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The Mercer Box 

mercer box: an INTRODUCTION:

With The Mercer Box, I propose a time passage to the moment when a germanium distortion was plugged into a plexi Marshall for the first time. Not only this box is fuelled by 2 tone-selected New-old-stock AC128 European germanium transistors, but it emulates the sound of a vintage plexi Marshall amp behind. Of course , this pedal is 100% made by my own hands, and use point-to-point wiring and true by-pass heavy-duty switch.


When it comes to obtain the marvellous Jimi sound, germanium fuzz face is on every mind. But , these original relics are very rare , expensive and....disappointing. Their sound is very far from the heaven distortion which was Jimi's trademark. The reasons are multiple:

-It seems than most of the fuzz face used by Jimi were Roger "The valve" Mayer's one-of-a-kind designs hidden inside empty fuzz face boxes. Roger Mayer recycling make very difficult any tracing of the actual design Jimi was playing into.You must read the Roger Mayer interview about this HERE

-These custom boxes were plugged into original 100w Marshall plexi. And these amps were used for their power in those ancient times when P.A. was in its infancy. This means that the amp distortion was always part of the sound.

-Last but not least, Jimi's hand made the final difference.


"I have been working on this equation for more than 5 years now, until I recently realise that without incorporating the Marshall response inside the pedal I could go nowhere. That Fuzz Face add saying " Natural amp distortion will enhance the Fuzz Face tone." was true.

I am, like most French guitarists of my generation , a fan of the sci-fi American author Philip Kindred Dick. If you read " Do Androids dream of electric sheep?" , you will find what a Mercer Box is. ( Do not rent the "Blade runner" movie because this essential part of the book has been simply removed. )

With this philosophy, I tried to work more on empathy than on logical thinking. I did not work on modelling a Marshall, but on discovering how germanium interacts with big valve amps harmonically wise, how the natural smoothing of the maxed valves tames the scorching power of a wild fuzz, how all this made possible the marriage of tube amps beauty and transistor distortion beast.

Of course, the amp you will plug in is still an important factor but you can obtain this tone on any existing rig, which is not the case of the original fuzz face.

Now, just like in the K.Dick book, close your eyes and plug mentally into Jimi's rig.


Besides classic volume and fuzz pots, The Mercer Box features the HATE and LOVE controls. ( HATE is left pot, LOVE the right one ).Classic "fuzz face on plexi" sound is obtained with HATE on 0 and LOVE on max, like the arrows suggest.It is up to you to change this settings to dial in less conventional sounds.

If you max everything up, HATE, FUZZ and LOVE, you will get an octave-up solo sound which will set you apart from all the other guitarists.


The Mercer Box can be used in conjunction with your favourite distortion/overdrive pedal to "plexi" your sound. Once again, it is not a modelization of a Marshall amp, but an attempt to emulate the union of transistors and valves. Settings for a Strat will be provided in the instructions.


If you are now curious , you can click HERE to reach the AUDIO DEMO of the mercer box

For more info on the mercer box , contact me at


For those tech heads , I have made a webpage about this wonder transistor, classifying the different types of existing AC128 germanium transistors, as well as a data sheet. It's HERE


The “Mercer Box” name comes from a PHILIP K.DICK (1928-1982) book “Do androids dream of electric sheep ?” (1968) , better known from the Ridley Scott movie adaptation “Blade runner” starring Harrison Ford and the beautiful Sean Young.

It is the Wilbur Mercer empathy box that started the Mercer Box concept. Exchanging the two handles with input and output jack plugs, the mystical experience of Wilbur Mercer became the mythical Jimi Hendrix Experience set-up.
It is worth noting that both events took place at the same year,

I strongly advice to buy this essential book, as this essential part was omitted for the movie adaptation.

Nearly all other Dick books are masterpieces but only the uncanny “The three stigmata of Palmer Eldritch” (1964) will immerse you in a no-return alternate world of Perky Pat doll and her Martian adepts.

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