sett1a= new Image(); 
sett1a.src="images/deejay-world.gif";
sett1b= new Image(); 
sett1b.src="images/deejay-world2.gif";

sett1a= new Image(); 
sett1a.src="images/deejay-world.gif";
sett1b= new Image(); 
sett1b.src="images/deejay-world2.gif";

sett2a= new Image(); 
sett2a.src="images/pro-audio.gif";
sett2b= new Image(); 
sett2b.src="images/pro-audio2.gif";

sett3a= new Image(); 
sett3a.src="images/synths-lab.gif";
sett3b= new Image(); 
sett3b.src="images/synths-lab2.gif";

sett4a= new Image(); 
sett4a.src="images/computer-music.gif";
sett4b= new Image(); 
sett4b.src="images/computer-music2.gif";