Parabolic microphone dish at DVinfo.net

Go Back   DV Info Net > The Tools of DV and HD Production > All Things Audio

All Things Audio
Everything Audio, from acquisition to postproduction.


Reply
 
Thread Tools Search this Thread
Old February 28th, 2007, 04:14 PM   #1
Major Player
 
Join Date: Jan 2007
Location: Gainesville, FL
Posts: 200
Parabolic microphone dish

The responses to Philip's post mention parabolic dishes. A couple weeks ago I thought I needed one to record some bird and alligator sounds. I found a parabolic dish on ebay for hobbyists that wasn't too expensive, about $40 with shipping. It's just a dish meaning that I have to mount an omni mike inside at the focal point about 4" from the surface in this case. A bit crude but smooth inside where it counts.

I'm waiting for the onmi to show up so I don't know how well it will work yet. Also, I picked up a $5.00 clear plastic salad bowl from WalMart that has quite a seashell effect. I'm going to try that too. It's a lot smaller but I couldn't resist it for the price. Plus, I can always put lettuce in it. That might make a good windscreen. Or, maybe shredded cabbage. Any recommendations?
Larry Vaughn is offline   Reply With Quote
Old February 28th, 2007, 04:42 PM   #2
Inner Circle
 
Join Date: Feb 2004
Location: switzerland
Posts: 2,131
why not use a satellite dish antenna.
It already has the arm at the focal point and you can find any size for very cheap (even for free).
Giroud Francois is offline   Reply With Quote
Old February 28th, 2007, 05:31 PM   #3
Major Player
 
Join Date: Jan 2007
Location: New York City
Posts: 523
Quote:
Originally Posted by Giroud Francois View Post
why not use a satellite dish antenna.
I think that'll work good if your sound source is the same distance as a satellite!
__________________
Andy Tejral
Railroad Videographer
Andy Tejral is offline   Reply With Quote
Old February 28th, 2007, 11:30 PM   #4
Major Player
 
Join Date: Jan 2007
Location: Gainesville, FL
Posts: 200
sat dish

You could use a sat dish. But they are not clear, meaning they are harder to aim and they weigh more.
Larry Vaughn is offline   Reply With Quote
Old March 1st, 2007, 09:22 AM   #5
Regular Crew
 
Join Date: Nov 2006
Location: Palm Beach, Florida USA
Posts: 99
Psssst...... $10 Wok works too....
Tim OBrien is offline   Reply With Quote
Old March 1st, 2007, 09:29 AM   #6
 
Join Date: Jan 2004
Location: Stockton, UT
Posts: 5,648
So does a very large popcorn-type tupper ware bowl with the bottom drilled out.
__________________
Douglas Spotted Eagle/Spot
Author, producer, composer
Certified Sony Vegas Trainer
http://www.vasst.com
Douglas Spotted Eagle is offline   Reply With Quote
Old March 4th, 2007, 08:55 AM   #7
Major Player
 
Join Date: Mar 2006
Location: NYC Metro area
Posts: 579
Homemade Dish:

Douglas Spotted Eagle: I've always wondered if something like that would work, but I've also always been under the impression that placement of the mic was absolutely crucial to getting decent sound, and placement would vary based on the pickup pattern and qualities of the mic being used.

How do you calculate all that? Or don't you? Is listening thru "trial and error" the best way? (Probably the easiest, but is it the best)?
__________________
Denis
------------
Our actions are based on our own experience and knowledge. Thus, no one is ever totally right, nor totally wrong. We simply act from what we "know" to be true, based on that experience and knowledge. Beyond that, we pose questions to others.
Denis Danatzko is offline   Reply With Quote
Old March 4th, 2007, 09:32 AM   #8
Inner Circle
 
Join Date: Nov 2004
Location: Baltimore, MD USA
Posts: 2,323
Bounce angles are important and even when you do get that right, the sound is wonky with a dish.

Regards,

Ty Ford
Ty Ford is offline   Reply With Quote
Old March 4th, 2007, 09:53 AM   #9
Major Player
 
Join Date: Jan 2007
Location: Gainesville, FL
Posts: 200
focal point

I read some info about this at a university web site that deals with ornithology. http://www.birds.cornell.edu/Macaula...bout/1920.html

http://www.telinga.com/index.html click on the white paper link. Could be a bit biased since they sell dishes but it seems like good info.

They say you need a mic placed at the focal point of the parabola. If the reflector isn't a true parabola, you wouldn't get the best results. Sat reflectors are parabolas as are some wire noodle strainers, which work for reflecting wi-fi signals but probably not sound.

Last edited by Larry Vaughn; March 4th, 2007 at 10:16 AM. Reason: add link
Larry Vaughn is offline   Reply With Quote
Old March 4th, 2007, 10:33 AM   #10
 
Join Date: Jan 2004
Location: Stockton, UT
Posts: 5,648
Quote:
Originally Posted by Denis Danatzko View Post
Douglas Spotted Eagle: I've always wondered if something like that would work, but I've also always been under the impression that placement of the mic was absolutely crucial to getting decent sound, and placement would vary based on the pickup pattern and qualities of the mic being used.

How do you calculate all that? Or don't you? Is listening thru "trial and error" the best way? (Probably the easiest, but is it the best)?
With a dish...you can never get "good sound." You just can't. But you can practice, and learn the way the setup works whether it's a BigEar or a popcorn bowl.
Same goes for mics that are being used normally. You learn how the mic works, what it's personality is like, and soon, you can use that mic without really thinking too much about placement, because it's a natural part of your workflow. You'll always have small tweaks, but small over a few seconds is better than lots of tweaks while you find the sweet spot.
__________________
Douglas Spotted Eagle/Spot
Author, producer, composer
Certified Sony Vegas Trainer
http://www.vasst.com
Douglas Spotted Eagle is offline   Reply With Quote
Old March 4th, 2007, 11:24 AM   #11
Major Player
 
Join Date: Dec 2005
Posts: 848
Many years ago magazines such a Popular Mechanics had articles on building dish mics using a round sled such as http://www.amazon.com/Flexible-Flyer...028820&sr=8-19

A threaded steel rod was used to offset the mic from the center of the sled to the focal point. Not sure if that example above has the right curvature, however the effectiveness of the mic should increase with the radius of the collector.
Jim Michael is offline   Reply With Quote
Old March 4th, 2007, 11:48 AM   #12
Inner Circle
 
Join Date: Nov 2005
Location: LOWESTOFT - UK
Posts: 2,125
A satellite dish is perfect for this - the idea is that the dish brings the source to a focal point - and you place the microphone capsule at the point and is works. Omnis are usually used as the are directly pressure operated. Cardioids do work, but focus is sometimes a bit tricky. The commment about satellites being a long way away is correct - but all this means is that the focal point is in a slightly different place. Gain wise, the bigger the dish the better. but the bigger dish soon becomes too heavy, and difficult to align properly. Satellite dishs are also often modified spheres - which although good for satellite, don't work as well, audio wise. Overall size also has an impact on frequency response - the bigger, the more bottom end you get - however - most people tend to use a decent graphic or parameteric eq to make them sound more natural. A big dish I had a few years ago, originally from a communicatiosn tower, was 5ft in diameter, and with an omni mic let me here low speaking voices nearly 70 feet away, which was pretty good. If you have access to the dish - give it a shot, the results are quite eerie!
Paul R Johnson is offline   Reply With Quote
Old March 29th, 2007, 07:16 AM   #13
Major Player
 
Join Date: Nov 2005
Location: Vittsjö, SKÅNE, SWEDEN
Posts: 266
Parabolic microphones

Hi,
I bought a parabolic microphone some 22 years ago from a nice man in Sweden, Klas Strandberg. See www.telinga.com
It is made of 1 mm polycarbonate and could be rolled in a bag. He has developed it during many years. If you visit his homepage you can listen to the sound and get great ideas. Many bird watchers are using them.
There are also interesting opinoins like:
If you want to record a bird at 50 meter, should it sound as you are at 50 m or at 1 m distance?
Good luck with your dish.
Johan Forssblad is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > The Tools of DV and HD Production > All Things Audio

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 11:23 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network