BIRTH OF A NEW AX84 HIGH OCTANE TUBE
(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:
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
August 5, 2006, 18 Watt Experiment (6 Hours)
February 4, 2006 (5
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
Worked for about 5 hours
tonight and accomplished the following:
Drilled and deburred the
chassis (about 40 holes)
Drilled turret board and
installed 42 turrets
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.
DRILLING THE CHASSIS
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.
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.
BUILDING THE TURRET BOARD
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.
NOT A BAD DAY'S WORK
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.
with topside parts in place. Starting to look like a real amp!
Go Back to Mick's Amps Page
MICK, STILL HARD AT WORK ON QUALITY
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