Logical Bass Pre-Amp

A great tone shaper for your bass.

Keeping it reasonably simple with a 3-band EQ and 20dB of boost. The onboard charge pump gets you all this lovely headroom from a standard 9V supply.

There are a couple of toggle switches on here too. One to adjust mid range, the other to adjust the input impedence to suit passive or active instruments. We're making this optional. Why not?

Due to the positioning of the switches they can't be secured to the enclosure with nuts. The board-mounted pots will hold everything nicely in place, so they aren't necessary. If you're uncomfortable with that you can choose to wire the AC/PAS switch offboard to allow space for nuts.

The kit is supplied with vertical-mount pots which have round shafts, so you'll need set-screw fitting knobs. Keep them small as the pot spacing is only 17.5mm.

If you want the PCB without parts there's a link for that at the bottom of the page.

Partial kit: PCB, all board-mounted components, pots.

Full kit: As above, plus footswitch and appropriate daughterboard/components for your selected bypass type (see Downloads section for details of those), jack sockets, DC socket, battery snap, hook-up wire, LED.

Enclosure (pre-drilled) is available as an option with full kits, and will take a battery. Knobs are not included.

Builds are only available with full kits including enclosure and vertical-mount pots. Please choose appropriate knobs.

Inspired by: Logical Bass Preamp

Difficulty: Easy-Medium

PCB size: 50 x 50mm

Knobs required: 5

Enclosure: 1590B

Direct-Connect compatible (4-way)

Check Specials for powder-coated enclosure availability.

Download the INSTRUCTION PDF