The VALVE is a ‘keep on’ pedal, and Jim Hagerman classifies it as a boost (upward of 20dB), but it is a tone charmer that has overdrive properties. At $129 USD, the VALVE is one of the best bangs for the buck, as it fattens up a Strat, makes humbuckers growl, and simply adds more life and dimension. Moreover, by placing a boost in front of the VALVE, to push its 12AU7 tube even harder, there is a BK Butler pedal effect, as demoed in the final lead section to the intro composition on the accompanying video. Now, keep in mind that this is a tube-driven pedal with no silicon involved, operating in starved-plate and starved-heater mode (viz., the tube receives adequate voltage, but the plate and grid are starved of higher voltages that would bring them within their intended headroom and total harmonic distortion parameters) and all done on a typical 9VDC power supply (also works with 12V). This configuration has not been successful until now, although others have tried. The Matsumi 12V ValveCaster attempts this, but has limited performance due to not addressing grid current at such a low bias. I did indicate what it does to a tone in general terms, but insofar as my own experience, I added the Hagerman Valve to two different tube amps (Orange Tiny Terror and the Peavey Classic 20), as well as the Fractal FM3 modeler. Jim Hagerman claims great things with solid state amps, but I did not have access to that platform. Without fail, the results were superb. This full-bandwidth pedal resulted in tube amps sounding thicker and richer; and the FM3 becomes more energized and realistic. Clean signals sounded glassier and vibrant, merely by placing the VALVE’s ‘level’ at parity (about 9:30 o’clock); and once past that level, there is increasing dirt/breakup, and to the point of a classic rock sound (with level cranked full). And yet, the amp still retains its underlying tonal characteristics. Dirty and hi-gain amps mixed very well with the VALVE, and with greater richness, gain and boost at only 10-o’clock, as though modded and super-charged. Of course, you can get a lot more saturated for those creamy, gooey leads by placing the level all the way up for lead solos. The VALVE is true-bypass and well-built with a heavy aluminum chassis power-coated in black with white lettering/graphics. It comes with a 12AU7 tube, which should be removed during transport, unless you have a protective pedalboard cover/case. Its design permits it to be Velcroed as usual, but also screwed down into a wooden pedalboard or bolted onto a metal unit. As mentioned, it takes both 9VDC and 12VDC power supplies, requiring only 135mA power (150mA if running 12V) via a standard negative-center cable. Other specs include 100k ohm input impedance and 100Hz to 20kHz bandwidth. One caveat is that the VALVE’s level control knob is small, which makes it a bit awkward if changing the level on stage. However, that is where an extra boost comes in handy (such as the Hagerman Boost), i.e., the VALVE can be left on and used to add dimension to rhythms, and then the added Boost engaged for fat leads and that BK Butler effect.