J-RETRO 01
Active/Passive Retro-Fit for J-Style Basses
Pre-Installation Checks
Pre-Installation Test Setup Diagram
- 1 Connect a 9v battery to the battery clip.
- 2 Get a high-quality audio player with a 3.5mm output socket and cue a track with broad frequency range.
- 3 Use the trailing test jack plug from the pre-amp to connect to your audio source.
- 4 Connect a mono instrument lead between the output jack of the preamp and the input of your bass amp or similar high quality audio input.
- 5 Add tests here to be defined.
- 6 Set the ACTIVE/PASSIVE switch (by the jack) towards the jack for active mode.
- 7 Turn up the Volume knob and test that sound is coming through your amplifier.
- 8 Test the Blend control by turning it fully clockwise (neck pickup) and anti-clockwise (bridge pickup).
- 9 Test the Bass, Treble, and Mid controls to ensure they’re functioning.
- 10 Try the Bright function by pulling the Treble knob.
Tools & Materials Required
- A small screwdriver (0.8 mm) for the screw terminals
- A soft cloth or chamois-type fabric to protect the instrument surrounding the cavity
- A Posi or Phillips crosshead screwdriver to suit the existing control plate screws
Installation Steps
- 1 Lay some soft cloth to protect the bass surrounding the cavity. Unscrew the 3 screws for the ‘bell’ plate on your bass and lift it out. Place the existing control plate assembly on the cloth.
- 2 Take several photos and make a note of where all the wires from the bass are connected to on the original plate so it can be returned to original later if required. Disconnect all the wires and remove the plate.
- 3 Make sure the J-RETRO 01 and its battery will fit in the cavity before connecting the wires.
- 4 Place the J-RETRO 01 on the leather or cloth protecting the bass and connect the wires using the screw terminals according to the connection diagram.
- 5 Clip the battery onto the battery clip and lay it into the cavity according to the diagram.
- 6 Before fitting the new plate make sure all the wires, including the battery wires, will not be trapped in any way by the circuit board or any other part of the pre-amp. Fit using the original 3 screws.
Connection Diagram – Side View
Battery Position – Top View
Need Help?
If you’re unsure about any part of the installation process, contact a qualified guitar technician or reach out to East UK for assistance at tech@east-uk.com
Website: www.East-UK.com
Specifications & Information
Overview
The J-RETRO 01 is designed to fit directly into standard “Jazz” style basses without modification, including a PP3 battery. Its high-quality circuit uses three stacked knobs and includes an active blend circuit plus a 3-band equalizer with bass, variable frequency mid, treble, and bright function.
Control Layout & Functions
VOLUME & BLEND
Volume (Upper Knob): Active circuitry after the volume knob provides a low impedance drive to your amplifier.
Blend (Lower Outer Knob): Continuously variable balance between pickups with progressive level compensation. Fully clockwise for neck pickup, fully anti-clockwise for bridge pickup. Midway position (with indent) gives equal mix.
Pickups Switch: Must be set pointing towards the jack for the Blend to function.
BASS & TREBLE
Treble (Upper Knob): Boost and cut control with central ‘flat’ position indented. (+12dB@3 kHz, -12dB@ 1kHz)
Bright Function: Pull the Treble knob for +8dB boost @7kHz.
Bass (Lower Outer Knob): Boost-only control. The frequency band of boost gets progressively lower as the boost is increased. (+15dB@50Hz)
MID LEVEL & FREQUENCY
Mid Boost/Cut (Upper Knob): Controls the amount of Mid boost or cut (+/- 12dB) at frequencies set by the Frequency knob. Midway indent is the ‘flat’ position.
Frequency (Lower Outer Knob): Continuously variable control that sets the Mid frequencies for boost or cut (150Hz – 3kHz).
ACTIVE/PASSIVE SWITCH
Location: By the jack output
Active Mode: Switch towards the jack – full functionality with active blend circuit and 3-band EQ.
Passive Mode: Switch opposite direction – basic “get-you-out-of-trouble” mode in case battery dies, but allows usable settings too.
Active & Passive Control Functions Diagram
Technical Features
- Active blend circuit prevents signal loss that occurs in many passive basses when both pickups are at full volume
- Switch allows for passive equal mix of both pickups
- Automatic power switching when mono jack is inserted
- PP3 battery compatible
- Direct fit for standard Jazz bass cavities
Pickup Gain Adjustment
Pickup Gain Adjustment Diagram
Warranty Information
Your East product is guaranteed to be free from defects in materials and workmanship for a period of one year from the date of original purchase.
- The original sales invoice or receipt indicating the date of purchase must be presented with any faulty unit
- The unit must have been installed competently according to the supplied instructions
- Damage due to accident, improper handling, installation or operation is not covered
- Transport or shipping costs are not covered
Proper Disposal
To dispose of electrical goods safely:
- Check local rules for specific laws about disposing of electrical waste
- Take old electrical items to a local recycling center
- If the item still works, consider donating it to another bass player
By disposing of your electrical goods properly, you help protect the environment!
