Few amplifiers have achieved the near mythic status of the Marshall JCM 800. When it first roared 
to life in the early 1980s, it didn’t just define an era - it ignited it. Kicking off a new generation of 
tones, the JCM 800 became the definitive voice of hard rock and heavy metal. Big, aggressive, and 
unmistakably British. It took the foundational crunch of the Plexi and added the gain, punch, and 
focus that powered a generation of guitar heroes. 

Marshall JCM 800 2203 (100w) and 2204 (50w) circuits, with their single channel, cascaded gain 
stages, and signature midrange roar, delivered a level of authority and articulation that set them 
apart from anything before or since. It was the perfect balance of power and precision. For 
countless players, the JCM 800 isn’t just an amplifier - it is the amplifier. 

Now, Synergy and Marshall have teamed up once again to bring you, for the first time ever, this 
legend in a three-tube, dual-channel preamp module. Utilizing Marshall’s original circuit design, the 
JCM 800 module delivers the raw energy, attack, and articulate overdrive of the iconic vertical
input 2203/2204 amplifiers. Whether you’re chasing the three-dimensional crunch of 80s rock or 
crushing tight gain for modern metal, the JCM 800 module gives you the legendary tonal experience 
that defined a generation.  

DUAL-CHANNEL, THREE-TUBE PREAMP  
Each of the JCM 800’s two identical channels feature independent Preamp, Bass, Middle, Treble, 
Presence, and Volume controls, giving you complete command over your gain structure and tonal 
response. From dynamic low-gain crunch to saturated high-gain sustain, the JCM 800 module 
delivers every nuance of the original amp’s voice. Independent Master Volume controls for each 
channel allow you to precisely balance rhythm and lead levels with all of the amp’s dynamic 
character and harmonic complexity.  

THREE-TUBE MODULE WITH BUILT-IN 0-WATT POWERAMP - A SYNERGY FIRST  
The JCM 800 module introduces Synergy’s revolutionary three-tube architecture - a first in modular 
preamp design.  
Beloved by generations of players, the original JCM 800 truly came alive when cranked, thanks to 
the magical interplay between its preamp and power amp stages. Synergy has now captured that 
same raw energy and unmistakable feel in a compact, modular form. Two 12AX7s drive the preamp,  
while a third 12AX7 powers the built-in 0-watt amplifier and phase inverter. With the JCM 800 
module you get the sag, feel, and harmonic bloom of a fully cranked JCM 800 head - at any volume.  
The JCM 800 module delivers the authority, grit, and edge that made this amp an icon in rock 
history, while propelling Synergy’s modular platform into bold new sonic territory.  
BRIGHT & HIGH/LOW INPUT SWITCHES  
Expanding on the original amp design, the JCM 800 module provides additional flexibility with two 
key features:  
• Bright Switch: A three-position toggle switch selects between two bright cap values or 
removes it entirely. This lets you tailor the attack and clarity of the preamp stage - from 
tight and biting to warm and smooth. It’s just like modding the bright cap on a vintage 
2203, without touching a soldering iron.  
• High/Low Input Switch: Faithfully replicates the dual input jacks found on the original JCM 
800, toggling between the high-gain “Lead” input and the lower-gain “Normal” input. This 
lets you instantly move from punchy, classic crunch to saturated modern drive.  

CATHODE SELECT FUNCTION  
The Marshall JCM 800 module features a three-position switch on the PCB, which allows you to 
configure the input tube bass response to match the original circuit of the selected module. These 
settings affect the feel and tightness. Each amp designer has a specific combination of components 
that make up their input tube circuit. We have selected the three most popular combinations which 
you can access with this switch: position 1 (1.5K resistor and 22uf capacitor), position 2 (2.7K 
resistor and .68uf capacitor) and position 3 (1.8K resistor and 1uf capacitor). Of course, you can 
experiment and try any position to see which you prefer. The JCM 800 module is preset to the 
center position (2.7K resistor and .68uf capacitor).  
Synergy hardware and interchangeable preamps are protected under US patent.  

The JCM800 module will only work in SYNERGY hosts (SYN-1, SYN-2, SYN-20IR, SYN-30, SYN-50). 
IT WILL NOT WORK IN ANY OTHER HARDWARE FROM OTHER MANUFACTURERS. 

MODULE FEATURES:  
• Authentic three-tube preamp based on the legendary Marshall JCM 800 (2203 / 2204 
Vertical Input)  
• 3 x 12AX7 preamp tubes for full harmonic complexity and dynamic response  
• Built-in 0-watt power amp and phase inverter for true amp-like feel  
• Two identical channels, each with: Preamp, Bass, Middle, Treble, Presence  
• Independent Master Volumes for rhythm/lead  
• Bright switch (three-position) adjusts bright cap value for tone shaping  
• High/Low Input switch replicates original JCM 800 input behavior  
• Cathode Select switch on PCB for adjustable tube response  
• Easy to install and remove from Synergy preamp docks