as if they didn't exist at very low audio frequencies and very high light frequencies.
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Old February 9th, 2012, 08:05 AM   #13
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Re: A Crazy Idea, is it workable ?

"Instead of a parabola I currently have a sensitive microphone with very low self-noise so that I can use a high gain setting. With this set-up I can record sounds that I cannot hear but I have to use an intricate suspension system to reduce handling noise picked up by the high gain."

Per the above, the Audio Technica BP4025 uses 1" capsules (low self noise) from the AT4050 series and sounds pretty darn nice.

I reviewed it a year or so back and was out in my suburban back yard on a Spring morning when I saw my neighbor walking up the street. When she was about 150 feet away, I heard a click. I thought, "that sounds like someone clacking chewing gum."

I started walking to her and when we met I asked if she was chewing gum. Yup!

About parabolas; I hear they suffer from some pretty weird frequency response anomalies due to the physics of the dish.

Regards,

Ty Ford

PS: Go for it and let us know how it works for you! Without unbridled experimentation, progress is slow.
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Old February 9th, 2012, 08:55 AM   #14
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Re: A Crazy Idea, is it workable ?

Friends,

All of this is very helpful and yes i am going to build it and even share the results here including the design.

I guess when we think out of box we make more progress

TY Ford , you nailed it in " Without unbridled experimentation, progress is slow"

now i am reading a lot all the links you folks provided and what all i can get on the net, i have one bird sound recording person around who uses a telinga , makes decent sound recordings with it however the best nature sound recordings i have found till date are from " http://www.listeningearth.com.au/LE/index.php"
They are just the best i have seen till date in terms of the quality and variety of nature sounds they produce. Have written to them too for help and will see what their response is.

Will post what i finally choose to put into the final rig

Till then welcome your suggestions as they will define a lot of what i will get.

Note that in India i dont get to try equipment before i buy and have to import it from sites like bhphotovideo , etc
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Old February 9th, 2012, 10:19 AM   #15
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Re: A Crazy Idea, is it workable ?

Hi Vishal,

Here's a link to the recording I made with the Audio Technica BP4025. The one in my neighborhood.

Dropbox - ATBP4025ambi08.wav - Simplify your life

Regards,

Ty Ford
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