I agree with LORD, my cabinet is 48w x 24d x 80h and my humidistat is at the top. I have always kind of gone by what people say about what to set the stat at. Some say 65% others 70%, It was a few years back I opened a box of NC's up that was on the top shelf that had been stored for about a year. When I opened the box nothing but mold, lucky for me it was only surface it had not reached inside the cigar, also it was only in 2 boxes. At that point I started listening to the cigars, I found out in my unit 63% is the optimal humidity, plus I bought a hygrometer for each shelf. I got them at Wally world for like $8, calibrated them and they work great. Now to tell you how the real world works where everything is not so perfect, I have my humistat set at 65%, the top shelf hygrometer reads 65%, second shelf 64% - 65% more on 64%, 3rd shelf 63% and 4th shelf bounces between 62% - 63%, and the very bottom storage area where I keep extra ashtrays, lighters and such usually reads 62%. Now for the kicker, if I have my humistat set on 65% those are the readings I get, if I set it to 70% the humidity the top shelf will be 73% - 75%, second shelf 73%, next shelf 73% and last shelf 72%. I dont know why there is a big jump in the humidity like that, it took me about a year to get it straitened out, now when I smoke a cigar I can tell a HUGE difference in the flavors. So you have to listen to your cabinet and cigars, when I first started collecting cigars and people told me that, I thought they had some mental issues but now I get it. Good luck you'll figure it out.
Update forgot to add.......I no longer go by what my humidistat says, I adjust the setting going by what the hygrometers say.