Top view.
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Front view.
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Internals.
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Here's some views of a guitar tube amplifier I constructed back in the late 90's using schematics from The Cooperative Tube Guitar Amp Project. This
project is called the AX84 P1. I built Rev 10 with the optional solid-state rectifier. (Note: the schematic has been revised
several times since 1999 and the most recent schematic should be used for new builds.)
I used a Hammond 10x6x2 chassis which turned out to be a bit of a squeeze, but everything ended up going in okay. The four huge
caps got stacked into the back corner. The vacuum tubes are made by Sovtek, a Russian manufacturer, and the two transformers are
made by Hammond in Canada. The output transformer was built only a few days before it turned up at my house.
Total cost of the project (keeping in mind I borrowed the tools and soldering iron) was;
269EX power transformer 35.06
125E output transformer 33.11
12AX7WA tube 9.90
EL84 tube 8.40
Hammond 10x6x2 chassis 11.00
2 x 9 pin sockets 3.76
mono input jack 3.50
8" 50W/4Ohm Eminence speaker 44.10
SPDT toggle switch 3.65
DPDT toggle 5.07
SPST toggle 3.29
various pots 5.00
500v 40uF caps 5.07
fuse holder and fuse 2.86
AC cable and grommet 9.50
misc resistors, caps, diodes 23.84
wire, solder terminals 15.00
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total US$222.11
Minimum order quantities on most resistors and caps pushed the price up, the most annoying case being C14 (0.005uF/1500V) where
Digi-Key had a minimum quantity of 10 at $1.26 a piece (note: C14 has been removed in later P1 revisions). Plus the speaker could
have been had for about $10 less at a number of places I found a week after my order went in.
Anyway, it sounds great. Very nice tone, and very little noise that only becomes evident at high volumes, and is quickly swamped
once the guitar gets played.
Oh yes, and I discovered later that since the invention of the transistor most "first projects" generally aren't high voltage.
Live and learn.
Update: 2024
The amp still sounds great after almost 25 years of admittedly light use. I will probably check the electrolytic capacitors soon
and see if it needs to be re-capped.
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