There are plenty of jokes about British electronics, most of them involving Lucas wiring, sports cars, and rainy weather. But when it comes to effects pedals and big amps, the Brits were there at the very beginning. In the late 1960s, Hiwatt founder Dave Reeves was building hand-wired 100-watt heads like the DR103 that became the backbone of loud rock stages, while Sola Sound in London was turning out Colorsound pedals, including the Power Boost, a clean-to-gritty transistor booster from around 1970. By the mid-1970s, David Gilmour was pairing a Colorsound Power Boost with his Hiwatt stacks, a combination that helped shape the guitar sound of Pink Floyd's Wish You Were Here. Released in December 2023, the Crazy Tube Circuits Hi Power puts both halves of that legendary rig into a single British Racing Green enclosure.

The right side is a faithful take on the Colorsound Power Boost, built around the same BC184 silicon transistors as the original and run at 18 volts thanks to an internal voltage booster. Crazy Tube Circuits adds a bypassable Master Volume, a smoother reverse-log gain taper, and a toggle that selects between the 18V PWR (Power Boost) voice and the 9V ODR (Overdriver) voice. The 2-band Baxandall EQ has a wide range, and the treble control does a great job of opening up humbuckers. This side is mostly about boost, with real distortion and fuzz arriving late in the sweep. ODR mode has less headroom and breaks up sooner than PWR, and both modes get fuzzy when cranked, but our favorite setting lives lower on the dial, where it adds a light, gritty edge you could leave on all night. Above all, it helps the guitar cut through a band mix, which is exactly what the original Power Boost was built to do. We are big fans.

The left side is an all-analog amp-in-a-box modeled on two classic EL34 heads: the 50-watt, 2xEL34 Hiwatt 504 and the 100-watt, 4xEL34 Hiwatt 103. You get Volume, Master, Bass, Middle, Treble, and Presence controls, plus a three-way switch that recreates the Normal, Bright, and Linked (jumpered) inputs of the original amp. We have spent a lot of time with EL34-powered heads, and the Hi Power nails that feel, with the upper-mid presence and clarity that makes these amps sound muscular, punchy, and forward. The EQ is flexible, and the lively response is a great match for humbuckers. Push the volume past about two o'clock and breakup starts to appear, which is where the two power-amp settings separate. The 504 feels a little softer and more compressed, while the 103 offers more headroom and a stiffer response. We leaned toward the smoother 504, since the 103 can drift toward fizz at higher settings. Even in its more compressed mode, the Hi Power delivers that classic EL34 punch that makes leads jump out without piling on gain. Like so many great 1970s guitar tones, it is more about volume and presence than outright distortion.

For overdrive and distortion, we liked setting the amp side up as a big, husky EL34 foundation and letting the Colorsound side supply the crunch, an approach that echoes how many of the best overdriven tones of the 1970s were built. A passive effects loop sits between the two sections, so you can add your favorite pedals between the boost and the amp, or run each half as a separate effect with an external looper. A power-up preset function lets you choose whether each footswitch starts bypassed or engaged when power is applied, which is a big plus for switcher users.

The popular Crazy Tube Circuits Unobtanium paired two of the most sought-after overdrive circuits ever made. The Hi Power takes a less obvious path, but the results are every bit as impressive, making it a great choice for players chasing Hiwatt clean headroom, Colorsound boost, and authentic vintage British amp tone on a pedalboard.

Specifications

• Dual analog pedal: Colorsound Power Boost-style boost/overdrive (right) and Hiwatt-style amp-in-a-box (left)
• Boost side controls: Volume (reverse-log taper), Master (bypassable), Bass, Treble
• Boost side 2-band Baxandall EQ
• Boost side PWR/ODR toggle: 18V Power Boost or 9V Overdriver voicing
• Original-spec BC184 silicon transistors
• Amp side controls: Volume, Master, Bass, Middle, Treble, Presence
• Amp side 103/504 toggle: 100W (4xEL34) or 50W (2xEL34) power section response
• Amp side B/L/N toggle: Bright, Linked, or Normal input
• Passive effects loop (send/return) between the boost and amp sections
• Two footswitches, true bypass
• Selectable power-up bypass/engage preset for each footswitch
• Power: 9V DC, 2.1mm center-negative, approximately 84mA (internally boosted to 18V for the boost side)
• Power supply not included
• Dimensions: approximately 4.7" W x 3.8" D x 2.1" H (119 x 97 x 53 mm)
• Weight: approximately 15.7 oz (444 g)
• Made in Greece

In the words of Crazy Tube Circuits:

HI POWER is our next endeavour in pedal + amp-in-a-box overdrives inspired by the sonic combination of two British tone machines that helped shape the sound of Pink Floyd’s Wish You Were Here Album.

On the right side of the pedal, you will find a recreation of the Colorsound Power Boost featuring the true-to-the-original spec BC184 transistors running on 18V DC (via an internal voltage booster circuit) and the ultra-flexible 2-band Baxandall EQ circuit. We’ve added extra features, like a bypassable master volume control, a reverse-log gain control to ensure better sweep and transition from clean to mean (compared to the original’s linear taper) and a toggle switch the engage the latter higher gain / lower headroom version of the original boost circuit called Overdriver.

On the left side of the HI POWER you will find an all-analog circuit set out to emulate the sound and feel of a Hiwatt amp. Following the path of the famed British tube amplifier our circuit offers authentic amp tone and feel. From the big bold high-headroom clean sounds to the face-melting crunchy tones.

True to the last detail we have included the full EQ section along with a presence control located at the negative feedback of the power amp simulation circuit. A headroom toggle switch selects between the high headroom 100w power section provided by a quartet of EL34s or the lower headroom and compression provided by a 50W power section with a pair of EL34s when hit hard. Similar in operation to the original amp design the master volume control was designed to produce more gain at higher settings.

We’ve taken our design a step further by adding a switch to select between input channels. You can select between the full frequency response of the normal channel of the amplifier, the increased presence and tight low end of the bright channel input or the enhanced frequency response and added gain of those inputs linked together.

Like our other dual overdrive/amp-in-a-box designs we have also included a passive effects loop to give you the option to connect your beloved pedals between your booster/overdrive and amp in a box or use the two sections as separate and independent effects when using an external bypass switcher/looper.

HI POWER also features a power-up bypass/engage pre-set function for the onboard footswitches. That way you can select which state your pedal will go to when you plug the power supply. This function comes in especially handy to people that use remote pedal switchers / loopers as they only set the power-up state of the pedal once and then operate from the controller.