click on any photo for A larger picture)

Click here to go to Build Index

This page details the construction of an AX84 High Octane style amplifier:


  • Hi-Gain 12ax7 Preamp

  • 6BQ5/EL84/SV83 Power Tube in Class-A Single Ended Configuration provides a surprisingly loud 5 watts or so of output power

  • Cathode-follower driven Bass, Mid and Treble tone controls allow you to shape your sound. Alter the values of the components in the tone stack to tailor your sound.

Many thanks to Ramiro Silva for his excellent construction web page with plans, photos, the works. Ramiro is a gifted amp builder with extraordinary attention to detail.

See his amps website here:

Build Index

February 4, 2006, Building the Turret Board; Drilling Chassis Part I  (5 Hours, cumulative time 5 hours)
February 6, 2006, Drilling Chassis Part II-Finished! (30 Minutes, cumulative time 5.5 hours)
February 9, 2006, Polished Chassis To Near Mirror Finish (1 Hour, cumulative time 6.5 hours)
February 13, 2006, Circuit Board Wiring I (6 Hours, cumulative time 12.5 hours)
February 15, 2006, Circuit Board Wiring II-Finished! (30 Minutes, cumulative time 13 hours)
February 16, 2006, Painted the Chassis-Finished! (1 Hour, cumulative time 14 hours)
February 21, 2006, Wiring the Chassis, Part I (5 Hours, cumulative time 19 hours)
February 25, 2006, Wiring the Chassis, Part II...amp complete (6 Hours, cumulative time 25 hours)
Rough sound cuts of this fine amp.

April 5, 2006, Design and construction of Line out (3 Hours)
April 18, 2006, Prototype Reverb (2 Hours)

August 5, 2006, 18 Watt Experiment (6 Hours)



February 4, 2006 (5 hours)

Cost of Materials, including shipping and a few extras: $268.70 (18% of cost was shipping!)

After several weeks of reviewing the plans, lurking on the AX84 forum, scouring the web for construction details, scrounging for parts, and acquiring a nice drill press, I started building.

Worked for about 5 hours tonight and accomplished the following:

  1. Drilled and deburred the chassis (about 40 holes)

  2. Drilled turret board and installed 42 turrets

  3. Installed all switches, jacks, power lamp, fuse holder, etc. (just to test for fit)

Printing Ramiro's drawings and using them for templates was a great help. Just taped them onto the chassis and turret board, and drilled with templates in place. To print the PDFs so they line up, use "Tile Large Pages" in print dialogue box. This will print the drawing on four pages that you can tape together to make a template. Also turn on "Cut Mark's" in the print dialogue box to give yourself alignment marks.


I assembled all the drawings printed from Ramiro Silva's website. Note the most important tool for amp construction...a large cup of coffee.

Here I have taped the template onto the un-drilled Hammond chassis. Notice the blue plastic protective film on the chassis.

Purchased a nice set of Irwin step bits at Lowes. The three bit set, 3/16" - 7/8", was about $50. These are even cheaper on eBay.

 After drilling I manually deburred the holes on the inside of the chassis. The outside was in excellent shape and didn't require deburring.


Step one was to tape the board template to the FR4. This board material was supplied by Hoffman Amps.

Hoffman Amps also sells this excellent staking tool for flaring the turret lugs on the board. Click HERE for tool description (opens new window).

Turret lugs give the board a very professional appearance and make soldering easy.

The staking tool flares the lugs under the board, giving them a finished look and holding them firmly in place.


Top view of High Octane after one "day" (about 5 hours). Notice the cool tube radio in the background, a late 40s/early 50s Zenith flip dial. My daughter is amazed that this radio "only plays oldies music".

View of underside of High Octane with all switches and controls installed, and the turret board in position. Will of course need to remove and reinstall all these parts during soldering and final assembly, but couldn't resist seeing how it will look.

High Octane with topside parts in place. Starting to look like a real amp!

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