12" speaker for convertible pine cab and EL84 amps

I've ordered a lightweight 1x12 pine cab. It's convertible--open back and closed back option. I'm looking for a speaker that will sound good both open and closed for different flavors. I primary will be playing EL84 amps--12-18 watts. I primarily play clean on the edge of amp breakup. I'm looking for a speaker that is well balanced and offers good clarity and note definition, but I'd also like to maintain the chimey EL84 character. 

I couldn't find much as I searched the site and forum about convertible cabs, and I know a lot of speakers really only sound good in open back cabs or closed back cabs, and not the other. So, I'm a little lost. Any help would be appreciated.