Need help with Cheddar - PH levels

[Duntov]

My Cheddars have generally turned out okay but I want improvement.  I have been trying to achieve a 6.0-6.1 ph level at draining the whey but keep falling short.  The best I have been able to achieve is 6.22.  If I cook any longer the curds go too dry.  Here are the basic ingredients I have been using:

3 Gal. Raw Milk
¼ Tsp. Mesophilic Direct Set (C101)
1 Pinch Mesophilic MA 4001
1/3 Tsp. single strength liquid animal rennet in ¼ cup purified water

What do I need to do different to get to that magical 6.0-6.1 ph at draining??  Different cultures, too much/too little?

[awakephd]

How long do you let it ripen before adding the rennet?

[Duntov]

How long do you let it ripen before adding the rennet?

I let the cultures ripen for 30 minutes.  Then add the rennet and wait 45 minutes.

[Gregore]

Try stirring less vigorously , I have never made cheddar so do not have to worry about getting ph so low before hooping .  But things that effect curd moisture are , stirring and  heat  , you could change the heat but that will effect other things down the line more than stirring less.