These Jazz Bass pickups, like the Ironstone Stratocaster & Telecaster range, are based on Alnico V magnet Pole Pieces for warm vintage tone. They feature resistances of 7.3K (bridge) and 7.1K Ohm for a balance of full authoritative bass, but with crispness in the tone to stand out in the mix. Their classic construction includes traditional fibre flat work bobbins and flat pattern Alnico pole pieces, spaced at 63mm (neck) and 65mm (bridge). To complete the vintage appeal, a generous length of waxed cloth (‘push-back’) connection cable is fitted.
The pickups are configured as RWRP configuration, i.e. noise cancelling when selected / blended together. They are wax potted to reduce microphonics.
Standardly supplied with a fully comprehensive mounting kit of screws, springs, 2 lengths of self adhesive foam to attach under the pickups to support the mounting and a length of latex tubing. Simply cut this tubing into appropriate lengths for your instrument (approx 1cm), and use an alternative to the conventional springs, providing a firm yet adjustable mount.
Please note some Jazz Bass pickups come in differing physical sizes. These are 95mm (Bridge) and 91mm (Neck) long.
The wiring colour code is;
Bridge pickup: Yellow = signal , black = ground
Neck pickup: White = signal , black = ground
Jazz Bass Hum Cancelling Dummy Coil Sound Clips:
The following sound clips give a sense of the hum reduction based on a test guitar where the dummy coil is able to be switched in and out. Note, a normal installation would have the dummy coil permanently wired (so no switching noise). The recordings were made with the test guitar laying flat, giving the highest level of background mains hum (try this yourself!).
Version 1 starts with the dummy coil off and a note played. After the note has faded, at 14 secs the coil is switched on giving the significant reduction in background hum. At approximately 25 seconds, the coil is switched off giving the jump in background hum.
Version 2 is the reverse of version 1. It starts with the dummy coil on and a note played. After the note has faded, at 12 secs the coil is switched off giving the significant increase in background hum. Another is played (24 seconds) and then at approximately 35 seconds, the coil is switched back on, giving the hum cancelling effect.
Jazz Bass related links:
For all things Bass check out Basschat,
the UK Bass Guitar players forum.
Dummy Coil Compatibility & Installation
The Ironstone Dummy Coil system is designed to work with a standard Jazz Bass wiring and pickup configuration.
Your Jazz Bass should have the following criteria;
1) It should standardly wired with 2 separate volume potentiometers, one per pickup (rather than a single volume and blend control).
2) Your existing pickups need to be Reverse Wound Reverse Polarity (RWRP). That simply means that with both volume controls at full, the existing pickups hum cancel. Ironstone’s own pickups and the majority of Jazz Bass pickups are built this way.
3) Space requirements;
The dummy coil is designed to be mounted ‘under’ the 3 control potentiometers, either attached to the base of the 3 potentiometers via the supplied sticky pads or mounted on the base of the control well. Either approach requires there to be a clear space between the bottom of the potentiometers and the bottom of the control well of 20mm.
Jazz Bass Dummy Coil Installation:
The Ironstone Jazz Bass Dummy Coil comes with simple to follow wiring and installation instructions. The dummy coil is specifically designed to work with standard Jazz Bass pickup and wiring configurations. Please check the compatibility tab on this page before purchasing.
The connection configuration of the dummy coil in a standard Jazz Bass set-up ensures that hum cancelling occurs in all levels of pickup volume blend. So either pickup selected at any point of the volume control on its own, all the way to both pickups on full volume (in which case the dummy coil is effectively removed from the circuit leaving that hum cancelling setting the same as before the coil installation).
What will be evident is a reduction in the overall volume of the guitar output for any given volume control setting. This is a by-product of the coil removing unwanted signal. Simply turn your amp up a little to compensate.
It is entirely possible to have the dummy coil configured via a switch so that it can be switched in and out of circuit as you want. But for most installations, the dummy coil would typically be hard-wired under the control plate.
1 x Dummy Coil ready to wire in
Self adhesive mounting pads
Full installation photo instruction sheet