DIY Aquaphone material selection

Question

First I would like to say that I really love this place. As a sounddesign student, social sounddesign has been invaluable and a great inspiration! Thanks to all of you for that!

Now, on with the subject :-)

I would like to start a brainstorm on selecting and testing different materials for a DIY Aquaphone. I found one online, but was not really charmed by it. This guy seemed to use very low resonance materials and soldered it as opposed to welding. In the end it produced a scratchy not so charming sound with alsmost no sustain. This could also be functional for a difference purpose of course, but I'm specificly aiming for a nice long ring and good resonance, just a nice round sound. So, I would like to select materials accordingly.

I have found that the best choice for the base of the aquaphone would probably be compareable to those pans that really give a nice ring when excited by hitting it and also pitch modulate that sound through moving a bit of water inside the pan. Allthough I have no idea what they are made of, some materials proven to do this better than others. I can imagine this has to do with the density of the materials molecules and thus affecting the resistance soundwaves encounter when traveling through it. In my case it is a very cheap little saucepan.

I plan to buy another one and ask someone with welding experience what the possibilities are as it will most likely be a composite material. The idea is to weld those 2 saucepans together to get the base of the instrument. I also fear that it will be hard to get a neat round hole in one of the pan bottoms, for the handle to be put in later. I imagine using a ironcutter will get kinda messy.

In the DIY I found online the guy uses straightened clothes hangers soldered on the rim of the base to be bowed or hit. I would like to use somethign thicker, better sounding.

The thing I'm not sure about is, how I should test different type of metal bars without adding a sound producing element. Can I go to a construction market with my violin bow and just see which materials appear to generate the most friction and vibration? Is this a good criteria without actually hearing anything?

So my most important question would be:

How do i test the acoustic properties (relevant to this specific purpose) of different materials without having it welded to the final resonating chamber?

Are there any tables which give me the speed in which sound can advance through different materials and go with the one that has the least amount of resistance/highest speed/higher density/lower density? How would that relate to thickness/length and welding points. I have so many questions I can't stand it!

I know it's an ambitious plan but I have faith and thought this forum to be a good place to share ideas on this! Maybe I missed some really important things or some info that will answer some of my questions, so any ideas, recommended reads in particular or help in any way is much appreciated!

thanks for reading! (english is not my first, so i'm sorry if this was a tough read)

Tom.

DIY the way i dont want to do it: http://www.instructables.com/id/The-Aquaharp/

the real deal:

http://www.waterphone.com/

Update

the base is made of stainless steel (kind of obvious now i think of it.) and the rods are made of bronze. I called a metalworker and he told me that those cannot be welded together so it's going to be a mechanical connection. This raises questions, should I use screw-thread with bolts or some other connecting element. The bronze will set me back about 100 euros so its too expensive to just go and screw around. :) I need those questions answered before i start sawing and cuttin into the bronze. This also means i have to know the lengths of the rods before connecting them as i think shortening them after will put too much of a strain on the rest of the construction. This is a bummer because I was hoping to tune them as I go along.

update

once again i was misled by my own chaotic mind :) The aquaphone is, in fact welded. As shown on images on the official website. Can't believe i missed that! Luckily i found a metalwork-artist willing to test how strong the connection will be when welding bronze on to stainless steel.

update

The metalwork artist I contacted told me that there is special kind of welding wire used to weld bronze onto stainless steel. I find this hilarious because it shows that you need a fellow art freak to get this kind of information, rather than asking a professional welder, who told me this was not possible at all!

Sadly this welding wire is also quite expensive, but it is possible! So far my research gives me enough options to actually do this. However, because of the high costs, estimated around 300 euros for the entire project. Im also thinking about a less expensive prototype with different, less expensive materials. I know 300 euros is still way cheaper than buying one (1700,- euros) But I am also saving up for Adam a7x's :p Soooo, yeah.. not really swimming in cash atm :p

Which brings me back to my first question; How do I find out what other materials have compareable properties to bronze in a waterphone setup? How do i test this without having to make a prototype with all materials included? I can only think of copper to be a good second candidate but copper is not alot cheaper than bronze so thats not a viable option.

I'm beginning to understand why one would build a crappy version first, getting comfortable with the construction process and then build one with all the fine expensive materials.

update 30-07-13

I have to say guys, I am not done with this project by a long shot. It is really ambitious and naive to think one can do this from scratch without any knowledge on metalworking. It is awesome to find out all these things about metal working I have never heard of though. I definitely found myself a new interest. I do plan on starting practice with forming metal sheets and torch welding. So someday I MIGHT be able to learn and make something that comes in the vicinity of the video that Lenny Paul posted.

For now I have planned on doing it budget style and I am looking for SS materials that come as close to what I find suiting. The best option for the base I have found so far are SS feeding bowls for dogs. I found some that seem to have a suitable rim and, if not too thick, resonate quite nice.

I listened to alot of SS bowls/dishes and similar kitchen stuff and I think most of them showed the needed properties. The thing with bowls/dishes was that most of em have a curved or unequal rim and I figured it would be a problem getting the rods on that. Also, I would prefer to have the top flattened and the bottom rounded. I am still looking for something that will fit on the bottom that has the same diameter and also suitable rim. If I cannot find that I will just place two of the same on top of each other and deal with that.

There are prettier options but I feel that if I'm becoming picky I might as well make a computer model and put in a custom order. I might still do that, but only if its not too expensive. If it is I will postpone that option for when I really want to invest and also do the bronze rods. By then, I might even have the ability to get my freak on with some metal sheets and make it a fully autonomous hobby project..

Concerning the SS materials; Making the hole in the top will not be a problem I think. I need to find the right saw for that but that seems not to hard to accomplish. For fixing the rods I will try a similar approach as the metal worker did in the video that was posted. I thought of slightly flattening the rods on one side so when hanging them through the holes in the rim of the base they won't fall through. And then just weld them..

The material for the rods will probably also just be SS. I have not thought of any good alternative other than bronze and I am definitely not using that this first go.

lingering questions;

1. I would like to find some length indications for the rods.
2. I wonder if SS rods will work. Should test one when I have the base ready. which emphasizes my wish for my own torch welder and the ability to practice that because now I would have to visit a metalworker for every single thing I'd like to test. I find that a bit awkward and is probably also expensive.

Well, I thought I'd update a bit. Also hoping that some may have some feedback on my findings/questions.

All your responses were very helpful and cleared a lot of things up for me. I am very glad to have posted this here. Thanks to all of you!

Answer 1

Well, with the material prices you are quoting + plus the research/development that must have gone into the originals, the cost of a Waterphone is entirely reasonable I'd say. I do lust for one myself (just listen to the Tom Waits song "Shoreleave" to understand why). I guess getting all the individual elements of the instrument together in just one package is the hard part. Getting the bowed water sound can likely be had for much less than the waterphone - but then it will also be less flexible, less playable. Wish I could afford one...

Answer 2

I am curious what specific wire did the metalwork artist recommend to you? To join bronze rods to stainless steel I would try one of two different ways: silver soldering via torch or bronze brazing via TIG. I've used regular Silicon Bronze extensively to braze weld steel using TIG, but have read that you need a flux to braze/braze weld to stainless due to the chromium oxide layer present.

As both a sound designer/engineer and a metal fabricator I've been wanting to build my own waterphone for a while now. I'm just now starting the research phase, but these devices are rather simple in construction. The main challenge seems to be joining the bronze to SS of course. As always it's best to do some tester pieces before starting on a full size prototype. No sense in wasting expensive materials on your first go around.

Also copper rods would be a poor choice to replace bronze in this application. It's way too soft and does not resonate very well at all. Not to mention it gets dead soft when you heat it up enough to solder/braze/weld it, so the rods would probably bend too easily when playing.

One thing to keep in mind about professional welders is that most of them only specialize in one area. Like guys that do structural steel welding with wire feed/stick welders, or guys that only do aluminum with spool guns, or stainless steel with TIG only. They work from prints and use the same machines/processes day in and day out because it's both what they know and what makes them money. Now a metal artist on the other hand will typically work with every metal on the planet at some point. As such they are much more versed on how to join dissimilar metals and via the various different processes. Just different worlds as far as metal fab goes.

Answer 3

Sounds like an interesting project.

Perhaps this will help. Not sure.

http://www.thenakedscientists.com/forum/index.php?topic=10888.0

"Resonance just means that if you vibrate something in some way at a resonant frequency it will vibrate very strongly.

You can vibrate objects in many different ways, and depending on the way you are vibrating it or even how fast you are vibrating it whether the resonances are a property of the material, the shape of the material or a combination of the two can change.

for example the resonant frequency of a pendulum in a clock is a property of the shape of the pendulum not of the brass you made it of."

Personally, I tend to think that unless you have a bunch of engineering experience, building an instrument like this would have to be somewhat of a trial-and-error process. The guy (Richard Waters, I believe) who invented/builds the original waterphone has had years to perfect his technique, and they are as expensive as they are for a reason.