piezoelectric?

[xwingband]

I'm not against innovation...

I just don't see any inadequacies with a speaker. Using Erv's stuff as an example... it's loud to the point where any more and I'd be afraid of disturbing people. It resonates and vibrates the hilt and certainly sounds just like the movie to me.

[Tenric Starkindler]

Well I'm sold on Erv's sound set up.
Now when will he have some for sale?

[SaberSentinel]

Slightly off topic.

I have plenty of 1" diameter 1/4" thick speakers...

xwing, where did you get those speakers? I have been looking for speakers that small for a while.

[xwingband]

I got them off Mouser... let me dig up the order.

http://www.mouser.com/search/refine.aspx?Ntt=25RF006

They're actually 1.06" but the outer edge can take the sanding to get it to 1".

[SaberSentinel]

Thanks

[erv]

Piezo speaker with more loudness than membrane speaker ? How come ?
Quick lesson about acoutics (no offense) :
- volume of a sound is due to vibration of the air. To get this effect, air must be "pumped" back and forth. To get loud volume, the amplitude has to be large, ie the displacement of the membrane must be important.
- large displacement is not enought : it then depends on the spectrum the speaker can generate. Take a big speaker and big current do drive it : if the speaker filters a lot of the spectrum, then it might sound less than a smaller speaker with a better bandwith
- piezo will consume less power : true : it as almost an infinite resistance, it's mainly driven by voltage not current
- piezo have almost no vibration and reduced bandwitdh, they cannot be louder than an equivalent sized dynamic speaker, except maybe for a specific sound, at the exact freq of the piezo resonnance freq.

Now about sound synthesis. I don't think IMHO that making a synthesis board is smaller and easier than playback. Have you tried to synthetise a saber sound ? Not just a simple buzz, but many waveforms shape, oscillator and LFOs in it. This just for the hum. You're going to need a lot of oscillators and operators to produce the result. Second : the hum for instance was made out of some recordings, not synthesis. I'm not sure whic rumor is right, but I've heard about TV noises, and mikes spining in the air to get a doppler effect.

My question is now : what is the relationship between making a saber sound synthesis and using a piezo (I've read the posts several times, I don't see the connection).
Last thing I can add : about the vibration of the speaker, my very first saber was actually so loud that I got the vibration of the air inside the hilt, and it was quite rumbling, pretty cool effect without any motor ! But if you plan to do this with a piezo, the whole energy of the vibration will go in the hilt and will mute the piezo. Result : very small sound and in the best case, a tiny vibration.
Erv'

[james3]

I just wish everyone would learn to use the edit button. We have all been guilty of a little double posting every now and then but wow it seems the all the rage lately.

[Weaver]

I've actually had some ideas on this subject as well. Has anyone considered attempting to establish the necessary electrical field via electromagnetic inductance? I was considering the feasibility of routing the speaker outputs of the PCU through an audio amplifier (powered via Power Xtender, directly driven from the battery pack or a secondary battery pack), then running the current through one or more electromagnetic field coils. If I understand the technology correctly, the resulting field should pulse in sync with the sound output from every sound file on the card, producing an equivalent vibration in the crystal.

The setup I had in mind would physically link the crystal to the chassis, attempting to transfer as much of that vibration to the outer hull of the saber as possible. This should transform the entire hilt into a resonance chamber which would produce sound and vibration. How strong would depend on how much power you put through the crystal. I could see doubling the power requirements of any saber with this setup, possibly with a dedicated secondary battery pack specifically for the crystal.

The only problem I see arising is the potential for this electromagnetic field to interfere with or damage the electronic components of the saber (i.e. PCU board, SD card, etc, etc). If it is possible to find a material which would isolate and contain electromagnetic fields, I'd line the crystal chamber with it to prevent such damage. More research is needed.

I realize speakers are more efficient and practical for all our concerns, however there is one point to consider that hasn't yet been made. In canon, the blade of a lightsaber is produced by the adegan crystals (exactly how varies depending on source). The sound it makes is pretty likely to be a direct result of the energy of the blade. I think it's a little closer to "movie accurate" to have the crystal chamber produce the saber's sound, as opposed to a speaker in the pommel. It's more difficult, more complex, more expensive, but...for my money...more "real".

I will continue to read up on the subject until such time as I am educated enough to begin experimentation. For now, this exists in my mind as the proverbial "star" to shoot for. It geeks me out to think about how it might work, even if it isn't possible with our current technology.

[Silver Serpent]

That is an impressive necropost. That being said, I would like to answer a few of your points:

You seem to want the quartz crystal in your crystal chamber to act as the speaker. The piezoelectric effect *could* allow the crystal to vibrate in time with the sound effects, but the volume you're likely to experience is very very low, if audible at all. Piezoelectric earphones have been invented before, but they're not terribly loud and have poor sound fidelity. See: http://en.wikipedia.org/wiki/Crystal_earpiece for more information.

If you'd like to line your chamber with something to isolate the EM field, you'll need a powerful diamagnetic substance. Theoretically any superconductor would do the trick, but there aren't any known that operate at room temperature. Bismuth is relatively non-toxic and one of the stronger diamagnetics. Pyrolitic carbon would do the trick too, though it may be harder to source some of that.

Piezoelectric vibrations are very very small. You're just not going to get a good hum from them. A small vibration motor, or a good speaker with resonance will get you plenty of volume and vibration. I'm not trying to discourage you from trying something new, just be aware that you may be trying to use the wrong tools for the goal at hand. Venting the sound out your crystal chamber would give the *appearance* of the crystal making the sound, and it'd be much simpler.

[Weaver]

It's appreciated, Silver Serpent. For what it's worth, I know it will likely be impossible. I just have to experience things for myself before I can be convinced that they can or can't be done.

I didn't mention it in my earlier post (and I'm not sure why), but it's actually not my intent to have the crystal itself produce the sound. I was able to get my hands on a vibratory speaker (Vibe It was the name of the product) which purported to transform any hollow object into a speaker. I didn't believe it, but I decided to try it out for myself. Long story short, any hollow object I placed the vibration generator on magnified the effect of the device, producing audible sound. I think it may be possible to achieve that effect here.

In the end, it basically amounts to a "what if" question that can only be answered one way: Try it. Once I get my hands on the proper equipment, I'll be happy to do just that. Sink or swim, I'll post my results. That way we will at least know, as a community. I'm not trying to fuel another "black blade" goose chase; just genuinely curious about the possibilities.

On the necroposting subject: Um...sorry. I used the forum search to ferret out all the posts mentioning the word "piezoelectric" and failed to check the dates. I had no idea I was resurrecting a five year old discussion! Hey, at least some of us newbies know how to use the search function, right?