Introducing The Bully: https://gr-research.com/product/old-school-bully-kit/
The Brute’s “big brother” is even bigger, badder and he’s not holding back!
The Bully brings both high efficiency and 12″ servo subwoofers to the fight, offering detailed and impactful bass with extension flat to 20Hz
This make them easy to drive even with low-powered tube amplifiers, plus the Subwoofer’s PEQ function and extension filters give you full control over the bass response.