Double Bass Home Made Pickup Success Nine Bucks!!

[phatcactus]

Also, don't capacitors bleed out certain frequencies? Maybe the capacitor bleeds out exactly the nasal tones, making it sound good?

Caps do bleed out trebles, but the main problem with the piezo (sans-preamp) is that it doesn't put out any bass frequencies. So cutting the trebles could pretty much cut the whole output. However, I'm completely unfamiliar with impedances this high (and electronics in general, for that matter) so maybe something else is going on.

 

[Easy Rider]

Well, there should be some low frequency output? Ok, the resonance frequency of for example the ones I got for my E-drum kit is about 4,4 kHz, but still?
But that's dynamically. I found out piezos can hold a charge, the ones I have can hold about 21000 pF (30%).
So I figure it should be possible to use it in a condensor mic fashion. And I don't think it has a charge of it's own, like a electret. For it to charge it'll probably need a power source, so that's where the battery comes into play.
And I have absolutely no idea about how the frequency output would behave when the piezo is hooked up like that.
Well, according to Scott it should be quite good.

The proof of the pudding is in the eating, so perhaps I should just give it a try, and see what comes out.

And oh yeah, about how high an impedance are we talking here? The resonance impedance of a piezo is about 300 Ohm, that's not too high is it? Or does the impedance go sky high outside the resonance frequency?

EZ

 

[phatcactus]

The proof of the pudding is in the eating, so perhaps I should just give it a try, and see what comes out.

Exactly.

And oh yeah, about how high an impedance are we talking here? The resonance impedance of a piezo is about 300 Ohm, that's not too high is it? Or does the impedance go sky high outside the resonance frequency?

300 seems extremely low. I'm not sure what resonance impedance is, though. I've read that normal piezo pickups have an impedance of more than a megohm (one million ohms), and that normal, passive magnetic pickup are usually between 5,000 and 10,000 ohms. Thus the need for a preamp.

I still have no idea what I'm talking about, though, and I have no means of measuring impedance, so maybe I'm way off.

 

[mje]

...
... Also, don't capacitors bleed out certain frequencies? Maybe the capacitor bleeds out exactly the nasal tones, making it sound good?

EZ

Yes, the capacitor/resistor combination will act as a low-pass filter, cutting the highs to a degree.