The minimum distance of a rear ported speaker to the back wall is a good question Dazler and one that may get a lot of different answers. The most common answer that I have seen to this question on various forums seems to 12" and I tend to agree - I would go no closer than this. If you can't get a at least a foot, go front ported.
The manufacturer of my speakers, that are rear ported, recommends a minimum of a meter or 3.2' but in my case, that would be impossible to attain. I have settled for roughly half or 19" and am very pleased with the results.
The manufacturer of my speakers, that are rear ported, recommends a minimum of a meter or 3.2' but in my case, that would be impossible to attain. I have settled for roughly half or 19" and am very pleased with the results.