Randall Brahma module

Randall MTS Brahma module

Randall described the module as follows:

    The Randall MTS Series Brahma Guitar Preamp Module brings you mouth-watering classic hi-gain tone that represents George Lynch's signature rhythm sound. This preamp has the classic British voicing with signature American tone modifications. It's Lynch's variation of the vintage Plexi tone.


From new this module was noisy in my RM80 and positively squealed uncontrollably in my RM20C.  Early Randall MTS modules are know for having pots that develop cracks in their internal resistance tracks.  With this in mind, I disassembled the module and then re-inserted it into the amp so I could isolate which pot was causing the problems.  The gain pot was the one at fault.  It is a 1M log pot from Alpha (A1M designation).  Replacing the pot fixed my issues.

Randall MTS Brahma module top view of PCB with tube shield removed


The Brahma has an interesting combo of caps and resistors at the C3 position:

Randall MTS Brahma module C3 capacitor/resistor arrangmenet


Kapo_Polenton did the following to his Brahma:

    I started from a Brahma but the key is that the Brahma itself wasn't like the other Brahma that I have. This thing had no gain.. I also find it still has a few diff cap values in C7 and C13. R7 is gone (common gain mod mentioned here often) and I put a 100K in R14 like the Mr. Scary. Silver mica 100p on the tube board because my brahma was missing that too, .0022 in C8 and 100k in R22 like the scary. C3 is probably fairly important as it is the combination of resistors + caps that the brahma is known for and gives it that feel and tone I think.


I've traced out the Brahma module and drawn the schematic:

Brahma module schematic

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