#10

We used some PWM (T class ) amps. Not the best audio quality (but a lot better than the TWSU ones), but small, affordable and powerful enough.
We used one amp for every exciter

#11

I am beginning work on an installation piece where I hope to make 6 singing dangling objects. I still need to experiment with what objects I would use, but I’m imagining big aluminum sheets or thin wood panels or found shapes.

Anyways, I’m hoping to test out a setup of:

6 separate output channels from k-mix
—> 3 small stereo class d amps
—> 6 exciters attached to objects
powered by this one power supply

I was wondering if @papernoise, @rick_monster or anyone with experience in this area could let me know if i’m making a silly mistake. Would this setup work? I’m mostly unsure of the power supply and amp/speaker pairing…like can that power three amps sufficiently? I’m not very experienced with diy power and speaker stuff. I can make custom cables (ie. two 1/4" to stereo 1/8" for two channels kmix to one amp)

Also, I don’t really know what to expect in terms of volume and frequency range, but I don’t think it needs to be amazing. I just want to make sure it is somewhat loud and somewhat good fidelity I guess.

Thanks in advance for any help!

Also, @papernoise, the kvsu piece is really lovely. Great job with that! I’m kinda ripping your ideas…

1 Like
#12

class D amps is exactly what we had used with the exciters. Commercial class D amps are usually stereo so I don’t see the big problem with attaching two exciters to each. But of course this depends on the actual exciter.
Not really an expert but the amps are rated for less than the speaker, which should be safe, the problem is usually when you have an amp which is too powerful for the speaker.
If you want to go with a switching PSU for this maybe look at Meanwell, while they are not made for audio they seem to work ok for most applications. The only thing to keep an eye on is how much current the whole system will draw, 480W seems overkill, but you should ask somebody who knows more about this than I do.
From a more safety-related point of view you’d certainly be better off using 3 12V bricks instead of an open frame thing like this.
For the Acousmatic Strings thing we used amps with an enclosure, and these came with their own brick. These are often sold as a low-cost music amp solution and will not be much more expensive than the more DIY solution you found.

Hehe no problem, keep me updated I’m really curious to see what you make with this!

A question to the community: Are you all ok if I split this topic into a “exciter speaker” one? This doesn’t have much to do with contact mics anymore…

1 Like
#13

Thanks for the reply!

I’m going to look into those things and get back to ya. For now, I’d be happy with a new thread. I aaaalmost did it for that post :grimacing:

#14

Okay, so after reevaluating, I came up with this shopping list:

6 of these exciters
3 of these amps

much more simple…the lepai amp looks good, but do you happen to know what you used if its better? From what I can tell, this amp is 20W and the exciter is 24W so it will be a little underpowered. maybe that is fine since any more would approach more speaker distortion?

2 Likes
#15

Forgot to add one thing. I’d like to encourage you to try out different exciters before committing to one solution. We made the error to not do that beforehand, and it would have totally be worth the extra work in retrospect. So, get a bunch of them, try them out, see how they behave and sound. Not all exciters will work the same.

1 Like
#16

When you’re talking about amplifying multiple singing dangling objects and working with exciters it sounds like you’re making a version of David Tudor’s Rainforest IV. I imagine you’re aware but just in case not, worth looking into the beauty of that piece that has been presented many many times
http://www.getty.edu/research/tools/guides_bibliographies/david_tudor/av/rainforest.html

7 Likes
#17

This sounds really cool. Excited to check out the show!

1 Like
#18

I’ve been meaning to update my work in progress, but post opening, here are some photos of my installation utilizing transducers on objects. thx @papernoise @stephenvit and @sns for the wonderful information.

Today, I am performing the 6 channels of audio with precomposed and improvisatory textures. If you’re in Austin, TX stop by today between 11-6p.

If anyone is interested I can add some more info about my setup. its pretty fun :slight_smile:

Uploading: IMG_0276.JPG… Uploading: IMG_0278.JPG…

3 Likes
#19

Something went wrong with the image upload.

#20

A dad in New England makes DIY transducer speakers with “flat frequency response”, wired in serial without a crossover. Says they cost ~ $45 each including mounting hardware, which consists of hooks and plastic fishing line. A good set of studio monitor speakers that don’t consume much interior space are missing from my setup. Perhaps this is the answer?

He mentions they bottom out around 120 Hz so a subwoofer with a crossover would be useful to get a full spectrum. The part where he mounts the transducer and counter weights to remove material resonance is particularly interesting.

4 Likes
#21

at 14:30 in the video…stoic…15:30…ok I’ll move a lil’ bit.
edited to say, this video is super interesting. This dad from New England is the cool science teacher I never had.

#22

A little thing I’ve tried (some of you might have seen the photos in the //// pictures of our sound-making machines //// thread) is to use an old oil can as a resonator/reverb effect.

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The results so far have been a bit of a mixed bag I have to say.
The mix/exciter placement as shown above didn’t really work well, so I’ve swapped them and it’s already a bit better. I guess the can is too small to do an actual reverb, but it’s nice as a resonating/shaping effect.
It’s very easy to overdrive the whole thing (as you can hear in the recording below) and I have to drive the preamp to the max to get a decent level out of it.

Here’s a little recording I’ve made yesterday night:

In the recording you always hear the dry sound first and the processed one after that. Except for the “ticks” at the beginning where the dry sound is missing.

6 Likes
//// pictures of our sound-making machines ////
#23

Ahhh, I’m so bad at checking responses…I think I was nervous about my performance and didn’t allow the images time to upload :sweat_smile:

This is the static piece that had an ongoing generative piece playing through the 6 channels for each of the 6 dangling objects.

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This is inside the white cabinet.
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This is the setup for the day I did a live performance for 6 channels. It was so fun.
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And here is a vid when I was prepping the performance.

6 Likes
#24

Nice, I think it shows some promise. Did you try having the exciter and the pickup both on the body of the can? Maybe the seam on the end cap is damping the vibration. I want to try a can like this as a resonant hydrophone.

#25

Resonant hydrophone? I can kind of picture what you mean, i think. Is there an example anywhere?

#26

These are smallish ones. I wonder what a large metal drum would sound like.


3 Likes
#27

Have you tried suspending the can in the air? Any time I’ve used this technique with any object, finding a way to suspend it improved the reverberation and sound significantly.

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#28

Looks to me like that piece of twine on the handle of the jug must have been for suspension – I was thinking the same thing.

#29

I mostly keep it suspended via the handle. It does sound a little bit more reverby, but not a lot more.
Of course less things block the object from vibrating, the better.

Yes exactly!