I created these speakers in Blender, I didn't have any blueprints but used reference images I got from the product website http://www.krksys.com/Classic
The materials are procedural textures created within Blender, I also exported image textures from the procedural textures. You will find two collections in the .blend file, one has the speaker with procedural textures applied and another with image textures in 2049 x 2049 resolution.
Materials are both Eevee and Cycles compatible.
SOME DETAILS: Total polygon face count is 91,497. The models contain overlapping UVs in some parts. I included an unpacked and packed native .blend file in case you may find linking textures tedious.
You are free to use this model as you like but be aware it is a real product owned and copyrighted by KRK Systems, so you will need to do some research before using it on your specific project.