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This is our old projects area, and is provided for reference. If you're starting on a new build, please click on one of the other projects areas to your left

This project is undergoing maintenance. Some files may be missing or out of place while this is being completed.


The P1 eXtreme is an evolution of the P1 amplifier which pushes the original design out to the limits and part way into HO territory, while keeping the essential simplicity of the original P1,with the idea of seeing see how far you could go with just two tubes. It does this by increasing the preamp gain, with the preamp voiced for optimum signal swing and distortion, adding a master volume control and then an octal power tube running at higher rail voltages for a ?bigger? sound. One of the great features of this amp is the way the sound can be varied on the Gain control between clean to edge of breakup, mild bluesy P1-style overdrive, and on to full classic Marshall-style crunch. With hot humbuckers or a boost pedal and the gain control cranked, you can even get metal sounds. The amp is also very touch-responsive, and you can easily vary its tone on your guitar's volume control. Variations of the P1 eXtreme have also been built with pre-boost stages and reverb. Like the standard P1, this is an ideal first build project, and it's a great amp to gig with too.


  • High voltage-gain, specially voiced preamp provides rich preamp distortion and drives output tubes hard
  • Can be used with most octal power tubes, including 6L6, 6V6, EL34, KT66, KT88, 6550 for fatter tone. Just adjust bias resistor and output load impedance to suit. The bigger tubes can provide giggable volume levels.
  • Gain and Master Volume controls for a wide range of tones and sound levels, with variable proportions of preamp and power amp distortion
  • Similarity to regular P1 means that it can be built using any common P1 layout, with only a few minor differences to take into account
  • Gain boosted and reverb versions.

Thanks go to Chris Hurley and the AX84 community for the original P1, and support during the coming together of the P1 eXtreme. Special thanks also to NeatPete, MattH, ToneMonkey and Bobby (daschnoz) Kirbos for their involvement in the project, as well as to Paul Ruby and Doug Hammond for some inspirational ideas.

Note! The P1 Project page has some materials that may be useful to Hi-Octane builders as well, such as a theory document and a terminals trip drilling suggestion.

A Kit for this project is available... Please visit

Project Coordinator: Chris Hurley --- Skill Level: Beginner/Intermediate --- Status: Ready to Build
Primary Documents:
•ADOBE ACROBAT DOCUMENT: Rev 05.11.23 (11/23/2005 of the P1, P1-eXtreme, Hi-Octane Build Guide : [download]
•ADOBE ACROBAT DOCUMENT: Rev 06.03.16 (03/16/2006) of the P1-eXtreme bill of materials : [download]
•ADOBE ACROBAT DOCUMENT: Rev 06.03.16 (03/16/2006) of the P1-eXtreme Schematic : [download]
•ZIP ARCHIVE: Rev 06.03.16 (03/16/2006) of the P1-eXtreme templates and layouts : [download]
•ZIP ARCHIVE: This archive contains all of the primary documents for revision 05.11.23 of this project : [download]

Variation Schematics:
•SCHEMATIC: Bobby Kirbos' variable cascode boosted P1-eX : [download]
•SCHEMATIC: BOM for the rev 2 P1-eXtreme (for reference only- superceded by newer version) : [download]
•SCHEMATIC: Brian Schmittling's Super-eXtreme variant. schem, BOM and pic : [download]
•SCHEMATIC: P1-eXtreme layout drawing from Nik ( (for reference only- superceded by newer version) : [download]
•SCHEMATIC: Rev 2 of Phil's P1-eXtreme Schematic (for reference only- superceded by newer version) : [download]

•MPEG AUDIO: Bobby Kirbos' cascode-boosted P1-eXtreme (max gain) : [download]
•MPEG AUDIO: Bobby Kirbos' cascode-boosted P1-eXtreme (moderate gain) : [download]
•MPEG AUDIO: Bobby Kirbos' P1-eXtreme at Max Gain : [download]
•MPEG AUDIO: Bobby Kirbos' stock P1 eXtreme with 6L6 - dirty : [download]
•MPEG AUDIO: Chris Hurley spends a couple of hasty minutes with Brian's Super eXtreme (11/17/04, EL34, 412 cab, Samick RL/3) : [download]
•MPEG AUDIO: Clip of Maccabee's clean p1-eXtreme : [download]
•MPEG AUDIO: John Dixon playing Phil Rowley's original prototype version, with an EL34 : [download]
•MPEG AUDIO: Maccabee's P1-eXtreme with 6V6 - dirty : [download]

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