Wednesday, July 13, 2016

Feeding the buzz.

Nathan dropped by with his Ibanez RG series guitar. Last year we dressed it up with some gold hardware and a new Floyd Rose tremolo.  At the time we swapped out his pickups for a pair of used Ibanez humbuckers that were never quite satisfactory. Over the years Ibanez has come up with countless combinations of pickups and there is a dizzying array of wiring schematics on the web, not all of them useful.  Some require specialized model-specific switches to allow combinations of coil splitting, and series/parallel output.

As it turned out, the two humbuckers he'd acquired were designed for use in a model with a single coil in the middle position. They worked fine with a three position switch but in a 5-way situation they produced weird, buzzy, low-output tones.  It seems as if they were designed to always employ the now-nonexistent single coil in the circuit to boost the signal. 

For quietest possible operation, here's a thorough shielding job involving copper tape in every cavity. Recently I've been trying something new.  Shielding wisdom promote the idea of "star grounding", wherein every grounding wire is run to a common point connected to the ground lug on the output jack.  This reduces ambient hum from induced grounding loops.

 Most often the back of the volume pot is specified as the common point. This poses some challenges. There can be upwards of 7 different wires leading to the same surface, and the heat required to melt the solder and get a good joint on one wire will often loosen another! Very annoying.  It also complicates things if you need to switch out the volume pot.  I've been adding a screw near the pot to which I attach all the "permanent" wires from the different shielded cavities, the bridge and so on.  Encapsulated as it is within the copper cage, there seems to be no audible increase in hum.
We replaced the pickups with H4's from EMG, which looked right at home in the Ibanez.  The sound of the H4A alnico in the neck position was particularly gratifying and Nathan was very happy with the results.

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