For the sake of clarity and accuracy, Brian Ding is the designer/owner of Rythmik Audio. He designed and has made all the Rythmik plate amps and woofer drivers, including those Danny Richie uses in his subs. Danny is the designer owner of GR Research, known primarily for his open baffle loudspeaker DIY kits, though he also offers sealed designs and subs (see below).
The confusion exists because Brian and Danny have collaborated on two do-developed products:
1- The 12" woofer is available in two versions: the "standard", with an aluminum cone, and the "G" (for GR Research), with a paper cone. Danny took Brian’s 12" woofer and integrated his own paper cone, which he prefers to aluminum. If you want the Rythmik F12 Sub, buy it from Brian, the F12G from Danny.
2- The Rythmik Audio/GR Research OB/Dipole Subwoofer. Co-developed by Brian and Danny. It uses Brian’s Servo-Feedback A370 plate amp, with a dipole cancellation-compensation shelving circuit also designed by Brian installed. Danny took the 12" paper cone woofer and optimized it for OB use. The OB/Dipole Sub (available in several versions) is more Danny’s baby than Brian’s. It is available as a kit only, sold by both Rythmik Audio and GR Research. The OB/Dipole Sub flat pack kits (that the woofers are mounted into) are available through Danny/GRR.
