Here's something a brewer taught me that might helps you taste diacetyl.
Make a wort about 1.040 to 1.050. Keep the IBU/SG ratio down to about 0.25 to 0.3.
Get a yeast like Wyeast 1007 (German Ale) that likes it fairly cool. Spilt the yeast into 3 to 5 batches, after pitching the yeast. Ferment one at 62F, one at 70F, and one at 78F ect... After it's fermented, bottled/kegged and carbed, chill the beer and sample side by side.
It works real well. It's just takes time.