On the right is a computer animation of a modal analysis from a steel-string guitar showing the vibration of the guitar top at an exaggeration of 1 million.
Sir Isaac Newton, presented in 1686 the "Laws of motion" in relation to Galileo Gallilei's "Law of inertia" (1638; ~50 years before).
Consequences from Newton's 1st & 2nd law of motion are:
- To move a mass it takes energy.
On a stringed instrument, this energy usually comes from the tuned strings when plucked and has a definite vibration energy.
- The extra mass that a so-called pickup system applies to the vibration area takes energy from the strings by the implied inertia of this extra mass and changes the instrument's sound characteristics badly.
Any mass that is applied by a pickup element to the area of vibration robs energy from the strings. The mass of so-called pickup systems is definitely to the detriment of an instrument soundboard due to its implied inertia since this is ruining the ability of a soundboard to vibrate.
The result of mounting an extra mass to an instrument's soundboard is:
- loss of overtones, which is the foundation of an instrument's sound characteristics.
- loss of response
- loss of sustain
- loss of projection
- change of the instrument's 'voicing'
Hiding such pickup elements under the saddle or on the rear of the soundboard inside the instrument body makes no difference to the harm that is done to the instrument by mounting anything in the sensitive vibration area. The implied inertia of the mass that is applied (stuck or clamped) by mounting a pickup element to the soundboard does not go away by hiding the pickup somewhere ...
The evil thing with all these so-called 'pickup systems' is, that they can only work, if -and only if- they are mounted in the vibration area of a soundboard; e.g. the top of a guitar, mandolin, ukulele, acoustic bass, etc. These 'pickup elements' (better known as 'piezos' or called 'transducers' when it turned out that 'piezos' sound awful) are all of sort 'bend-wave-sensor' and they can only 'feel' longitudinal waves that are running through a material - usually wood in case of a guitar soundboard. From the 'feeling' of longitudinal waves such a pickup-element then interprets an electrical signal that is generated from the characteristics of the pickup-element's sound characteristics itself determined by its own material.
Some even call these pickup elements 'contact microphones' (regardless of whether they are made of piezo-ceramics, carbon, or work electro-statically). This is a complete mock of potential customers ...
A real microphone -as the name implies- measures and 'hears' the movement of air molecules - this is what we call 'sonic' and is what reaches human ears. This is why microphones are said to sound 'natural'.
So-called 'pickup systems' will ruin an instrument badly right before it can pick up and interpret any tone from the waving material. The instrument's integrity is damaged, at the moment when the decision is made to mount such a thing to the soundboard of the instrument.