The PastFX Mischief is a distortion pedal from the Australian builder PastFX, built on the ProCo Rat circuit and its classic LM308 op-amp. Where the original Rat gives the player three controls, the Mischief expands that layout with a four-way clipping selector, a three-way Bass switch, a Sizzle button and a Pulse Bypass, all in a compact enclosure1. Delicious Audio's Paolo De Gregorio describes PastFX as a builder whose "tweakable variations of classic pedal circuits" have become familiar, and notes that "a RAT-style distortion couldn't be missing from its roster"2.
Circuit and clipping options
At the heart of the Mischief sits the LM308 op-amp chip. Guitar Pedal X's Stefan Karlsson calls it "the classic LM308 OpAmp chip at its heart"1, and Delicious Audio describes the pedal as "a circuit featuring the original LM308 op-amp found in the vintage RATs"2. The LM308 is the chip long associated with the vintage Rat sound, so the Mischief keeps that part of the original circuit intact while changing what surrounds it.
The Pulse switch selects between four clipping arrangements1:
| Pulse position | Clipping |
|---|---|
| White | Stock symmetrical clipping4 |
| Blue | Asymmetrical clipping4 |
| (further positions) | LED clipping and Germanium-Mix1 |
| Pulse Off button | Clipping removed from the circuit1 |
Guitar Pedal X sums the choices up as "Symmetrical Silicon, Asymmetrical Silicon, LED and Germanium-Mix, with Pulse Off"1. The Pulse Off mode is a familiar idea to Rat players: Karlsson notes that "Pulse Off ≈ Deucetone", meaning it roughly equates to the variant found on ProCo's own Deucetone Rat1. In his year-end roundup he singled out the Germanium-Mix position, writing that the Mischief "sounds fantastic - with a really clever clipping section - and where the Ge-Mix sounds exceptional"3.
Controls
The three main knobs keep the original Rat layout. Delicious Audio notes that "its three main knobs reflect the ones found in the original RAT pedals (Gain, Volume and Filter)"2, with the Gain control reflecting the one on the original pedals. Around them sit the additions that define the Mischief1:
| Control | What it does |
|---|---|
| Filter | Tone control, clockwise operation3 |
| Bass | Three-way switch: Turbo Bass, Neutral, Bass3 |
| Gain | Distortion amount, as on the original Rat23 |
| Volume | Output level3 |
| Sizzle | Pushbutton for extra bite4 |
| Pulse | Clipping selector: Symmetrical, Asymmetrical, LED, Ge-Mix3 |
| Pulse Off | Button that bypasses the clipping stage13 |
Karlsson's verdict on the layout: "A really smart execution of a Rat - its the perfect complement of controls!"5
"PastFX's Verlie has done yet another genius smart take on a classic pedal"
Price and availability
The Mischief is a RAT-style distortion from Australian builder PastFX, whose first demo videos were circulating by the time of Delicious Audio's coverage2. Guitar Pedal X's review described the pedal as sounding "fantastic - with a really clever clipping section - and where the Ge-Mix sounds exceptional"3. Its clipping options cover Symmetrical Silicon, Asymmetrical Silicon, LED and Germanium-Mix, with a Pulse Off setting1.
The Mischief's clipping selector includes a Pulse Off position alongside its Symmetrical Silicon, Asymmetrical Silicon, LED and Germanium-Mix options1, and its three main knobs mirror the Gain, Volume and Filter controls of the original RAT pedals2.
Videos
Leon Todd
The Pedal Picassos
slyelessar
Questions
What circuit is the PastFX Mischief based on?
The Mischief is based on the ProCo Rat distortion circuit. Delicious Audio describes it as a RAT-style distortion featuring the original LM308 op-amp found in vintage RATs, and Guitar Pedal X counts it among the many takes on the ProCo Rat circuit. PastFX expands the original three-control layout with a four-way clipping selector, a three-way Bass switch, a Sizzle button and a Pulse Bypass.
What clipping options does the Mischief have?
The Pulse switch offers four clipping choices: symmetrical silicon, which is the stock Rat arrangement, asymmetrical silicon, LED clipping, and a Germanium-Mix option. A separate Pulse Off button takes the clipping out of the circuit entirely, a mode Guitar Pedal X notes roughly equates to the Deucetone Rat variant.
What does the Sizzle button do?
PastFX describes the Sizzle pushbutton as a control for extra bite. It sits alongside the Filter, Bass, Gain and Volume controls and the Pulse clipping selector, giving the player a quick way to add top-end edge on top of the chosen clipping mode.
Which op-amp does the PastFX Mischief use?
The Mischief uses the LM308 op-amp chip, the chip associated with vintage RAT pedals. Guitar Pedal X calls it the classic LM308 OpAmp chip at the heart of the pedal, and Delicious Audio likewise describes the circuit as featuring the original LM308 op-amp found in the vintage RATs.
How much does the PastFX Mischief cost?
Guitar Pedal X listed the Mischief at $175 USD in its 2024 best new distortion pedals roundup, and at $229 AUD from the PastFX webstore in its July 2024 review. A Guitar Pedal X buying guide from August 2024 gives the price as $175 / $135.
Who designed the PastFX Mischief?
Guitar Pedal X credits the design to Verlie of PastFX, describing it as another smart take on a classic pedal from the Australian builder, whose roster includes tweakable variations of well-known circuits.
Sources (5)
- Guitar Pedal X, Guitar Pedal X, 2024-07-10
- PastFX Mischief Distortion, Delicious Audio, 2024-06-27
- Guitar Pedal X, Guitar Pedal X, 2024-12-17
- Mischief LM308 Distortion, pastfx.com, 2026
- Guitar Pedal X, Guitar Pedal X, 2024-08-30
