DIY Stereo Field Dish Microphone (WIP) (3 Viewers)

[Pee-wee Pete]

Moreover, there is the frequency dependence to consider. The waves diffract upon entering the dish aperture, so none of the "rays" actually strike the surface along the dish normal/perpendicular, and they are not parallel. In the high frequency limit the effect is negligible, but not for low frequencies. Hence the low-frequency performance loss. One could deviate from a parabolic surface in order to compensate for this, to get better low-frequency gain, but then you'd hose up the higher end of the spectrum. There are no solutions, there are only trade-offs.

Interesting. I will keep that in mind as I hunt for the best focal point of the wok.
Thanks.

 

[3dpan]

A few days ago, when the dish was in stock the price tag was 69 GBP.
Perhaps "Sold out" is another term for "price rise coming up".
But hopefully I'm just being pessimistic.

 

[3dpan]

Moreover, there is the frequency dependence to consider. The waves diffract upon entering the dish aperture, so none of the "rays" actually strike the surface along the dish normal/perpendicular, and they are not parallel. In the high frequency limit the effect is negligible, but not for low frequencies. Hence the low-frequency performance loss. One could deviate from a parabolic surface in order to compensate for this, to get better low-frequency gain, but then you'd hose up the higher end of the spectrum. There are no solutions, there are only trade-offs.

That's a very interesting analysis of the paraboloid, by Michael Hurben.
Thank you for that link,
Cheers,
Alec

 

[Pee-wee Pete]

A few days ago, when the dish was in stock the price tag was 69 GBP.
Perhaps "Sold out" is another term for "price rise coming up".
But hopefully I'm just being pessimistic.

I think I will be happy with the wok. I am new to bird watching and sound recording, and I am definitely not (yet) an audiophile. So I don't know what is good or not.

Three weeks ago I ordered a book, Bird Watching for Dummies, and it arrived yesterday. It took me at least an hour to make a quick perusal. I was astonished how deep and extensive the subject of bird watching can go. The book is about 380 pages, and covers several hundred aspects of the hobby. So, a bird watcher could easily buy a hundred specialized books about bird watching, let alone reading up on the birds themselves.

My recorder should be arriving in a weeks time. That is a learning curve on its own. But I am looking forward to the day I hook it up to the non-prabolic dish and hear how well or bad it captures distant sounds.

In the meantime I plan to hook up a function generator (sinewave) to a speaker. Set it on mid frequency range, say 1 kHz. Aim the dish at it and find focal point(s) for the mic(s). Record whatever the microphones can pick up within our audio frequency range _ and/or my own hearing range. Then test it out on the real world of nature.

Oh well, that is my plan, but as usual I am sure to come across a lot of hickups along the way.

 

[Pee-wee Pete]

While waiting for parts etc., I decided to carry on with the exercise of making microphone mounts according to my understanding of where the focal points will be. However, this exercise may become mute after I actually do the sound testing of the dish. And finding that the focal point(s) are elsewhere. Cutting out the shapes from 2mm ABS styrene sheet was no easy task.





I created a wider gluing surface (about 4mm) so it will adhere better to the centre partition of the dish (that is if I use these brackets).

Below I was testing a secondhand (bass) speaker I salvaged from somewhere. It sound was okay but the signal maybe too weak directly from the function generator. An amp may need to be used for testing where the dish focal point is. The used frequency here is 1000 Hz.

 

[Pee-wee Pete]

Today I found my drill handle which I never use. It can clamp on a 40mm dia PVC pipe. From this I was looking for a way to mount the dish onto the pipe. Also, on how to mount the sound recorder. The idea turned out to be quite simple. Then I went to the hardware shop and bought several plumbing pipe bits.



The centre image looked a bit bulky. To minimize this I will trim off 10mm of each piece, leaving 5-6mm for gluing. I know that plumbers PVC glue is very strong, so it should hold for my purposes.

The right hand image shows roughly how it ought to look like. . . but we will see. My plans have a nasty habit of changing.
PS: I might be getting the Tascam DR-40x in the post late next week.

 

[3dpan]

You are making great progress.
You could shrink the bulk by using eg, 32mm plumbing bits. Then a 32-40mm sleeve for the drill handle to clamp on.
The hardware shop might even do a trade, 32mm for your 40mm parts.

 

[3dpan]

I think I will be happy with the wok. I am new to bird watching and sound recording, and I am definitely not (yet) an audiophile. So I don't know what is good or not.

Three weeks ago I ordered a book, Bird Watching for Dummies, and it arrived yesterday. It took me at least an hour to make a quick perusal. I was astonished how deep and extensive the subject of bird watching can go. The book is about 380 pages, and covers several hundred aspects of the hobby. So, a bird watcher could easily buy a hundred specialized books about bird watching, let alone reading up on the birds themselves.

My recorder should be arriving in a weeks time. That is a learning curve on its own. But I am looking forward to the day I hook it up to the non-prabolic dish and hear how well or bad it captures distant sounds.

In the meantime I plan to hook up a function generator (sinewave) to a speaker. Set it on mid frequency range, say 1 kHz. Aim the dish at it and find focal point(s) for the mic(s). Record whatever the microphones can pick up within our audio frequency range _ and/or my own hearing range. Then test it out on the real world of nature.

Oh well, that is my plan, but as usual I am sure to come across a lot of hickups along the way.

Just checked that UK link, the dish is listed again at the original price 69 GPP.

Parabolic Reflector

A true parabolic dish for audio recording. Diameter: 500mm Focal Length: 140mm Material: ABS Flexible Plastic Handle: Aluminium, rubber grip and standard tripod compatible Weight:

www.parabolicmicrophone.co.uk

I haven't seen a better price for reflector/handle.

 

[Pee-wee Pete]

Just checked that UK link, the dish is listed again at the original price 69 GPP.

Parabolic Reflector

A true parabolic dish for audio recording. Diameter: 500mm Focal Length: 140mm Material: ABS Flexible Plastic Handle: Aluminium, rubber grip and standard tripod compatible Weight:

www.parabolicmicrophone.co.uk

I haven't seen a better price for reflector/handle.

Thank you so much for checking it out. Let me see, 69 GPP to AUD = $135, Hmm. If I become unhappy with my current plan I will buy it.
Hang on! I tried through their checkout to find the frieght costs. They put up a banner saying that they cannot send it to my address (Australia). So, that is that, as they say. Pitty.

Thanks for your efforts 3dpan.

Oh, by the way. I read your suggestion about reducing pipe diameter, except for the handle bit. Good idea, but unfortunately I aready cut the fittings. Also, today is my first day since last time that I got out of bed. Suffered a throbbing head-cold for last four days. I still got it but its doable, so I am up and about again.
Cheers.

 

[3dpan]

Looking on the bright side, you've probably saved a fortune in shipping costs.

As an alternative you could purchase this budget priced parabolic mic, $43.39 AU with free shipping.
Downside is the diameter, and no tripod mount. Upside is total cost includes headphones, electronics, 'scope viewfinder, and hours of playing.

Parabolic Microphone Monocular, Parabolic Sound Collecting Dish Bionic ESA | eBay

Built in 8x magnification monocular. Fain bird songs are readily detected. lasting Durable: Its built-in monocular is great for spotting animals from afar or for watching at the slightest details of smaller animals.

www.ebay.com

I already have one for myself, worth every penny, even with its limitations.

 

[Pee-wee Pete]

Looking on the bright side, you've probably saved a fortune in shipping costs.

As an alternative you could purchase this budget priced parabolic mic, $43.39 AU with free shipping.
Downside is the diameter, and no tripod mount. Upside is total cost includes headphones, electronics, 'scope viewfinder, and hours of playing.

Parabolic Microphone Monocular, Parabolic Sound Collecting Dish Bionic ESA | eBay

Built in 8x magnification monocular. Fain bird songs are readily detected. lasting Durable: Its built-in monocular is great for spotting animals from afar or for watching at the slightest details of smaller animals.

www.ebay.com

I already have one for myself, worth every penny, even with its limitations.

I have seen similar on Amazon too (free prime shipping). They seem to be popular.
You mentioned something that I failed to consider. 'tripod mount'. The upside is that I have not assembled the PVC parts (too crook to bother about it). Well it looks like I will replace the Tee joint with a cross tee.

 

[Pee-wee Pete]

I have seen similar on Amazon too (free prime shipping). They seem to be popular.
You mentioned something that I failed to consider. 'tripod mount'. The upside is that I have not assembled the PVC parts (too crook to bother about it). Well it looks like I will replace the Tee joint with a cross tee.

Have ordered a tripod mounting plate from Aliexpress for $6.40 inc shipping. Will arrive next week.

 

[Pee-wee Pete]

Getting a rough idea of what this project will look like, including a tripod mount.


Proceeding to assemble the pieces.






I soon discovered that the handle's hand guard will get in the way of the extention to the tripod. So I had to trim it down to size.

 

[Pee-wee Pete]

I trimmed certain plumbing sections, to make the whole unit more compact. The three end caps will not be glued into place like the rest of the unit. This is so I can access the attachment s to them in the future if they need repair or replacement. The short pipe sections are the sleeves that go in between the sections.


Here I am adding some form of cushioning to cut down on any creaking between dish and mounting unit.


Attaching the adapters to the end plugs.
Before loctite was more accessable, I used nail polish to secure the nuts to the bolts. It works, to a degree, so I keep using it (the bottle is about 35 years old and still usable).


Assembled, without microphones attached to the dish, nor any wiring to the digtal recorder (yet).
Oh yeah, the Tascam finally arrived a few days ago. There was a bit of a delay in America.