Breaking a Wine Glass with Sound

[Oguru]

Hi

I'm new to the forum and am looking for some help with recommendations about what kind of set up I will need to break a wine glass using nothing but sound as a demonstration for children.

I made something before that I got to work once, using a speaker mounted in a perspex box connected to an amplifier. However, the speaker blew more often than not, and the amplifier was very large.

This website describes a good way of doing it using a compression driver instead of a speaker:

How to breaking glass with sound | Acoustics, Audio and Video | University of Salford

So i'm looking for a reliable compression driver that can be used repeatedly without failing that will go down to 800hz or below as that is the frequency required, and apparently 140db is needed. They used a Fane CD280 which says the sensitivity is 108db... is this the volume at 1 meter away?

I will also need an amplifier that will work and be reliable. Size and weight is a bit of an issue as there will be other demonstrations. Would something like this work?

S.M.S.L SA-98 TDA7498 Class-T Digital Amplifier AMP HI-FI High Power 2 X 100W | eBay

As the output is only going to 1 compression driver and nothing else does this mean the wattage is doubled, and what about matching up wattage and ohmage between the speaker and amp? I'm pretty clueless about this kind of stuff so any guidance would be greatly appreciated.

Thanks

Peter

 

[mickeymoose]

If you want to use sound at 140dB-SPL to demonstrate the breaking of a drinking glass to children I suggest you take the children to a kingdom far, far away. Let's say Belgium or Denmark.
On the other hand, you could demonstrate the effect of sympathetic vibration by playing a Florence Foster Jenkins recording of Die Zauberfloete (Queen of the Night aria) at slightly elevated room volume.
Cheers, E

 

[Pano]

See if you an find the Myth Busters episode about this. It wasn't easy.

 

[Don Hills]

Several examples:
https://www.youtube.com/watch?v=bJj4Wjjf0WI
https://www.youtube.com/watch?v=ECNDpCYvaOc
https://www.youtube.com/watch?v=CdUoFIZSuX0

The first two use professional PA compression drivers, the third uses what appears to be a PA style midrange driver screwed to a baffle with a small hole to concentrate the sound waves.

 

[TNT]

Take care of yours and others ears. This is dangerous. Find really thin glass with very pronounced resonance. Be close. Actually I think you should watch the youtube flix and then skip it all together.

//

 

[Ron E]

I recall a professor doing this in a small auditorium and it was really loud, and I was ~10 rows back. If you have to do this, You might consider building a hush box and projecting a camera image on a screen.

 

[Oguru]

Thanks for the replies. However, as i mentioned before I have built something before that worked successfully and in demonstrations I make sure everyone has sound blocking headphones on (the same as the ones builders use for heavy duty equipment), so none of this is an issue.

I am looking specifically for technical guidance as the rig i made before had an amp that was too large and a normal speaker in it, which kept on blowing and only broke 1 glass. Can anyone give me some advice on the technical questions i had please?

 

[Cal Weldon]

Those vids sum it up. You need a robust compression driver, a stand, a tone generator and a bridgeable PA amp. The amp can never be too large. You are better with thin walled wine glasses. You should consider enclosing this to prevent flying glass. Some type of netting should work well. Hearing protection is a must.

This can be done rather easily but have you considered a budget?

 

[Oguru]

Those vids sum it up. You need a robust compression driver, a stand, a tone generator and a bridgeable PA amp. The amp can never be too large. You are better with thin walled wine glasses. You should consider enclosing this to prevent flying glass. Some type of netting should work well. Hearing protection is a must.

This can be done rather easily but have you considered a budget?

Thanks for your response. Yeah, I got some thin cheap glasses before and managed to get one to break before the speaker did... The whole set up is mounted inside a plastic box to ensure the glass is contained, and I have hearing protection for everyone that will be present

 

[korpberget]

I lost a speaker on a glass once, and it broke.