(Work in progress ...)
Piezo is it! Piezo is it! Piezo is it!
If asking people who believe this, the resulting answer always is a swell of the marketing hype that manufacturers of piezo pickups unleash to their audience - regardless of what harm they do to the instrument.
Well, let's step through the facts ...
When were piezo elements invented? ...
"French physicists Jacques and Pierre Curie discovered piezoelectricity in 1880. The piezoelectric effect results from the linear electromechanical interaction between the mechanical and electrical states in crystalline materials with no inversion symmetry."
(Wikipedia, https://en.wikipedia.org/wiki/Piezoelectricity)
In audio technology, piezo pickup systems were used in record players in times post World War II up to the late 1960ies, since audio industries were not able to produce coils that were small enough to build electro-magnetic pickup systems. But with the invention of electro-magnetic pickups, the piezo technology vanished quickly from the market, since these were known for their harsh and screechy sound ...
Of what is a piezo pickup essentially made? ...
The easy answer is: 'sand'. This 'sand' is bound by an electrically conductible ceramic substrate, that keeps the crystals closely together which is essential that a piezo element can work at all.
The actual piezo element is in turn bound to a metal plate or bar with a weight of several grams.
- Barium titanate.
- Lead titanate.
- Lead zirconate titanate (PZT)
- Lithium niobate.
- Lithium tantalite.
- Potassium niobate.
- Sodium tungstate.
What does a piezo element actually do?
Frequency range and linearity of piezo elements ...
| Piezo pickup | Modern electret condenser microphone |
 |
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Comparing the linearity of piezo pickup in contrast to a modern high-grade electret condenser microphone cartridge (as used with AniMic/i or AnyMic cable microphones) over the audible frequency range of 20Hz ... 20kHz piezo pickups show their overall deficiency.
Actually one cannot speak of linearity at all in piezo pickups. The response rate is constantly degrading towards increasing frequencies and the response value is erratic and changes tremendously with every frequency step.
This is not only to the detriment of overtones (which are in the areas of higher frequencies) but the harsh sound characteristic of piezo pickups that are often criticized is coming from this erratic response behavior of piezo pickup elements.
Types of piezo pickups ...
- Disks/plate
- Bars or tubes (for 'under saddle' mount)
- soft (tubes)
- hard (bars)
What do all these types have in common?
Conclusion
Indeed, a piezo element, often termed a 'contact microphone,' doesn't perceive sound in the way our ears do. Instead, it's a transducer that converts mechanical vibrations (like those in an instrument) into electrical signals. The term 'contact microphone' is more about its application, emphasizing that it's placed in direct contact with the source of sound vibrations, rather than implying it 'hears' in the way our ears do. It's essential to clarify such terminology to avoid misunderstandings and provide a more accurate understanding of the technology.
Piezo pickups are soundboard killers in any shape and color they are coming along. In particular with nylon-stringed instruments they sound quacky and twangy.
