a whole lot of VST‘s advertise either being Additive or Subtractive synths, and I cant tell the difference.
C'mon. You really don't know this? A keyboard is an instrument withA KEYBOARD. It could be a grand piano, a cheap little electronic thing, a big expensive keyboard that rock stars use on stage, it could be asynthesizer. If it has a keyboard, it'sA KEYBOARD. There are lots of keyboard instruments around that have thousands of different sounds and instruments on them with sequencers and percussion, etc. People call these keyboards. But they're also synthesizers because they synthesize their sounds. Is there a piano inside that little keyboard? No. It's a synthesized piano sound. A synthesizer is an electronic instrument that synthesizes sounds. The vast majority of synthesizers are keyboard instruments. There are guitar synthesizers, there are drum synthesizers, there are all sorts of synthesizers. But most synthesizers are keyboard instruments. So if someone says I play synthesizer, it probably means he/she plays a keyboard synthesizer. If someone says I play keyboard, it could mean piano, organ, synthesizer, etcany instrument with a keyboard. But these days, it probably means they play a keyboard synthesizer. There's also analog versus digital synthesis, but that's for another day. Just because you know how to play the sounds on your synthesizer doesn't mean you're a keyboard player. A keyboard player knows how to play real keyboard instruments like pianos and organs. So if your keyboard playing consists of triggering sounds on your synthesizer, you really can't claim to be a keyboard player.
The Yamaha DX-7 is an example of the first additive synthesizer, where you use a series of algorithms to generate different frequencies from scratch to build a specific sound. You start from no wave and go swell it by combining frequencies. There are several algorithms to choose from, and each one is useful for certain types of sounds. You build every sound from spcific frequencies, and you can invent one mathematically in your head then see what it sounds like. Pythagoras would have loved it. Synthesizers before that were subtractive. Like a Minimoog. You can pick from specific waves, but the sound is already generated without doing anything to it. And current is running through the sound, so one venue might have current running at a different frequency than your garage, which is why in the 1970s, lots of keyboard players seemed out of tune. You had to retune your keyboard based on the quality of power at the gig. Each synth had square wave, sine wave (like the end of Lucky Man by ELP), sawtooth wave. You subtract frequencies from the sound to modify it, and you blend different waves at different voltages using the potentiemeters. It gives that raw, analog sound, which a great DX-7 programmer can emulate pretty well, but is limited by the number of available algorithms. Which is why digital (additive) sythensizers have a thinner sound sometimes, but also why they make perfect piano, kalimba, lute or string sounds (though it helps to bank several digitals to get a GREAT string sound). So additive starts from no sound and you build individual algorithms of frequencies in combination to create any sound. Subtractive starts with a preset sound, and you diminish or attenuate certain frequencies to modify it. Does that help?
