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Shattering Glasses?



 
 
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  #1  
Old February 4th 05, 12:54 AM
John Schutkeker
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Default Shattering Glasses?


I'm designing a system for shattering wine glasses with high intensity
sound, but my design doesn't "feel" right to me, and I need somebody to
tell me if I've forgotten something important. I need an oscilloscope to
measure the resonant frequency of the glass and a frequency generator to
produce it. I need stereo speakers and a stereo amplifier powerful enough
to generate the sound to break the glass.

But how do I correctly get the signal from the frequency generator into the
stereo amplifier. Do I need a pre-amp, or do I just wire it straight in?
If I need a pre-amp, how do I spec it, on the outputs of the freq generator
and the input of the amplifier? What if I'm using a receiver with the pre-
amplifier and the amplifier built-in? Can I just use the pre-amp that was
intended for the turntable?

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  #2  
Old February 4th 05, 01:11 AM
Eric K. Weber
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Default

Selecting the correct wine glass might be the most important item.

Rgds:
Eric

"John Schutkeker" > wrote in message
. 30.44...
>
> I'm designing a system for shattering wine glasses with high intensity
> sound, but my design doesn't "feel" right to me, and I need somebody to
> tell me if I've forgotten something important. I need an oscilloscope to
> measure the resonant frequency of the glass and a frequency generator to
> produce it. I need stereo speakers and a stereo amplifier powerful enough
> to generate the sound to break the glass.
>
> But how do I correctly get the signal from the frequency generator into

the
> stereo amplifier. Do I need a pre-amp, or do I just wire it straight in?
> If I need a pre-amp, how do I spec it, on the outputs of the freq

generator
> and the input of the amplifier? What if I'm using a receiver with the

pre-
> amplifier and the amplifier built-in? Can I just use the pre-amp that was
> intended for the turntable?
>



  #3  
Old February 4th 05, 01:11 AM
Trevor Wilson
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Default


"John Schutkeker" > wrote in message
. 30.44...
>
> I'm designing a system for shattering wine glasses with high intensity
> sound, but my design doesn't "feel" right to me, and I need somebody to
> tell me if I've forgotten something important. I need an oscilloscope to
> measure the resonant frequency of the glass and a frequency generator to
> produce it. I need stereo speakers and a stereo amplifier powerful enough
> to generate the sound to break the glass.
>
> But how do I correctly get the signal from the frequency generator into
> the
> stereo amplifier. Do I need a pre-amp, or do I just wire it straight in?
> If I need a pre-amp, how do I spec it, on the outputs of the freq
> generator
> and the input of the amplifier? What if I'm using a receiver with the
> pre-
> amplifier and the amplifier built-in? Can I just use the pre-amp that was
> intended for the turntable?


**You'll find that this task is not as easy as it seems. You'll probably
need a wine glass with a weakened structure and HUGE SPLs. Really HUGE SPLs.
The amplifier is the least of your concerns. I'd be searching for a speaker
with at least 100dB/W/M SPL capability.

I'm guessing you will want to measure the glass's resonant frequency and
drive the sig gen with that frequency. I don't know how you'll measure the
glass's resonant point, without altering. Schrödinger's Cat and all that.


--
Trevor Wilson
www.rageaudio.com.au


  #4  
Old February 4th 05, 05:37 AM
Kevin McMurtrie
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Default

In article 4>,
John Schutkeker > wrote:

> I'm designing a system for shattering wine glasses with high intensity
> sound, but my design doesn't "feel" right to me, and I need somebody to
> tell me if I've forgotten something important. I need an oscilloscope to
> measure the resonant frequency of the glass and a frequency generator to
> produce it. I need stereo speakers and a stereo amplifier powerful enough
> to generate the sound to break the glass.
>
> But how do I correctly get the signal from the frequency generator into the
> stereo amplifier. Do I need a pre-amp, or do I just wire it straight in?
> If I need a pre-amp, how do I spec it, on the outputs of the freq generator
> and the input of the amplifier? What if I'm using a receiver with the pre-
> amplifier and the amplifier built-in? Can I just use the pre-amp that was
> intended for the turntable?


Most signal generators have a variable output. Set it to around 0.5 to
1.0 volts.

As others mentioned, breaking the glass could be difficult. You'll need
a glass with an extremely high Q; one that rings easily and loudly when
rubbed. You'll also need precision frequency tuning to resonate an
object with such a high Q. Most wine glasses won't break before your
ears do.
  #5  
Old February 4th 05, 07:58 AM
Eiron
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Default

John Schutkeker wrote:

> I'm designing a system for shattering wine glasses with high intensity
> sound, but my design doesn't "feel" right to me, and I need somebody to
> tell me if I've forgotten something important. I need an oscilloscope to
> measure the resonant frequency of the glass and a frequency generator to
> produce it. I need stereo speakers and a stereo amplifier powerful enough
> to generate the sound to break the glass.
>
> But how do I correctly get the signal from the frequency generator into the
> stereo amplifier. Do I need a pre-amp, or do I just wire it straight in?
> If I need a pre-amp, how do I spec it, on the outputs of the freq generator
> and the input of the amplifier? What if I'm using a receiver with the pre-
> amplifier and the amplifier built-in? Can I just use the pre-amp that was
> intended for the turntable?


You don't need a 'scope or a signal generator.
Stick a contact microphone on the glass base, plug it into a low-level
input on a guitar amp, turn it up to 11 and let feedback do its work.

You could rent a soprano for a couple of hours from your local
choral society.

http://www.worldofglass.com/exhibiti....asp?NewsID=12

--
Eiron.
  #6  
Old February 4th 05, 08:13 AM
Kevin McMurtrie
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In article >, Eiron >
wrote:

> John Schutkeker wrote:
>
> > I'm designing a system for shattering wine glasses with high intensity
> > sound, but my design doesn't "feel" right to me, and I need somebody to
> > tell me if I've forgotten something important. I need an oscilloscope to
> > measure the resonant frequency of the glass and a frequency generator to
> > produce it. I need stereo speakers and a stereo amplifier powerful enough
> > to generate the sound to break the glass.
> >
> > But how do I correctly get the signal from the frequency generator into the
> > stereo amplifier. Do I need a pre-amp, or do I just wire it straight in?
> > If I need a pre-amp, how do I spec it, on the outputs of the freq generator
> > and the input of the amplifier? What if I'm using a receiver with the pre-
> > amplifier and the amplifier built-in? Can I just use the pre-amp that was
> > intended for the turntable?

>
> You don't need a 'scope or a signal generator.
> Stick a contact microphone on the glass base, plug it into a low-level
> input on a guitar amp, turn it up to 11 and let feedback do its work.


I've tried that and it didn't work. The feedback loop finds many odd
local resonances based on them having much better phase alignment than
the primary resonance frequency. It would take a lot of fussing with
the microphone and speaker positions to make it work.

> You could rent a soprano for a couple of hours from your local
> choral society.
>
> http://www.worldofglass.com/exhibiti....asp?NewsID=12

  #7  
Old February 4th 05, 08:24 AM
Cyrus
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Default

In article 4>,
John Schutkeker > wrote:

> I'm designing a system for shattering wine glasses with high intensity
> sound, but my design doesn't "feel" right to me, and I need somebody to
> tell me if I've forgotten something important. I need an oscilloscope to
> measure the resonant frequency of the glass and a frequency generator to
> produce it. I need stereo speakers and a stereo amplifier powerful enough
> to generate the sound to break the glass.
>


I see 2 ways to go about this-

1. Pick the wine glass, measure the resonant frequency as you described.
And design a high sensitivity/high spl/bandpassed speaker configuration
that best reproduces that frequency range.

2. Pick a high sensitivity/high spl/bandpassed speaker configuration and
find a wine glass that its resonant frequency falls into.

Either way its just a matter of time and money.

Why not just throw the wine glass? Whats the point of this show?

> But how do I correctly get the signal from the frequency generator into the
> stereo amplifier. Do I need a pre-amp, or do I just wire it straight in?


Use the computer that sent this message, find a software frequency
generator, output a line level signal to a mixer/amp.

> If I need a pre-amp, how do I spec it, on the outputs of the freq generator
> and the input of the amplifier? What if I'm using a receiver with the pre-
> amplifier and the amplifier built-in?


I seriously doubt a receiver has enough wattage for something of this
nature, but anything can happen with the high sensitivity that a
correctly set up speaker configuration can provide.

> Can I just use the pre-amp that was
> intended for the turntable?
>


Phono inputs will have an RIAA eq curve.

--
Cyrus

*coughcasaucedoprodigynetcough*


  #8  
Old February 4th 05, 08:42 AM
Eiron
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Default

Kevin McMurtrie wrote:

>>You don't need a 'scope or a signal generator.
>>Stick a contact microphone on the glass base, plug it into a low-level
>>input on a guitar amp, turn it up to 11 and let feedback do its work.

>
>
> I've tried that and it didn't work. The feedback loop finds many odd
> local resonances based on them having much better phase alignment than
> the primary resonance frequency. It would take a lot of fussing with
> the microphone and speaker positions to make it work.


In that case, plug the microphone into your computer.
Use a free frequency measurement program such as:
http://www.aptuner.com/cgi-bin/aptuner/apmain.html
to measure the resonant frequency of the glass when you tap it.

Then it is easy enough to generate a sinewave on the computer
and either cut a CD or plug the computer's line out into your amp.

--
Eiron.
  #9  
Old February 4th 05, 12:30 PM
Laurence Payne
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Default

On Fri, 04 Feb 2005 00:54:26 GMT, John Schutkeker
> wrote:

>I'm designing a system for shattering wine glasses with high intensity
>sound, but my design doesn't "feel" right to me, and I need somebody to
>tell me if I've forgotten something important. I need an oscilloscope to
>measure the resonant frequency of the glass and a frequency generator to
>produce it. I need stereo speakers and a stereo amplifier powerful enough
>to generate the sound to break the glass.



Why do you need to know the numbers? Why does the amp/speakers need
to be stereo?

Set up your generator and sweep the frequency until the glass "rings"
and shatters. If it's going to - I think your main problem will be
finding suitable glasses.

If you want an idea what sort of frequency to start at, make the glass
"sing" by rubbing the rim. Use your ears to match the generator
frequency. Try simple multiples of that frequency too.
  #10  
Old February 4th 05, 01:01 PM
Arny Krueger
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"John Schutkeker" > wrote in message
. 30.44
> I'm designing a system for shattering wine glasses with high intensity
> sound, but my design doesn't "feel" right to me, and I need somebody
> to tell me if I've forgotten something important. I need an
> oscilloscope to measure the resonant frequency of the glass and a
> frequency generator to produce it. I need stereo speakers and a
> stereo amplifier powerful enough to generate the sound to break the
> glass.
>
> But how do I correctly get the signal from the frequency generator
> into the stereo amplifier. Do I need a pre-amp, or do I just wire it
> straight in?


Just about any good signal generator has enough output to drive just about
any power amp to full power, and beyond.



 




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