18V Mod
The EMG 81 power source can be modified from 9V to 18V by adding a second 9V battery wired in series. This increases the headroom of the pickup and decreases distortion, particularly with regard to transients. Although the majority of EMG's pickups are rated for 27V operation, they recommend a maximum of 18V, citing the negligible performance increase.
There are two main ways to perform this modificaiton. One method involves using separate battery harnesses for each battery. There are several different ways to achieve this, and wiring diagrams can be found all over the internet. The other involves using a separate 9V snap leading to the control cavity to wire two batteries in series outside of the battery compartment.
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