Group Velocity Manipulation

Materials with highly porous skin structures have extremely large surface areas. Just one gram of such material can have a surface area equal to half of a football field. So, a single DFPC may have an actual surface area the size of a large metropolis. Because they are traveling along the skin only, this is what the high frequencies see. The lower, desirable frequency, 50 or 60 Hz, sees the 6 feet from the wall to the gear and goes there directly, while the undesirable noise is getting lost in a vast cityscape. The low frequencies take the metro, the high frequencies have to walk.

In the Firewall, this is even more extreme. The filter inside the Firewall is only 50 cm long, but its conductive double skin, if completely unfolded, would be disproportionately gigantic. From the point of view of the high frequency noise? A whole other world in which to get lost forever.

The amount of filtering effectiveness at the skin increases with frequency in a smooth fashion. Even the second skin of the Firewall filters in a "fade-in" type way, completely dependent on the frequency in question.

Therefore, with the Firewall, we have an extremely dispersed frequency response, with the 50 or 60 Hz fundamental at the very head of the pack. Just the way we want it for great sound quality.

And, since the dynamic demands of a sound system are source signal dependent, in real time we demand juice from the power supply in synch with the signal. We do not wait for 1/50 of a second before we politely ask our power supply for a bit of juice for this here rather impatient guitar player. He wants it NOW, because he's on a roll letting his emotions loose on that fine Goth guitar.

We have arrived at the leading edge of time. The Firewall is not saying "NO!" to the high frequency demands which give speedy instant power to the dynamics the gear needs; rather, the Firewall is saying to the guitarist's soulful demands: "YES, PLENTY for the TAKING, but ONLY from the 50 Hz army of loyal combatants, NOTHING from the unreliable skin, and nothing from that unpredictable space above the skin, either!" By the time the high frequency noise comes around, we'll all be packing it in and heading to an afterparty, talking about this amazing sound we've made.