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

Note: This article is about an old, discontinued version of the L2A Reamplifier. The instructions below do not apply to the current kit.

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

Mount both output jacks in the chassis. This will keep the work steady and allow us to better gauge the wire lengths needed.
Trim the leads of the inductor and a length of black wire according to the distance between the jacks.
Place the 820pF capacitor between the two pins of the Passive jack.
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)
Solder the remaining leads of the inductor and wire to their respective pins on the switching side of the Active jack.

Comments

Alex on February 23, 2015 04:01

Hi, I want to try this to improve reamping results. Could I just use a spare single coil pickup instead of the resitor and inductor in your schematic? Seems that both inductance and resistance would then be ok by definition. So running the DI-recorded dry signal through an old pickup and use the cap to emulate high frequency roll off of the guitar cable?
By the way, in reamping situation, would this capacitor actually be necessary if the high frequency roll off has already been captured via DI-recording? The dry recorded signal will already contain less high frequency because it was recorded by the guitar with cable in the first place…
Thanks! Alex

R.A. on November 12, 2014 18:03

Hey Peterson, the mod was easy and I put it together in a matter of minutes. (Haven’t tested it yet though; I’m location recording all week and won’t be doing any reamping for a while.)

There’s a typo in your instructions on this page however. For step 3, that should definitely be an 820pF capacitor, not 820pF resistor. Of course it’s obvious from the context, but you’ll probably want to fix it to avoid confusion.

Cheers!

Peterson Goodwyn on November 12, 2014 18:03

Thanks for the correction. Glad to hear the build was a piece of cake.

Morten Andreasen on November 12, 2014 18:03

Hi. Have you considered making a 500 series edition of a combined LINE2AMP and the Passive Pickup Emulator Kit? I realise that this would add cost and it is strictly not neccecery since they are both passive units, but it would be great to have everything nice and tidy in a 500 rack. I would pay for a pre-assembled unit. BR. Morten

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