I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical heating
element at the centre of a spun reflector.

Thanks (I am aware of the professionally priced reflectors from Sweden.)
--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm

Malcolm Stewart wrote:
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical heating
element at the centre of a spun reflector.

Old (solid) satellite dish.

For 7Khz song, you need surface accuracy of 1/4 * 340m/s /7000Hz = 1.25cm.
One way of cheating is to take a strip of plywood.
Now, form it into a curve.
Yes, it's flat, but as long as it's only a small strip, it can fairly well
approximate a strip of a parabola.

In message , Malcolm Stewart
writes
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical heating
element at the centre of a spun reflector.

Thanks (I am aware of the professionally priced reflectors from Sweden.)

I'm sure I've seen el cheapo ones somewhere, maybe maplin
--
geoff

"Malcolm Stewart" wrote in
message ...
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I
could
cannibalise for their parabolic shape. Any ideas would be welcome.
Best
I've thought of so far is an old radiant heater with the cylindrical
heating
element at the centre of a spun reflector.

I had ideas about this years ago and considered taking a papier mache
mould of the round end of a spacehopper.

Malcolm Stewart wrote:

I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical heating
element at the centre of a spun reflector.

Thanks (I am aware of the professionally priced reflectors from Sweden.)

What I would do is glue chunks of blue foam together, then make a
parabilic shaped template, and use a wire brush and maybe spinnin the
lot and sand a parabola on that.

You can then lay upo a fibergallss one obver teh top, nd when set, rip
the foam away and use acetone to clen it all off.

Voila! a parbolic reflctor.

Or just nick someones sky dish instead.

On Sat, 19 Mar 2005 23:59:21 -0000, "Malcolm Stewart"
babbled like a waterfall
and said:

I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical heating
element at the centre of a spun reflector.

Thanks (I am aware of the professionally priced reflectors from Sweden.)

Blow up a balloon. Coat it with wax polish and then cover a suitable
end in glass fibre to the shape you require.

They are better if you also have a tube on the front to prevent side
noise.

Malcolm Stewart wrote:

I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical heating
element at the centre of a spun reflector.

How about printing yourself a parabola on a graph (using excel or
something), use that to cut some templates from ply which you then
assemble into a star pattern. Finally lay it up with firbreglass tissue
and resin....

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"Malcolm Stewart" wrote in
message ...
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical
heating
element at the centre of a spun reflector.


Be aware that most satellite dishes are offset and the dish axis doesn't
point directly at the satellite. Given a dish (eg Sky) which is nominally
vertical and the satellite is at approx 36 deg. elevation or so (from
London) the offset is 36 deg and the LNB is 36 deg below the dish parabolic
axis. Dishes which are true parabolic have the LNB on the central axis
usually on a tripod arrangement and the dish is pointed up directly at the
satellite.

john

On Sat, 19 Mar 2005 23:59:21 -0000, Malcolm Stewart wrote:

I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical heating
element at the centre of a spun reflector.

Thanks (I am aware of the professionally priced reflectors from Sweden.)

Not a domestic item but ...

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=75020720 78

How about a Wok

In article ,
Malcolm Stewart wrote:
I'd like to try recording birdsong using a microphone at the
focus of parabolic reflector. Currently, I'm having difficulty
thinking of domestic items which I could cannibalise for their
parabolic shape. Any ideas would be welcome. Best I've thought
of so far is an old radiant heater with the cylindrical heating
element at the centre of a spun reflector.

How about a big torch, the sort that takes a
lantern battery?

Enough room in there also to do a small battery
powered preamplifier.

--
Tony Williams.

On Sun, 20 Mar 2005 09:31:30 +0000 (UTC), Alex wrote:

How about a Wok

Mine's more a section of a sphere (must be a name for that) raher than a
parabola. The particular property of a parabola he needs to exploit is that
there's a point of focus.

In article , Ian
Stirling writes
Malcolm Stewart wrote:
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical heating
element at the centre of a spun reflector.

Old (solid) satellite dish.


There are some plastic lightweight transparent dishes around., Have a
Google for them....

--
Tony Sayer

nog wrote in
:


How about a Wok

on the wild side?

mike

In article ,
Malcolm Stewart wrote:
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector. Currently, I'm having difficulty thinking of
domestic items which I could cannibalise for their parabolic shape. Any
ideas would be welcome. Best I've thought of so far is an old radiant
heater with the cylindrical heating element at the centre of a spun
reflector.

Don't think metal is a good idea - too much 'ring' to it. Glass fibre
would be my choice.

As others have said, an old satellite dish of the large type you plonked
in the garden?

IMHO, you'll need something larger than a metre or so for decent results.

--
*A hangover is the wrath of grapes.

Dave Plowman London SW
To e-mail, change noise into sound.

On Sat, 19 Mar 2005 23:59:21 -0000, "Malcolm Stewart"
wrote:

I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.

Some good suggestions have been made in this thread.

However, have you thought about putting the microphone close to where
the birdies are tweeting? You could run an extension cable for the
microphone etc. Or maybe set up a tiny radio microphone like this one:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...14955 08&rd=1

My knowledge of parabolic reflectors is very limited, but I thought
the general idea was to focus everything coming in from one specific
direction into a focal point (where your microphone would be). So
wouldn't it be the case that if the birdies weren't in line with
wherever the parabola is pointing then their enthusiastic singing
would be missed, or at best subdued?

Andrew

In article ,
Andrew McKay wrote:
My knowledge of parabolic reflectors is very limited, but I thought
the general idea was to focus everything coming in from one specific
direction into a focal point (where your microphone would be). So
wouldn't it be the case that if the birdies weren't in line with
wherever the parabola is pointing then their enthusiastic singing
would be missed, or at best subdued?

If you just wanted general bird song, then any mic would do. But if trying
for one specific bird - and not getting close enough to scare it off -
parabola is a very good way of doing it. You listen to the output of the
mic and point it to get best results.

The beauty of a parabola is it adds gain and directionality to the chosen
mic 'for free'.

Rifle type mics work by rejecting unwanted sounds so sort of lose gain.

Of course a rifle mic is easy to carry and handle - not so a large
parabola.

Last time I actually used a parabola was on a cup final at Wembley
(mutter) years ago. The idea was to get close up sound of the ball being
kicked - from the top of the grandstand.;-) Worked much better than rifle
mics on the touchline.

Must have been about the most boring job ever - panning it around after
that ball.

--
*If at first you don't succeed, avoid skydiving.*

Dave Plowman London SW
To e-mail, change noise into sound.

Thanks guys for all your suggestions.

A bit of background:-
I'm using either a camcorder or a MiniDisc recorder.

1 So far I've tried placing a pair of small omnis around the top of a fence
post spiked with bird food. Very successful for capturing the wing-beats as
birds came down to feed, and also caught some calls very well indeed. Mikes
also captured the distant noise of road repair work.

2 Have captured some excellent soundscapes, including birdsong, via dummy
head stereo - using a pair of omnis on the sides of my baseball cap. But
traffic noise was a problem.

Hence I'm now thinking about making a reflector system. I'll lose the
stereo effects but hopefully the traffic noise will also be reduced.
(Location wise, I'm close to the M1, and traffic noise is apparent more or
less everywhere in and around Milton Keynes, and in Salcey Forest (a few
miles north) which is cut by the M1.)

--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm

"John" wrote in message
...

"Malcolm Stewart" wrote in
message ...
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical
heating
element at the centre of a spun reflector.


Be aware that most satellite dishes are offset and the dish axis doesn't
point directly at the satellite. Given a dish (eg Sky) which is nominally
vertical and the satellite is at approx 36 deg. elevation or so (from
London) the offset is 36 deg and the LNB is 36 deg below the dish
parabolic axis. Dishes which are true parabolic have the LNB on the
central axis usually on a tripod arrangement and the dish is pointed up
directly at the satellite.

john


Anybody want to buy a 1.8m centre lnb dish on a tripod mount?

On Sun, 20 Mar 2005 11:11:57 +0000 (GMT), Dave Plowman (News) wrote:

IMHO, you'll need something larger than a metre or so for decent
results.

Depends how much MF and LF response he wants... there is a
relationship between dish diameter and the lowest frequency that it
will focus effectively. They do have a lot of "suck" and directivity
though at the expense of frequency response. Do a UK google search on
"sound mirrors" for real parabs...

Last time I rigged a parab was at Headingly on a test match to get the
whack of leather on willow, there where also mics buried in the pitch
and cabled back, these had to be delayed.

--
Cheers
Dave. pam is missing e-mail

In article ,
Malcolm Stewart wrote:
2 Have captured some excellent soundscapes, including birdsong, via dummy
head stereo - using a pair of omnis on the sides of my baseball cap. But
traffic noise was a problem.


Steep high pass filtering (bass cut) will help a great deal with traffic
noise with minimal effect on most bird song. However, such steep filters
aren't easily available outside pro recording equipement, but you might
find a suitable prog to do this in your PC. Can't help there as I don't
have one. ;-)

--
*Stable Relationships Are For Horses.

Dave Plowman London SW
To e-mail, change noise into sound.

"Malcolm Stewart" wrote in
message ...
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical
heating
element at the centre of a spun reflector.

Thanks (I am aware of the professionally priced reflectors from Sweden.)
--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm


You might try the audio-orientated newsgroups. Perhaps rec.audio.pro or
similar. there's bound to be someone in the trade who's used devices like
you want.

Peter Scott

On Sun, 20 Mar 2005 13:21:31 +0000 (UTC), "John"
wrote:

Anybody want to buy a 1.8m centre lnb dish on a tripod mount?

I think he was wondering about how to listen to tweeting noises at the
end of his garden, not the lower crested twit on the surface of Mars


Andrew

On Sun, 20 Mar 2005 12:29:59 +0000 (GMT), "Dave Plowman (News)"
wrote:

Must have been about the most boring job ever - panning it around after
that ball.

In this day and age you'd think they'd put a little something into the
ball so that it was self-tracking.

Alternatively, pass a bung to all the other players to ensure they
give the ball to Michael Owen. That way it won't be going anywhere

Andrew

On Sun, 20 Mar 2005 13:02:18 -0000, "Malcolm Stewart"
wrote:

Hence I'm now thinking about making a reflector system. I'll lose the
stereo effects but hopefully the traffic noise will also be reduced.
(Location wise, I'm close to the M1, and traffic noise is apparent more or
less everywhere in and around Milton Keynes, and in Salcey Forest (a few
miles north) which is cut by the M1.)

It might be a silly suggestion, but can't the traffic noise be
filtered out dynamically?

Not my specialist area by any means, but it seems to me that the TV
crews doing roadside interviews do this pretty well without having an
awful lot of equipment with them.

Andrew

In article ,
Peter Scott wrote:
You might try the audio-orientated newsgroups. Perhaps rec.audio.pro or
similar. there's bound to be someone in the trade who's used devices like
you want.

There are, but I think the OP has checked up on those prices. ;-)

--
*Why is the time of day with the slowest traffic called rush hour?

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andrew McKay wrote:
Must have been about the most boring job ever - panning it around after
that ball.

In this day and age you'd think they'd put a little something into the
ball so that it was self-tracking.

Wasn't this day and age, though. ;-)

--
*Why doesn't Tarzan have a beard? *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andrew McKay wrote:
Anybody want to buy a 1.8m centre lnb dish on a tripod mount?

I think he was wondering about how to listen to tweeting noises at the
end of his garden, not the lower crested twit on the surface of Mars

The one I used for ball being kicked FX at Wembley was IIRC about 2 metres
in diameter.

--
*If a mute swears, does his mother wash his hands with soap?

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andrew McKay wrote:
It might be a silly suggestion, but can't the traffic noise be
filtered out dynamically?

To a certain extent, yes.

Not my specialist area by any means, but it seems to me that the TV
crews doing roadside interviews do this pretty well without having an
awful lot of equipment with them.

The obvious way is to get the mic as close to the wanted sound as
possible, and to use a directional mic.

But you might find problems getting a bird to tweet with a ruddy great
mic shoved up its beak.

--
*I must always remember that I'm unique, just like everyone else. *

Dave Plowman London SW
To e-mail, change noise into sound.

In article om,
Dave Liquorice wrote:
IMHO, you'll need something larger than a metre or so for decent
results.

Depends how much MF and LF response he wants... there is a
relationship between dish diameter and the lowest frequency that it
will focus effectively. They do have a lot of "suck" and directivity
though at the expense of frequency response.

Yes. I'm not sure they're exactly of the best quality, as the ones I've
seen tend to have been used with any old mic that was lying around.

Last time I rigged a parab was at Headingly on a test match to get the
whack of leather on willow, there where also mics buried in the pitch
and cabled back, these had to be delayed.

Yet another problem to add to digital this and that. But I suppose at
least that parab would have been fixed since the balls are hit only on one
axis?

--
*Reality? Is that where the pizza delivery guy comes from?

Dave Plowman London SW
To e-mail, change noise into sound.

In article , "Malcolm Stewart"
says...
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical heating
element at the centre of a spun reflector.


I'd have a go at making one. Cut a couple of templates from
hardboard or similar, mount on a piece of board and use to shape a
lump of expanded polystyrene (ideally with a hot wire, but a handsaw
would probably do). Smooth the former with a thin layer of filler,
cover in aluminium foil, then laminate with fibreglass, papier-mache
....

In article om, Dave
Liquorice writes
On Sun, 20 Mar 2005 11:11:57 +0000 (GMT), Dave Plowman (News) wrote:

IMHO, you'll need something larger than a metre or so for decent
results.

Depends how much MF and LF response he wants... there is a
relationship between dish diameter and the lowest frequency that it
will focus effectively. They do have a lot of "suck" and directivity
though at the expense of frequency response. Do a UK google search on
"sound mirrors" for real parabs...

Last time I rigged a parab was at Headingly on a test match to get the
whack of leather on willow, there where also mics buried in the pitch
and cabled back, these had to be delayed.


He's only after birds song and I don't suppose they do Baritone and
Bass)
--
Tony Sayer

In article , Malcolm Stewart
writes
Thanks guys for all your suggestions.

A bit of background:-
I'm using either a camcorder or a MiniDisc recorder.

1 So far I've tried placing a pair of small omnis around the top of a fence
post spiked with bird food. Very successful for capturing the wing-beats as
birds came down to feed, and also caught some calls very well indeed. Mikes
also captured the distant noise of road repair work.

2 Have captured some excellent soundscapes, including birdsong, via dummy
head stereo - using a pair of omnis on the sides of my baseball cap. But
traffic noise was a problem.

Hence I'm now thinking about making a reflector system. I'll lose the
stereo effects but hopefully the traffic noise will also be reduced.
(Location wise, I'm close to the M1, and traffic noise is apparent more or
less everywhere in and around Milton Keynes, and in Salcey Forest (a few
miles north) which is cut by the M1.)


Sounds like their opening another classic FM network some where

Did you do the original one?....
--
Tony Sayer

On Sun, 20 Mar 2005 15:48:42 +0000 (GMT), "Dave Plowman (News)"
wrote:

But you might find problems getting a bird to tweet with a ruddy great
mic shoved up its beak.

That's true enough. Unless it is the greater spotted politician bird
then you can be sure it'll squawk all day long

Andrew

Tony Williams wrote:

How about a big torch, the sort that takes a
lantern battery?

Enough room in there also to do a small battery
powered preamplifier.


Similar idea was suggested in an issue of Everyday Electronics, many
years ago...or was that the infrared torch link? Was a long time ago

Lee
--
Email address is valid, but is unlikely to be read.

On Sun, 20 Mar 2005 15:43:17 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Peter Scott wrote:
You might try the audio-orientated newsgroups. Perhaps rec.audio.pro or
similar. there's bound to be someone in the trade who's used devices like
you want.

There are, but I think the OP has checked up on those prices. ;-)

Do not know how efficient they are but are there not some available in
the toy market? .not sure where I have seen them for sale.
maybe it was Maplin or possibly Toys R Us in the section which has
Telescopes,metal detectors etc.

G.Harman

In message , John
writes

"John" wrote in message
...

"Malcolm Stewart" wrote in
message ...
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I could
cannibalise for their parabolic shape. Any ideas would be welcome. Best
I've thought of so far is an old radiant heater with the cylindrical
heating
element at the centre of a spun reflector.


Be aware that most satellite dishes are offset and the dish axis doesn't
point directly at the satellite. Given a dish (eg Sky) which is nominally
vertical and the satellite is at approx 36 deg. elevation or so (from
London) the offset is 36 deg and the LNB is 36 deg below the dish
parabolic axis. Dishes which are true parabolic have the LNB on the
central axis usually on a tripod arrangement and the dish is pointed up
directly at the satellite.

john


Anybody want to buy a 1.8m centre lnb dish on a tripod mount?

Put it in an envelope and post it down ...

Put it aside in the pigsty for me

--
geoff

In message , OG
writes

"Malcolm Stewart" wrote in
message ...
I'd like to try recording birdsong using a microphone at the focus of
parabolic reflector.
Currently, I'm having difficulty thinking of domestic items which I
could
cannibalise for their parabolic shape. Any ideas would be welcome.
Best
I've thought of so far is an old radiant heater with the cylindrical
heating
element at the centre of a spun reflector.

I had ideas about this years ago and considered taking a papier mache
mould of the round end of a spacehopper.

Not a parabola though, is it

--
geoff

In message , Andrew McKay
writes
On Sun, 20 Mar 2005 13:21:31 +0000 (UTC), "John"
wrote:

Anybody want to buy a 1.8m centre lnb dish on a tripod mount?

I think he was wondering about how to listen to tweeting noises at the
end of his garden, not the lower crested twit on the surface of Mars


Earth calling Beagle II, Earth calling beagle II ...

--
geoff

Do not know how efficient they are but are there not some available in
the toy market? .not sure where I have seen them for sale.
maybe it was Maplin or possibly Toys R Us in the section which has
Telescopes,metal detectors etc.


Sometimes in Lidl as toy spy mics, but they;re only 6" diam so won't be at
all effective.