By Paul McGowan, PS Audio

I’ve always been fascinated that a simple push of the automobile’s accelerator pedal engages a huge and powerful machine into action.  Just think of all that’s happening when you press that pedal – forces far greater than the slight pressure of the pedal are awakened and the beast springs into action.  So it is with a musical instrument.

The simple pluck of a string or the vibrating of a mouthpiece generates music loud and clear.  What’s similar between the press of an accelerator pedal and the pluck of a string is the idea that one small action sets into motion far bigger events than one would imagine.

If you have an accelerator pedal that’s not connected to an engine and you depress it, not much happens.  Similarly if you pluck a string not connected to an instrument, not much happens either.  The vibrating string of a violin or guitar moves back and forth rapidly but makes almost no sound if it is plucked or bowed in open air; standing alone in a room.  It is the addition of a mechanical amplifier that allows us to actually hear the motion of the string; just as it is the car’s engine that responds to the push of the pedal.

With a wind instrument the mechanical amplifier is a tuned horn and, in the case of a stringed instrument, a shaped box .  It is primarily the box or the horn that determine the way the instrument sounds; less so the string or the mouthpiece that vibrates in response to the player.

A guitar is a great example for understanding this.  Compare the size and shape of an acoustic guitar, which uses an attached box for its amplifier, to that of a modern electric guitar that has nothing more than a electrical pickup beneath its strings.  Strum the acoustically amplified guitar and room filling sound emanates from its opening beneath the strings; try the same on the electric guitar, sans electronic amplifier and speaker, and very little sound comes out.  Both require a means of amplifying the motion of the string to work.

It is fascinating to me the importance of the acoustic amplifier to hear a plucked string and that knowledge didn’t escape early instrument makers either.  They realized early on that the size and shape of this amplifier favored some frequencies more than others and, coupled with the starting transients of the plucked or blown notes, determined almost entirely the sound each instrument makes.

The small body of a violin means a small acoustic output, which is why there are so many violins in an orchestra.  A viola and a cello are the same instrument as a violin – they just have bigger amplifiers – so you need fewer of them to make the same sound pressure.

So when you listen to massed strings in an orchestra it isn’t really the strings you are listening to; rather it is the output of their acoustic “power” amplifiers you’re hearing instead.  And, just like audio amplifiers, the way each of these amplifiers is built determines how it sounds – small amplifiers, small sound.

For more on this story go to:

http://www.pstracks.com/pauls-posts/gas-pedals-plucks/10426/