synthesiser

[frank1]

Could someone please tell me what the major differences are between a keyboard and a synthesiser?  I am really confused and have a Yamaha keyboard and get Keyboard magazine that has all this stuff about synthesisers.  Are they mainly for people who write songs.  I am pretty much a beginner around level 3 or 4.  Thanks a lot.
Frank

[tekime]

The term synthesizer is often used loosely, but basically a synthesizer is a digital instrument that can generate its own sounds, and often mimic instruments by synthesizing timbres. The keyboard you see on some synths is a control mechanism, whereas some synths have no keyboard and are controlled by MIDI.

Most digital keyboards have a computer on-board, with specialized hardware that has stored samples of real instruments. This, technically, is not a synthesizer. But again... people tend to use the term quite loosely.

[iansinclair]

on the other hand, there are a number of digital pianos out there which can produce an array of other sounds -- some pitched, some not (e.g. drums) depending on which combinaton of pushbuttons you press on the control panel.

From my point of view, the biggest difference that I can see is that the principle aim of a digital piano is to reproduce, electronically, an acoustic piano as closely as possible -- so you will have a weighted, touch sensitive (hopefully hammers) keyboard, and the sound will originate, one hopes, from sampled waveforms from real pianos, pulled together and looped by a computer.  Same principle applies to electronic organs, where one hopes the sounds of the various stops originate from sampled waveforms.

A synthesizer, on the other hand, while it may have the sampled waveforms, does not have to -- and creates its sounds by assembling wave forms of various frequencies and with various enveloping (speed of increase/decrease in volume) under computer control.  It is inherently much more flexible as to what sounds it can make -- but it is not necessarily intended to sound "like" anything else at all.  Nor does it have to have a piano-like keyboard -- although that is a useful control device.  To get the most out of a synthesizer, you have to have a computer program feeding it information as to the nature of the sounds wanted (such as MIDI).

[nystul]

A synthesizer does not have to be digital or computer controlled.  I actually think the term makes a lot more sense if you understand a bit about the instruments before digital audio.  The classic synths of the 60s and 70s used voltage controlled oscillators to generate primitive, harmonically rich tones ("square", "sawtooth", "triangle", etc.), voltage controlled filters to shape and tame those harmonics, and other electronic devices to further manipulate the tone.  Those instruments were the basis for a lot of the sounds people typically associate with synthesizers.  Those instruments had precursors going back before WWII like the theremin and Hammond's Novachord (actually very synthlike and so far ahead of its time that nobody knew what to do with it). 

What they all have in common with their digital counterparts is using electronics to generate and manipulate tones.  That is more or less what makes something a synth.  A modern synth can use recorded samples for the tone generation but I don't think that really makes it a synth unless it has some creative techniques to manipulate those sounds.

Personally I think the guys who designed pipe organs centuries ago were on the right track.  They tried to create tone of stringed instrument or human voice by combining different sized pipes just so, and actually had some relatively good results!