Transcript ChassisLayout

AX84 P1 Rev. 11
A Successful Layout
The following three slides show how I laid out my P1. I used
standard parts like a Hammond 125E output transformer and
RatShack terminal strips.
The power transformer came from my father’s old collection.
There is no manufacturer’s name on it anywhere, but it has exactly
the voltages specified in the circuit diagram. I assume that a
Hammond or other suitable transformer will be roughly similar
in size, so will fit comfortably.
The pots are cheapo Alphas, two bucks at Ampwares. The power
supply caps are from AES. The input jack is a Switchcraft: note
that the terminals are laid out differently that those on the crummy
RatShack Chinese abominations.
The chassis is a standard 13 ½ x 5 x 2 Hammond aluminum job.
I’m really happy
with the result! It’s
very quiet, no hum,
a little hiss when
cranked all the way
up.
And best of all, it sounds
great!
Thanks to all the folks
at the AX84 site:
http://www.ax84.com/
AX84 P1 Rev. 11
Chassis Layout, Bottom View
7.5”
Output Jack
12AX7
2.5”
2.0”
EL84
1.25”
Hole w/ grommet
Output Transformer
Holes used to mount
terminal strips
1.5”
3.5”
Input Jack
1.0” 2.25”
5.5”
Vol
3.5”
IEC Connector
under Fuseholder
Holes used to mount
terminal strips
Power Transformer
4.0”
1.5”
1.5”
Bass
4.75”
5.0”
Hole w/ grommet
Hole w/ grommet
Mid
6.0”
Treble
Standby Power Pilot
0.625”
1.25”
2.0”
13.5”
This layout is for mounting “Bassman”-style in the back of a cabinet, or for “upside-down” mounting, with
the tubes pointing down, front panel facing forward. For a “hi-fi” type layout (tubes pointing up), look at
the drawing in a mirror. The transformers are on top of the chassis, their leads coming through grommeted
holes. Adjust the locations of the power transformer and the output transformer to fit your particular iron.
AX84 P1 Rev. 11
Signal& PS Wiring, Bottom View
B+
1K/1W
B+
47uF
100K
220K/1W
-|-
47uF
2.2M
100/1W
56K
100uF
130
.015
.015
270pF
820
1 uF
470K
470pF
470K
.022
68 K
1.5K
1 uF
47uF
-|-
100K
1K/1W
100K
10K/1W
47uF
Approx. star
ground point
Input Jack
Vol
Bass
Mid
Treble
47uF
-|-
220K/1W
10K/1W
To see this more clearly, set the magnification factor to 150%.
There is really much more room than it appears. Most parts
are smaller than shown…
All of the grounds are brought together at a “star ground” just
to the left of the output transformer primary. This point is
isolated from the chassis. The only chassis connection is at
the input jack.
AX84 P1 Rev. 11
AC Wiring, Bottom View
100
100
Approx. star
ground point
Input Jack
Vol
Bass
Mid
Treble
To see this more clearly, set the magnification factor to 150%.
There is really much more room than it appears. Most parts
are smaller than shown…
The fuse holder is mounted above or below the IEC connector.
The pilot light is a cheapo RatShack job, 110V, with wire leads.
SPST Pilot
110V
220K/1W