Hydrophone Drop Rig

Build an Underwater Drop Rig. This is the build portion of this Instructable.
www.instructab...
I will show you how to build two different kinds of rigs. One that can go snorkeling or diving with you, and one that can be stashed and record for days. It uses 3.5mm input recorders and a high impedance buffer to get stellar audio results. The instructable has all the details for parts etc.

[@zero2spearo]

I love how you can get the whole stereo experience when you are throwing the pebbles in at the end.

[@SoundSleuth]

Thanks! That's why there are two of them!

[@PunchDuk]

I’m not an electronics guy, but these videos are making me want to be. Great job explaining, and keep up the good work!

[@kaipaquin7060]

So cool! Thanks for sharing the build!

[@betoblanco603]

Just a respectful observation, the epoxy mold method seems to prevent the best contact from the mics with the water first because of the material which conducts vibrations and sound pressure but not as efficient as others and second the capsule it's in the center and not near the surface where it contacts the water. I've seen people use Plastidip, liquid plastic which in my opinion just covers the capsule enough making a more direct contact with the water, it's lighter and not as rigid which conducts better the vibrations. Results in a much more crisp and detailed sound rather than a "boxy" sealed sound.

[@SoundSleuth]

It’s actually about the density of the material that the cylinder is embedded in. We want as it close to that of water for cleanest transfer of acoustic energy. My original build that embedded the PCB with the piezo cylinder has received great reviews and sounds excellent. It uses the same resin.

[@TheErilaz]

I have successfully used marine silicone.

[@soundhobo]

That’s a job well done 👍

[@difang8327]

Hi, great instruction! I am about to make the diving version of it. However, I cannot find the Sony PCM-A10 in Europe... And importing from US will double the price... Are there any other small but high-quality recorders that you can recommend? Thanks!

[@SoundSleuth]

Yep, these work well, You just cant do 96kHz www.amazon.com/Sony-ICD-UX570-Digital-Recorder-ICDUX570BLK/dp/B082QL6KLG/

[@MrHondaguy77]

I have absolutely no idea how you built this, but I really need one. I inspect pools for water leaks and really could use this. Is there anyway I can pay you to make me one?!?!

[@TheErilaz]

I have successfully used marine silicone to fill containers with piezoelectric elements.

[@WorldPowerLabs]

Quick question: with STEMinc apparently out-of-business, or soon to be, do you know of an alternate source for usable piezo cylinders?

[@SoundSleuth]

Yes I am about to update the Instructables

[@Swarmish]

Hey, I thought I posted a question yesterday, but I don't see it so I'll try asking again (sorry for the spam if the original does post). I'm just starting to get into hydrophones and built my first one last night using a piezo disc with enclosure that was meant for guitar pickups (scrappily sealed with hot glue). What kind of differences does a piezo cylinder offer vs the piezo disc? Also I did notice the loud hum with my last night build that I tested in my tub. Should adding a copper wire to ground into the water nullify the hum that my build has? I am considering following your build video to make a new pair of hydrophones as I am really impressed by the audio in this video as well as your video for the whales. Thank you so much for sharing your findings in such great detail! I've always wanted to record underwater sounds, so I'm excited to explore this even further.

[@SoundSleuth]

Glad you are exploring underwater sound. You have to have a ground to the water to prevent humm and buzz. I found that out the hard way -- as in after my first build and I had published. To the Disc vs Cylinder. All the commercial ones are cylinders. And actually they keep them hollow which I also became aware of. I plan on updating both builds very shortly.

[@misterbusiness3964]

I'll also be curious for those updates! Thank you. I've never built one of these, and would buy two from you, but as I understand you are just offering the instructables. Does anyone else sell similar quality hydrophones? Thomas Rex Beverly referred me to someone, but alas, that was a dead end. @@SoundSleuth

[@SoundSleuth]

@@misterbusiness3964 reach out to me via email. [e-mail]

[@misterbusiness3964]

Email sent!@@SoundSleuth

[@metaforest]

5-min epoxy is not long-term water proof. It will degrade and soften fairly quickly.

[@SoundSleuth]

It probably isn't the best method but works well for me. Do you have suggestions for improvemnets?

[@metaforest]

@@SoundSleuth Try JB-Weld it has about the same consistency as 5-min epoxy. There is a 5-min version of JB-Weld as well, but I don't think it cures as nicely as the regular formula.

[@SoundSleuth]

@@metaforest lol I’m pretty sure that’s the brand of five min epoxy I use

[@metaforest]

@@SoundSleuth I'm not talking about the clear stuff they make... that is not water resistant. I'm talking about the gray stuff. Totally different chemistry.

[@dreamcat4]

hi, for the cables sealing with epoxy, it might be nice to makke a more flexible cable relief on top of that. so as an extra step, this could be achieved with a polyeurethane based product. for which toluene is the solvent. there might be several pu based products available on the market. however for more information about the method which i heard about, robrenz has an instructional video over on his channel cryptically called 'secrets of goop' here is link kzbin.info/www/bejne/gIaVm6aYfLOWkKc&pp=ygUPcm9icmVueiB0b2x1ZW5l