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Latest on Piezos

#41
rudy4444 said:
Interesting information, except it is incorrect. Bassamatic's reply provides the factual information relating to piezo transducers.

Sorry, no "capacitance" involved in the process.
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I have a degree in Physics and an entire career designing audio acoustics and transducers - loads of factual experience that disagree with your opinion. When you measure the impedance of a piezoelectric transducer (I have actually done this) up to the point where the resonance occurs (which is typically above the audio range), it is a capacitive source.
 
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#43
Mickey666 said:
Would it be possible to use an on board passive preamp with an undersaddle transducer (acoustic style) bridge?

Just another idea I had...
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What do you mean by "passive preamp"? The only thing I know that is passive that gives you more output than input is a transformer. A transformer that is wired that way (to give you voltage gain) also steps the impedance up, which is definitely going the wrong way when you're starting with a source that already needs a very high load impedance.
 
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#44
I have installed a single piezo in one of my basses out of interest. So far only passive and parallel, which is actually nonsense, but can be a nice effect when slightly mixed in.

I didn't have any piezos in mind for my next project, but I'm still interested. That's why I'm happy about this thread. I just happened to find a set of inexpensive piezos that actually belong in a Schaller bridge. So I'll try to install them, even if I don't have a matching bridge...

The piezos are very small. This just gave me an idea: has anyone ever tried to clamp piezos directly to the strings so that they can vibrate freely with the strings? Maybe that doesn't make any sense, but what difference could it make with regard to the sound compared to mounting them in the bridge (assuming that the vibration of the strings is not damped too much by the piezos)?

I will test it...
 
#45
micguy said:
What do you mean by "passive preamp"? The only thing I know that is passive that gives you more output than input is a transformer. A transformer that is wired that way (to give you voltage gain) also steps the impedance up, which is definitely going the wrong way when you're starting with a source that already needs a very high load impedance.
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I was reading something last night about a passive pre being available through BBG, I didn't get a chance to go down that rabbit hole (it was in a Google search) I'll have to see if I can find it again...
I'm trying to eliminate the need for a battery along with the other controls.
I've never used anything with a pre, so I know literally nothing about them... always been a single pickup/passive kinda guy, never had need of anything active
 
#47
13ghosts said:
has anyone ever tried to clamp piezos directly to the strings so that they can vibrate freely with the strings? Maybe that doesn't make any sense, but what difference could it make with regard to the sound compared to mounting them in the bridge (assuming that the vibration of the strings is not damped too much by the piezos)?

I will test it...
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I'll speculate "not much" since the piezo material will simply be going along for a ride, not being squeezed or bent. But experimentation is good, even if results are not what you hope for.
 
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#48
T_Bone_TL said:
I'll speculate "not much" since the piezo material will simply be going along for a ride, not being squeezed or bent. But experimentation is good, even if results are not what you hope for.
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I agree, the piezoelectric effect comes from bending the material. If it was attached directly to the strings the only thing that would cause bending would be the acceleration of the material plus a bit of air resistance. I expect you might get some odd harmonics and stuff from such an arrangement, perhaps vaguely like a spring reverb -- though to prevent any further confusion the two devices work entirely differently.
 
#49
T_Bone_TL said:
I'll speculate "not much" since the piezo material will simply be going along for a ride, not being squeezed or bent. But experimentation is good, even if results are not what you hope for.
Click to expand...

That's correct thinking - you need to put pressure on a piezo to get output, just moving it won't get you there. Thus having it under the bridge, where pressure waves are taking energy from the strings into the body makes sense.

If you've ever broken a bone, you may have experienced that it doesn't hurt unless you put pressure on it, and then it feels like an electric shock. Well, it feels like an electric shock because it is. Your bones are piezoelectric (they heal in part by using electric fields to bring ions into the break), and when you put pressure on a break, you are literally crating electricity that your nerves can feel. The point is, pressure is what makes the signal, whether it's an acoustic guitar or a broken bone.
 
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#50
T_Bone_TL said:
I'll speculate "not much" since the piezo material will simply be going along for a ride, not being squeezed or bent. But experimentation is good, even if results are not what you hope for.
Click to expand...
Jeff Siddall said:
I agree, the piezoelectric effect comes from bending the material. If it was attached directly to the strings the only thing that would cause bending would be the acceleration of the material plus a bit of air resistance. I expect you might get some odd harmonics and stuff from such an arrangement, perhaps vaguely like a spring reverb -- though to prevent any further confusion the two devices work entirely differently.
Click to expand...
micguy said:
That's correct thinking - you need to put pressure on a piezo to get output, just moving it won't get you there. Thus having it under the bridge, where pressure waves are taking energy from the strings into the body makes sense.

If you've ever broken a bone, you may have experienced that it doesn't hurt unless you put pressure on it, and then it feels like an electric shock. Well, it feels like an electric shock because it is. Your bones are piezoelectric (they heal in part by using electric fields to bring ions into the break), and when you put pressure on a break, you are literally crating electricity that your nerves can feel. The point is, pressure is what makes the signal, whether it's an acoustic guitar or a broken bone.
Click to expand...

Thank you all! Your assessment is clear... I'll still attach a piezo to one as a test and then report back
 
#54
Mickey666 said:
Would it be possible to use an on board passive preamp with an undersaddle transducer (acoustic style) bridge?

Just another idea I had...
Click to expand...

It would be great if you could. The problem being there's no such animal, as an actual pre-amp uses an auxiliary source of energy to ADD to what you're producing from your pick up.

A "transformer" is another device that doesn't give you any more than what you put into it. Conservation of energy is a fundamental principal of physics, so that's a no go, too. If any of those things were options the perpetual motion nuts would be all over it.

Another point is you do not need to put pressure on all types of piezo pickups to get an output. Soundboard transducers work all day long without any pressure applied, and often have output levels that exceed their undersaddle brethren. That's because they are working in bending mode.

I suggest anyone reading this topic to do their own research because there's a whole boatload of pseudo-science being relayed as "fact".

That's the best I can offer before turning my attention to topics that are more productive.
 
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#57
Mickey666 said:
I've asked about that before... and for some reason, no one said anything about it being an option
Just keep coming up with different ways to stuff batteries in there.
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If you are interested in making your own, or in having someone make one for you, ESP is a wealth of information on all sorts of audio stuff, including piezo preamps:

Piezo Preamps
 
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#58
Max Bogosity said:
You may have missed it, but go back and have a look at post #20.
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I actually did see that, and meant to reply... but was side tracked down another rabbit hole... don'tcha just love ADD
I was reading some stuff in a thread about acoustics that said a bunch of what you were talking about...
It looks like I'm going to go with an under saddle transducer like an acoustic with a bone saddle, probly using a modified upright style tailpiece instead of string through due to the length of the Explorer body.

Probly go with an amp with built-in capability like Mark bass, or just use a pedal... more rabbit holes, woo-hoo
 
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