J-Core-2B

Trickfish J-Core 2 Band Bass Preamp for Jazz Bass®

Measuring Tool Bullet IconDESIGNED FOR J BASSES WITH A TOP MOUNT JACK

Puzzle Bullet IconDIRECT REPLACEMENT FOR STANDARD JAZZ AND SIMILAR BASSES

Original Bullet IconBASED ON FLEXCORE W/TWEAKS FOR J BASSES

Configuration Bullet IconKNOBS INCLUDED

 

empty box iconFREE SHIPPING IN THE USA
configuration iconEXPERT TECHNICAL SUPPORT
checklist iconIN STOCK MEANS IN STOCK

 

 

DESCRIPTION

The J-Core preamp takes Trickfish's widely acclaimed Flexcore Onboard Bass Preamp to the next level - now in a hassle-free Jazz Bass plate drop-in design. No modifications, no soldering, just pure performance.

Powered by the incredibly flexible and supremely musical Mike Pope-designed preamp with a 2-band EQ, the J-Core puts tonal control at your fingertips.

All this, plus a 9-volt battery, fits neatly into your existing Jazz Bass control cavity. Effortless design meets exceptional sound.

A hallmark of a truly versatile Jazz Bass is its passive tone control. Some players prefer a subtle tone roll-off that preserves midrange presence, while others lean toward a darker, more classic passive tone. The J-Core comes stock with a .022 Cap and can be easily customized with an additional through-hole parallel capacitor.

For years, the Flexcore has set the benchmark for players seeking unparalleled fidelity, clarity, and warmth from their active instruments. Until now, however, it wasn’t available as a drop-in replacement for Jazz Basses.

With the J-Core, you can finally bring the renowned flexibility and performance of the Flexcore into the Fender universe — elevating your sound without changing what you love about your instrument.

CONFIGURATION

2 Pickup - 3 Knob (with top mounted jack)
Volume/Tone Stack - Blend - Treble/Bass Stack

TECH & SPECS

J-Core preamp kit includes:

  • Prewired Output Jack
  • Battery Connector Clip
  • Preinstalled on a Jazz Bass Control Plate
  • Black Aluminum Knobs (2 Stacked & 1 Single)


FREQUENCY SPECIFICATIONS

  • Treble: +/- 15dB at 6kHz or 10kHz
  • Bass: +/- 12dB at 46Hz or 90Hz


FREQUENTLY ASKED QUESTIONS

Will the Trickfish J Core 2 fit in the Squier Affinity Series Jazz Bass VI?

Yes.



Customer Reviews

Based on 6 reviews
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J
John D.
J Core 2 band pre for Jazz Bass

I installed this on a Lakeland DJ5 Skyline. The improvement in tone is phenomenal. The single coils are the originals that came factory installed on the bass. They sounded decent but left me wanting. I was looking to replace the pickups but decided to try this route first. Glad I did. Of course, the single coils are now dead quiet (the noise was getting to me), but moreover the tone is now rich, punchy, deep and full. It's awesome to have both tone control and stacked treble and bass. The neck pickup is full on in P territory with tone rolled back and using both with a slight favor to the bridge gives me the punchy openness that I love on a Jazz bass. Bridge pickup soloed cuts the mix extremely well and has the growl and bite that was missing before. I'm not sure if I'll upgrade the pups now or not. Loving this tone.

Couple of things- the Lakeland Jazz plate is not same as Fender, so until I drill the original plate to accept the mini switch, it's a little funky on the install. This is purely cosmetic as the alignment is slightly off.

Be careful attaching the pickup hot and ground leads. I errantly had a ground installed into a 9V attachment meant for jumping active pups. I contacted FBT and talked with Max (promptly returned my call) prior to talking with Max I found my error and everything was golden. If you do make this wiring error you'll get scratchy pot sounds in the blend knob and a static pop when toggling on and off the active circuitry.

FBT is my go to site for bass pickups, harnesses and preamps. The guys are outstanding on customer service support. Thank you!

J
Jodie H.
Trickfish 2band J Bass Pre-Amp

I purchased the Flexcore Mike Pope pre amp a few years ago for My used Fodera bass. It’s fantastic! So when I saw they were doing one for the J Bass I was on Board.
I purchase the Trickfish 2 Band J Bass preamp. Installed it in my Frankistien j bass. Instant improvement in the sound I was looking for, although I miss the midrange tone control that the flexcote has.
Overall I would recommend this preamp as it requires no cutting or modifying my bass. I’m not a lurthier, but even O’l thumbs Jodie installed it without a problem. The biggest thing though is the people at Fat Bass Tone. They sell the best products, are extremely well informed on install, and advise before you make stupid decisions. I am purchasing from them from now on. They will insist your happy with all purchases.

Regards Jodie Hill bassist

R
Rafael

Absolutely the best upgrade for a jazz bass . Unbelievable how awesome this preamp is . The highest quality and Super easy install as well. Put this in my Fender Custom shop 66’ Jazz bass keeps the passive tone i love and then ive got the clean punchy tone of the Trickfish magic !

M
Michael G.
Trickfish J-Core 2 Band Bass Preamp for Jazz Bass

Instantly improved my tone. The five minute install couldn't have been easier. Thanks

T
Thomas M.
Solid

Installed in a G&L Pancho Tomaselli and it sounds great. Great to me means a variety of different tones. There is a lot of room for tiny, or very large, tweaks, which I love. So that's what makes it great for me.

The volume pots work really well, super duper fine tuning on both of the volume controls. The blend, middle knob, so far, I tend to keep it directly mid, in perfectly blended position. The best tweaking for this knob is a little out of straight middle. That way you can really hear the blend and how it really effects your tone. All the way, one way or the other is dramatic tonally. Which, you might be going for. However, I feel like the blend knob should not be trifled with. Again, great for me. Thank you Trickfish! And thank you FatBassTone.com! Thomas, Bull Island Instruments, Poq., VA 23662

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