What's the brand?

Many many places. Anyone, chime in, with the ones you know.

Antique Radio Supplyhttps://secure.tubesandmore.com/ They supply a lot of people. Type corners into the search field, and see what comes up.

GavinMajesty wrote: What's the brand?

Hughes & Kettner WARP X

Great link Tommy! They have nice stuff
I saw a lot of stuff for Marshall and Fender, but nothing for H&K yet.
Please keep the suggestions coming

Parts Express has good variety of cabinet parts from Penn Fabrication. A lot of manufacturers use these. Check it out.