Parabolic Microphone Suspension

[Conrad Obregon]

I've been using a 9 inch Sound Shark parabolic microphone for bird and other wildlife videos. I have it mounted on a magic arm to keep it away from camera noise. Occasionally it still picks up a little vibration noise from the rest of the gear. I've looked for some kind of suspension system to isolate the microphone but none of the ones I've found allow for the mounting of a parabolic mic. Has anyone dealt with this situation?

[Allan Black]

Hi Conrad. I haven’t but if you do a search here using different terms you may get some help.

And here’s a bunch of links https://awsrg.org.au/australian-wild...ing-resources/

Cheers.

[Conrad Obregon]

Thanks for the response. I've actually done a lot of searching for solutions particularly from nature sound recording groups. These people have developed many good techniques with parabolic mikes, but they use either hand held apparatus or mount their mics directly to a tripod which they aim at the sound. I want to mount the parabolic mike to my fluid head so that it turns with the camaera/lens for video. Right now I'm trying to modify a Rycote suspension for hand held recorders. This might work but requires hardware modifications. With the lock down, it has been hard to browse for parts.

[Chris Soucy]

Hi Conrad,

In short, to answer your question, no, I haven't had to deal with this situation.

However, with zero knowledge of your mic's layout or physical connection options, can I throw some ideas at you?

Does any combination from these two sources float your boat:

https://www.cameragrip.com/camera-cl...ting-brackets/

https://rycote.com/microphone-windsh...vision-studio/

If neither is useful I think I'll need more info.

Regards,


CS

[Paul R Johnson]

A couple of years ago, we experimented with two 3m surplus satellite dishes. Put each one at the opposite side of a lake, and if you spoke into the mount where the feed point would have fitted, somebody on the other side could put their ear to it and hear a normal level voice over 100m away. Amazing it works like this.

[Greg Miller]

Paul, those were darned big dishes. Just moving them and getting them anchored for the test must have been a significant project.

Conrad, are you sure the mic is picking up structure-borne vibration, and not sound transmitted through the air?

I imagine you've seen photos of the very old carbon mics of this ilk:
http://antiqueoutings.com/wp-content...-universal.jpg
http://uv201.com/Microphone_Pages/Mi...ersal_mike.jpg

Perhaps you could rig something like this for your parabolic dish. Of course I'd suggest some sort of elastic suspension, rather than metal springs. Soft elastic, at a low tension, should transmit only the very lowest (hopefully subsonic) frequencies. With a slightly different configuration the mounting ring would not need to be so much greater diameter than than dish itself. Perhaps just affix mounting points on the dish every 30º or so, then lace a continuous piece of elastic from the dish to the ring, back to the dish, back to the ring, etc.

Of course I don't know how you'd mount this to your tripod/ camera rig ... that wasn't obvious to me from info I could find about the mic. Although it does seem darned expensive for something that small. Personally, I'd be playing with an orphaned plastic soup bowl, a spun aluminum colander or a stainless steel mixing bowl, although it probably wouldn't be a true parabolic curve. (Hmmm, maybe this will give me something to do while we're sequestered at home for the next eight weeks. After I get tired of cleaning grout with a toothbrush.)

[Conrad Obregon]

Thanks for all your suggestions.

Some people may not visualize what I'm talking about, so here's an operator's eye view. The circle is the parabolic mike, covered with a dead cat. When the fluid head moves the mic moves. The arrows suggest where a suspension might go. I'm trying to fit out a Rycote lyre designed for a small field recorder, but I can't get it apart to install the necessary hardware to fit into this setup. I also want to keep the weight down, since I hike a mile or so with all this gear in a back pack to get into the woods, and at my age, I don't want to add too much weight.

[Jim Michael]

Seems like a suspension for a large diaphragm mic may work. The orientation is similar and the threaded fittings are easily adapted to 1/4-20 etc. The new type from Rode is similar to lyre and the older type use elastic bands.

[Greg Miller]

That photo is very helpful, thanks.

I'd fear that if you mount it from the bottom (as you do now), with all the weight above the mounting point, it might be top heavy. Any suspension that's stiff enough to keep it from drooping might be too stiff to isolate it well.

The Rycote lyre (041119) certainly looks worth a try. It has a 1/4"-20 male thread on top, and your mic (according to specs) has a 1/4"-20 female thread on the bottom, so that would seem to mate easily. The Rycote has a 3/8"-16 female thread on the bottom, which is quite universal. Can't you get some sort of stock adapter for your rig, so you don't need to take it apart and modify something?

Also, I think Mr. Michael's suggestion would be a good starting point. You might end up getting a machine shop involved before you're finished ... or else a lot of gaffer tape. ;-)


Or this:

Amazon

 

Amazon

looks like looks like a lower price option. But we come back to the question of whether it's stiff enough to support more mass and a higher center of gravity (compared to the pocket recorders that it's designed for).

[Bob Hart]

As a hack, I would be tempted to examine using a bicycle rim with hub and spokes stripped out. Mutilate your parabolic dish by drilling holes around the rim, one less than the spoke holes in the bicycle rim, then using theraband cut into thin strips, lace the dish evenly inside the bicycle rim as a suspension. Use the valve stem hole in the rim for your mounting bolt. An alternative to cutting the theraband into thin strips would be to loop-tread woven cord through the spoke holes and likewise around the holes in the rim of the dish, then weave thicker strips of theraband or even chained elastic bands through the loops for a suspension. You will need to acoustically isolate the mic cable too through a piece of foam. - Just a thought.

[Chris Soucy]

Hi again................

Thanks for the piccie, gave me a whole heap of info.

OK, suggestion. That amount of sail area on such a long lever must give rise to some very interesting vibration effects in even a slight breeze. Ditch the long arm.

Replace with something like this:

https://www.cameragrip.com/hague-dsb...-shoe-bracket/

I have selected this beast because (do confirm this) it appears that both the bar in relation to it's central shoe mount AND each of the end shoe adapters can be rotated 90 degrees, so that your mic AND whatever is currently using your shoe mount can be mounted on the camera either East/ West OR North/ South (ie one behind the other in line with the lens axis).

Immediate benefits:

a) Mic is in line with lens axis so no parallax errors.
b) If mic is in front, the other units controls are easily accessible.
c) Lever length reduced markedly shifting any vibration frequency into ultra sound territory.

The only gotcha is if the respective masses on each end of the bar are radically different. Either move one of the shoe adapters closer to the centre for the heavier unit or balance the weights with something.

Thoughts?

Regards,


CS

[Jim Michael]

Brilliant Bob.

[Greg Miller]

Originally Posted by Bob Hart

As a hack, I would be tempted to examine using a bicycle rim with hub and spokes stripped out.

That's a very interesting detailed exposition on my suggestion in post #6. Given that the OP is using a roughly 9" dish, and says he wants to keep weight to a minimum, I think a bicycle wheel (unless it was from a midget bicycle) is going to be rather big.

Your idea certainly eliminates the need to fabricate from scratch some sort of mounting ring ... I was still trying to find a simple off-the-shelf answer for that. I made the mistake of searching Google for "hoop" and got about 1/4 million hits. :-0

[Conrad Obregon]

Thank you all for your suggestions.
I've tried the kind of rig Chris suggests. It pick up more camera noise and obstructs my own vision. (I'm working with a 500 mm lens, and often, a 1.4 teleconverter.) I need to be able to sight along the lens to find things like birds. I recognize the long arm is a problem, and experimented with marginally shorter arms but the arm I'm using seems the least noisy.

I'm surprised that no one else seems to have experience with a parabolic mic. The sound field is much deeper than with shotgun. Here's a recent sample, shot from about 80 yards away.

YouTube (Short URL)

[Greg Miller]

Beautiful! Nice steady shot, too.

Have you thought about locating the mic in front of the camera, and below the lens, rather than mounting to the side as it is now? Would that allow a shorter (more rigid?) arm?