Mojotone Princeton Reverb Clone Project

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The amp kit was shipped in three boxes. The first two boxes contained everything except the wood cabinet. The cabinet itself arrived a couple of weeks later (the exact timing depends on what is going on in the Mojotone woodshop).

Photos of all parts

IMG_5650-7e4cc2 IMG_5651-4e384e IMG_5652-f6bc8a IMG_5654-20e655 IMG_5655-b87d56 IMG_5656-c0b4ea IMG_5657-99f5b9 IMG_5658-e7c128 IMG_5659-966e1c IMG_5660-324a65 IMG_5661-bbf7b6 IMG_5662-a6916f IMG_5663-6325e8 IMG_5664-5b615b IMG_5665-c8ef43 IMG_5666-7d3665 IMG_5667-a11aef IMG_5668-89429e IMG_5669-803392 IMG_5670-3df0a9 IMG_5671-ada7b0 IMG_5672-6ccfab IMG_5673-397cbf IMG_5674-e745f8 IMG_5675-ea0e12 IMG_5676-ec5761 IMG_5677-e2c118 IMG_5679-2cf44c IMG_5680-d880f4 IMG_5681-ec23a6 IMG_5682-1480cf IMG_5683-8e9c2a IMG_5684-200cee IMG_5685-57240b IMG_5686-1dc21c IMG_5687-4c6379

Parts list

Resistors (mostly carbon comp, default power rating is 1/2 Watt)

47                1   bottom of mixer (to ground)
100               2   6.3V loop (since not center tapped)
1K                1   cathode of driver
1K-2W             1   power at output (metal oxide)
1.5K              4   cathode 12AX7
2.2K              1   cathode 12AT7
2.7K              1   negative feedback loop
6.8K              1   to ground of tone
22K               1   bias circuit
3.3K              1   trem cathode
15K-2W            2   power on mixer & driver (metal oxide)
56K               2   phase split on driver
68K               2   input circuits
100K              7   3 input (plate/tone), 1 plate mixer, plate reverb ret, 
                      next to diode, near speed pot on trem
220K              4   2 input of 6V6s, reverb ret input, plate of trem
470K              1   reverb return
1M                6   3 in trem, 1 input, grid on driver, grid on 12AT7/reverb
3.3M              1   between tone/mixer on reverb pullout


VALUE               TYPE      COUNT  NOTE
100uF@100V          AL/elect      1  by diode
40/20/20/20uF@500V  can           1  power supply
25uF@50V            sprague atom  6  cathode: reverb(3), trem(1), in(2),mix
0.1uF@600V          orange        4  tone, driver out(2), trem output
0.047uF@600V        orange        2  bottom of tone, death cap
0.022uf@600V        orange        3  tone out, mix out, trem out-ish
0.02uF@500V         disc          1  (20nF) trem
0.01uF@500V         disc          2  (10nF) trem(2)
0.0033uF@600V       orange        1  (3.3nF) reverb return
500pF@500V          silver mica   1  reverb in
250pF@500V          silver mica   1  treble tone
10pF@500V           disc          1  reverb in/ret


1N4007   1  rectifier diode for 6V6 bias supply, 1A 1000V


TYPE             COUNT  NOTE
screw 4-40 1/4"      8
screw 4-40 3/8"      6
keps nut 4-40       14

screw 6-32 1/2"      6  pan head, phillips drive, zinc machine screw
keps nuts 6-32       6  for copper head baffle screws

screw 8-32 3/8"      6  pan head black oxide
keps nuts 8-32      10  for speaker screws and chassis straps

screw 10-32 3/4"     8  
keps nuts 10-32      8  for tweed chassis screws

total provided screws: (8 + 6) + 6 + 6 + 8 = 34
total provided nuts:   14 + 6 + 10 + 8 = 38
The above does not include the chassis mounting straps screws/nuts, the truss head screw that goes with the white cable clamp, the screws used with the 1/4 inch speaker jack, or screws/nuts that are pre-installed in the cabinet. Note that the kit appears to include more screws and nuts than needed to build the amp, so you have to puzzle out which ones to use where. Some data to help:

Misc parts

NAME                            COUNT   NOTE
white power cable clamp             1
truss head screw                    1   black cabinet corner screws
grommet for 3/8" holes              6   (3 more than needed?)
RCA phono jacks                     4
#47 pilot light bulb                1
light lens (red)                    1
pilot light assembly                1
chassis straps/screw/nut 4 5/8"     1
3M pot                              1   speed
1M-A pot (vol/tone)                 1   volume
250K-A pot                          2   treb/bass tone
250K-L intensity                    1   intensity
100K-L pot reverb-lvl               1   reverb level
knobs                               6
1-9/16" (40mm) mounting clamp       1
18/3 power cord strain rel.         1
18/3 power cord 6'                  1
3 lug terminal strip                2   you decide where to use them
fuse holder                         1
1A slow blow fuse                   1
swcraft J11 out/ext 1/4"jack        1
switch J12A 1/4" shorting jack      3
eylet rect board+backing            1
eylet PR board+backing              1
9-pin tube sockets shield base      4
9-pin shields                       4
8-pin tubs socket                   3
tube clip for octal base tube       3
SPDT ground toggle switch           1
SPST power/stand switch             1
green 18Ga solid wire             10'   heater hookup wire
black 18Ga stranded                3'   speaker wire
white 18Ga stranded                3'   speaker wire
white 22Ga solid                  25'   main hookup wire
Note that if you want to install a 3 lug terminal strip on a power transformer screw, you may have to split apart the strip's loop to get it to fit around the screw.

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This page maintained by Chuck Cranor