I have owned infinity speakers since 2002. I had a 7.2 system with Primus 360 towers all the way around. Then I upgraded to the Alpha 50 towers (4), Alpha 20 (4), and eventually the 25es surround (2). I continued to evolve into the Beta series. Beta 50 (2) and matching center, dipoles and subs for 7.2. I sell high end audio and my 7.2 system puts to shame anything matching its original retail price and will outperform any speaker I've heard double its price. I have always wanted the Revel F12s. I finely found a mint used pair locally and brought them home last night. They are different from the Betas. Betas are more forward, have greater transparency, better attack, but also tend to be bright, and are lean in the mids. The f12s are full in the mids, softer on top and less fatiguing. This is arguably a formula for a very musical speaker, where the betas may prove to be better for cinema. It really comes doen to personal preference. I am extremely familiar with the betas. I have mated numerous amps, preamps and high end cables to them. I am still getting to know the Revel f12s and look forward to many hours of doing the same.
Many people in threads don't believe there are any differences between these two speakers internally. There are, and I've got pictures to prove it. The drivers inside the Revels are much more substantial. So there a way to post pics? Is so I will attach.
