©2019 Open Acoustic Devices

Apr 2, 2018

Acoustic cloth

27 comments

https://www.akustikstoff.com/Speaker-Cloth-Samples:::116.html

 

I am going to build my own housing for the unit. I came across this site that provides samples of acoustic cloth including waterproof at a reasonable price. It also is easy to treat the ordinary cloth with a water repellant spray.

Hope this helps.

Apr 4, 2018

Thanks Fran, very cool cloth. It would be great if you could post a picture of your finished housing.

Apr 5, 2018

Thanks Fran, I've ordererd a sample of the water proof cloth.

Oct 1, 2018

Hi David

I have now tried the cloth and to test it I used the same enclosure box as you and drilled a 5mm hole for the mike. I then glued a square of the material over the hole and put it in the shower to simulate heavy rain. Unfortunately I ended up with water inside the box. I did the same again to check but same result. I then removed the cloth and covered the hole with Elec tape put it under the shower again - no water.

 

 

Oct 1, 2018

@robwat It will seep with very heavy rain. But generally a shower is extremely intense, whereas a box on a tree will be far less exposed.

Oct 1, 2018

@David Martin Thanks David I just wanted to be sure given the damage that can be done should any water get in

Apr 5, 2018

Will do

Apr 6, 2018

The samples have turned up and I have 41 pieces of hydrophobic cloth. I may be in the market to distribute some.....

 

Apr 6, 2018

Please can I try one will pay for it. FRAN

Apr 8, 2018

Also keen to try one. I think I will only need a tiny amount for my needs. Please let me know if you would be willing to sell one on

Apr 8, 2018

Been looking into how I could do this -I think paypal and to cover costs would be (for UK) £1.20 for one sheet inc 1st class P&P and 30p per additional sheet, of course, if you are close to Bristol UK you could pop in. The sheets have filing holes and laser cut numbers so the max size of virgin sheet is 12x12 cm. My email is david at brownfamilymail.co.uk so you can drop me your address and I can send you a paypal invoice.

 

Hi David, I bought an Audiomoth and I'm trying to build the case. Do you still have clothes from Akoustikstoff? How do they work? Could I buy you a piece? I live in Segovia, Spain, zip code 40004

Thanks

Sep 20, 2018

@atropellos fauna (Javi Llorente) yes I still have plenty and I think it would be about 2 euro to post one piece to you (3-5 day delivery), if you wanted two then 2.30 euro. The cloth itself is hydrophobic and when I pour water into it - just forms into beads on the surface without wetting the cloth. If you want to send me your email and full address via https://sites.google.com/view/audiomoth/about and I will send you a paypal invoice.

Cheers

David B

Just for anyone finding the above post, I'm now out of cloth. It's gone round the world. David Brown.

Apr 8, 2018

I have tried making some bat recordings using a film of 3 micron aluminised Mylar over the microphone port and even sounds up to 192kHz are still coming through and the results seem comparable with a Petterson M500-384 although the noise profile is not so good. Details of how to see the recordings are in the 'sample recordings' thread.

Is the Mylar film you have used waterproof or at least hydrophobic?

Not specifically hydrophobic - it is basically polyethylene film with a very thin film of aluminium - not much more than a molecule thick, but just enough to be conductive. The advantage is that it is very very light (in 3.5um thickness) and therefore has minimal effect on the sound especially at high frequencies. I use it as I had stocks in hand for making microphone diaphragms for ultrasonic capacitance microphones with responses which are flat to 180kHz or so. Figured if it works as a diaphragm should be good as a screen and at least blocks bulk ingress of water.

Thank you for the information.

 

I am not able to collect the devices every day and they have to stay outside for two weeks or longer. Because of that, it is important the vent do not let the water comes inside during rain. Maybe it stays dry in combination with silica gel in the case.

May 14, 2018

Below are some photos of the container i have made using a small plastic craft box, cheap make up sponge and bird fat cage, approx £6. Still need to cut hole for microphone and acoustic cloth

 

 

 

May 14, 2018

 

 

May 14, 2018

 

Here are a couple of mine. They are sufficiently waterproof to be out in the rain.

And a more distant shot

 

 

May 14, 2018

"I have tried making some bat recordings using a film of 3 micron aluminised Mylar over the microphone port " - does any one else read that as 'I put it in a crisp packet'? :)

May 15, 2018

s by moving it to and fro, not magically passing through it)Absolutely not a crisp packet - but also not very readily available. This stuff is thinner and lighter than clingfilm and is used for the diaphragms of ultrasonic capacitance microphones that work to over 200kHz. Small mass means that the sound waves have to do less work to move it (and sound transmission across a diaphragm is done by moving the diaphragm to and fro not by magically passing through it) and therefore sound attenuation is minimal. Clingfilm is an alternative but is about 12micron and therefore more massive. Anythin in the form of a grid or mesh tends to attenuate high frequencies and cause dips and peaks in the frequency response, and directionality at lower frequencies.

Jul 2, 2018

Hi David Martin,

 

I would appreciate if you let us know what's the box's brand and which glue did you used to fix the acoustic membrane? Thank you!

 

Best,

Noelia

Jul 2, 2018

I used the smallest box from Really Useful Products http://www.reallyusefulproducts.co.uk/uk/html/onlineshop/rub/b00_07litre.php in recycled black and a normal hot glue gun to attach the cloth. The trick is to ensure you get a really good bead of glue adhering to the plastic, then place the cloth over it and use the tip of the hot gun to push it into the glue. Not the best method and a bit tricky but it worked. I tried other adhesives (cyanoacrylate) but it didn't adhere well. I haven't tried some other plastic cements.

Jul 2, 2018

Please note these boxes as they come are not waterproof. I cast a seal with silicone - I am sure a conventional bath sealant would work as well as the mould making rubber I used.

New Posts
  • Hi all, I thought I would share my case with the community, it is a variation on a theme but it has worked well in the few tests I have done. The case is a Lock & Lock rectangular 180ml container (HPL805): http://www.reallyusefulproducts.co.uk/uk/html/onlineshop/locklock/rec_hpl805.php The inner foam housing is 2 layers of EFP30 Polyethylene closed cell foam sheets 20mm thickness. One is supporting the AudioMoth the other is cut to fit the AudioMoth inside : https://www.easyfoam.co.uk/closed-cell-polyethylene-foam.php Then over the hole drilled for the microphone I have used Buzzer Waterproof Acoustic Membranes brought on Alibaba: https://www.alibaba.com/product-detail/Buzzer-Customize-Size-Black-Waterproof-Acoustic_60812354593.html?spm=a2700.galleryofferlist.0.0.6c233527JZ969G&s=p The box remained watertight under a tap at full strength, focused directly on the acoustic membrane, so I am hoping rain at an angle won't pose too much of an issue. Only thing I am a bit nervous about is the glue holding the membrane, if it will withstand tropical humidity. I will keep everyone updated. Cheers
  • Hello! I am a phd and my focus is to record felid vocalizations in zoo enclosures. I need large number of samples and large number of species, so I was thinking to buy many audiomoth to handle in the exhibits. I just wondering if the quality of registrations can be good also in environments with strong noises such as visitors voices, zoos speaker voices, other animal vocalizations etc. what do you suggest? Any previous experiences? thank you Ros
  • Hello all. For those who are looking for some inspiration: I found a cheap yet practical shock-/waterproof case. Available in three colours (beige, black orange) in the Geek/Wish store. With some minor adaptations it’s ideal for the AudioMoth. The inner lining consists of foam in which the shape of the AudioMoth can be easily cut out. For the fixation of the membrane I was inspired by the Aurita design and used a PVC shoulder washer. After drilling a hole just above the mic I enlarged it until the washer fits tightly. Since the materials (plastic vs PVC) are difficult to glue I used butyl tape to attach the shoulder washer. The membrane, standard cling film (10 micron), is mounted on top of the washer. In order to prevent damage by the sharp edges there there is an O-ring on top. The second O-ring stretches the membrane over the first one and provides extra protection against water ingress. I also provide a silicagel packet to prevent condensation on the membrane and as extra safety in case of the membrane is compromised. It is advised to check the membrane after each battery change because the cling film degrades due to weather conditions. Also the O-rings suffer from UV-degradation after a time so be sure to check their condition as well. The box has two ‘eyelets’, very convenient to attach the box. The box costs 2€ and together with the other stuff you have an excellent enclosure for less than 5€ and 15 minutes crafting.
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