The PastFx 18V Power Booster is an analog pedal that PastFx describes as "a boost, EQ, overdrive, and mild fuzz based off the legendary Power Boost circuit"1. In the maker's words it is "a versatile little dirt box capable of light tonal grit, hair-raising overdrive, light to medium fuzz, and/or clean to gloriously filthy boost", with Bass and Treble controls for further tone shaping1. It sits across several categories at once: a clean boost at low settings, an overdrive or light fuzz pedal when the gain comes up, and a two-band EQ throughout.
PastFx positions it as "a pedalboard-friendly recreation and expansion of the Buffalo FX Power Booster"1, which in turn follows the Colorsound Power Booster circuit2.
Controls and the Hot/Mild switch
The pedal carries controls for Gain, Level, Bass, Mild and Treble, which PastFx says shape the sonic character of the effect1. On top of the knobs there is a new external switch that selects between "Hot" (the factory default) and "Mild" gain headroom1.
The Mild control only does something when the switch is in Mild mode. PastFx describes it as allowing "adjustable lower gain levels to taste", and notes that it interacts with the Gain control1. In practice that gives the pedal two personalities: Hot for the full-gain behavior of the original circuit, and Mild for a tamer range you can fine tune.
| Control | What it does |
|---|---|
| Gain | Sets the drive level of the circuit1 |
| Level | Master volume for the output level1 |
| Bass | Bass side of the two-band EQ1 |
| Treble | Treble side of the two-band EQ1 |
| Mild | Lower gain adjustment, active only in Mild switch mode1 |
| Hot/Mild switch | Selects gain headroom; Hot is the factory default1 |
PastFx also lists a dedicated master volume, an external gain control, and an adjustable internal gain switch among the pedal's features1. The master volume is a meaningful addition over the original circuit, as explained below.
Power: 9V to 18V
The Power Booster runs on a 9 to 18V DC center negative power supply, and PastFx says 18 volts allows slightly more gain1. Current draw is 5mA at 9V and 10mA at 18V1, low enough that it shares easily with other pedals on a powered board. No battery option is listed in the maker's specifications.
PastFx states that product specifications are subject to change without notice, as the company is always looking for ways to improve its products1.
The Colorsound Power Booster lineage
The circuit the pedal recreates has its own history. The original Colorsound Power Boost shares its topography with the Colorsound Overdriver but ran at 18V, which is where the PastFx pedal's name and voltage range come from3. On That Pedal Show, the circuit was presented as the "Colorsound Power Boost (18V by Stu Castledine)"4.
A well-known limitation of the original design is that it had no master volume: you could not max the gain and then pull the output level back down. DIY layout site Tagboardeffects addressed exactly this, with its builder Zach writing3:
"so I figured that it would be much more usable to be able to max the gain and control the output level"3
Zach, Tagboardeffects3
Tagboardeffects produced four layouts of the 18V Colorsound Power Boost: two identical to the original early and late versions, and two with an added master volume pot3. The PastFx pedal's dedicated master volume brings that same usability to a finished product, letting you run the gain high and set the output level independently3.
Transistors
PastFx builds the pedal with BC169 and BC184 transistors1. The original Colorsound Power Boost came with BC184L transistors, though Tagboardeffects notes that any NPN silicon transistor should work in a build3. One builder reported using 2N5088s, "which match well with the hfe of bc184l and they sound great"3. Tagboardeffects also warns builders using BC184L to mind the pinout, as some are ECB and need their legs crossed3.
Where it sits in the PastFx range
PastFx also makes recreations of other vintage circuits, including the Canberra Overdrive and the TD-Y Overdrive. The 18V Power Booster is the company's take on the Power Boost lineage, expanded with the Hot/Mild switch, the Mild control, and the master volume that the original never had1.
Videos
TheSuperFunAwesomeHappyTimePedalShow
The Pedal Picassos
ebi-san workshop
Questions
Is the PastFx 18V Power Booster true bypass?
Yes. PastFx specifies true bypass operation for the 18V Power Booster, so with the pedal disengaged the guitar signal passes through without buffering. Input impedance is 1 MΩ.
Can the PastFx 18V Power Booster run at 9V?
Yes. It runs on 9 to 18V DC through a center negative power supply. PastFx says 18 volts allows slightly more gain, so 9V works fine but with a little less push. Current draw is 5mA at 9V and 10mA at 18V.
What does the Mild switch do on the PastFx Power Booster?
The external switch selects between Hot, the factory default, and Mild gain headroom. In Mild mode a separate Mild control becomes active, allowing adjustable lower gain levels to taste, and it interacts with the Gain control.
What is the PastFx 18V Power Booster based on?
It is a recreation and expansion of the Buffalo FX Power Booster, which itself follows the Colorsound Power Booster circuit. That circuit shares its topography with the Colorsound Overdriver but runs at 18V.
What transistors does the PastFx 18V Power Booster use?
PastFx builds it with BC169 and BC184 transistors. The original Colorsound Power Boost came with BC184L transistors, and DIY builders have noted that 2N5088s match well with the BC184L's gain.
Does the PastFx 18V Power Booster take a battery?
The maker's specifications do not list a battery option. The pedal requires a 9 to 18V DC center negative power supply, drawing 5mA at 9V and 10mA at 18V.
Sources (4)
- 18V Power Booster, PastFx, 2026
- 18V Power Booster by PastFx, RockBoard PedalPedia, 2026
- Guitar FX Layouts: 18v Colorsound Power Boost, Tagboardeffects (tagboardeffects.blogspot.com), 2017-09-21
- Understanding Overdrive, Distortion, Boost & Fuzz With Josh Scott Of JHS Pedals, That Pedal Show, 2018-11-16
