Hydrophones

Yes, from my experience I end up buying the slightly more affordable version then end up getting what I should have in the first place. Dolphin Ear are the other contenders http://www.dolphinear.com/pro.html

Inspired by this post on fish vocalizations (A Catalog of River-Dwellers) and my recent acquisition of a Mixpre 10 II, I picked up an Aquarian H2a XLR. It arrived today so I put it in my bag and set off for the nearest lake in hopes of capturing some fish talk.

Now this lake is known to be the domain of a thuggish gang of bluegill who will attack interlopers on sight. I have personally been bitten by them many times while swimming! As expected, they bird-dogged me the whole way down the dock. However, upon setting up my rig and donning the phones, I heard nary a fishy blerp. They simply floated there, looking at me as if to say “what’s my motivation?”.

Fortunately I’d had the foresight to bring with me a motivator in the form of some crunchy dried cheese bits. The introduction of cheese to the situation didn’t prompt any vocalizations that I can distinguish, but it did make for some entertaining fishy mastication sounds.


I am getting a bit more self noise than I would like coming from this hydrophone. I’d say the dynamic range is there as loud sounds (not in this clip) are reproduced well, but sufficient gain for quiet sounds brings up the hiss. Is there a better device to capture the softer sounds of the underwater world, or do I just have to live with the noise?

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So cool! I was really hoping I’d find bluegills in the Marie Fish book, but I guess that family isn’t found in Rhode Island where she was doing her studies. I hear that fish crunching away though, amazing! I love it.

I have had the same issues with my little bit of hydrophone experimentation. I was asking a friend who knows way more about this stuff than I do and he suggested a small phantom-powered preamp as close to the microphone as possible would be the way to go. The shorter the distance between the preamp and the mic, the more amplification you can get out of the piezo disk without as much noise. (As I understood it anyway.)

I’d like to experiment with this, he said he could recommend a simple preamp circuit to build so I can pass that along at least – he’s on this forum too but I don’t know his username haha, so maybe he’ll chime in.

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The XLR version of this mic (which I’m using) is 48V phantom powered. I assume the amplifier is in the XLR rather than the head though. I have to think that there are limitations in sensitivity in a contact type mic vs something with a light diaphragm.
I did pick up the contact mic accessory for this hydrophone and recorded some with it today. I should have some samples and comments on that soon. I think I got some good percussive sounds out of a swim step and a few boats.

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Nice. The wall I ran into was trying to record a mic frozen into a block of ice. Except for the beginning and end it was mostly noise floor. On the other hand Collin Olan made a fantastic recording in 2002: https://www.discogs.com/Collin-Olan-Rec01/release/228323 but I don’t know why he was able to get such better amplification! (it’s an amazing recording)

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Yeah! I love that ice and snow stuff. The first time I heard something like that was some years ago. I was driving alone at night from Portland to Seattle listening to college radio. They were playing a whole album (someone from Scandinavia I think) which had a lot of highly amplified snowflakes landing and ice creaks. As I drove further, the radio signal gradually degraded in the most beautiful way. I had a bit of a moment then, still remember it.
Here are some relevant recordings, some of which are using hydrophones or contact mics. http://www.gruenrekorder.de/?page_id=107 Several of these recordists are getting the small sounds of snow and ice very loud without much noise (with unsophisticated equipment). I’ve much to learn it seems.

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I’d love to know what this was if you remember! Was it Daniel Blinkhorn’s FrostbYte?

http://audiobulb.com/albums/AB065/AB065.htm

The ‘frostbYte cycle’, a collection of ongoing pieces central to which are location- based field recordings I made whilst on expedition throughout the Arctic region of Svalbard (Spitsbergen).

Thanks so much for the link to the Gruenrekorder The Sound of Snow and Ice comp, lots of great folks on this, it looks great!

(Also lines told me to shut up I’m talking too much so stepping away slowly for a bit now, lol. I’m really excited about doing more underwater and ice recordings.)

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Does anyone know if that H2A mic could be used in boiling water?

I’d ask them before trying. It seems like the metal and rubber materials might expand at different rates. It does feel very durable though.

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If you’re familiar with the artist Leafcutter John, who I like a lot, you may already know that he’s into making microphones…

This looks right on point…

https://flypaper.soundfly.com/produce/how-to-build-a-diy-hydrophone/

me + my partner did this a few years ago:

Two compositions derived from an ongoing acoustical investigation
of glaciers, frozen soils, ice formation and melting, and other sub-zero environments, assembled using untreated sound recordings captured by means of hydrophones.

we used the Aquarian H2a XLR.

asked the same to a guy from Aquarian Audio (years ago, do not remember his name), he told me it is possible and he even sent me a video of him doing it, but he warned me that the hydrophone he used to accomplish that worked for some months then suddenly began to malfunction or it even died.

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Just made my first hydrophone contact mic. I’ve been wanting to work with microsounds and field recordings. Hydrophones seem to offer another way to gather sound (as has been discussed here). Playing around with contact microphones that I already had, I wanted to finally get around to making my own.

The first thing I noticed about all the DIY hydrophones is that many are made of plastic and need to be weighted down. Thinking about how I could make this mic with fewer pieces, I opted for a brass plumbing cap. It’s heavy, the piezo element I purchased fit inside of it nicely, and I was able to not only seal it with hot glue, but also fill the entire case with it, for extra vibration reduction. Before filling the cap with glue/gluing in the piezo, I knotted the cable to make sure it wouldn’t pass through the hole in the cap.

Pairing this with my ZOOM F1 recorder / @pulplogic CTACT box, I am able to get some really nice lo-fi recordings from my bathroom sink. Much to explore and other casings, wirings, piezo pieces to test, etc. At this point, I’m happy enough that it’s waterproof and heavy, and looks nice.

A short audio example - first through CTACT box into ZOOM F1, then just straight into the ZOOM F1. The CTACT offers a different sound, with more audio present, but does accentuate different bands of audio.


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I was commissioned once to build a DIY hydrophone for an artist working on a project on the ocean. It came together quite nicely I thought since it past the bathub tests and felt pretty sturdy. It was designed like a plexi-glass sandwich like:

Generic piezo preamp worked well (I think I used this one) I also potted the center with resin.

Apparently what happened is when they tried to launch it out into the ocean it was immediately torn off from the end of the cable. What I took from that is that strain relief is one of the most important things to consider. You really have to isolate where the wires attach to the piezo, to where it exits the case. A water tight gland would be good. Maybe even potting the entire device in plasti-dip or something similar. You want to avoid and cables being right angle to the case without some kind of strain-relief

If I was going to rebuild it now I’d probably go with something a bit more robust like:

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Your hydrophone is far nicer looking than mine, and the piezo is way bigger! Bigger piezo, that’s my next step!

As for cord strain, that was something else I had definitely taken into consideration. Since it’s narrow RCA (shielded) cable, I knotted it on the inside of the cap, and rolled the small amount of excess along the threading. The cap is about an inch wide with a 3/4" opening.

A question or two - does the rubbery finish of the hot glue gun glue transmit energy to the piezo less well than a firmer glue? Also, would an encased piezo element reduce the pickup? I have piezo elements that come with a small plastic case around them.

OK. Figured it out. Yes, the coating does make a difference, but it’s not heavy. What does make a difference is that when I solder my cord to the wrong post, it is quiet. Re-did that, and now the rubbery coated one is loud. I figured this out today when I made another, using JB Weld’ “Clearweld w/Syringe”. It makes a nice covering for the microphone, dries hard. When the covering is harder, it tends to pick up more vibration-wise. Neat! Now I got two of these. We’ll see what I can pick up. They also work as excellent contact microphones.

Paired with the CTACT box, it’s an entire new world of sound(s). Who knew hair could sound so cool?

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I’m in the middle of experimenting with hydrophone builds too – my first hydrophone came from the folks at cold gold, and I got one with a really long cable (like 25 feet) so I could toss it into the river. Unfortunately I think because the cable is really long, the noise floor is terrible. Doing some experiments with it at home in a jug of frozen water for example, all the detail gets lost in the noise floor.

Have you (or anyone else) experimented with the effect of cable lengths? It’s something I plan to do – a friend suggested that I just stick an amplifier circuit near the piezo element and power it with phantom to use really long cables, but for a simpler approach I’m curious how long the cable needs to get for the noise floor to start to make it useless for detailed sound!

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Shielded cable makes a big difference, attached directly piezo and grounded. Also adding a copper shield or metal shield around the piezo should help too if that’s connected to ground as well.

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As mine are all about 4’ in length, I haven’t had too much interference. Shielded cable, definitely. My piezo elements are actually enclosed in a small plastic case, which doesn’t seem to make much of a difference, but definitely keeps the piezo from getting bent/scratched/disfigured. I can get some hum, if the CTACT box is turned up all the way prior to the ZOOM F1, but that’s over-doing it. The signal doesn’t need to be that loud.

I’ve also noticed that in certain parts of my house, where I stand on a wooden floor over a concrete foundation, can cause hum. Holding the CTACT box can eliminate it, or sometimes raise it. Not sure what else I can do. If there’s a way to ground the mono cable, I’d love to know. The piezo elements are already grounded in their plastic case, otherwise having a black and red wire out of it would be weird / for show?

The combination of glues and plumber’s putty inside of a brass casing seem to do a pretty decent job of interference reduction; at this juncture, though, I’m just guessing.

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Ok, I know that this was posted somewhere on lines before (maybe the contact mic thread?) but thought that this would be a good place to repost regarding the current discussion re piezo solutions and ground hum elimination:

I recently built a pair of these using light weight shielded cables, lots of heat shrink tube where the leads coming off the piezo disks met the cable, and gave them a generous coat of plasti-dip. The reduction in hum/selfnoise vs single unbalanced contacts I’ve made in the past is surprisingly good.

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Today I experimented with a hydrophone made from a piezo sensor molded into a polyurethane sphere. This hydrophone uses a small JFET preamp which really helps to reduce the electromagnetic interference from the kettle’s heating element. I tried this before with a passive piezo and had a lot of interference.

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