I don't know, but my cold brew is delicious according to multiple sources, and even drinking it black I wouldn't say it's sour or bitter.
We get either medium or light roasted beans, which I expect is a big factor, but that's just because we don't like the dark roast (whether brewed hot or cold).
I like when it has a fudgy-ness to it. Where the mouth feel is thicker than it really is. Occasionally it turns out that way. Some coffee shop cold cold brew does too.
I tried many waters, ratios, temperatures, extraction times. Usually kinda sour. I need to work on it more. When I get back to it, I'll start measuring pH.
