ax84 p1 rev. 11 a successful layout the following three slides show how i laid out my p1. i used...
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AX84 P1 Rev. 11A Successful Layout
The following three slides show how I laid out my P1. I usedstandard parts like a Hammond 125E output transformer andRatShack terminal strips.
The power transformer came from my father’s old collection.There is no manufacturer’s name on it anywhere, but it has exactlythe voltages specified in the circuit diagram. I assume that aHammond or other suitable transformer will be roughly similarin size, so will fit comfortably.
The pots are cheapo Alphas, two bucks at Ampwares. The powersupply caps are from AES. The input jack is a Switchcraft: notethat the terminals are laid out differently that those on the crummyRatShack Chinese abominations.
The chassis is a standard 13 ½ x 5 x 2 Hammond aluminum job.
I’m really happywith the result! It’svery quiet, no hum,a little hiss whencranked all the wayup.
And best of all, it soundsgreat!
Thanks to all the folksat the AX84 site:http://www.ax84.com/
7.5”
Output Jack
AX84 P1 Rev. 11 Chassis Layout, Bottom View
1.5”
IEC Connector under Fuseholder
1.0” 2.25”3.5”
4.75”6.0”
Input Jack Vol Bass Mid Treble
This layout is for mounting “Bassman”-style in the back of a cabinet, or for “upside-down” mounting, withthe tubes pointing down, front panel facing forward. For a “hi-fi” type layout (tubes pointing up), look atthe drawing in a mirror. The transformers are on top of the chassis, their leads coming through grommetedholes. Adjust the locations of the power transformer and the output transformer to fit your particular iron.
13.5”
0.625”1.25”2.0”
PilotPowerStandby
5.0”
2.0”
1.25”
4.0”
12AX7 EL84
Power Transformer
Output Transformer
Hole w/ grommet
Hole w/ grommet
Hole w/ grommet
Holes used to mountterminal strips
Holes used to mountterminal strips
1.5”3.5”
5.5”
1.5”
2.5”
AX84 P1 Rev. 11Signal& PS Wiring, Bottom View
Input Jack Vol Bass Mid Treble
10K/1W
1 uF
1.5K
1 Meg
68 K
.022
470K
470pF470K
1 uF
820
270pF
.015
.015
220K/1W
100K 100K 100K
B+
130
100uF
56K
2.2M
47uF
47uF
47uF
47uF
47uF
-|-
-|-
-|-
100/1W220K/1W
1K/1W
1K/1W
10K/1W
B+
To see this more clearly, set the magnification factor to 150%.There is really much more room than it appears. Most partsare smaller than shown…All of the grounds are brought together at a “star ground” justto the left of the output transformer primary. This point isisolated from the chassis. The only chassis connection is atthe input jack.
Approx. starground point
AX84 P1 Rev. 11AC Wiring, Bottom View
Input Jack Vol Bass Mid Treble
220K/1W
To see this more clearly, set the magnification factor to 150%.There is really much more room than it appears. Most partsare 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.
Approx. starground point
100
100
SPST Pilot110V