It all started with the 20th Silo which I am very proud of owning. It adds more punch and midrange as Lovejoy said, which makes it really resonant and very clear whether on clean or crap load of distortion. There is a reason why its called a tone block .
The 20th Silo is not chambered either. Sounds great to my ears. I have a regular Silo as well, but its not comparing apples to apples what with the different pickups and rosewood neck.
It started with the 20th Anniversary Silhouette in 2006, and then it was implemented into the BFR JP, LUKE and Albert Lee, Axis and ASS guitars. They all have it, and then the 25th Ani came out with the tone block AND another innovation of chambering. Which then carried over to the 10th Anniversary of the JP model. I'm still waiting for a Silo Special BFR with a tone block .
that thing Mahogany Tone Block or "MTB" used to be EBMM secret weapon no photos were shown and BP told us that it's like a bottle of vodka. Now with the 25th EBMM is showing us how it's implemented in the guitar and this is nice
I had a chance to try both Silo 20th, Luke BFR and ASS BFR that have the MTB. It really add something to the sound, now like it or not that's another story