Trickfish | J-Core Jazz Bass Plate Preamp | Mike Pope-Designed FlexCore Circuit | 4-Band & Side Mount Jack

The Trickfish J-Core Jazz Plate Preamp brings the acclaimed Flexcore onboard bass preamp into a convenient drop-in Jazz Bass control plate format. Designed for players who want a serious active preamp upgrade without modifying their instrument, the J-Core installs into a standard Jazz Bass control cavity with no soldering required.

At the heart of the J-Core is the Mike Pope-designed Flexcore preamp circuit, known for its clarity, warmth, punch, and musical response. Available in either 2-band or 4-band EQ configurations, it gives Jazz Bass players a highly flexible tonal platform while preserving the familiar feel and layout of the instrument.

The 4-band version offers deep control over bass, low mids, high mids, and treble, with internally selectable frequency centres for each band. Rocker-style mini switches replace traditional jumper selectors, making it easier to fine-tune the EQ response to suit your bass, playing style, and preferred tone.

For players who prefer a simpler setup, the 2-band version provides powerful bass and treble shaping in a streamlined format. Both versions also include selectable output gain options, allowing you to set the preamp response and level to better match your instrument, amp, and signal chain.

The J-Core also retains the importance of a proper passive tone control, with a stock .022 capacitor and the option to customise the response with an additional through-hole parallel capacitor. Complete with a prewired output jack, battery connector clip, and preinstalled Jazz Bass control plate, the Trickfish J-Core is a premium upgrade for players who want active flexibility without losing the classic Jazz Bass identity.

Features:

• Drop-in active preamp for Jazz Bass-style instruments
• Based on the acclaimed Trickfish Flexcore onboard bass preamp
• Mike Pope-designed preamp circuit
• Available in 2-band or 4-band EQ configurations
• No soldering required
• Designed to fit into an existing Jazz Bass control cavity
• Includes prewired output jack
• Includes battery connector clip
• Preinstalled on a Jazz Bass control plate
• Internally selectable EQ frequency centres
• Rocker-style mini switches for easier internal adjustment
• Selectable output gain: 0dB, +3dB, +6dB, or +8dB
• Passive tone control with stock .022 capacitor
• Can be customised with an additional through-hole parallel capacitor
• Matte black knobs available as an option
• 2-band version available with top-mounted jack
• 4-band version available with side-mounted jack

Frequency Specifications:

• Treble: +/- 15dB at 6kHz or 10kHz
• High Mid: +/- 15dB at 600Hz or 900Hz
• Low Mid: +/- 12dB at 330Hz or 473Hz
• Bass: +/- 12dB at 46Hz or 90Hz