Weighing in at 44 pounds,
the Tube Equipment Corporation Model SR-71 Blackbird is a Dynamic Mu™ stereo compressor/limiter using the original Fairchild 670 design with modern components. It has compression character highly reminiscent of the 670 with flatter high frequency response owing to Sowter Mumetal-core input transformers, which we really like. It also employs faster release times for modern percussive material, output controls, the "DC Threshold" (Ratio) control relocated to the main panel and a true hardwire bypass. We think these enhancements provide a more versatile product.
With twin 15 watt tube amps driving the sidechains, much like both the venerable 670 and SR-71's renown Mach III aviation namesake, it's very fast.