Pro Co Sound FATRAT Distortion Pedal with MOSFET and FAT Tone

In this review the Pro Co Sound FATRAT Distortion Pedal is assessed for players wanting the classic RAT character with more tonal flexibility; the single biggest reason to buy is its selectable clipping and FAT mode that adds a thicker low end while keeping the historical RAT bite. The reviewer found the FATRAT useful for both guitarists and bassists who need a familiar distortion palette plus an option for smoother upper mids via the MOSFET clipping. Build and component accessibility also stand out thanks to the socketed op-amp for easy swapping and the pedal's US construction.

Key Features

• Selectable Clipping: Switch between the original RAT clipping and a new MOSFET circuit to choose between classic grit and a more amp-like, smoothed upper mid response.
• FAT Mode: The FAT selection increases bass response for a thicker tone, useful for bassists or guitarists who tune down for extended range styles.
• Socketed Op-Amp: A socketed op-amp lets users change chips without soldering, enabling easy tonal experiments beyond the stock OP07DP.
• US Manufacturing: Built entirely in the United States, the pedal feels solid and consistent in quality compared with earlier RAT models.
• Wide Voltage Range: The pedal accepts nine to 18 volts DC, offering more headroom and the ability to dial in cleaner or more dynamic response.

Who It's For

The FATRAT is ideal for electric guitarists who like the classic RAT voice but want more tonal options, and for bass players seeking a distortion pedal with enhanced low end and the ability to retain definition. Players who swap op-amps or experiment with different clipping types will appreciate the practical design choices aimed at customization.

Those who should look elsewhere include musicians who need a compact pedalboard footprint or the simplest possible stompbox, since a few customers have noted the pedal is larger than some other compact drives. If absolute minimalist controls are preferred, a single-mode boutique distortion may be a better fit.

Pros & Cons

Pros

• Multiple clipping options deliver both authentic RAT bite and a smoother MOSFET tone for greater versatility.
• FAT mode provides a noticeable bass lift that works well for down-tuned guitars and bass guitar applications.
• The socketed op-amp makes tonal experimentation easy without soldering, extending the pedal's useful life for tone geeks.

Cons

• Size: a few users mention the pedal is a bit big for tight pedalboard layouts.

Specifications

Model	FATRAT Distortion Pedal
Clipping Options	Original RAT or MOSFET clipping
FAT Feature	Selectable bass enhancement for thicker tone
Op-Amp	Socketed (stock OP07DP, user-replaceable)
Power	9 to 18 volts DC
Country of Manufacture	Built in the United States

Our Verdict

The Pro Co Sound FATRAT is a strong choice for players who want the classic RAT personality with modern flexibility; its selectable MOSFET clipping and FAT mode expand the pedal's usable range while the socketed op-amp invites customization. It represents good value for musicians who prioritize tone variety and durability, though those needing the smallest footprint should check dimensions before purchase.

Frequently Asked Questions

Can I run the pedal at 18 volts?
Yes, the FATRAT supports nine to 18 volts DC to increase headroom and dynamic response.

Does the FAT switch work for bass guitar?
Yes, the FAT selection increases bass response and is specifically useful for bassists and down-tuned guitars.

Can I change the op-amp myself?
Yes, the pedal includes a socketed op-amp so users can swap the stock OP07DP for other compatible chips without soldering.