Plexi SE PCB

Two Amps

The Plexi SE PCB (SE stands for Single Ended) is a circuit board for use in a low wattage tube guitar amplifier. It runs a 6V6 power tube in single ended configuration so the output power is rated for around 5 watts. The pre-amp is driven by two 12AX7 tubes, which can be configured to clone the pre-amp of two historically significant Marshall amplifier circuits. Depending on how you configure the amp, the Plexi SE PCB can have a:

  1. A Plexi (aka 1959 Super Lead) preamp
    The Plexi configuration has two channels, bright and normal, one input, and a full tone stack (treble, middle, bass). Since it only has one input jack, the Plexi SE PCB ties the Normal and Bright channels together similar to jumpering the inputs. The Volume I (Bright) and Volume II (Normal) channels both serve along with the tone stack to dial in a WIDE range of tones.

    The bright and normal channels allow the use of various guitar styles. Of course humbuckers work well, but the Plexi accomodates single coil pickups, too. Just add some of the normal channel to fatten up the tone and increase the bass response.

  2. A High Gain Cascaded (aka JCM800) preamp.
    The Cascade configuration is essentially a one trick pony - rock and metal. It has one channel that feeds into three gain stages. The circuit is equipped with a Gain control (Volume I), a full tone stack (Treble, Middle, Bass) and a Master Volume (Volume II). The master volume allows you to dial up the distortion with the preamp gain while keeping your playing volume at reasonable levels.

Build Information

What All Do I Need? Sorry, but we do not sell the complete kit. We focus our efforts on the design, development, and production of quality circuit boards for use in guitar amplifiers. So all we sell is the circuit board. But a circuit board does nothing on its own, right? That's why we've published all of the supporting documentation to guide you through the entire process; from an itemized parts list to an illustrated build manual. Refer to the Build Information support page for all of the technical stuff.


The quality of these boards is superb. With the construction features listed below, this board will take plenty of abuse and is sure to stand the test of time.

  • 1/8" thick board material instead of the usual 1/16"
  • double sided copper layers
  • 2 oz. copper layers
  • full board ground plane
  • plated through holes
  • ventilated socket mounts
  • detailed artwork indicating component number and value
  • RoHS compliant

The boards have a blue solder mask with white silkscreen layer for the component labeling and artwork. Refer to the Plexi SE support page for all of the supporting documentation. Scroll down to the bottom of the page to buy this PCB!

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