Jazz Bass Hum Cancelling Dummy Coil



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Legacy (Discontinued) Product

Jazz Bass Dummy Coil Summary:

Suitable for use with Ironstone or other Jazz Bass pickups, this Jazz Bass Hum Cancelling Dummy Coil system is designed as a simple retro-fit to overcome the frustrating mains hum that conventional Jazz Bass pickups suffer from.
Assuming your guitar uses two standard RWRP pickups arranged with two standard volume potentiometers, then a straight-forward 2 wire installation of the Ironstone dummy coil system will eliminate nearly all of your unwanted hum from every combination of the two volume controls.
The Jazz Bass Hum Cancelling Dummy Coil system is easy to install with just some basic soldering skill, following the supplied photo assisted instructions.
Please note: The price above is the UK total price including standard Royal Mail postage. Non UK customers will be advised of an additional small postal charge during the checkout process.

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Jazz Bass Hum Cancelling Dummy Coil

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

Product contents;
1 x Dummy Coil ready to wire in
Self adhesive mounting pads
Full installation photo instruction sheet

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.

Jazz Bass related links:

For all things Bass check out Basschat, the UK Bass Guitar players forum.
And check out Fender’s own Jazz bass Forum

Dummy Coil Compatibility

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.


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