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AUDIO FORUMS >> D.I.Y. >> Exciters
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Message started by 4krow on 02/15/16 at 06:09:13

Title: Exciters
Post by 4krow on 02/15/16 at 06:09:13

Guys, I'm getting a head rush from an errant inspiration. Quite awhile back, at a coffee shop, some kid came in with cylinder shaped device that was a speaker, an exciter to be more exact. I didn't really care, cuz it is just another mindless fad device...go away....but then, he puts it on the counter top and it sounds kinda good. And then he puts it on other surfaces and it sounds different on each. No surprise so far. Next thing i know he is outside and places it on the big picture window, and I am hearing sound that shouldn't be this good. Blows my mind, and in time I forget about it. Yah, the Parts Express catalog comes and I look at the various models. Not one clue what I would do with one of these things, but for $20-40, it could be fun. Ok, you read this much, now you tell me, you guys have any experience with these things? And so, what do you think? I even saw a hybred exciter using a ribbon for high frequencies. Hmmmm

Title: Re: Exciters
Post by martin on 02/15/16 at 12:02:05

I've never even heard of anything like you describe, but it sounds kinda cool. I'll have to google it. Please post updates and pics if you decide to build one.

Title: Re: Exciters
Post by Archie on 02/15/16 at 18:22:49

A couple years ago a friend showed me how when he played music through his iPhone when holding it, it was a quiet whine but when put on a solid surface it bloomed. I guess it transferred the vibrations and used the surface as a soundboard. (Sort of the opposite of what some of use are trying to achieve with our speaker isolation at home.)

Is this the principle of the "exciter" that you saw? Or is it something different?

Title: Re: Exciters
Post by 4krow on 02/19/16 at 15:53:18

Yes, the idea is that the 'speaker' uses the surface that it is placed on to resonate sound. That being said, it is important to choose a surface that makes the accurate reproduction of the music being played. My thinking is that a very thin sheet of glass suspended on an easel might be a good start. Of course, a less expensive second would be to use corragated plastic sign board. I am probably going to start with this sometime within the next few weeks. Too many irons in the audio fire right now to concentrate like I need for a new project. The Carver C9 units are keeping me a bit too busy, and this will be a welcome break from that.

Title: Re: Exciters
Post by Archie on 02/19/16 at 16:11:07

Seems like wood would be good. What kind of wood is a piano soundboard made from? Or a violin?

Title: Re: Exciters
Post by Lon on 02/19/16 at 16:13:54

Regarding piano, from wiki (what I thought, just double-checked)

The upper surface of the sound board, depending on the instrument, is called a top plate, table, sound-table, or belly. It is usually made of a softwood, often spruce. The rear part, known as the back, typically does not contain sound holes and is made of a hardwood such as maple or pear.

Violins are often made from maple or spruce or poplar.

Title: Re: Exciters
Post by Archie on 02/19/16 at 16:25:55

And I think the wood might be shaped across its thickness to tune it to the sound? Gets complicated!

Title: Re: Exciters
Post by Lon on 02/19/16 at 17:27:48

Yes, it's definitely complicated, the inside face carving of violin wood for instance is an amazing science!

Title: Re: Exciters
Post by 4krow on 02/24/16 at 05:45:59

These are great observational discussions. That is the intent for me asking. No doubt, this could become an actual science project for sure. That's when I see those folks out there with a lab, personal, and funding at their disposal to contemplate 'what if?' at a great advantage in life. Yes, Steve is one the few. Wouldn't surprise me if he hasn't already crossed this bridge at some point before me.

Title: Re: Exciters
Post by Archie on 02/24/16 at 16:53:54

I wonder how one would do set on a piano soundboard? Maybe it could be tried without taking anything out of the piano? The piano board should already be tuned to just about any frequency needed.

Title: Re: Exciters
Post by 4krow on 02/26/16 at 06:43:50

Well, the instructions that I read said that wood was not the best conductor for these. I'm thinking that it has to do with mass, and the fact that these don't likely have a load of power to begin with. You can however place more than one on a single surface to enhance bass and treble. Interestingly, you would not use a symetrical pattern for this.