Hello, I am trying to create a synthesis engine within my work rather than having lots of large .wav files. Ive looked around and i cant seem to find anything that will work in real time. Does anyone have any ideas please?

This helps?
http://www.synthedit.com/

or

http://synthmaker.co.uk/index.htm?

if you are more or less a 'purist' (like myself) and want to write it yourself, you may have a hard time; particularly getting it to sound good. my experiences with synth programming involved making a basic sine wave in a directsound buffer and went no further :P

if you are willing to bend a bit though, extended module (.XM files) provides very decent sound quality and are typically much smaller than mp3 files. they embed PCM samples for their instruments and work like midi beyond that; but sound phenomenally better than stock midi voices. there is a library called "mini-FMOD" that is specifically for playback of XM files, and was engineered to be as small in compiled size as possible; particularly for use in those notorious '64kb demos'.

according to the site for mini-fmod, it only adds 5kb to your executable and includes full source code (no unfashionable DLL files to distribute with your project)

info and download
http://fmod.org/fmoddownload.html#sece