Flatten 3/4" She Oak board?

Hello all,
I've made a red She Oak baffle for a loudspeaker face, and I was about to glue it to the maple veneered MDF carcass when I noticed it is bowed across it's width. It is about 18" long by 6" wide and is warped such that ends are upturned about 0.5mm at each end -- enough to be noticeable. Is there any way I can flatten it without using a planer? Wetting, clamping, steaming or some kind of ritual sacrifice perhaps?
Thanks for any advice,
Thomas Hood
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.