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Hi there, welcome to my blog - La Revolution Deux. It's an odd name - but I like it! Here you will find all the info on my various DIY Guitar effects builds, amplifiers and guitars. Everything from a humble Ibanez tubescreamer to the holiest KLON Overdrive.

You may also find a few effects builds that I am looking to move on - usually in exchange for other effects/gear/cash. You can always check my ebay account to see what I've got up for grabs.

Have fun, enjoy the blog - Fred Briggs :-)


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Monday, 23 January 2012

Carl Martin - Plexitone

The Carl Martin Plexitone has been around for yonks (good word!) and has remained popular with it's high gain tones and wide versatility allowing the Plexitone to cover most bases required when playing anything other than Folk (Yuk) music.

Here's the description from the Carl Martin website:

"The Carl Martin PlexiTone, is as the name might indicate an unusual high gain three step rocket of an overdrive.The PlexiTone offers two step overdrive, the crunch channel and the high gain channel, on top of that it gives you an up to 20dB clean boost channel.
The crunch channel goes from subtle overdrive to hard rock gain stage, the high gain channel goes from rock gain stages to absolutely meltdown, with loads of gain and low end, and all in a tone that brings the memory back to the early 80's high gain guitar hero's.
The PlexiTone has as most Carl Martin pedals a built in regulated (+/-12V) power supply, to secure the necessary headroom that gives you the great tone."
Check out this comprehensive demo video of the Plexitone in action:

As you can see it sounds pretty nice. I bet you wanna know what's going on in there. Well here's the schematic provided by GnognoFasciani:

As you can see we've got the standard opamp type clipping circuit with a couple of LEDs in there to provide the distortion BUT with an interesting change - that dual +12v to -12v supply provided by the onboard transformer. This gives the pedal it's great headroom and dynamic appeal by ensuring that the opamp is never pushed into it's clipping region, this means all the clipping is done via the LEDs and not harshly in the opamp itself.

Here's a PCB layout by Bucksears:

As you can see he's used a voltage doubling circuit to supply the opamp with +/-18v - even more headroom! I like this, I like it a lot! Here's the link to the PCB transfer he produced: http://www.box.com/s/qe94dk4inkufhtk2nlid

And here's a link to the freestompboxes.org forum topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=1113


  1. Replies
    1. This is a schematic from a Plexitone unit that was traced.

  2. Hi....

    In the PCB schematic the list of components include 3 transistors that the PCB lay-out does not include....why is the reason ?

  3. Hi there , I was using the carl martin plexitone in India and due the electricity fluctuations I burned the transformer , hence I used a new one which was 220 V one instead of the original , Now I get a constant and a lound hum each time I kick in the drive fucntion any suggestions ?

  4. can you mail me you reply at asherjoe19@gmail.com

  5. This pcb doesent works


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