Sweet, and Sour, Cherries for extract clone of Troeg's Mad Elf

I'm researching and putting together an extract clone of Troeg's Mad Elf, and apparently the secret is to use 1/2 sweet cherries, and 1/2 sour cherries, not just all sweet.

Anyone have a line on how the cherries I buy should be packaged? I see some dried, I see some in a light syrup, I see "Tart" cherries (same as sour or is there a difference?), pureed cherries, etc.

So many kinds... suggestions? Marco Polo a good brand?

Thanks!

Whichever you choose, make sure the cherries don't contain any preservatives or oils. Fresh cherries would be best, but since it's not cherry season, see if you can find a frozen source for your needs. Extracts can also help out in a pinch, but they'll require a lot more experimentation to get the flavor right.

People seem to have good results with the Oregon brand canned cherries. Apparently they're pretty high quality.

Thanks aiptasia.

I found frozen tart cherries... 5lb bags at Frank Farms, but they are out of Sweet Cherries.... but those are much easier to find. I can likely find them at my local Trader Joes.

Now to search more on HBT to find out how much to add for a medium level of cherry flavor goodness.