How to Add a Guitar Pickup Emulator to Your LINE2AMP July 25, 2012 14:46 4 Comments

The PPE mod equips your LINE2AMP reamping kit with a classic, single-coil pickup output which, in addition to providing a new tonal option, allows it to interface more "authentically" with vintage guitar amps and effects.

While browsing Jack Orman's excellent "Lab Notebook" series, I came across his drawing of a simple guitar pickup emulation circuit. This article and the Passive Pickup modification for the LINE2AMP are greatly indebted to Orman's article. There are three electrical properties we must recreate to mimic a guitar pickup: inductance, impedance, and capacitance. Accordingly, our passive emulator circuit consists of only three components--you guessed it: an inductor, a resistor, and a capacitor. Together, these components form an low-pass filter with a resonant peak that is largely responsible for the unique tonal signature of a passive pickup. Passive Pickup Emulator Schematic

The component values in the LINE2AMP (pictured above) recreate the performance of a standard single-coil pickup. The inductor and capacitor set the cutoff value for the low-pass filter at 5.5kHz, while the resistor damps the ringing of the resonant peak. This creates a filter with a smooth bump around the resonant frequency and a gradual LPF after.Passive Pickup Frequency Response

Approximate Frequency Response

Performing the Passive Pickup Mod

A note on the pictures: While the pictures show the jacks oriented with their pins facing the lid of the case, it's better to position them sideways so that their pins point toward each other, facing the center of the case. This ensures that they will not short against the metal case.
Begin by building your LINE2AMP according to the assembly instructions. The output jacks included in your kit are switching, meaning they contain two sets of terminals which are connected when the jack is unplugged and disconnected when the jack is plugged in. The stock output is the "Active" jack. We will connect the "Passive" jack to the switching terminals of the Active jack via the 1H inductor and hookup wire. When the Active jack is plugged in the connection to the Passive jack is broken, so both outputs cannot be used at the same time.Passive Pickup Assembly
Illustration 1
  1. Mount both output jacks in the chassis. This will keep the work steady and allow us to better gauge the wire lengths needed.
  2. Trim the leads of the inductor and a length of black wire according to the distance between the jacks.
  3. Place the 820pF capacitor between the two pins of the Passive jack.
  4. Place one of the inductor leads in the Tip pin and one end of the black wire in the Sleeve pin of the Passive jack. Solder the inductor, capacitor, and wire in place. (Illustration 1)
  5. Solder the remaining leads of the inductor and wire to their respective pins on the switching side of the Active jack.