Parabolic reflector

[Malcolm Stewart]

Last March I asked for ideas on how to knock up a low cost parabolic reflector for recording birdsong on my MiniDisc recorder. Lots of ideas came in and thanks to the warmer weather I've now taken advantage of Maplin's special offer on their 700W Nikkai radiant heater which was going at my local shop for £3.98.

removed the wiring, heating element & support, rear plastic cover and front wire grill; and used one of the now surplus screwed rods as a mount for my microphone. First results in my local wood were very encouraging. Pointing it at the tops of trees, I could pick up the noise of wind rustling the leaves whilst pointing horizontally the rustling noise was absent. Got some quite impressive (to me!) bird song recordings on my first outing. Not bad for £4 and more goodies to go in my junk box.

[BigWallop]

How did you find the focal point for the microphone position? Did you know a good way is to shine a light on the dish and watch for the point where the light reflects to. It gives a rough idea of where to put the tip of the mic' so it actually picks up more accurately from the dish reflection.

Great idea though, and, at that price, you can't complain. :-)

Good hunting.

[sbeeny]

Fantastic idea. I'm currently looking to do the same thing. I will implement and get back to you with any results.

Groovy

S

[Dave Plowman (News)]

It's normal to have it clamped in rubber so you just listen to the output and slide it in or out for maximum level.

[BigWallop]

But shining a light on to a reflective surface will give a rough idea of where the focal point is. It is not exact, but it gives a good round'a'bout area to place the mic' in the first place.

For none shiny surfaces you can use a speaker on low and then set the mic' to the point where is picks up the best sound level. Place the speaker around two or three metres away from the dish, put a very low level sound on to it, then set the dish to point at it.

[Dave Plowman (News)]

It's a long time since I played with a pro one, but IIRC it's best adjusted for the distance it's going to be used at.