Drawing 1
FRONT
#6
#6
#6
#6
#4
#4
#4
#4
#10
#10 #10
#10
#10
#10#10
#10
#6
#6
#6
#6
#6 #6 #6 #6
#6
#6
#6 #6
#6
#6#6
#6#6
#6
T10 T12
T11 T14
V4 V3V2 V1
GROMMET 1
GROMMET 2
GROMMET 4
GROMMET 3
GROMMET 5
T13
TR1 TR1
TR1 TR1
TR2 TR2
TR2
TR2
R(BIAS)
REAR
SID
E
SID
E
TOP
FRONT
#6
#6
#6
#6
#4
#4
#4
#4
#10
#10 #10
#10
#10
#10#10
#10
#6
#6
#6
#6
#6 #6 #6 #6
#6
#6
#6 #6
#6
#6#6
#6#6
#6
T10 T12
T11 T14
V4 V3V2 V1
GROMMET 1
GROMMET 2
GROMMET 4
GROMMET 3
GROMMET 5
T13
TR1 TR1
TR1 TR1
TR2 TR2
TR2
TR2
R(BIAS)
COLD HOT
Drawing 2
FRONT
#6
#6
#6
#6
#4
#4
#4
#4
#10
#10 #10
#10
#10
#10#10
#10
#6 #6
#6
#6
#6 #6 #6 #6
#6
#6
#6 #6
#6
#6#6
#6#6
#6
T10 T12
T11T14
V4 V3V2 V1
GROMMET 1
GROMMET 2GROMMET 4
GROMMET 3
GROMMET 5
T13
TR1 TR1
TR1 TR1
TR2 TR2
TR2
TR2
R(BIAS)
Pin 1
Pin 9
Pin 1
Pin 9
Pin 1
Pin 8Pin 8
Pin 1
COLD HOT
Mount the bias pot with solder lugs
directed towards the front.
25KL
Drawing 3
REAR
#6 Locking Lugs
FRONT
#6
#6
#6
#6
#4
#4
#4
#4
#10
#10 #10
#10
#10
#10#10
#10
#6 #6
#6
#6
#6 #6 #6 #6
#6
#6
#6 #6
#6
#6#6
#6#6
#6
T5 T10 T12
T11T14
T2
T1
T3
T4
V4 V3V2 V1
GROMMET 1
GROMMET 2GROMMET 4
GROMMET 3
GROMMET 5
T13
TR1 TR1
TR1 TR1
TR2 TR2
TR2
TR2
R(BIAS) Secondary
1. Yel
2. Grn/Yel
3. Blk/Yel
4. Grn
5. Blk
Primary
1. Blu
2. Red
3. Brn
Cut
1. Blu/Yel
2. Brn/Yel
Pull the wire out as
far as possible
before cutting it as
far inside the bell
as possible.
COLD HOT
Drawing 4
FRONT
#6
#6
#6
#6
#4
#4
#4
#4
#10
#10 #10
#10
#10
#10 #10
#10
#6 #6
#6
#6
#6 #6 #6 #6
#6
#6
#6 #6
#6
#6#6
#6#6
#6
T10 T12
T11T14
V4 V3V2 V1
GROMMET 1 GROMMET 2
GROMMET 5
T13
TR1
TR1
TR1 TR1
TR2
R(BIAS)Primary
1. Blu
2. Blk
3. Brn
4. Wht
Secondary
1. Grn
2. Grn
3. Grn/Yel
4. Red
5. Red
6. Red/Yel
7. Vio
1650P
Cut
1. Yel
2. Yel
3. Yel/Blk
Pull the wire out as
far as possible
before cutting it as
far inside the bell
as possible.
Cut
1. Blu/Yel
2. Wht/Blk
3. Blk/Red
4. Brn/Yel
COLD HOT
Drawing 5
FRONT
#6
#6
#6
#6
#4
#4
#4
#4
#10
#10 #10
#10
#10
#10 #10
#10
#6 #6
#6
#6
#6 #6 #6 #6
#6
#6
#6 #6
#6
#6#6
#6#6
#6
T10 T12
T11 T14
V4 V3V2 V1
T13
TR1
TR1
TR1 TR1
TR2
R(BIAS)
1650P
37
4B
X
COLD HOT
Drawing 6
#6 Locking Lugs with slit cut
DANGERHIGH VOLTAGE
MAY BE PRESENT
ON FILTER CAPACITORS
DO NOT TOUCH!
TOP
TOP
ON
OFF
POWER STANDBY BASS TREBLE VOLUME INPUT
0 10
5
2 8
3
4 6
7
1 9
0 10
5
2 8
3
4 6
7
1 9
0 10
5
2 8
3
4 6
7
1 9
MOD 101TUBE AMP KIT
www.modampkits.com
TOP
ON
OFF
POWER STANDBY BASS TREBLE VOLUME INPUT
0 10
5
2 8
3
4 6
7
1 9
0 10
5
2 8
3
4 6
7
1 9
0 10
5
2 8
3
4 6
7
1 9
MOD 101TUBE AMP KIT
www.modampkits.com
Mount the pots with solder lugs
directed towards the bottom.
Mount the standby switch with solder
lugs directed towards the top.
Mount the lamp holder with solder
lugs directed towards the bottom.
250KA 250KA 1MA
0 0 0
Drawing 7
Remove all 6 screws from the
terminals. You will not need
them for this project.
TOP
≈120VAC
60Hz
2A
SLO BLO
OUTPUT TO
SPEAKER(S)SELECTOR
IMPEDANCE (Ω)
4
8 16
20
TOP
≈120VAC
60Hz
2A
SLO BLO
OUTPUT TO
SPEAKER(S)SELECTOR
IMPEDANCE (Ω)
4
8 16
20
TOP
Leave this strain relief hole open for
now.
FUSE
4
Drawing 8
1
2
3
4
56
78 9
1
23
4
56
78 9
V4 V3 V2 V1
12
34
56
78
12
34
56
78
Primary
1. Blu
2. Blk
3. Brn
4. Wht
Secondary
1. Grn
2. Grn
3. Grn/Yel
4. Red
5. Red
6. Red/Yel
7. Vio
Secondary
1. Yel
2. Grn/Yel
3. Blk/Yel
4. Grn
5. Blk
Primary
1. Blu
2. Red
3. Brn
R(BIAS)TR1
TR2
T1
T2
T3
T4
T5
T6
T7
T8
T9
FRONT
Drawing 9
1
2
3
4
56
78 9
1
23
4
56
78 9
V4 V3 V2 V1
12
34
56
78
12
34
56
78
Primary
1. Blu
2. Blk
3. Brn
4. Wht
Secondary
1. Grn
2. Grn
3. Grn/Yel
4. Red
5. Red
6. Red/Yel
7. Vio
Secondary
1. Yel
2. Grn/Yel
3. Blk/Yel
4. Grn
5. Blk
Primary
1. Blu
2. Red
3. Brn
R(BIAS)
TR1
TR2
T1
T2T3
T4
T5
T6
T7
T8
T9
FRONT
Drawing 10
FRONT
1
2
3
4
56
78 9
1
23
4
56
78 9
V4 V3 V2 V1
12
34
56
78
12
34
56
78
Primary
1. Blu
2. Blk
3. Brn
4. Wht
Secondary
1. Grn
2. Grn
3. Grn/Yel
4. Red
5. Red
6. Red/Yel
7. Vio
Secondary
1. Yel
2. Grn/Yel
3. Blk/Yel
4. Grn
5. Blk
Primary
1. Blu
2. Red
3. Brn
R(BIAS)
TR1
TR2
T1
T2T3
T4
T5
T6
T7
T8
T9
.001µF
630V1M470
1M
22K
47
.1µF630V
82022
µF
50V
68K
20K
.1µ
F
630V
.1µ
F
63
0V 100K 100K100K 82K
6.8K 68K
500
500V
.022µF
630V
.022µF
630V
470 470
220K 220K1.5K 1.5K
1N4007
2.7K
2.4K 22µF 50V
1* 1*
6L6GC
VERSION
T6
5W 1K5W 1K
EL34
VERSION
OR
Drawing 11
1N4007
1* = measure these resistors to note that they are not exactly 1.0 Ω.
It is important to copy the
orientation of polarity
shown for each of the
three diodes.
#4
#4
#4
#4
#6
T11 T14
V2 V1
DANGERHIGH VOLTAGE
MAY BE PRESENT
ON FILTER CAPACITORS
DO NOT TOUCH!
22
µF
50
0V
80
µF
45
0V
80
µF
45
0V
22
µF
50
0V
22
µF
50
0V
22
µF
50
0V
220K
4.7K1K
5K
220K
D
B
HV
E
C
V3
cathode
T10 T12 T13
ABOVE VIEW
T11T10
80µF 450V
80µF 450V
220K
220K
HV
T12
22µF 500V
22µF 500V
T13
T14
22µF 500V
22µF 500V
5W
5K
C
4.7K
1K
D
E
B
V3
cathode
SIDE VIEW
Drawing 12
ground
Terminal 1
Terminal 2
Terminal 3J3
J3
J2
J1
J1 & J2
CHASSIS TOP (INSIDE VIEW) WITH COMPONENT NAMES (3)
FRONT
1
2
3
4
56
78 9
1
23
4
56
78 9
V4 V3 V2 V1
12
34
56
78
12
34
56
78
Primary
1. Blu
2. Blk
3. Brn
4. Wht
Secondary
1. Grn
2. Grn
3. Grn/Yel
4. Red
5. Red
6. Red/Yel
7. Vio
Secondary
1. Yel
2. Grn/Yel
3. Blk/Yel
4. Grn
5. Blk
Primary
1. Blu
2. Red
3. Brn
R(BIAS)
TR1
TR2
T1
T2T3
T4
T5
T6
T7
T8
T9
.001µF
630V1M470
1M
22K
47
.1µF630V
820
68K
20K
.1µ
F
630V
.1µ
F
63
0V 100K 100K100K 82K
6.8K 68K
.022µF
630V
470 470
220K 220K1.5K 1.5K
1N4007
2.7K
2.4K 22µF 50V
1* 1*
5W
1Ω
10W 360Ω
.022µF
630V500
500V
22
µF
50V
1M
Tie, but do not solder these
connections yet.
BASS TREBLE VOLUME
Filter Caps
1. HV
2. B
3. C
4. D
5. E
6. V3 cathode
Drawing 13
A
B
C
D
E
F
G
H
I
J
A
B
C
D
E
F
G
H
I
Red/Yel
&
Grn/Yel
Brn&Blue
1N4007
STEP 1
SIDERed
Grn
Grn
Red
Red
STEP 2
SIDE
Vio
BrownBlue
CHASSIS TOP (INSIDE VIEW) WITH COMPONENT NAMES (3)
FRONT
1
2
3
4
56
78 9
1
23
4
56
78 9
V4 V3 V2 V1
12
34
56
78
12
34
56
78
Primary
1. Blu
2. Blk
3. Brn
4. Wht
Secondary
1. Grn
2. Grn
3. Grn/Yel
4. Red
5. Red
6. Red/Yel
7. Vio
Secondary
1. Yel
2. Grn/Yel
3. Blk/Yel
4. Grn
5. Blk
Primary
1. Blu
2. Red
3. Brn
R(BIAS)
TR1
TR2
T1
T2T3
T4
T5
T6
T7
T8
T9
.001µF
630V1M470
1M
22K
47
.1µF630V
820
68K
20K
.1µ
F
63
0V 100K 100K100K 82K
6.8K 68K
.022µF
630V
470
220K 220K1.5K 1.5K
1N4007
2.7K
2.4K 22µF 50V
1* 1*
5W
1Ω
.022µF
630V500
500V
22
µF
50V
1MBASS TREBLE VOLUME
“D” “E”
470
“C”
“B”“HV”
10W 360Ω
.1µ
F
630V
Drawing 14
A
B
C
D
E
1N4007
CHASSIS TOP (INSIDE VIEW) WITH COMPONENT NAMES (3)
FRONT1
2
3
4
56
78 9
1
23
4
56
78 9
V4 V3 V2 V1
12
34
56
78
12
34
56
78
Primary
1. Blu
2. Blk
3. Brn
4. Wht
Secondary
1. Grn
2. Grn
3. Grn/Yel
4. Red
5. Red
6. Red/Yel
7. Vio
Secondary
1. Yel
2. Grn/Yel
3. Blk/Yel
4. Grn
5. Blk
Primary
1. Blu
2. Red
3. Brn
R(BIAS)
TR2
T1
T2T3
T4
T5
T6
T7
T8
T9
.001µF
630V1M470
1M
22K
47
.1µF630V
820
68K
20K
.1µ
F
63
0V 100K 100K100K 82K
6.8K 68K
.022µF
630V
470
220K 220K1.5K 1.5K
1N4007
2.7K
2.4K 22µF 50V
1* 1*
5W
1Ω
.022µF
630V500
500V
22
µF
50V
1MBASS TREBLE VOLUME
470
BHV
10W 360Ω
Tie, but do not
solder these
connections yet.
Tie, but do not
solder these
connections yet.
To Fuse
.1µ
F
630V
Drawing 15
Brn&Wht
A
B
C
D
E
TR1
1N4007
Keep the body of this resistor from
leaning against the nearby wires.
20 AWG
Wire
20 AWG
Wire
1
23
4
56
789
1
23
4
56
789
V4V3V2V1
12
34
56
78
12
34
56
78
Primary
1. Blu
2. Blk
3. Brn
4. Wht
Secondary
1. Grn
2. Grn
3. Grn/Yel
4. Red
5. Red
6. Red/Yel
7. Vio
Secondary
1. Yel
2. Grn/Yel
3. Blk/Yel
4. Grn
5. Blk
Primary
1. Blu
2. Red
3. Brn
R(BIAS)
TR2
T1
T2T3
T4
T5
T6
T7
T8
T9
.001µF
630V1M
470
1M
22K
47
.1µF630V
820
68K
20K
.1µ
F
63
0V
100K100K 100K82K
6.8K68K
.022µF
630V
470
220K220K 1.5K1.5K
1N4007
2.7K
2.4K22µF 50V
1*
1*
5W
1Ω
.022µF
630V
500
500V
22
µF
50V
470
Tie, but do not
solder these
connections yet.
Tie, but do not
solder these
connections yet.
A
BC
1
23
4
12
3
4
1
2
3
4
blk
red
.1µ
F
630V
REAR
Drawing 16
Blk & Blu
TR1
A
B
1N4007
1
23
4
56
789
1
23
4
56
789
V4V3V2V1
12
34
56
78
12
34
56
78
Secondary
1. Grn
2. Grn
3. Grn/Yel
4. Red
5. Red
6. Red/Yel
7. Vio
Secondary
1. Yel
2. Grn/Yel
3. Blk/Yel
4. Grn
5. Blk
Primary
1. Blu
2. Red
3. Brn
R(BIAS)
TR2
T1
T2T3
T4
T5
T6
T7
T8
T9
.001µF
630V1M
470
1M
22K
47
.1µF630V
820
68K
20K
.1µ
F
63
0V
100K100K 100K82K
6.8K68K
.022µF
630V
470
220K220K 1.5K1.5K
1N4007
2.7K
2.4K22µF 50V
1*
1*
5W
1Ω
.022µF
630V
500
500V
22
µF
50V
470
Tie, but do not
solder these
connections yet.
Tie, but do not
solder these
connections yet.
A
BC
1
23
4
12
3
4
1
2
3
4
yel
grn
grn/yel
blk/yel
blk
red
blk
.1µ
F
630V
REAR
Drawing 17
1N4007
1
23
4
56
789
1
23
4
56
789
V4V3V2V1
12
34
56
78
12
34
56
78
R(BIAS)
T1
T2
T3
T4
T5
T6
T7
T8
T9
.001µF
630V1M
470
1M
22K
47
820
68K
20K
.1µ
F
63
0V
100K100K 100K82K
6.8K68K
.022µF
630V
470
220K220K 1.5K1.5K
1N4007
2.7K
2.4K22µF 50V
1*
1*
5W
1Ω
.022µF
630V
500
500V
22
µF
50V
470
Tie, but do not
solder these
connections yet.
Tie, but do not
solder these
connections yet.
A
BC
1
23
4
12
3
4
1
2
3
4
yel
grn
grn/yel
blk/yel
blk
red
blk
.1µF630V
.1µ
F
630V
REAR
Drawing 18
A
BC
D
E
F
B
A
C
D
E
B
A
D
C
1N4007
1
23
4
56
789
1
23
4
56
789
V4V3V2V1
12
34
56
78
12
34
56
78
R(BIAS)
T1
T2
T3
T4
T5
T6
T7
T8
T9
.001µF
630V1M
470
1M
22K
47
820
68K
20K
100K100K 100K82K
6.8K68K
.022µF
630V
470
220K220K 1.5K1.5K
1N4007
2.7K
2.4K22µF 50V
1*
1*
5W
1Ω
.022µF
630V
500
500V
22
µF
50V
470
Tie, but do not
solder these
connections yet.
Tie, but do not
solder these
connections yet.
A
BC
1
23
4
12
3
4
1
2
3
4
yel
grn
grn/yel
blk/yel
blk
red
blk
.1µF630V
.1µ
F
63
0V
.1µ
F
630V
REAR
Drawing 19
A
B C
D
E
F
G
H
I
1N4007
1
23
4
56
789
1
23
4
56
789
V4V3V2V1
12
34
56
78
12
34
56
78
R(BIAS)
T1
T2
T3
T4
T5
T6
T7
T8
T9
.001µF
630V1M
470
1M
22K
47
820
68K
20K
100K100K 100K82K
6.8K68K
.022µF
630V
470
220K220K 1.5K1.5K
1N4007
2.7K
2.4K22µF 50V
1*
1*
5W
1Ω
.022µF
630V
500
500V
22
µF
50V
470
Tie, but do not
solder these
connections yet.
blk
red
.1µF630V
.1µ
F
63
0V
.1µ
F
630V
REAR
Drawing 20
ABC
1N4007
20 AWG
Wire20 AWG
Wire
20 AWG
Wire
≈120VAC
60Hz
2A
SLO BLO
FUSE
≈120VAC
60Hz
2A
SLO BLO
FUSE
≈120VAC
60Hz
2A
SLO BLO
FUSE
T9
T9
Channellock Pliers
1"
Drawing 21
A
B
C
You will have to squeeze very tightly with the pliers to
fit the strain relief and power cord into the chassis
hole. This is what gives the cord a secure fit.
1
23
4
56
789
1
23
4
56
789
V4V3V2V1
12
34
56
78
12
34
56
78
R(BIAS)
T1
T2
T3
T4
T5
T6
T7
T8
.001µF
630V1M
470
1M
22K
47
820
68K
20K
100K100K 100K82K
6.8K68K
.022µF
630V
470
220K220K 1.5K1.5K
1N4007
2.7K
2.4K22µF 50V
1*
1*
5W
1Ω
.022µF
630V
500
500V
22
µF
50V
470
blk
red
.1µF630V
.1µ
F
63
0V
T9
.1µ
F
630V
REAR
Brn & Wht
White
Green
Black
A
B
C
Drawing 22
1N4007
# 1 0# 1 0
# 1 0 # 1 0# 1 0
# 1 0
# 1 0
# 1 0
# 6
T14
V4
V3
TR 1
TR 1
TR
1
R(BIAS)
16
50P
374BX
CO
LD
HO
T
DA
NG
ER
HIG
H V
OL
TA
GE
MA
Y B
E P
RE
SE
NT
ON
FIL
TE
R
CA
PA
CIT
OR
S
DO
NO
T T
OU
CH
!
22µF 500V
80µF 450V
80µF 450V
22µF 500V
22µF 500V
22µF 500V
COM Ω
Ω01.6
Start with pot turned
all the way to cold.
ON
OFF
POWER STANDBY
UNPLUGGED
R =
WARNING:
Do not measure resistance with
amplifier power on.
Drawing 23
12AX7/
ECC83
12AT7/
ECC81
# 1 0# 1 0
# 1 0 # 1 0# 1 0
# 1 0
# 1 0
# 1 0
# 6
T14
V4
V3
TR 1
TR 1
TR
1
R(BIAS)
16
50P
374BX
CO
LD
HO
T
DA
NG
ER
HIG
H V
OL
TA
GE
MA
Y B
E P
RE
SE
NT
ON
FIL
TE
R
CA
PA
CIT
OR
S
DO
NO
T T
OU
CH
!
22µF 500V
80µF 450V
80µF 450V
22µF 500V
22µF 500V
22µF 500V
COM V
mV37.5
Start with pot turned
all the way to cold.
ON
OFF
POWER STANDBY
PLUGGED
IN
Connect
to
Speaker
Cabinet
BASS TREBLE VOLUME
0 10
5
2 8
3
4 6
7
1 9
0 10
5
2 8
3
4 6
7
1 9
0 10
5
2 8
3
4 6
7
1 9
Set for
mV(DC)
V
R= I
OHM’S LAW
V =
VR =I
OHM’S LAW
x
mV56.1
Set for
mV(DC)
V =COLD 6L6GC
BIAS
POINT
37.5 mV
1.6 Ω
= 23.4 mA56.1 mV
1.6 Ω
= 35.06 mA
6L6GC bias range: 10 mA – 50 mA(35 mA is used commonly)
(35 mA) (1.6 Ω)x = 56 mV
Apply Ohm’s Law to find the corresponding mV
reading for your resistor value:
I = 35 mA
R = 1.6 Ω
V = ?
· Higher Value: easily overdriven
· Lower Value: cleaner
6L6GC’s
12AX7/
ECC83
12AT7/
ECC81
Drawing 24
# 1 0# 1 0
# 1 0 # 1 0# 1 0
# 1 0
# 1 0
# 1 0
# 6
T14
V4
V3
TR 1
TR 1
TR
1
R(BIAS)
16
50P
374BX
CO
LD
HO
T
DA
NG
ER
HIG
H V
OL
TA
GE
MA
Y B
E P
RE
SE
NT
ON
FIL
TE
R
CA
PA
CIT
OR
S
DO
NO
T T
OU
CH
!
22µF 500V
80µF 450V
80µF 450V
22µF 500V
22µF 500V
22µF 500V
COM V
mV10.2
Start with pot turned
all the way to cold.
ON
OFF
POWER STANDBY
PLUGGED
IN
Connect
to
Speaker
Cabinet
BASS TREBLE VOLUME
0 10
5
2 8
3
4 6
7
1 9
0 10
5
2 8
3
4 6
7
1 9
0 10
5
2 8
3
4 6
7
1 9
Set for
mV(DC)
V
R= I
OHM’S LAW
V =
VR =I
OHM’S LAW
x
mV76.8
Set for
mV(DC)
V =COLD 6L6GC
BIAS
POINT
10.2 mV
1.6 Ω
= 6.4 mA76.8 mV
1.6 Ω
= 48.0 mA
EL34 bias range: 10 mA – 75 mA(35 mA is used commonly)
(48 mA) (1.6 Ω)x = 76.8 mV
Apply Ohm’s Law to find the corresponding mV
reading for your resistor value:
I = 48 mA
R = 1.6 Ω
V = ?
EL34’s
12AX7/
ECC83
12AT7/
ECC81
Drawing 25
