What is a pad?

Guess you are asking about the sound made by a synth. Here is a quick reference, maybe not the best but you will get the idea http://en.wikipedia.org/wiki/Pad_(music)#Synth_pad

Hey rick, it does get confusing. 

A "pad" is also a verb and noun for lowering a signal.  Such as "you need to pad the preamp since the signal is so hot."  Mics and preamps usually have a pad built-in for use if you have a loud sound.

There are also auralex and whatnot "pads" to put your speakers on.  They decouple the speaker from the stand so sound isn't so readily transfered.

A synth pad comes out of orchestration and then pop music.  Strings or horns (usually) will play the chord underneath the main song structure, to fill in the spaces between more upfront, staccato instrumentation.  Usually this was a mellow, unobtrusive timbre to add body.  Synth pads are similar tonally, although movement w/in the sound adds some interest w/o drawing attention to itself (real string or horn players add their own movement simply by playing). 

If you look in DimPro (and many other synths) Presets you'll see "Pads" as a subfolder.  This contains sounds that will work as pads, although those hardly ever cover all "pad" instrumentation.  A slow attack, longish delay and slow, non-pitched based change is what you looking for.

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