Benson Portable Distortion 424 MKII Pedal

The Benson Portable Distortion 424 MKII is a distortion pedal based on the preamp circuit from the Tascam 424 MKII cassette recorder — specifically the slow, low-fidelity op-amp design that gave those machines their characteristic sound. Benson adapted the channel strip circuit for pedal use, keeping the unusually low input impedance that loads down a guitar pickup in a way that shapes the tone before any clipping happens.

The gain range is wide. At lower settings it functions as a clean boost; pushed further it moves through overdrive and into fuzz territory without losing coherence. The onboard EQ is genuinely useful across that range, not just a tonal afterthought. Internal voltage doubling provides 18V of headroom, which gives the circuit more dynamic range than the power supply voltage would suggest.

Lo-Z / Buffer Switch

A side-mounted switch toggles between two input modes. In Lo-Z mode (switch out), the pedal runs at its native low input impedance — best used first in the signal chain for the most characteristic response. With the buffer engaged (switch in), the input impedance is normalized and the pedal can be placed anywhere in the chain without loading issues.

Controls

The control tapers follow the original 424 MKII hardware, which means they don't behave like standard audio-taper pots. The trim knob in particular works differently than expected — this is intentional, carried over from the source unit.

Specs

Power: 9V DC, center negative, Boss-style barrel connector
Current Draw: ~30mA
Internal Headroom: 18V
Battery: Yes (activated when input cable is plugged in and no DC supply connected)
Note: Do not exceed 9V DC.
Made in the USA.