’81 brit-800 50w · 2019-06-27 · this 50w giant created your favorite heavy rock and metal...
TRANSCRIPT
A S S E M B LY I N S T R U C T I O N SWith loads of helpful tips!
’81 BRIT-800 50W A M P L I F I E R K I T
ORIGINAL BRITISH CIRCUIT
The king of shred
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Contents
About this iconic amp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Parts list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Tools and supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Amp voltages are seriously dangerous! . . . . . . . . . . . . . . . . . . . . . . . . . . 6
How to use a snuffer stick . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
How to read resistor values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Capacitor values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Complete wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Prepping the turret board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Tips for great soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Installing the chassis-mounted components . . . . . . . . . . . . . . . . . . . 11
Wrapping parts onto the turret board . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Soldering components to turret board . . . . . . . . . . . . . . . . . . . . . . . . . 33
Installing the turret board in the chassis . . . . . . . . . . . . . . . . . . . . . . . 35
Installing parts and preparing for testing . . . . . . . . . . . . . . . . . . . . . . 40
Testing and troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Final assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Tips for using this amp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Photograph of completely wired chassis . . . . . . . . . . . . . . . . . . . . . . . 45
Learning more: secrets revealed in the schematic . . . . . . . . . . . . . . 46
Circuit schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
More iconic amp kits from StewMac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Full page wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Tube replacement chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
COPYRIGHT WARNINGThis material is protected by copyright and has been created by and solely for the purposes of StewMac . You may not sell, alter or further reproduce any part of this material, or distribute it to any other per-son . Where provided to you in electronic format, you may only print from it for your own private use . Failure to comply with the terms of this warning exposes you to legal action for copyright infringement .
How to build this kit!
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’81 BRIT-800 50W AMPLIFIER KIT ORIGINAL BRITISH CIRCUIT
This amp is an ICONThis is the defining British circuit that dominated the '80s .
This 50W giant created your favorite heavy rock and metal albums . Used by Slayer and Pixies, and recorded on early Metallica albums, this circuit produces that screaming guitar tone that your mother despises . With solid-state rectification there's no sag, and the distortion created by this ciruit is way more about treble than mids or bass .
StewMac ICON KITS bring classics that are no longer made, or are simply unaffordable, within reach . And the best part is you get to build them with your own hands .
We give painstaking attention to parts selection, authentic materials, and instantly recognizable details—everything that makes the originals so sought after .
Build it with StewMacThese immersive instructions walk you through every step of creating your ’81 Brit-800 . And you’ll learn a lot, gaining a deep knowledge of your amp’s inner workings .
Follow our steps closely for safety, too: we’ve carefully laid out a path that even newcomers can follow in handling electrical components .
Building an amp can seem daunting, but nobody makes it easier than StewMac . Watch for helpful tips along the way, too—we’re here to help!
Let’s get building!
Iconic British tone is now in your hands
Be excited!Your new StewMac ’81 Brit-800 will be a blast to play through and even more fun to build .
This amp is renowned for its saturated lead tone that is bright and tight, with an in-your-face crunch . You can scoop the mids and have a completely different tone in an instant . Often overlooked, the clean tone is rich, full, and gives this amp unrivaled presence onstage . This amp fueled the sound of ’80s heavy metal .
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Here’s how to build this amp!
Wiring goes like this:1. First, you’ll wrap the leads, connecting them without solder. 2. Then double-check all the connections. Don’t rush!3. When everything checks out, it's time to solder. The numbered steps tell you when.
Get the turret board ready, starting at Step 1 on page 9.You’ll prep the metal chassis too.
Learn more:You don’t need to read the schematic, but it’s fun! See how your guitar’s signal gets processed into sound on page 47.
Sort your components by type, using the parts list.Quick look:
OutputGain Processing Gain GainProcessing Negative feedback
See page 9
#10735 © 2019 StewMac
GroundJackTransformer Preamp tube
plategrid
cathode
Power tube
gridplate
cathode
screen
Capacitor Electrolytic Cap. DiodeResistor Potentiometers Rectifier tube
plate cathodefilamentplate
Shieldedcable
’81 BRIT-80050WO R I G I N A L B R I T I S H C I R C U I T
OutputGain GainGain
Power
Processing Processing
Pow
er
Negative Feedback
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Hardware
r (4) M6 machine screw, 30mmr (4) M6 cagenut
r (12) 8-32 machine screw, 3/8"r (12) 8-32 locknut
r (6) 6-32 locknut
r (4) 4-40 threaded standoff, 1/2"
r (10) 4-40 machine screw, 3/8"
r (14) 4-40 machine screw, 1/4"r (16) 4-40 locknut
r (3) Filter cap mounting clamp
r (1) Small rubber grommet
r (4) Large rubber grommet
Capacitors & diodes
r (1) 10pF 500V silver mica
r (1) 47pF 500V silver mica
r (3) 500pF 500V silver mica
r (1) .001μF (1nF) 630V Mojo Dijon
r (7) .022μF (22nF) 630V Mojo Dijon
r (2) .01μF (10nF ) 630V Mojo Dijon
r (1) .68μF 630V Mojo Dijon
r (2) 8μF 150V Sprague Atom
r (3) 50μF+50μF 500V electrolytic filter cap
r (1) 1N4007 1000V rectifier diode
r (2) 1N5408 1000V rectifier diode
r (1) Cabinet
r (1) Chassis
r (1) Turret board
r (1) Faceplate/backplate set
Resistors
r (1) 470Ω .5W carbon composite
r (2) 820Ω .5W carbon composite
r (1) 2.7K .5W carbon composite
r (1) 4.7K .5W carbon composite
r (2) 5.1K .5W carbon composite
r (1) 10K .5W carbon composite
r (1) 15K .5W carbon composite
r (1) 33K .5W carbon composite
r (1) 47K .5W carbon composite
r (1) 56K .5W carbon composite
r (1) 82K .5W carbon composite
r (6) 100K .5W carbon composite
r (2) 220K .5W carbon composite
r (3) 470K .5W carbon composite
r (3) 1M .5W carbon composite
r (2) 220K 2W metal oxide
r (2) 10K 5W ceramic
r (1) 1K 5W ceramic5W 1K
5W 10K
+8µF
510K47
10
.01μF
.68μF
.001μF
Green Brown Red Gold
Brown Green Orange Gold
Red Red Yellow Gold
Yellow Violet Brown Gold
Gray Red Brown Gold
Red Violet Red Gold
Yellow Violet Red Gold
Brown Black Orange Gold
Orange Orange Orange Gold
Yellow Violet Orange Gold
Yellow Violet Yellow Gold
Brown Black Green Gold
A magnifier helps!
Green Blue Orange Gold
Gray Red Orange Gold
Brown Black Yellow Gold
Red Red Yellow Gold
50μF + 50μF
500V
+
.022μF
Parts list
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Parts listTubes, lamps, fuses, and sockets
r (4) Four-lug jack
r (3) Nine-pin tube socket
r (3) Shield for nine-pin tube socket
r (2) Eight-pin tube socket
r (2) Spring retainer for eight-pin socket
r (3) 12AX7 preamp tube (also called ECC83S)
r (2) EL34 power tube
r (2) Fuse socket
r (1) Fuse (3 amp, slow blow)
r (1) Fuse (1/2 amp, slow blow)
r (1) Power inlet
Control pots and more
r (1) 10KL bias pot
r (3) 1M control pot (A-audio taper)
r (1) 5K control pot (L-linear taper)
r (1) 25K control pot (L-linear taper)
r (1) 250K control pot (L-linear taper)
r (1) Impedance selector switch
r (1) Voltage selector switch
r (1) Power switch (5 lugs)
r (1) Standby switch (4 lugs)
r (6) Knob
r (2) Three-lug terminal strip
r (2) Ground tab
r (1) Power cord
Wire
r (1) White wire
r (1) Green wire
r (1) Shielded wire
r (1) White heater wire
r (1) Black heater wire
r (1) Bare copper bus wire
Transformers
r (1) Power transformer
r (1) Output transformer
r (1) Filter choke
Heat-shrink tubing
r (2) 1/8” diameter (2-1/2” length)
12AX7
EL34
4
3 2
18
76
5
6
4 3 21
987
5
1MA
5K
25K
250K
10KL
4Ω
8Ω 16Ω
110V
220V 230V
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#0531 StewMac Solder Monster
#3000 Guitar Tech Screwdriver Set
#1606 Wire Stripper
#1607 Wire Cutter
#0501 Solomon SL-30 Soldering Station
#1609 Round Nose Bending Pliers #0505
Kester Pocket-Pak Solder
StewMac’s Solder Monster holds parts while you solder
Tools and supplies
Required Phillips screwdrivers, #1 and #2 Item #3000 Guitar Tech Screwdriver Set
Needle nose pliers Item #1610 Long Nose Pliers
Wire cutter Item #1607 Wire Cutter
Wire stripper Item #1606 Wire Stripper
Soldering iron (preferably 40W) Item #0501 Solomon SL-30 Soldering Station
Solder (at least one Pocket-Pak) Item #0505 Kester Pocket-Pak Solder
Solder sucker Item #0503 Solomon Solder Sucker
Drill with a 5/32" bit For mounting turret board and filter cap
Ruler Item #4905 StewMac Shop Rule
Digital multimeter Item #3618 Fieldpiece Pocket Multimeter
Snuffer stick (bleed resistor) Item #1552 Snuffer Stick
Pencil Wooden chopsticks Glue Wood glue, white glue, or contact cement for gluing a paper label inside the cabinet
Butane lighter or matches For heating heat-shrink tubing
Contact cement
Helpful Round nose bending pliers Item #1609 Round Nose Bending Pliers
Solder wick Item #0504 Solder Wick, 5-foot roll
Soldering aids Item #0521 StewMac Soldering Aids
Soldering stand Item #0506 Solomon Soldering Stand
Solder Monster, or helping hand tool Item #0531 StewMac Solder Monster
Chassis stand Item #10750 Chassis Stand
Printed circuit board vise Scratch awl or center punch Item #3000 Guitar Tech Screwdriver Set
Tray for loose parts Bias meter for accurate biasing Item #1580 VHT Tube Tester + Amp Bias Meter
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High voltage, even when unpluggedWhen you turn on an amp, the capacitors are designed to take on a charge and hold it . That stored voltage is enough to injure you seriously, or even kill you .
These components aren’t a threat until the first time you plug the amp in . The stored electricity can be safely discharged to ground with a snuffer stick . See how to use it below .
Once your amp has been turned on, don’t touch the wiring with your bare hands—even after turning it off . If you need to press on a contact, use a chopstick or Sharpie marker, which are both non-conductive . Don’t use a pencil, because graphite is conductive .
It’s important that you understand the dangers so you’re working safely . Here’s how to do it right .
Wear rubber-soled shoesRubber soles increase the insulation between yourself and the ground .
Take off your ringA metal ring on your finger can bridge a hot connection to ground .
Wear safety glassesRosin-core solder sometimes bubbles up, and it can spew molten specks into the air . You don’t want molten solder in your eyes .
It’s better not to work aloneElectrical shocks can incapacitate you, and having someone available to call 911 can be a lifesaver .
How to use a snuffer stickTo discharge a capacitor, clip the snuffer stick lead to ground—preferably a mounting bolt on the power transformer . Hold the tip of the stick to the cap’s positive lead and use your multimeter to watch the voltage drain to less than 18V .
Take breaks and stop when you’re tiredFatigue leads to mistakes, and no one can afford mistakes when working with electricity .
Stay suspiciousWhether it’s the first time you’ve been inside a live ampli-fier or the 100th time, don’t become complacent . If you discharge the caps and walk away for a few minutes, check again for residual voltage when you return . Capacitors can self-charge through a phenomenon known as dielectric memory .
Check before powering on It’s easy to forget that you a left a stray tool or wire in the chassis . It’s also easy to forget to re-attach the speaker wire, and that can fry an output transformer in seconds . Constant vigilance is your friend when working on amps .
Always unplug itUnplug the amp whenever you don’t specifically need it plugged in . Some points are always hot when the amp’s plugged in, even if the power switch is off . These points include the lugs on the fuse socket, power switch, and standby switch .
Amp voltages are seriously dangerous!
Professionals who work on amps take these safety habits very seriously
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A resistor’s value—the amount of resistance it creates—is rated in ohms (Ω) . Larger ohm values mean more resistance . For example, a 100Ω resistor creates ten times as much re-sistance as a 10Ω resistor .
The resistors used in amplifiers are too small to have value numbers printed on them . Instead, a system of colored bands tells their values . The key to reading these bands is provided below . However, an easier way to decode these bands is to download one of the many smartphone apps for this purpose .
One band will be the nearest to an end of the resistor . That band tells the first value . Combine it with the value of band 2 to get a two-digit number (68 in our example below) . Multiply that number by band 3 (68 x 1,000 = 68,000) . Thou-sands are represented by the letter K, so this resistor is 68K (kilo-ohms, or KΩ) .
If there is a fourth band, it will be either silver or gold . This indicates the tolerance allowed during manufacturing . The resistors used in this kit have a +/- 5% tolerance, represented by a gold band 4 .
A magnifying glass helps a lot . The bands on a 470Ω resistor are yellow/violet/brown, and the bands on a 47K resistor are yellow/violet/orange . They’re easily confused!
Can’t read the colors?You can always use a multimeter to test a resistor’s value . Set your meter to ohms and connect the test leads on each side of the resistor .
Capacitor values are typically printed on the component . The key values with caps are their capacitance and voltage .
Think of a capacitor as a container that can hold electricity . Capacitance, measured in farads, refers to how much elec-tricity this container can hold—its capacity . One farad (1F) would be much too large for use in an amplifier . Caps for amps are rated in millionths of a farad, called microfarads (μF), or trillionths of a farad: picofarads (pF) . The voltage spec for a cap refers to how much DC voltage it can handle at any given time .
A unique property of capacitors is that they don’t allow DC current to flow past them, only AC current . This is important in parts of an amplifier circuit, such as the path between a preamp stage and a power amp stage . Here, a “coupling capacitor" will block DC voltage, allowing only the AC guitar signal to pass .
Filter capsCapacitors also filter out 60Hz hum, or “ripple," after the AC current from the wall is converted to DC . These capacitors are called filter caps, because they filter out the ripple from a power supply . The filter caps in this amp are the 50μf + 50μf electrolytic can capacitors . This means that each physical capacitor has two caps inside, each with their own positive lug, and they share a common negative lug .
Electrolytic capsElectrolytic capacitors contain electrolyte: a liquid or gel that gives them a large storage capacity . Electrolytic caps are typically polarized .
Polarized capsSome capacitors have polarity and some don’t . It’s extremely important to install polarized caps correctly in a circuit . The positive lead of an electrolytic cap will be indicated by an indented ring around one edge of the capacitor . The nega-tive lead will often be indicated by a band of arrows pointing to the negative lead .
Installing capacitors with the polarity backwards will make the circuit malfunction and quickly destroy the capacitor—even causing it to explode .
Band 1 Band 2 Band 3 Band 4 1st Digit 2nd Digit Multiplier Tolerance
6 8 x1,000 +/- 5%
68K +/- 5%K = 1,000
Blue
Read this band first (closest to an end)
Gray Orange Gold
BLACK 0 0 1 None +/- 20%
BROWN 1 1 10
RED 2 2 100
ORANGE 3 3 1,000
YELLOW 4 4 10,000
GREEN 5 5 100,000
BLUE 6 6 1,000,000
VIOLET 7 7
GRAY 8 8 0.01 +/- 10% SILVER
WHITE 9 9 0.1 +/- 5% GOLD
50μ
F +
50μ
F50
0V
NegativePositive
+ 8μF
How to read resistor values Capacitor values
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V5EL34
V4EL34
POWER STANDBY PRESENCE BASS MIDDLE TREBLE MASTER VOLUME
PREAMPVOLUME
INPUT (NORMAL)
H.T. FUSE
V312AX7
V212AX7
V112AX7
SPEAKER EXTENSIONSPEAKER
VOLTAGESELECTOR
IMPENDANCESELECTOR
FILTER CAP 3
FILTER CAP 2FILTER CAP 1
MAINS INPUT MAINSFUSE
1MA
12
43
12
43
1MA
1MA
250KL
25KL
1MA
5KL
43
2 1
87
65
43
2 1
87
65
3
6
5
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4
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4321
9 8
75 6
4321
9 8
756
4321
9 8
75D-
-
D-
-
D-
-
A
B
3
6
5
2 1
4 4 2
3 1
4 2
3 1
.1μF
5W 1K5W 1K
.001μF 510K
1
29
2
26
3 4 5 6 7
20 2122 23 24
27
25
28
8 9 10 11 12 13 14 15 16 17 18
34 35 36 37 38 39 40 44 45 46333231
19
30 41 42 43
.022μF
.022μF
.68μF
+
500pF
500pF
.022μF
.022μF
.022μF
5W 10K
5W 10K
.022μF
.022μF
.01μF
47
+
8µF
+
8µF
10
Complete wiring diagram
Our diagrams show a flat view of the metal chassis
Here’s the complete Brit-800 50 wiringWhen you’ve finished the kit, you’ll have connected all the parts shown in this wiring diagram . If it looks complex now, don’t worry; we’ll start at the very beginning and do this one step at a time .
Your amp-building skills will get stronger with each step!
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Start by prepping the turret board
n Wrap the leads tightly for a good electrical contact before soldering . Don’t use solder to “glue" loose joints .
n Melt a small amount of solder onto the tip of the iron (“tinning" the iron) . Hold the tip against the joint for a few seconds, until the connection reaches soldering temperature .
Also tin component leads like multi-strand wires to help the solder flow .
You’re ready to build!
Tips for great soldering!
STEP 1
Number the turretsThe steps refer to the turrets by num-ber . Number the turrets on your board by putting tape along the edges and writing with a fine-point marker . You’ll remove the tape before installing the board .
Leave the turrets in the center of the board (#19–28) unmarked . You can identify these turrets by referring to the diagrams .
n Keep your soldering tip clean by wiping it often on a damp sponge . Keep it tinned by occasionally melting a little solder onto it .
n Feed solder to the connection not to the iron . Keep the iron on the con-nection for a second longer to allow time for all of the flux to cook out of the joint .
n Don’t ever blow on the hot solder or touch anything until the joint is completely cool . A good solder joint is shiny—a sign that it was left to cool undisturbed .
1
29
2
26
3 4 5 6 7
20 2122 23 24
27
25
28
8 9 10 11 12 13 14 15 16 17 18
34 35 36 37 38 39 40 44 45 46333231
19
30 41 42 43
n Trim away the excess wires after the joint has cooled .
n Plan ahead so each joint is only soldered once . Resoldered joints are messy and more likely to fail .
n Position the parts so their specs face out so you can read them later . Many builders also align resistor bands to read in the same direction .
n How much insulation to strip? With plastic insulation, strip 3/8" from the wire ends . Push-back wire works best when you strip away about 1/4" of the cloth wrap .
Component leads are wrapped onto the turrets and left unsoldered while you add other parts . This way, you can check your work and make correc-tions without having to redo a solder joint . Ideally you solder a turret only once, which is the best way to get clean, trouble-free connections .
When it's time to solder, flow the solder all the way around the turret .
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tsid
e th
e ch
assi
s . In
stal
l the
mai
ns fu
se
sock
et b
y re
mov
ing
the
nut,
slid
ing
the
sock
et th
roug
h th
e ch
assi
s, a
nd fa
sten
ing
it w
ith t
he n
ut . T
o ke
ep t
he p
anel
tig
ht
agai
nst
th
e ch
assi
s d
uri
ng
ass
emb
ly,
secu
re e
ach
corn
er o
f th
e p
anel
wit
h a
pie
ce o
f mas
king
tap
e .
S
TE
P 3
Pre
p t
he
sin
gle
ter
min
al s
trip
W
ith
a w
ire
cutt
er, s
nip
th
e m
oun
tin
g ho
les
on th
e th
ree-
lug
term
inal
str
ips
as
pic
ture
d ab
ove .
Cu
t o
ne
1" p
iece
of
gre
en w
ire
and
rem
ove
the
insu
latio
n . W
rap
and
sol
der
th
e w
ire a
cros
s al
l thr
ee lu
gs, e
lect
rical
ly
conn
ectin
g th
em . T
his
will
be
used
as
a gr
ound
ing
strip
.
S
TE
P 4
Inst
all fi
ve r
ub
ber
gro
mm
ets
Squ
eeze
th
ese
into
th
e fi
ve h
ole
s as
sh
own .
The
se p
rovi
de
stra
in re
lief f
or th
e tr
ansf
orm
er w
ires
that
will
pas
s th
roug
h th
e m
etal
cha
ssis
.
Insi
de
a tr
ansf
orm
er is
a p
rimar
y co
il an
d a
seco
ndar
y co
il . Y
our 1
20V
AC
hou
seho
ld
curr
ent g
oes
into
the
prim
ary
coil
and
is
tran
sfor
med
into
hig
her
volt
age
whi
ch
is o
utp
ut
by
the
seco
nd
ary
coil .
Th
is
volt
age
can
be
as h
igh
as 5
00V,
and
is
refe
rred
to a
s hig
h te
nsio
n (H
.T .) .
The
lead
s co
nnec
ting
to t
hese
tw
o co
ils a
re c
alle
d p
rimar
y an
d se
cond
ary
lead
s .
S
TE
P 5
Mo
un
t th
e p
ow
er t
ran
sfo
rmer
The
pow
er t
ran
sfo
rmer
has
ten
lea
ds .
Se
para
te th
ese
into
col
or-c
oded
pai
rs a
nd
twis
t the
se s
ets
toge
ther
:
Two
solid
red
lead
s
Thic
k so
lid b
lack
Th
ick
solid
ora
nge
Red
/yel
low
str
iped
Th
in s
olid
bla
ck
Thin
sol
id o
rang
e
Thin
sol
id y
ello
w
Feed
the
twis
ted
red
lead
s an
d th
e so
lid
blu
e an
d so
lid b
row
n le
ads
thro
ugh
the
grom
met
clo
sest
to th
e p
ower
sw
itche
s .
Feed
th
e tw
o t
wis
ted
tri
os
of
lead
s th
roug
h th
e ne
arby
gro
mm
et, a
s sh
own
on th
e w
iring
dia
gram
.
Use
fo
ur
8-3
2 x
3/8"
mac
hin
e sc
rew
s w
ith lo
cknu
ts t
o m
ount
the
tra
nsfo
rmer
on
th
e ou
tsid
e of
th
e ch
assi
s . A
dd
th
e th
ree-
lug
gro
und
ing
str
ip o
n t
he
bac
k rig
ht m
ount
ing
scre
w a
s sh
own .
S
TE
P 6
Mo
un
t th
e o
utp
ut
tran
sfo
rmer
One
sid
e of
the
out
put
tra
nsfo
rmer
has
re
d, w
hite
, and
bro
wn
wire
s . T
hese
are
th
e p
rim
ary
lead
s o
f th
e tr
ansf
orm
er .
Twis
t th
e re
d an
d w
hite
wire
s to
geth
er .
Pas
s th
ese
thre
e w
ires
th
rou
gh
th
e g
rom
met
ed h
ole
clo
sest
to
th
e fr
on
t p
anel
of t
he c
hass
is .
The
othe
r sid
e of
the
outp
ut tr
ansf
orm
er
has
ora
ng
e, g
reen
, ye
llow
, an
d g
ray
wir
es .
Thes
e ar
e th
e se
con
dar
y le
ads
of
the
tran
sfo
rmer
. Tw
ist
the
gre
en +
ye
llow
+ g
ray
seco
ndar
y w
ires
toge
ther
. Pa
ss a
ll fo
ur o
f th
ese
wire
s th
roug
h th
e gr
omm
eted
hol
e as
show
n on
the
wiri
ng
diag
ram
.
Use
four
8-3
2 x
3/8"
mac
hine
scr
ews w
ith
lock
nuts
to m
ount
the
tran
sfor
mer
on
the
outs
ide
of th
e ch
assi
s .
S
TE
P 7
Mo
un
t th
e fi
lter
ch
oke
The
filte
r cho
ke is
a si
ngle
-coi
l tra
nsfo
rmer
, al
so c
alle
d an
indu
ctor
, tha
t hel
ps sm
ooth
ou
t th
e A
C r
ipp
le l
eft
over
in
the
hig
h vo
ltag
e si
gn
al .
This
mea
ns
the
filt
er
chok
e on
ly h
as t
wo
lead
s, o
ne r
ed a
nd
one
bla
ck . T
wis
t the
se le
ads t
oget
her a
nd
thre
ad th
em th
roug
h th
e la
st g
rom
met
ed
hole
, in
the
mid
dle
of th
e ch
assi
s .
Use
fo
ur
8-3
2 m
ach
ine
scre
ws
and
lock
nuts
to m
ount
the
filte
r cho
ke o
utsi
de
of t
he c
hass
is . A
dd
a gr
ound
ing
tab
on
the
top
righ
t mou
ntin
g sc
rew
as
show
n .
stew
mac
.co
m
12
©20
19 S
tew
Mac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
PRES
ENCE
BASS
MID
DLE
TREB
LEM
AST
ER
VOLU
ME
PREA
MP
VOLU
ME
INPU
T (N
ORM
AL)
H.T
. FU
SE
V3
12A
X7
FILT
ER C
AP
3
FILT
ER C
AP
2FI
LTER
CA
P 1
V2
12A
X7V1
12A
X7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
VOLT
AG
ESE
LECT
OR
IMPE
ND
AN
CESE
LECT
OR
MA
INS
FUSE
MA
INS
INPU
T
BA
-
BA
-
BA
-
4 3
21
87
65
4 3
21
87
65
6
43 2 1
9875
6
43 2 1
9875
64
3 2 1
9875
stew
mac
.co
m
13
©20
19
Stew
Mac
S
TE
P 8
Mo
un
t th
e fi
lter
cap
acit
ors
The
filte
r cap
acito
rs a
re h
eld
to th
e ch
assi
s w
ith
mo
un
tin
g c
lam
ps .
Th
ese
clam
ps
atta
ch to
the
cap
acito
r on
the
sam
e en
d as
the
lugs
, and
are
then
mou
nted
to th
e ch
assi
s usi
ng 4
-40
x 3/
8" sc
rew
s and
nut
s .
Posi
tion
the
clam
p so
you
can
mou
nt th
e ca
pac
ito
r’s n
egat
ive
(–)
lug
fac
ing
th
e fr
ont p
anel
of t
he c
hass
is .
Thes
e th
ree
filte
r cap
s w
ill b
e re
ferr
ed to
as
filte
r cap
1, fi
lter c
ap 2
, and
filte
r cap
3 .
Thei
r pos
itive
lugs
are
ass
igne
d th
e le
tter
s A
& B
for c
larit
y .
Mo
un
t th
e fi
lter
cap
s an
d c
lam
ps
as
show
n in
the
wiri
ng d
iagr
am .
S
TE
P 9
Gro
un
d t
he
filt
er c
aps
Cut
a 2
-1/2
" g
reen
jum
per
. So
lder
on
e en
d of
this
jum
per
to th
e ne
gativ
e (-)
lug
of fi
lter c
ap 1
. Wra
p th
e ot
her e
nd o
f thi
s ju
mp
er to
the
nega
tive
lug
of fi
lter c
ap 2
, b
ut d
on't
sold
er it
yet
.
Cu
t a
1-1/
2" g
reen
jum
per
. So
lder
on
e en
d of
this
jum
per
to th
e ne
gativ
e lu
g of
fil
ter
cap
2 a
long
with
the
jum
per
fro
m
filte
r ca
p 1
. Wra
p t
he
oth
er e
nd
of
the
jum
per
to th
e cl
oses
t lug
of t
he th
ree-
lug
grou
ndin
g st
rip, b
ut d
on't
sold
er it
yet
.
Cut
anot
her
1-1/
2" g
reen
jum
per
. Sol
der
on
e en
d to
the
nega
tive
(-) lu
g of
filte
r cap
3 .
Sol
der
the
othe
r end
of t
he ju
mp
er to
th
e ne
arby
gro
undi
ng ta
b .
S
TE
P 1
0
Co
nn
ect
the
filt
er c
ap p
osi
tive
lug
sC
ut t
wo
1" g
reen
jum
per
s an
d r
emov
e th
e in
sula
tion .
Wra
p on
e ju
mp
er b
etw
een
filte
r ca
p 1
's p
ositi
ve lu
gs a
nd w
rap
the
ot
her b
etw
een
filte
r cap
2's
pos
itive
lugs
. D
on't
sold
er th
ese
jum
per
s ye
t .
S
TE
P 1
1
Ad
d o
ne
gro
un
din
g t
ab
Use
a 4
-40
x 1/
4" s
crew
and
lock
nut
to
mou
nt a
gro
und
ing
tab
on
the
chas
sis
hole
bet
wee
n fil
ter c
ap 1
and
filte
r cap
2 .
S
TE
P 1
2
Inst
all t
he
two
larg
e tu
be
sock
ets
wit
h s
pri
ng
ret
ain
ers
Ori
ent
thes
e ei
ght-
pin
tub
e so
cket
s so
th
at p
in 1
is c
lose
st t
o th
e re
ar p
anel
of
the
chas
sis .
Use
4-4
0 x
3/8"
mac
hin
e sc
rew
s an
d lo
cknu
ts t
o m
ount
the
se s
ocke
ts o
n th
e ou
tsid
e of
the
cha
ssis
. Inc
lud
e a
sprin
g re
tain
er o
n th
e b
otto
m o
f ea
ch s
ocke
t to
pro
vid
e su
pp
ort f
or th
ese
thre
e tu
bes
w
hen
they
’re in
stal
led
late
r .
S
TE
P 1
3
Inst
all t
he
thre
e sm
all t
ub
e so
cket
sPo
sitio
n th
ese
nine
-pin
soc
kets
so
pin
9
is c
lose
st to
the
rear
pan
el o
f the
cha
ssis
. U
se t
wo
4-40
x 1
/4" m
achi
ne s
crew
s an
d lo
cknu
ts t
o m
ount
the
thr
ee r
emai
ning
tu
be
sock
ets .
S
TE
P 14
Inst
all t
he
H.T
. fu
se s
ock
et +
on
e ju
mp
er
Inst
all t
he h
igh
-ten
sion
fuse
sock
et in
the
bac
k p
anel
.
Cut a
1" g
reen
jum
per
. Sol
der
one
end
to
the
bac
k lu
g of
the
H .T
. fus
e so
cket
. Sol
der
the
othe
r end
of t
he ju
mp
er to
the
clos
est
lug
of th
e th
ree-
lug
grou
ndin
g st
rip a
long
w
ith th
e ju
mp
er a
lread
y in
pla
ce .
S
TE
P 1
5
Inst
all t
he
mai
ns
inp
ut
+ t
wo
ju
mp
ers
Use
4-4
0 x
3/8"
scr
ews
and
lock
nuts
to
inst
all
the
pow
er in
put
wit
h it
s ce
ntra
l gr
ound
lug
faci
ng th
e ch
assi
s op
enin
g .
Cut o
ne 2
-1/4
" gre
en ju
mp
er . S
old
er o
ne
end
of th
is ju
mp
er to
the
cent
ral g
roun
d lu
g of
the
mai
ns in
put
. Wra
p t
he o
ther
en
d o
f th
is j
um
per
to
th
e g
rou
nd
tab
b
etw
een
filte
r cap
1 a
nd fi
lter c
ap 2
.
Cu
t o
ne
3" w
hit
e ju
mp
er .
Sold
er o
ne
end
of th
is ju
mp
er to
the
right
lug
of th
e p
ower
inle
t an
d so
lder
the
oth
er e
nd o
f th
is ju
mp
er to
the
bac
k lu
g of
the
mai
ns
fuse
soc
ket .
S
TE
P 1
6
Ad
d t
he
stan
db
y sw
itch
Mou
nt th
e st
andb
y sw
itch
by p
ushi
ng th
e sw
itch
thro
ugh
the
fron
t of
the
cha
ssis
an
d p
ullin
g th
e fo
ur b
lack
tab
s ou
t fro
m
the
swit
ch h
ou
sin
g s
o t
hey
sit
tig
ht
agai
nst t
he in
sid
e of
the
chas
sis .
S
TE
P 1
7
Inst
all t
he
bia
s p
ot
Mou
nt t
he 1
0KL
bia
s p
ot in
the
floo
r of
th
e ch
assi
s as
sho
wn .
In b
uil
din
g t
his
am
p,
you
’ll c
ut
pie
ces
of w
ire to
mak
e co
nnec
tions
. Th
ese
con
nec
tin
g w
ires
are
cal
led
jum
per
s, a
nd y
ou’ll
use
a lo
t of t
hem
in
bui
ldin
g th
is a
mp .
stew
mac
.co
m
14
©20
19 S
tew
Mac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
PRES
ENCE
BASS
MID
DLE
TREB
LEM
AST
ER
VOLU
ME
PREA
MP
VOLU
ME
INPU
T (N
ORM
AL)
H.T
. FU
SE
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
VOLT
AG
ESE
LECT
OR
IMPE
ND
AN
CESE
LECT
OR
FILT
ER C
AP
3
FILT
ER C
AP
2FI
LTER
CA
P 1
MA
INS
FUSE
MA
INS
INPU
T
4 3
21
87
65
6
43 2 1
9875
6
43 2 1
9875
64
3 2 1
9875
BA
-
BA
-
BA
-
12
43
1MA
250KL
25KL
1MA
5KL
4 3
21
87
65
12
43
LO HI
ST
EP
00
Enla
rged
tosh
ow d
etai
lM
ount
jack
s ou
tsid
eon
the
fron
t pan
el
12
43
12
43
LO HI
stew
mac
.co
m
15
©20
19
Stew
Mac
S
TE
P 1
8
Inst
all t
he
rem
ain
ing
co
ntr
ol p
ots
Mou
nt th
e co
ntro
l pot
s so
thei
r thr
ee lu
gs
are
faci
ng
th
e ch
assi
s o
pen
ing
. W
hen
w
e re
fer t
o th
ese
lugs
as
left
or r
ight
, it’s
as
sum
ing
you’
re lo
okin
g at
the
pot
from
th
e sa
me
po
int
of
view
as
the
wir
ing
diag
ram
. M
ount
them
as
follo
ws:
Pres
ence
: 5KL
pot
Ba
ss: 1
MA
pot
Mid
dle
(mid
s): 2
5KL
pot
Tr
eble
: 250
KL p
ot
M
aste
r Vol
ume:
1M
A
S
TE
P 19
Wir
e th
e in
pu
t ja
cks
Use
tw
o 4-
lug
jack
s fo
r th
e in
put
jack
s .
For
thes
e st
eps,
we’
ll re
fer
to t
he n
ames
th
ey a
re g
iven
on
the
fron
t p
anel
, hig
h-
sens
itivi
ty a
nd lo
w-s
ensi
tivit
y .
Mo
un
t th
e ja
cks
tem
po
rari
ly o
n t
he
outs
ide
of th
e ch
assi
s, in
thei
r res
pec
tive
hole
s w
ith th
eir l
ugs
poi
ntin
g aw
ay fr
om
the
pow
er s
witc
h .
Mou
ntin
g th
e ja
cks
outs
ide
the
chas
sis
will
hol
d th
em in
pos
ition
and
giv
e yo
u ro
om to
do
the
tric
ky jo
b o
f wiri
ng th
em
up . A
fter
war
d, th
ey’ll
fit n
icel
y in
sid
e th
e ch
assi
s as
a p
re-w
ired
asse
mb
ly .
Cut a
1" p
iece
of w
hite
wire
and
wra
p o
ne
end
to lu
g 2
of t
he h
igh
-sen
sitiv
ity
jack
. W
rap
the
othe
r end
to lu
g 4
of th
e hi
gh-
sens
itivi
ty ja
ck .
Run
one
lead
of a
1M
resi
stor
thro
ugh
lug
1 of
the
high
-sen
sitiv
ity
jack
and
the
othe
r le
ad th
roug
h lu
g 2
of th
e hi
gh-s
ensi
tivit
y ja
ck . S
old
er th
ese
lead
s in
pla
ce o
n b
oth
jack
s, a
long
with
the
jum
per
wra
pp
ed to
lu
g 1,
and
trim
any
exc
ess
lead
s .
Cut
a 1-
1/8"
whi
te ju
mp
er a
nd w
rap
one
en
d to
lug
4 of
the
low
sen
sitiv
ity
jack
. W
rap
the
othe
r end
to lu
g 3
of th
e hi
gh-
sen
siti
vity
jac
k . S
old
er t
his
ju
mp
er i
n p
lace
on
bot
h lu
gs a
nd t
rim a
ny e
xces
s le
ads .
Cut a
2-1
/2"
whi
te ju
mp
er a
nd w
rap
one
en
d to
lug
2 of
the
low
-sen
sitiv
ity
jack
. W
rap
the
othe
r end
to lu
g 4
of th
e hi
gh-
sen
siti
vity
jac
k . S
old
er t
his
ju
mp
er i
n p
lace
on
lug
2 of
the
low
-sen
sitiv
ity
jack
an
d tr
im a
ny e
xces
s le
ad .
Cut a
2-1
/2" g
reen
jum
per
and
sold
er o
ne
end
to lu
g 4
of t
he h
igh
-sen
sitiv
ity
jack
al
ong
wit
h th
e tw
o ju
mp
ers
alre
ady
in
pla
ce . T
rim a
ny e
xces
s le
ads .
Rem
ove
thes
e w
ired
-up
inp
ut ja
cks
and
mou
nt t
hem
in t
he s
ame
hole
s on
the
in
sid
e of
the
chas
sis .
(The
ir lu
gs a
re n
ow
faci
ng th
e p
ower
sw
itch .
)
S
TE
P 2
0
Gro
un
d a
ll c
on
tro
l po
tsTu
rn a
ll p
ot s
haft
s co
unte
rclo
ckw
ise
to
thei
r ze
ro p
osit
ion
bef
ore
star
tin
g t
his
step
. Thi
s is
bec
ause
you
’ll b
e ap
ply
ing
heat
to th
eir c
ases
, and
if th
e he
at li
nger
s to
o lo
ng it
cou
ld c
reat
e an
imp
ress
ion
on
the
wip
er in
side
. Thi
s isn
’t a
conc
ern
if th
e p
ot is
in th
e ze
ro p
ositi
on .
Stra
ight
en o
ut th
e b
are
cop
per
wire
and
ru
n it
fro
m t
he p
ream
p v
olum
e p
ot t
o th
e p
rese
nce
pot
. Sta
rtin
g at
the
pre
amp
co
ntro
l pot
, sol
der
the
bar
e co
pp
er w
ire
to th
e b
ack
of e
ach
pot
. If y
ou a
re h
avin
g tr
ou
ble
ap
ply
ing
en
ou
gh
hea
t to
th
e b
ack
of th
e p
ot to
get
the
sold
er to
take
, cr
eate
a s
old
er p
uddl
e on
the
bac
k of
the
pot
bef
ore
atte
mp
ting
to so
lder
the
bar
e co
pp
er w
ire to
the
hous
ing .
Onc
e yo
u ha
ve t
he b
are
wir
e so
lder
ed
to t
he b
ack
of e
ach
pot
, trim
aw
ay a
ny
exce
ss w
ire .
stew
mac
.co
m
16
©20
19 S
tew
Mac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
PRES
ENCE
BASS
MID
DLE
TREB
LEM
AST
ER
VOLU
ME
PREA
MP
VOLU
ME
INPU
T (N
ORM
AL)
H.T
. FU
SE
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
VOLT
AG
ESE
LECT
OR
IMPE
ND
AN
CESE
LECT
OR
FILT
ER C
AP
3
FILT
ER C
AP
2FI
LTER
CA
P 1
MA
INS
FUSE
MA
INS
INPU
T
4 3
21
87
65
6
43 2 1
9875
6
43 2 1
9875
64
3 2 1
9875
BA
-
BA
-
BA
-
12
43
12
43
1MA
250KL
25KL
1MA
5KL
4 3
21
87
65
LO HI
.1μF
stew
mac
.co
m
17
©20
19
Stew
Mac
S
TE
P 2
1
Gro
un
d t
hre
e co
ntr
ol p
ots
Cut
thre
e 1"
jum
per
s of
gre
en w
ire, p
ull
off th
eir i
nsul
atio
n, a
nd b
end
one
end
of
each
into
a h
ook .
Star
tin
g w
ith
th
e p
ream
p v
olum
e p
ot,
sold
er th
e ho
ok e
nd o
f the
jum
per
to th
e le
ft lu
g of
the
pot
. Sol
der t
he st
raig
ht e
nd
of th
is ju
mp
er to
the
bac
k of
the
pot
.
Rep
eat t
his p
roce
ss fo
r the
mas
ter v
olum
e p
ot a
nd th
e m
ids
pot
.
S
TE
P 2
2
Ad
d o
ne
wh
ite
jum
per
Cut a
3" w
hite
jum
per
. Sol
der
one
end
of
this
jum
per
to th
e m
iddl
e lu
g of
the
treb
le
pot
. Sol
der
the
othe
r end
of t
his
jum
per
to
the
right
lug
of th
e m
aste
r vol
ume
pot
.
S
TE
P 2
3
Ad
d t
wo
wh
ite
jum
per
sC
ut
a 3-
1/2"
wh
ite
jum
per
. So
lder
on
e en
d to
the
left
lug
of t
he b
ass
pot
and
so
lder
the
oth
er e
nd t
o th
e rig
ht lu
g of
th
e m
ids
pot
.
Cut o
ne 4
-1/4
" w
hite
jum
per
. Sol
der
one
en
d t
o th
e m
idd
le lu
g of
the
bas
s p
ot .
Wra
p th
e ot
her e
nd to
the
left
lug
of th
e tr
eble
pot
, but
don
't so
lder
it y
et . Y
ou'll
b
e ad
ding
a ju
mp
er fr
om th
e tu
rret
boa
rd
here
late
r .
S
TE
P 2
4
Ad
d a
4.7
k re
sist
or
Run
on
e le
ad o
f a
4 .7k
res
isto
r d
ow
n th
rou
gh
th
e le
ft l
ug
of
the
pre
sen
ce
pot
. Sol
der
thi
s le
ad t
o th
e b
ack
of t
he
pre
senc
e p
ot a
nd t
hen
to t
he le
ft lu
g of
th
e p
rese
nce
pot
. Wra
p t
he o
ther
lea
d o
f th
is r
esis
tor
to t
he
rig
ht
lug
of
the
pre
senc
e p
ot b
ut d
on't
sold
er it
yet
.
S
TE
P 2
5
Ad
d a
.1μ
F ca
pac
ito
r So
lder
on
e le
ad o
f a
.1μ
F ca
p t
o t
he
mid
dle
lug
of t
he p
rese
nce
pot
. Sol
der
th
e ot
her
lea
d o
f th
is c
apac
itor
to
the
bac
k of
the
pre
senc
e p
ot . T
rim a
way
all
exce
ss l
ead
s fr
om t
he
com
pon
ents
on
the
pre
senc
e p
ot .
S
TE
P 2
6
Po
wer
tra
nsf
orm
er b
row
n a
nd
blu
e le
ads
+ o
ne
jum
per
Run
the
bro
wn
pow
er t
rans
form
er le
ad
to t
he g
roun
d ta
b b
etw
een
filte
r ca
p 1
an
d fil
ter
cap
2 . T
rim t
his
lead
to
leng
th
and
sol
der
it t
o th
e ta
b a
long
wit
h th
e gr
een
jum
per
from
the
mid
dle
lug
of th
e p
ower
inle
t .
Run
the
blu
e p
ower
tra
nsfo
rmer
lead
to
the
pow
er s
witc
h an
d w
rap
it to
the
top
le
ft lu
g .
Cut
one
1-1/
2" w
hite
jum
per
and
sol
der
on
e en
d to
the
bot
tom
rig
ht lu
g of
the
p
ower
switc
h . S
olde
r the
oth
er e
nd o
f thi
s ju
mp
er t
o th
e to
p le
ft lu
g of
the
pow
er
switc
h al
ong
with
the
blu
e tr
ansf
orm
er
lead
alre
ady
in p
lace
.
S
TE
P 2
7
Po
wer
tra
nsf
orm
er r
ed le
ads
Run
the
two
red
wire
s fr
om t
he p
ower
tr
ansf
orm
er s
tand
by s
witc
h . T
rim t
hese
w
ires t
o le
ngth
, sol
der o
ne to
the
bot
tom
le
ft lu
g of
the
stan
dby
switc
h, a
nd s
old
er
the
othe
r to
the
rig
ht b
otto
m lu
g of
the
st
and
by
swit
ch . E
ith
er w
ire
can
go
to
eith
er lu
g .
stew
mac
.co
m
18
©20
19 S
tew
Mac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
PRES
ENCE
BASS
MID
DLE
TREB
LEM
AST
ER
VOLU
ME
PREA
MP
VOLU
ME
INPU
T (N
ORM
AL)
H.T
. FU
SE
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
VOLT
AG
ESE
LECT
OR
IMPE
ND
AN
CESE
LECT
OR
FILT
ER C
AP
3
FILT
ER C
AP
2FI
LTER
CA
P 1
MA
INS
INPU
TM
AIN
SFU
SE
6
43 2 1
9875
6
43 2 1
9875
64
3 2 1
9875
BA
-
BA
-
BA
-
12
43
12
43
LO HI
4 3
21
87
65
4 3
21
87
65
stew
mac
.co
m
19
©20
19
Stew
Mac
S
TE
P 2
8
Inst
all t
he
hea
ter
wir
esTu
bes
requ
ire a
6 .3
V A
C c
urre
nt to
pow
er
thei
r fi
lam
ents
, w
hic
h a
re a
lso
cal
led
"hea
ters
" in
the
am
p w
orld
. Thi
s cu
rren
t is
pro
vid
ed b
y th
e p
ower
tra
nsf
orm
er
thro
ugh
the
oran
ge a
nd b
lack
lead
s .
The
Briti
sh st
yle
of ru
nnin
g he
ater
wire
s is
to tu
ck th
em in
to th
e b
otto
m b
ack
corn
er
of t
he c
hass
is . K
eep
ing
the
wire
s tu
cked
into
the
bac
k co
rner
of t
he c
hass
is, a
way
fr
om t
he s
igna
l car
ryin
g w
ires,
pre
vent
s th
e A
C c
urre
nt in
thes
e he
ater
wire
s fro
m
ble
edin
g 60
hz h
um in
to y
our s
igna
l .
S
TE
P 2
9
Co
nn
ect
to s
ock
et V
5Ru
n th
e tw
iste
d tr
io o
f ora
nge,
bla
ck, a
nd
stri
ped
red
/yel
low
pow
er t
ran
sfo
rmer
le
ads
to s
ocke
t V5
, kee
pin
g th
em d
own
as c
lose
to th
e ch
assi
s as
pos
sib
le .
Pull
the
stri
ped
red
/yel
low
lea
d o
ut o
f th
is t
wis
ted
trio
. Run
it to
the
sid
e lu
g of
th
e H
.T . f
use
sock
et, c
ut it
to le
ngth
, and
so
lder
it to
the
lug .
Cut
two
6" h
eate
r w
ires,
one
whi
te a
nd
on
e b
lack
. Tw
ist
them
to
get
her
ver
y ti
gh
tly,
lea
vin
g a
bo
ut
1" o
f th
e en
ds
un
twis
ted
. Jo
in t
he
wh
ite
jum
per
to
the
ora
ng
e le
ad b
y tw
isti
ng
th
e en
ds
tog
eth
er . J
oin
the
bla
ck j
ump
er t
o th
e b
lack
lead
.
Sold
er t
he
pai
r w
ith
th
e w
hite
wir
e to
p
in 2
of
sock
et V
5 . S
old
er t
he p
air
with
th
e b
lack
wire
to p
in 7
of s
ocke
t V5 .
Ben
d th
ese
wire
s in
to t
he b
ack
corn
er o
f th
e ch
assi
s an
d t
hen
ben
d t
he
bla
ck-a
nd
-w
hite
pai
r at a
90°
ang
le to
war
d so
cket
V4 .
S
TE
P 3
0
Co
nn
ect
to s
ock
et V
4Cu
t tw
o 6"
hea
ter
wire
s, o
ne w
hite
and
on
e b
lack
. Tw
ist t
hem
tigh
tly
toge
ther
.
Twis
t th
e en
d o
f th
e w
hite
wir
e to
th
e w
hite
jum
per
com
ing
from
V5 .
Tw
ist t
he
bla
ck w
ire w
ith th
e b
lack
jum
per
com
ing
from
V5 .
Sold
er t
he w
hite
pai
r on
to p
in 2
of
V4 .
Sold
er th
e b
lack
pai
r ont
o p
in 7
. Ben
d th
e w
ires
into
the
bac
k co
rner
of t
he c
hass
is,
and
on to
war
d so
cket
V3 .
Sold
er th
e w
hite
pai
r to
pin
2 of
sock
et V
4 .
Sold
er th
e b
lack
pai
r to
pin
7 o
f soc
ket V
4 .
Bend
thes
e w
ires
into
the
bac
k co
rner
of
the
chas
sis a
nd th
en b
end
the
bla
ck-a
nd-
whi
te p
air a
t a 9
0° a
ngle
tow
ard
sock
et V
3 .
Use t
his he
ater-w
ire tec
hnique
to
minimi
ze the
hum c
aused
by AC
voltag
eTh
e tw
iste
d gr
een
wire
s fro
m th
e p
ower
tran
sfor
mer
car
ry A
C v
olta
ge to
th
e he
atin
g fil
amen
ts in
the
tub
es . T
his
volt
age
will
cau
se y
our a
mp
to
hum
if th
ese
wire
s are
allo
wed
to ru
n to
o cl
ose
to si
gnal
-car
ryin
g w
ires .
Twis
t th
e w
ires
tig
htl
y to
get
her
This
tw
ist
isn’
t fo
r lo
oks;
it’s
an
imp
orta
nt h
um-c
ance
lling
tec
hniq
ue
to r
educ
e no
ise
in y
our
amp .
It w
orks
in a
way
sim
ilar
to t
he o
pp
o-
site
-wou
nd c
oils
in a
hum
buc
king
pic
kup .
Ro
ute
th
em a
way
To k
eep
tw
iste
d he
ater
wire
s aw
ay f
rom
sig
nal-
carr
ying
wire
s, r
oute
th
em in
to th
e b
ack
edge
of t
he fl
oor o
f the
cha
ssis
. Giv
e th
em a
sha
rp
right
ang
le b
end
tow
ard
the
next
sock
et a
nd a
noth
er sh
arp
ben
d b
ack
dow
n to
tha
t so
cket
. Thi
s ke
eps
them
shi
eld
ed a
nd a
way
from
sig
nal
carr
ying
wire
s .
stew
mac
.co
m
20
©
2019
Ste
wM
ac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
PRES
ENCE
BASS
MID
DLE
TREB
LEM
AST
ER
VOLU
ME
PREA
MP
VOLU
ME
INPU
T (N
ORM
AL)
H.T
. FU
SE
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
VOLT
AG
ESE
LECT
OR
IMPE
ND
AN
CESE
LECT
OR
FILT
ER C
AP
3
FILT
ER C
AP
2FI
LTER
CA
P 1
MA
INS
INPU
TM
AIN
SFU
SE
BA
-
BA
-
BA
-
12
43
12
43
LO HI
4 3
21
87
65
4 3
21
87
65
6
43 2 1
9875
6
43 2 1
9875
64
3 2 1
9875
3
6
521
4
3
6
52
1
4
stew
mac
.co
m
21
©
2019
St
ewM
ac
S
TE
P 3
1
Co
nn
ect
to s
ock
et V
3O
n so
cket
s V3
, V2,
and
V1
you
will
nee
d to
join
pin
s 4
and
5 to
geth
er . O
n th
ese
thre
e so
cket
s, g
entl
y tw
ist p
ins
4 an
d p
in
5 to
war
d ea
ch o
ther
so
thei
r eye
lets
line
up
. Be
very
car
eful
whi
le d
oing
thi
s, a
s th
ese
pin
s ar
e d
elic
ate .
Cut
two
6" h
eate
r w
ires,
one
whi
te a
nd
one
bla
ck . T
wis
t the
m ti
ghtl
y to
geth
er .
Twis
t the
end
of t
he w
hite
wire
toge
ther
w
ith t
he w
hite
jum
per
com
ing
from
V4 .
Tw
ist t
he b
lack
wire
with
the
blac
k ju
mp
er
com
ing
from
V4 .
Sold
er t
he w
hite
pai
r to
com
bin
ed p
ins
4+5
on V
3 an
d so
lder
the
bla
ck p
air t
o V3
p
in 9
. Ben
d th
e w
ires i
nto
the
bac
k co
rner
of
the
chas
sis,
and
on
tow
ard
sock
et V
2 .
S
TE
P 3
2
Co
nn
ect
to s
ock
et V
2Cu
t tw
o 6"
hea
ter
wire
s, o
ne w
hite
and
on
e b
lack
. Tw
ist
them
tig
htly
tog
ethe
r, le
avin
g ab
out 1
" unt
wis
ted
at b
oth
ends
.
Twis
t th
e lik
e-co
lore
d w
ires
of t
his
new
p
air i
n w
ith th
e lik
e-co
lore
d w
ires
of th
e tw
iste
d p
air c
omin
g fr
om V
3 .
Sold
er t
he p
air
of t
wis
ted
bla
ck w
ires
to
V2
pin
9 a
nd
so
lder
th
e tw
iste
d w
hite
w
ires
to V
2 p
in 4
+5 .
S
TE
P 3
3
Co
nn
ect
to s
ock
et V
1Ru
n th
e b
lack
-and
-whi
te tw
iste
d p
air i
nto
the
bac
k co
rner
of t
he c
hass
is a
nd to
war
d V1
. Sol
der
the
bla
ck w
ire to
V1
pin
9 a
nd
sold
er th
e w
hite
wire
to V
1 p
in 4
+5 .
Car
eful
ly in
spec
t ea
ch s
old
er jo
int
from
th
is h
eate
r w
ire
inst
alla
tio
n, a
nd
on
ce
the
sold
er jo
ints
hav
e co
oled
pus
h yo
ur
heat
er w
ires
into
the
floo
r of
the
cha
ssis
an
d in
to th
e b
ack
corn
er o
f the
cha
ssis
as
muc
h as
you
can
.
S
TE
P 3
4
Inst
all t
he
volt
age
swit
chU
sin
g t
wo
4-4
0 x
3/8
" sc
rew
s an
d lo
ckn
uts
, m
ou
nt
the
volt
age
sele
cto
r sw
itch
as sh
own
in th
e di
agra
m, w
ith th
e lu
g at
tach
ed t
o th
e m
iddl
e sh
aft
faci
ng
the
pow
er in
let .
S
TE
P 3
5
Co
nn
ect
the
volt
age
swit
chTh
e vo
ltag
e se
lect
or sw
itch
allo
ws y
ou to
se
t the
am
plifi
er’s
inp
ut v
olta
ge to
mat
ch
the
wal
l vol
tage
in y
our c
ount
ry .
Cut t
he p
ower
tran
sfor
mer
’s tw
iste
d tr
io
of o
rang
e, b
lack
, and
yel
low
lead
s to
an
app
rop
riate
leng
th t
o re
ach
the
volt
age
sele
ctor
sw
itch .
Sold
er th
e b
lack
wire
to th
e b
otto
m ri
ght
lug
(lu
g 1
in
th
e d
iag
ram
) . So
lder
th
e or
ang
e w
ire
to t
he b
otto
m m
idd
le lu
g (lu
g 2)
, and
the
yello
w w
ire to
the
bot
tom
le
ft lu
g (lu
g 3)
. All
othe
r lu
gs a
re e
mp
ty
at th
is p
oint
.
S
TE
P 3
6
Inst
all t
he
imp
edan
ce s
wit
chU
sing
two
4-40
x 3
/8" s
crew
s and
lock
nuts
, m
ount
th
e im
ped
ance
sel
ecto
r sw
itch
as
sh
own
in t
he
dia
gra
m, w
ith
the
lug
atta
ched
to
the
mid
dle
shaf
t fa
cing
the
p
ower
inle
t .
S
TE
P 3
7
Co
nn
ect
the
imp
edan
ce s
wit
chTh
e im
ped
ance
sel
ecto
r sw
itch
allo
ws
you
to
set
th
e am
plif
ier’
s im
ped
ance
to
mat
ch t
he
spea
ker
cab
inet
yo
u a
re
conn
ecte
d to
.
Cu
t th
e o
utp
ut
tran
sfo
rmer
’s t
wis
ted
trio
of
gra
y, g
reen
, an
d y
ello
w l
ead
s to
an
ap
pro
pri
ate
len
gth
to
rea
ch t
he
imp
edan
ce s
witc
h .
Sold
er t
he
yello
w w
ire
to t
he
bo
tto
m
righ
t lu
g (lu
g 1
in t
he d
iagr
am) .
Sold
er
the
gree
n w
ire to
the
bot
tom
mid
dle
lug
(lug
2), a
nd t
he g
ray
wire
to
the
bot
tom
le
ft lu
g (lu
g 3)
. All
othe
r lu
gs a
re e
mp
ty
at th
is p
oint
.
stew
mac
.co
m
22
©
2019
Ste
wM
ac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
PRES
ENCE
BASS
MID
DLE
TREB
LEM
AST
ER
VOLU
ME
PREA
MP
VOLU
ME
INPU
T (N
ORM
AL)
H.T
. FU
SE
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
VOLT
AG
ESE
LECT
OR
IMPE
ND
AN
CESE
LECT
OR
FILT
ER C
AP
3
FILT
ER C
AP
2FI
LTER
CA
P 1
MA
INS
INPU
TM
AIN
SFU
SE
BA
-
12
43
12
43
LO HI
4 3
21
87
65
4 3
21
87
65
6
43 2 1
9875
6
43 2 1
9875
64
3 2 1
9875
3
6
52
1
4
3
6
521
4B
A
-
BA
-
5W 1
K5W
1K
10
stew
mac
.co
m
23
©
2019
St
ewM
ac
S
TE
P 3
8
Gro
un
d o
ne
ou
tpu
t tr
ansf
orm
er
lead
Rou
te t
he
ora
ng
e o
utp
ut
tran
sfo
rmer
le
ad t
o th
e th
ree-
lug
gro
un
din
g s
trip
, tr
im i
t to
an
ap
pro
pri
ate
len
gth
, an
d so
lder
it to
the
right
lug
of th
e th
ree-
lug
grou
ndin
g st
rip .
S
TE
P 3
9
Filt
er c
ho
ke b
lack
an
d r
ed le
ads
+
ou
tpu
t tr
ansf
orm
er b
row
n le
ads
Ro
ute
th
e t
wis
ted
tri
o o
f th
e t
wo
filt
er c
ho
ke l
ead
s an
d b
row
n o
utp
ut
tran
sfor
mer
lead
tow
ard
filte
r ca
p 1
and
fil
ter c
ap 2
. Trim
the
blac
k fil
ter c
hoke
lead
an
d t
he
bro
wn
ou
tpu
t tr
ansf
orm
er t
o an
d ap
pro
pria
te le
ngth
and
sol
der
them
to
filte
r cap
1's
lug
B al
ong
with
the
bar
e ju
mp
er a
lread
y in
pla
ce . T
rim th
e re
d fil
ter
chok
e le
ad to
an
app
rop
riate
leng
th a
nd
sold
er it
to fi
lter c
ap 2
's lu
g A
alo
ng w
ith
the
bar
e ju
mp
er a
lread
y in
pla
ce .
S
TE
P 4
0
Ou
tpu
t tr
ansf
orm
er r
ed a
nd
wh
ite
lead
sRu
n th
e tw
iste
d r
ed a
nd
whi
te o
utp
ut
tran
sfor
mer
lead
s to
V4
and
V5 . U
ntw
ist
thes
e le
ads
at t
he
fro
nt
of
the
tub
e so
cket
s an
d r
oute
the
red
lea
d a
roun
d th
e V5
tub
e so
cket
as
show
n . T
rim it
to
an a
pp
rop
riate
leng
th a
nd s
old
er it
to V
5 p
in 3
. Run
the
whi
te le
ad to
V4
pin
3, t
rim
it to
an
app
rop
riate
leng
th, a
nd s
old
er it
to
V4
pin
3 . T
rim a
way
any
exc
ess
lead
s .
S
TE
P 4
1
Ad
d t
wo
1K
5W
res
isto
rsTh
ese
resi
stor
s p
rote
ct t
he p
ower
tub
es
and
th
e o
utp
ut
tran
sfo
rmer
, an
d i
n d
oing
this
can
get
ext
rem
ely
hot .
For t
his
reas
on, t
hey
need
to b
e m
ount
ed u
p a
nd
away
from
the
tub
e so
cket
s by
1/2
” .
Wra
p on
e le
ad o
f the
firs
t 1K
5W re
sist
or to
p
in 4
of V
5 an
d w
rap
the
othe
r lea
d to
pin
6
of V
5, s
tand
ing
it up
off
the
tub
e so
cket
1/
2" . S
old
er th
e le
ad w
rap
ped
to p
in 4
.
Wra
p o
ne
lead
of
the
seco
nd
1K
5W
re
sist
or to
pin
4 o
f V4
and
wra
p th
e ot
her
lead
to p
in 6
of V
4, s
tand
ing
it up
off
the
tub
e so
cket
1/2
" . So
lder
the
lead
wra
pped
to
pin
4 .
S
TE
P 4
2
Ad
d t
wo
wh
ite
jum
per
sCu
t one
3" w
hite
jum
per
. Sol
der
one
end
of
the
jum
per
to V
4 p
in 6
with
the
resi
stor
le
ad a
lread
y in
pla
ce . W
rap
the
othe
r end
to
V5
pin
6, b
ut d
on't
sold
er it
yet
.
Cut o
ne 4
" whi
te ju
mp
er . S
old
er o
ne e
nd
of th
e ju
mp
er to
V5
pin
6 w
ith th
e ju
mp
er
and
resi
stor
lead
alre
ady
in p
lace
. Wra
p
the
othe
r en
d t
o fil
ter
cap
2 lu
g B,
but
d
on't
sold
er it
yet
.
S
TE
P 4
3
Gro
un
d t
he
po
wer
tu
be
sock
ets
Cut
two
3/4"
bar
e co
pp
er ju
mp
ers
and
ben
d t
hem
bo
th i
nto
a U
sh
ape .
Ad
d on
e ju
mp
er b
etw
een
V5 p
in 1
and
pin
8 .
Sol
der
thi
s ju
mp
er t
o p
in 8
. Ad
d t
he
othe
r ju
mp
er b
etw
een
V4 p
in 1
and
pin
8 .
Sol
der
this
jum
per
to p
in 8
.
Cut a
4" g
reen
jum
per
. Sol
der
one
end
to
V4 p
in 1
alo
ng w
ith t
he ju
mp
er in
pla
ce
and
wra
p th
e ot
her e
nd to
V5
pin
8 .
Cut
a 4
" g
reen
jum
per
an
d s
old
er o
ne
end
to V
5 p
in 8
alo
ng w
ith t
he U
sha
pe
jum
per
. So
lder
th
e o
ther
en
d o
f th
is
jum
per
to th
e m
iddl
e lu
g of
the
thre
e-lu
g gr
ound
ing
strip
.
S
TE
P 4
4
Ad
d o
ne
jum
per
Ad
d a
3/4"
jum
per
bet
wee
n V3
pin
3 a
nd
pin
8 . S
olde
r the
jum
per
lead
to p
in 3
, but
d
on't
sold
er th
e le
ad in
pin
8 y
et .
S
TE
P 4
5
Ad
d o
ne
jum
per
+ o
ne
resi
sto
rA
dd
a 3/
4" w
hite
jum
per
bet
wee
n V2
pin
1
and
pin
7 . S
old
er th
is ju
mp
er to
pin
7 .
Add
a 1
00k
resi
stor
bet
wee
n V2
pin
1 a
nd
pin
6 . S
old
er th
e le
ad to
pin
1 a
long
with
th
e ju
mp
er in
pla
ce, b
ut d
on't
sold
er th
e re
sist
or le
ad in
pin
6 y
et .
S
TE
P 4
6
Ad
d a
10
pF
cap
acit
or
Ad
d a
10p
F si
lver
mic
a ca
p b
etw
een
pin
1
and
pin
3 o
f soc
ket
V1 . W
rap
the
lead
s of
this
cap
so
the
bod
y of
the
cap
sta
nds
up f
rom
the
tub
e so
cket
1/4
", b
ut d
on't
sold
er th
em y
et .
stew
mac
.co
m
24
©20
19 S
tew
Mac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
PRES
ENCE
BASS
MID
DLE
TREB
LEM
AST
ER
VOLU
ME
PREA
MP
VOLU
ME
INPU
T (N
ORM
AL)
H.T
. FU
SE
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
VOLT
AG
ESE
LECT
OR
IMPE
ND
AN
CESE
LECT
OR
FILT
ER C
AP
3
FILT
ER C
AP
2FI
LTER
CA
P 1
MA
INS
INPU
TM
AIN
SFU
SE
BA
-
BA
-
BA
-
12
43
HI
4 3
21
87
65
6
43 2 1
9875
64
3 2 1
9875
4 3
21
87
65
3
6
52
1
4
3
6
521
4
6
43 2 1
9875
1MA
12
43
LO
.001
μF51
0K
stew
mac
.co
m
25
©
2019
St
ewM
ac
S
TE
P 4
7
Ad
d o
ne
shie
lded
wir
eCu
t a
7-3/
4" le
ngth
of
bra
ided
, shi
eld
ed
wire
. Pul
l the
end
s of
the
bra
id b
ack
to
reve
al t
he in
ner
wire
, and
str
ip t
he e
nds
for s
old
erin
g .
Cu
t a
2" w
hit
e ju
mp
er . W
rap
on
e en
d tig
htly
aro
und
the
shie
lded
wire
, joi
ning
th
e tw
o w
ires
so
th
e w
hit
e in
sula
tio
n is
snu
gg
ed u
p t
o th
e b
raid
. Sol
der
thi
s co
nnec
tion .
Use
1/8
" hea
t-sh
rink
tubi
ng to
insu
late
the
sold
er jo
int a
nd ju
mp
er o
n on
e si
de o
f the
sh
ield
ed w
ire . U
se 1
/8" h
eat-
shrin
k tu
bing
to
insu
late
the
shie
ldin
g on
the
end
of th
e sh
ield
ed w
ire w
ithou
t the
jum
per
as w
ell .
Sold
er th
e sh
ort w
hite
jum
per
to th
e b
ack
of
the
pre
amp
vo
lum
e p
ot .
Wra
p t
he
cent
er le
ad o
f the
shie
lded
wire
—th
e en
d w
ith
th
e sh
ort
jum
per
—to
th
e m
idd
le
lug
of th
e p
ream
p v
olum
e p
ot, b
ut d
on't
sold
er it
yet
.
Run
the
shie
lded
wire
alo
ng th
e b
otto
m
corn
er o
f the
cha
ssis
and
sold
er th
e en
d to
p
in 7
of s
ocke
t V1 .
Trim
any
exc
ess
lead
s .
S
TE
P 4
8
Ad
d a
.001
μF
cap
acit
or
Sold
er o
ne le
ad o
f a .0
01μF
(1nF
) cap
to
the
mid
dle
lu
g o
f th
e p
ream
p v
olu
me
pot
alo
ng w
ith th
e sh
ield
ed ju
mp
er le
ad
alre
ady
in p
lace
. Wra
p th
e ot
her c
ap le
ad
to t
he r
ight
lug
of t
he p
ream
p v
olum
e p
ot, b
ut d
on’t
sold
er it
yet
.
S
TE
P 4
9
Inst
all a
50
0p
F ca
p +
a 4
70k
resi
sto
r,
sold
ered
to
get
her
Wra
p t
he
lead
s fr
om
th
e 50
0p
F ca
p
arou
nd th
e le
ads
of th
e 47
0k re
sist
or a
nd
sold
er th
em to
geth
er .
Sold
er o
ne
of t
he
resi
stor
lea
ds
to t
he
right
lug
of th
e pr
eam
p vo
lum
e p
ot a
long
w
ith t
he c
apac
itor
lead
alre
ady
in p
lace
. So
lder
the
oth
er re
sist
or le
ad to
lug
1 of
th
e lo
w in
put
jack
. Trim
aw
ay a
ny e
xces
s le
ads .
S
TE
P 5
0
Ad
d t
hre
e ju
mp
ers
Cut
a 16
" w
hite
jum
per
and
sol
der
one
en
d to
the
mid
dle,
pro
trud
ing
lug
of th
e vo
ltag
e se
lect
or s
witc
h .
Cut
a 13
" w
hite
jum
per
and
sol
der
one
en
d t
o t
he
sid
e lu
g o
f th
e m
ain
s fu
se
sock
et .
Cut
a 12
" w
hite
jum
per
and
sol
der
one
en
d to
the
left
lug
of th
e p
ower
inle
t .
Twis
t th
ese
thre
e w
ires
to
get
her
an
d ro
ute
them
as
show
n, to
war
d th
e p
ower
sw
itch .
Find
the
jum
per
that
has
con
tinui
ty to
the
left
lug
of th
e m
ains
inp
ut a
nd so
lder
it to
th
e b
otto
m le
ft lu
g of
the
pow
er s
witc
h .
Find
the
jum
per
tha
t ha
s co
ntin
uity
to
the
sid
e lu
g of
the
mai
ns fu
se s
ocke
t and
so
lder
it t
o th
e m
idd
le r
ight
lug
of t
he
pow
er s
witc
h .
The
last
tw
iste
d j
um
per
sh
ou
ld h
ave
cont
inui
ty to
the
mid
dle,
pro
trud
ing
lug
of th
e vo
ltag
e se
lect
or sw
itch .
Sol
der t
his
jum
per
to th
e to
p ri
ght l
ug o
f the
pow
er
switc
h .
Sto
p a
nd
insp
ect
you
r w
ork
This
is a
goo
d tim
e to
ste
p a
way
from
the
pro
ject
for
a f
ew m
inut
es . T
ake
a b
reak
b
efor
e re
view
ing
your
wor
k fo
r err
ors .
Whe
n yo
u’re
read
y to
go
at it
aga
in, v
ery
care
fully
wal
k th
roug
h ev
ery
conn
ectio
n yo
u’v
e m
ade
so f
ar . W
hen
eve
ryth
ing
chec
ks o
ut, y
ou’re
rea
dy
to m
ove
on t
o th
e tu
rret
boa
rd .
STOP
Be sus
piciou
s The
re's a
mistak
e, and
you’re
gonna
find it!
510K
stew
mac
.co
m
26
©
2019
Ste
wM
ac
1 29
2 26
34
56
7
2021
2223
24
27
25 28
89
1011
1213
1415
1617
18
3435
3637
3839
4044
4546
3332
3119
3041
4243
.022μF
.022μF
.68μF +
500pF
500pF
stew
mac
.co
m
27
©20
19
Stew
Mac
You
’re r
ead
y to
sta
rt p
utt
ing
par
ts o
n th
e tu
rret
bo
ard
. In
th
ese
step
s, y
ou’ll
w
rap
the
lead
s on
to t
he t
urre
ts w
ithou
t so
lder
ing,
and
the
sol
der
will
be
add
ed
late
r . Th
is a
llow
s yo
u to
che
ck y
our w
ork
and
mak
e co
rrec
tio
ns
wit
ho
ut
hav
ing
to u
ndo
sold
er jo
ints
. Id
eally
, you
sol
der
ea
ch jo
int o
nly
once
.
S
TE
P 5
1
Wra
p a
2.7
k re
sist
or
Wra
p a
2 .7
k re
sist
or b
etw
een
turr
ets
18
and
46 .
S
TE
P 5
2
Ad
d a
.68
uF
elec
tro
lyti
c ca
pac
ito
r +
tw
o ju
mp
ers
Ad
d a
.6
8u
F e
lect
roly
tic
cap
acit
or
bet
wee
n tu
rret
s 18
and
46 .
Thi
s ca
p is
p
olar
ized
so
be
sure
the
neg
ativ
e le
ad
goes
to
turr
et 1
8 an
d t
he p
osit
ive
lead
go
es to
turr
et 4
6 .
Ad
d a
2-1/
2" w
hite
jum
per
to tu
rret
46 .
Ad
d a
2" g
reen
jum
per
to tu
rret
18 .
S
TE
P 5
3
Ad
d o
ne
resi
sto
r +
on
e ju
mp
erA
dd
a 1
0k r
esis
tor
bet
wee
n t
urre
ts 1
8 an
d 45
.
Cut
a 1"
gre
en ju
mp
er a
nd r
emov
e th
e sh
ield
ing .
Add
this
bar
e ju
mp
er b
etw
een
turr
ets
25 a
nd 2
8 .
S
TE
P 5
4
Ad
d o
ne
resi
sto
r +
th
ree
jum
per
sA
dd
a 6
8k r
esis
tor
bet
wee
n t
urre
ts 1
7 an
d 25
.
Ad
d a
2-1/
4" w
hite
jum
per
to tu
rret
17 .
Ad
d a
3-1/
2" w
hite
jum
per
to tu
rret
45 .
Ad
d a
3-1/
2" w
hite
jum
per
to tu
rret
28 .
S
TE
P 5
5
Ad
d t
wo
res
isto
rs +
tw
o c
apac
ito
rsA
dd
one
100
k re
sist
or b
etw
een
turr
ets
24 a
nd 4
4 .
Ad
d a
no
ther
10
0k
resi
sto
r b
etw
een
turr
ets
24 a
nd 4
3 .
Ad
d a
.022
μF (2
2nF)
cap
acito
r b
etw
een
turr
ets
16 a
nd 4
4 . T
his
and
the
follo
win
g ye
llow
cap
acit
ors
are
not
pol
ariz
ed, s
o yo
u ca
n in
stal
l the
m in
eith
er d
irect
ion .
W
e re
com
men
d f
acin
g t
hem
all
in t
he
sam
e d
irec
tio
n,
mak
ing
th
eir
pri
nte
d sp
ecs
easy
to re
ad .
Ad
d a
no
ther
.02
2μF
(22n
F) c
apac
ito
r b
etw
een
turr
ets
15 a
nd 4
3 .
S
TE
P 5
6
Ad
d t
hre
e ju
mp
ers
Ad
d a
2-3/
4" w
hite
jum
per
to tu
rret
44 .
Ad
d a
5-1/
2" w
hite
jum
per
to tu
rret
43 .
Ad
d a
2-3/
4" w
hite
jum
per
to tu
rret
16 .
S
TE
P 5
7
Ad
d t
wo
res
isto
rs +
on
e ca
pac
ito
rA
dd
one
470
k re
sist
or b
etw
een
turr
ets
15 a
nd 2
3 .
Ad
d a
no
ther
470
k re
sist
or
bet
wee
n tu
rret
s 14
and
23 .
Ad
d a
50
0p
F si
lve
r m
ica
cap
acit
or
bet
wee
n tu
rret
s 15
and
23 .
S
TE
P 5
8
Ad
d t
wo
res
isto
rs +
th
ree
jum
per
sA
dd
an
820
Ω r
esis
tor
bet
wee
n t
urre
ts
14 a
nd 4
2 .
Ad
d a
100k
res
isto
r b
etw
een
turr
ets
14
and
41 .
Ad
d a
1-1/
2" g
reen
jum
per
to tu
rret
14 .
Ad
d a
3-1/
2" w
hite
jum
per
to tu
rret
23 .
Ad
d a
2-3/
4" w
hite
jum
per
to tu
rret
42 .
S
TE
P 5
9
Ad
d o
ne
resi
sto
r +
on
e ca
pac
ito
r +
o
ne
jum
per
Ad
d a
33k
res
isto
r b
etw
een
tur
rets
40
and
41 .
Ad
d a
50
0p
F si
lve
r m
ica
cap
acit
or
bet
wee
n tu
rret
s 22
and
41 .
Ad
d a
4-1/
2" w
hite
jum
per
to tu
rret
41 .
Wra
pp
ing
par
ts o
nto
th
e tu
rret
bo
ard
stew
mac
.co
m
28
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2019
Ste
wM
ac
1 29
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7
2021
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24
27
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89
1011
1213
1415
1617
18
3435
3637
3839
4044
4546
3332
3119
3041
4243
.022μF
.022μF
.022μF
5W 10K
5W 10K
.022μF
.022μF
.01μF
47
stew
mac
.co
m
29
©20
19
Stew
Mac
S
TE
P 6
0
Ad
d t
wo
cap
acit
ors
+ t
hre
e ju
mp
ers
Ad
d a
.022
μF c
apac
itor
bet
wee
n tu
rret
s 12
and
40 .
Ad
d an
othe
r .0
22μF
cap
acito
r b
etw
een
turr
ets
13 a
nd 4
0 .
Cut t
hree
6" w
hite
jum
per
s .
Ad
d th
e fir
st ju
mp
er to
turr
et 1
2 .
Ad
d th
e se
cond
jum
per
to tu
rret
13 .
Ad
d th
e th
ird ju
mp
er to
turr
et 2
2 .
S
TE
P 6
1
Ad
d o
ne
resi
sto
r +
on
e ju
mp
erA
dd
a 1
0K 5
W r
esis
tor
bet
wee
n tu
rret
s 11
and
39 .
Ad
d a
5-1/
2" w
hite
jum
per
to tu
rret
39 .
S
TE
P 6
2
Ad
d fo
ur
resi
sto
rsA
dd
a 1
0K r
esis
tor
bet
wee
n t
urr
ets
9 an
d 21
.
Ad
d a
470Ω
res
isto
r b
etw
een
turr
ets
21
and
37 .
Ad
d a
1M
res
isto
r b
etw
een
tu
rret
s 21
an
d 38
.
Ad
d a
1M
res
isto
r b
etw
een
tu
rret
s 21
an
d 36
.
S
TE
P 6
3
Ad
d t
wo
cap
acit
ors
Ad
d a
.022
μF c
apac
itor
bet
wee
n tu
rret
s 10
and
38 .
Ad
d a
.01μ
F ca
pac
itor
bet
wee
n tu
rret
s 9
and
36 .
S
TE
P 6
4
Ad
d fo
ur
jum
per
sA
dd
a 6-
1/2"
whi
te ju
mp
er to
turr
et 1
0 .
Ad
d a
2-3/
4" w
hite
jum
per
to tu
rret
38 .
Ad
d a
3-1/
2" w
hite
jum
per
to tu
rret
37 .
Ad
d a
3-1/
2" w
hite
jum
per
to tu
rret
36 .
S
TE
P 6
5
Ad
d fo
ur
resi
sto
rsA
dd
a 22
0k r
esis
tor
bet
wee
n tu
rret
s 8
and
20 .
Ad
d a
no
ther
220
k re
sist
or
bet
wee
n tu
rret
s 7
and
20 .
Ad
d a
n 8
2k r
esis
tor
bet
wee
n t
urre
ts
27 a
nd 3
5 .
Ad
d a
100
k re
sist
or
bet
wee
n t
urre
ts
27 a
nd 3
4 .
S
TE
P 6
6
Ad
d t
hre
e ca
pac
ito
rs +
tw
o
jum
per
sA
dd a
.022
μF c
apac
itor b
etw
een
turr
ets
8 an
d 35
.
Add
ano
ther
.022
μF c
apac
itor b
etw
een
turr
ets
7 an
d 34
.
Ad
d a
47p
F si
lve
r m
ica
cap
acit
or
bet
wee
n tu
rret
s 34
and
35 .
Ad
d a
3" w
hite
jum
per
to tu
rret
35 .
Ad
d a
4-3/
4" w
hite
jum
per
to tu
rret
34 .
S
TE
P 6
7
Ad
d t
wo
res
isto
rs +
tw
o ju
mp
ers
Ad
d a
100
K re
sist
or b
etw
een
tur
rets
6
and
33 .
Ad
d a
10K
5W c
eram
ic r
esis
tor
bet
wee
n tu
rret
s 5
and
32 .
Ad
d a
5" w
hite
jum
per
to tu
rret
33 .
Ad
d a
6-1/
2" w
hite
jum
per
to tu
rret
6 .
S
TE
P 6
8
Ad
d t
wo
res
isto
rs +
th
ree
jum
per
sA
dd
a 1
5K r
esis
tor
bet
wee
n t
urre
ts 3
0 an
d 31
.
Ad
d a
56K
res
isto
r b
etw
een
tu
rret
s 4
and
19 .
Cut
a 1"
gre
en ju
mp
er a
nd r
emov
e th
e sh
ield
ing .
Add
this
bar
e ju
mp
er b
etw
een
turr
ets
3 an
d 4 .
Ad
d a
5-1/
2" w
hite
jum
per
to tu
rret
19 .
Ad
d a
2" g
reen
jum
per
to tu
rret
3 .
stew
mac
.co
m
30
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2019
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1011
1213
1415
1617
18
3435
3637
3839
4044
4546
3332
3119
3041
4243
+ 8µF
+ 8µF
stew
mac
.co
m
31
©
2019
St
ewM
ac
S
TE
P 6
9
Inst
all t
wo
ele
ctro
lyti
c ca
pac
ito
rs +
o
ne
jum
per
Ad
d a
n 8
μF
elec
tro
lyti
c ca
p b
etw
een
turr
ets
4 an
d 31
. Thi
s ca
p is
pol
ariz
ed, s
o b
e su
re t
he n
egat
ive
lead
goe
s to
tur
ret
31 a
nd th
e p
ositi
ve le
ad to
turr
et 4
.
Ad
d a
no
the
r 8
μF
ele
ctro
lyti
c ca
p
bet
wee
n t
urr
ets
3 an
d 3
0 . T
his
cap
is
also
pol
ariz
ed, s
o b
e su
re t
he n
egat
ive
lead
goe
s to
tur
ret
30 a
nd t
he p
ositi
ve
lead
to tu
rret
3 .
S
TE
P 7
0
Ad
d t
hre
e d
iod
esA
dd
a 1N
4007
dio
de
bet
wee
n tu
rret
s 26
an
d 30
. No
te th
e p
ola
rity
of t
he
dio
de.
Th
e p
ositi
ve le
ad o
f the
dio
de is
indi
cate
d by
a s
trip
e at
tha
t en
d . T
he e
nd w
ith n
o st
ripe
is n
egat
ive .
Con
nect
the
neg
ativ
e le
ad t
o tu
rret
30 .
Con
nect
the
pos
itiv
e le
ad to
turr
et 2
6 .
Ad
d a
1N
5408
dio
de
bet
wee
n t
urr
ets
2 an
d 29
. Con
nect
the
neg
ativ
e le
ad t
o tu
rret
2 a
nd th
e p
ositi
ve le
ad to
turr
et 2
9 .
Ad
d a
no
ther
1N
5408
dio
de
bet
wee
n tu
rret
s 1
and
29 .
Con
nect
the
neg
ativ
e le
ad t
o tu
rret
1 a
nd t
he p
ositi
ve le
ad t
o
turr
et 2
9 .
S
TE
P 7
1
Ad
d o
ne
resi
sto
r +
th
ree
jum
per
sA
dd
a 22
0k 2
W r
esis
tor
bet
wee
n tu
rret
s 2
and
26 .
Ad
d a
7" w
hite
jum
per
to tu
rret
29 .
Cu
t tw
o 1
0" w
hit
e ju
mp
ers
and
tw
ist
them
tog
ethe
r . A
dd
one
end
of
one
to
turr
et 1
. A
dd
on
e en
d o
f th
e o
ther
to
turr
et 2
.
Sto
p a
nd
insp
ect
you
r w
ork
All
the
com
pon
ents
and
wire
s are
now
on
the
turr
et b
oard
. Tak
e a
bre
ak to
rest
you
r ey
es b
efor
e m
akin
g su
re y
ou’v
e fo
llow
ed
each
ste
p c
orre
ctly
.
To fi
nd n
o m
ista
kes
at t
his
stag
e w
ould
b
e su
rpris
ing,
and
its
muc
h le
ss w
ork
to
find
them
now
tha
n af
ter
sold
erin
g! A
s yo
u ch
eck
your
wor
k, m
ake
sure
all
the
conn
ectio
ns a
re ti
ght .
STOP
Be fus
sy Fin
d the
mistak
e now
, not
later!
stew
mac
.co
m
32
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2019
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ac
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2223
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27
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1011
1213
1415
1617
18
3435
3637
3839
4044
4546
3332
3119
3041
4243
Beh
ind
bo
ard
vie
w
stew
mac
.co
m
33
©
2019
St
ewM
ac
S
TE
P 7
2
Sold
er t
he
com
po
nen
ts o
n t
he
turr
et b
oar
dIt
’s t
ime
to s
et a
ll th
e co
nnec
tions
with
so
lder
.
Revi
ew t
he
tip
s fo
r g
reat
sol
der
ing
on
pag
e 9,
then
sol
der
eac
h co
nnec
tion
on
the
turr
et b
oard
.
Aft
er a
ll th
e jo
ints
are
sol
der
ed c
lip t
he
exce
ss le
ads
from
the
tur
rets
. Trim
min
g th
e ex
cess
lead
s is
imp
orta
nt t
o av
oid
a sh
ort i
n yo
ur c
ircui
t . C
heck
all
your
sold
er
join
ts to
mak
e su
re t
hey’
re s
hiny
, and
to
see
that
you
did
n’t m
iss
one .
S
TE
P 7
3
Ad
d n
ine
beh
ind
-th
e-b
oar
d
jum
per
sC
ut
thes
e ju
mp
ers
to l
eng
th a
nd
tri
m
3/8"
of
shie
ldin
g off
eac
h en
d . R
un t
he
exp
osed
end
s up
into
the
bot
tom
of t
he
turr
ets
and
sold
er th
em in
to p
lace
.
Cut a
5" w
hite
jum
per
and
sold
er o
ne e
nd
to th
e b
otto
m o
f tur
ret 2
4 . R
oute
the
free
en
d st
raig
ht to
the
top
of t
he b
oard
, tur
n it
at a
90-
deg
ree
angl
e to
the
right
unt
il yo
u re
ach
the
bac
k of
turr
et 1
1, a
nd th
en
ben
d it
at a
90-
deg
ree
angl
e ag
ain
and
pla
ce t
he le
ad in
the
bac
k of
the
tur
ret .
Don
’t so
lder
it y
et .
Cut a
3-1
/2" w
hite
jum
per
and
sold
er o
ne
end
to th
e b
otto
m o
f tur
ret 1
1 al
ong
with
th
e ju
mp
er a
lread
y in
pla
ce . R
oute
the
fr
ee e
nd o
f thi
s ju
mp
er to
war
d th
e b
ack
of tu
rret
44 .
Cut a
3" w
hite
jum
per
and
sold
er o
ne e
nd
to th
e b
otto
m o
f tur
ret 3
2 . R
oute
the
free
en
d o
f th
is ju
mp
er t
owar
d t
he b
otto
m
of t
he b
oard
and
tur
n it
at a
90-
deg
ree
ang
le t
o t
he
left
un
til
you
rea
ch t
he
bac
k of
turr
et 3
4 . T
hen
turn
it a
t ano
ther
90
-deg
ree
angl
e an
d pl
ace
the
lead
in th
e b
ack
of tu
rret
27,
but
don
't so
lder
it y
et .
Cut a
4" w
hite
jum
per
and
sold
er it
to th
e b
ack
of t
urre
t 27
alo
ng w
ith t
he ju
mp
er
lead
alre
ady
in p
lace
. Rou
te th
e fr
ee e
nd
of th
is ju
mp
er to
war
d th
e b
otto
m o
f the
b
oard
and
turn
it a
t a 9
0-d
egre
e an
gle
to
the
left
unt
il yo
u re
ach
the
bac
k of
turr
et
39 . T
hen
tur
n i
t at
an
oth
er 9
0-d
egre
e an
gle
and
pla
ce t
he le
ad in
the
bac
k of
tu
rret
39,
but
don
't so
lder
it y
et .
Cut
anot
her
4" w
hite
jum
per
and
sol
der
on
e en
d to
the
bot
tom
of t
urre
t 39
alon
g w
ith t
he ju
mp
er a
lread
y in
pla
ce . R
oute
th
e fr
ee e
nd o
f th
is ju
mp
er t
owar
d th
e b
ack
of tu
rret
25 .
Cut a
2-1
/2" w
hite
jum
per
and
sold
er o
ne
end
to th
e b
otto
m o
f tur
ret 9
. Rou
te th
e fr
ee e
nd u
p to
war
d th
e to
p o
f the
boa
rd,
turn
it a
t a
90-d
egre
e an
gle
to t
he r
ight
un
til y
ou r
each
the
bac
k of
tur
ret
6, a
nd
then
ben
d it
at a
noth
er 9
0-d
egre
e an
gle
and
sold
er th
e le
ad in
the
bac
k of
turr
et 6
.
Cut
a 12
" w
hite
jum
per
and
sol
der
one
en
d to
the
bot
tom
of t
urre
t 5 . R
oute
the
free
end
of t
his
jum
per
tow
ard
the
bac
k of
turr
et 2
9 .
Cut a
7" w
hite
jum
per
and
sold
er o
ne e
nd
to th
e b
otto
m o
f tur
ret 2
0 . R
oute
the
free
en
d to
war
d tu
rret
1 .
Cut a
5-1
/2" w
hite
jum
per
and
sold
er o
ne
end
to th
e b
otto
m o
f tur
ret 3
1 . R
oute
the
free
end
tow
ard
turr
et 1
.
S
TE
P 7
4
Ad
d t
wo
mo
re b
ehin
d-t
he-
bo
ard
ju
mp
ers
Cu
t a
4" w
hit
e ju
mp
er a
nd
a 5
" w
hit
e ju
mp
er . S
trip
1"
of in
sula
tion
fro
m o
ne
end
of e
ach .
Ad
d a
5 .1K
resi
stor
to th
e st
ripp
ed e
nd o
f ea
ch o
f th
ese
jum
per
s . O
nce
the
sold
er
join
ts c
ool,
add
1" o
f hea
t-sh
rink
tub
ing
to in
sula
te th
e so
lder
join
t .
On
ce t
he
hea
t-sh
rink
co
ols
, so
lder
th
e re
sist
or-f
ree
end
of t
he 5
" ju
mp
er t
o th
e b
otto
m o
f tur
ret 8
. Rou
te th
e en
d of
this
ju
mp
er w
ith th
e re
sist
or a
ttac
hed
tow
ard
turr
et 3
1 .
Sold
er t
he
resi
sto
r-fr
ee e
nd
of
the
6"
jum
per
to
the
bot
tom
of t
urre
t 7 .
Rou
te
the
end
of t
his
jum
per
with
the
res
isto
r at
tach
ed to
war
d tu
rret
31 .
S
TE
P 7
5
Ch
eck
the
con
tin
uit
y o
f yo
ur
bac
k-o
f-b
oar
d ju
mp
ers
On
ce a
ll o
f th
ese
sold
er
join
ts a
re
set,
flip
th
e b
oar
d b
ack
over
an
d t
est
for
con
tin
uit
y o
n e
ach
pai
r o
f tu
rret
s co
nnec
ted
by
bac
k-of
-boa
rd r
uns .
Use
a
mul
tim
eter
for
con
tinu
ity
test
ing
, as
des
crib
ed o
n p
age
41 .
S
TE
P 7
6
Glu
e b
ehin
d-t
he-
bo
ard
jum
per
s d
ow
n
As
you
r am
p a
ges
, it
will
nee
d p
arts
re
pla
ced
. W
hen
yo
u h
eat
a tu
rret
to
rem
ove
a w
orn
-out
par
t, a
beh
ind
-the
-b
oar
d j
um
per
co
uld
co
me
dis
lod
ged
fr
om t
he b
ack
of t
he t
urre
t, in
trod
ucin
g a
who
le n
ew p
rob
lem
. To
pre
vent
thi
s,
app
ly a
dim
e-si
zed
am
ount
of
cont
act
cem
ent
to e
ach
wir
e's
insu
lati
on
as
show
n . T
his
will
hol
d th
e ju
mp
ers
tight
to
the
bac
k of
the
boa
rd e
ven
whe
n yo
u he
at t
he tu
rret
and
sol
der
liqu
ifies
.
Allo
w t
his
glue
to c
ure
over
nigh
t . Th
is is
a
good
cha
nce
to s
top
and
dou
ble
che
ck
all
of y
our
conn
ecti
ons
one
mor
e ti
me
bef
ore
ins
talli
ng
th
e tu
rret
bo
ard
int
o th
e ch
assi
s .
Sold
erin
g c
om
po
nen
ts t
o t
urr
et b
oar
d
stew
mac
.co
m
34
©
2019
Ste
wM
ac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
PRES
ENCE
BASS
MID
DLE
TREB
LEM
AST
ER
VOLU
ME
PREA
MP
VOLU
ME
INPU
T (N
ORM
AL)
H.T
. FU
SE
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
VOLT
AG
ESE
LECT
OR
IMPE
ND
AN
CESE
LECT
OR
FILT
ER C
AP
3
FILT
ER C
AP
2FI
LTER
CA
P 1
MA
INS
INPU
TM
AIN
SFU
SE
BA
-
BA
-
BA
-
4 3
21
87
65
6
43 2 1
9875
6
43 2 1
9875
4 3
21
87
65
3
6
52
1
4
3
6
52
1
4
12
43
12
43
LO HI
6
43 2 1
9875
1MA
1MA
250KL
25KL
5KL
1 29
2 26
34
56
7
2021
2223
24
27
25 28
89
1011
1213
1415
1617
18
3435
3637
3839
4044
4546
3332
3119
3041
4243
stew
mac
.co
m
35
©
2019
St
ewM
ac
You
're
read
y to
inst
all t
he
turr
et
bo
ard
in t
he
chas
sis
It's
tim
e to
rem
ove
yo
ur
tap
e w
ith
the
turr
et n
umb
ers .
Wh
en t
he
bo
ard
's
inst
alle
d, y
ou w
on't
be
able
to g
et to
the
tap
e to
rem
ove
it . F
rom
thi
s p
oint
on
, yo
u ca
n id
entif
y ju
mp
ers
and
turr
ets
by
refe
rrin
g to
the
diag
ram
s .
S
TE
P 7
7
Inst
all f
ou
r th
read
ed s
tan
do
ffs
To k
eep
th
e tu
rret
bo
ard
co
nn
ecti
on
s fr
om s
hort
ing
agai
nst
the
met
al c
hass
is,
the
boa
rd is
mou
nted
on
four
thr
ead
ed
stan
do
ffs
that
ho
ld i
t aw
ay f
rom
th
e ch
assi
s .
Use
4-4
0 sc
rew
s to
mo
un
t th
ese
fou
r st
and
offs
to t
he c
hass
is a
s sh
own
in t
he
diag
ram
.
S
TE
P 7
8
Inst
all t
wo
filt
er c
ap le
ads
Befo
re m
ount
ing
the
turr
et b
oard
in th
e ch
assi
s, t
wo
beh
ind
-the
-boa
rd ju
mp
ers
need
to b
e so
lder
ed to
the
filte
r cap
that
w
ill b
e un
der
the
tur
ret
boa
rd o
nce
it's
m
ount
ed .
Sold
er th
e ju
mp
er fr
om th
e b
ack
of tu
rret
11
to lu
g A
of fi
lter c
ap 3
.
Sold
er th
e ju
mp
er fr
om th
e b
ack
of tu
rret
39
to lu
g B
of fi
lter c
ap 3
.
S
TE
P79
Inst
alli
ng
th
e tu
rret
bo
ard
in t
he
chas
sis
Lin
e u
p t
he
tu
rre
t b
oar
d o
n t
hes
e st
and
offs
and
use
4-40
scr
ews
to m
ount
th
ese
four
sta
ndoff
s to
the
chas
sis .
S
TE
P 8
0
Sold
er t
he
pre
amp
vo
lum
e p
ot
Sold
er t
he g
reen
jum
per
fro
m t
urre
t 18
to
the
bac
k of
the
pre
amp
vol
ume
pot
.
Sold
er th
e gr
een
jum
per
from
lug
4 of
the
high
inp
ut ja
ck to
the
bac
k of
the
pre
amp
vo
lum
e p
ot .
S
TE
P 8
1
Sold
er t
he
inp
ut
jack
sSo
lder
the
whi
te ju
mp
er f
rom
tur
ret
17
to lu
g 1
of th
e hi
gh s
ensi
tivit
y in
put
jack
.
Sold
er th
e w
hite
jum
per
from
turr
et 1
6 to
lu
g 4
of lo
w s
ensi
tivit
y in
put
jack
.
S
TE
P 8
2
Sold
er t
he
mas
ter
volu
me
po
tSo
lder
the
gree
n ju
mp
er fr
om tu
rret
14
to
the
bac
k of
the
mas
ter v
olum
e p
ot .
Sold
er th
e w
hite
jum
per
from
turr
et 1
0 to
th
e m
iddl
e lu
g of
the
mas
ter v
olum
e p
ot .
S
TE
P 8
3
Sold
er t
he
treb
le p
ot
Sold
er t
he ju
mp
er f
rom
tur
ret
22 t
o th
e rig
ht lu
g of
the
treb
le p
ot .
Sold
er t
he ju
mp
er f
rom
tur
ret
13 t
o th
e le
ft lu
g of
the
treb
le p
ot w
ith th
e ju
mp
er
alre
ady
in p
lace
.
S
TE
P 8
4
Sold
er t
he
mid
s p
ot
Sold
er t
he ju
mp
er f
rom
tur
ret
12 t
o th
e m
iddl
e lu
g of
the
mid
s p
ot .
S
TE
P 8
5
Sold
er t
he
pre
sen
ce p
ot
Sold
er t
he j
ump
er f
rom
tur
ret
6 to
the
rig
ht lu
g of
the
pre
senc
e p
ot a
long
with
th
e re
sist
or le
ad a
lread
y in
pla
ce .
S
TE
P 8
6
Sold
er t
he
gro
un
d ju
mp
erSo
lder
the
gree
n ju
mp
er fr
om tu
rret
3 to
b
ack
of th
e p
rese
nce
pot
.
S
TE
P 8
7
Sold
er t
he
jum
per
s to
th
e st
and
by
swit
chRu
n th
e tw
iste
d p
air
of w
hite
jum
per
s fr
om tu
rret
s 1 a
nd 2
to th
e to
p le
ft a
nd to
p
right
lugs
of
the
stan
dby
switc
h . S
old
er
one
jum
per
to th
e to
p le
ft lu
g an
d so
lder
th
e ot
her
jum
per
to
the
top
rig
ht lu
g . It
d
oes
not
mat
ter
whi
ch ju
mp
er g
oes
to
whi
ch lu
g .
Four
sta
ndo
s
Inst
alli
ng
th
e tu
rret
bo
ard
in t
he
chas
sis
Tip
s fo
r le
ad d
ress
wit
h ju
mp
ers
As
gen
eral
ru
le f
or
inst
alli
ng
th
ese
jum
per
s, w
hen
two
jum
per
s cr
oss
over
ea
ch o
ther
, ben
d th
em s
o th
ey c
ross
at
90°
angl
es r
athe
r ru
nnin
g si
de-
by-
sid
e .
This
lead
dre
ss d
etai
l infl
uenc
es th
e am
p’s
soun
d, e
spec
ially
on
a hi
gh-g
ain
circ
uit
like
this
one
.
stew
mac
.co
m
36
©
2019
Ste
wM
ac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
PRES
ENCE
BASS
MID
DLE
TREB
LEM
AST
ER
VOLU
ME
PREA
MP
VOLU
ME
INPU
T (N
ORM
AL)
H.T
. FU
SE
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
VOLT
AG
ESE
LECT
OR
IMPE
ND
AN
CESE
LECT
OR
FILT
ER C
AP
3
FILT
ER C
AP
2FI
LTER
CA
P 1
MA
INS
INPU
TM
AIN
SFU
SE
BA
-
BA
-
3
6
521
4
12
43
LO
12
43
HI
BA
-
4 3
21
87
65
4 3
21
87
65
6
43 2 1
9875
6
43 2 1
9875
64
3 2 1
9875
3
6
52
1
4
1 29
2 26
34
56
7
2021
2223
24
27
25 28
89
1011
1213
1415
1617
18
3435
3637
3839
4044
4546
3332
3119
3041
4243
stew
mac
.co
m
37
©
2019
St
ewM
ac
S
TE
P 8
8
Sold
er t
he
jum
per
s to
V1
Sold
er th
e ju
mp
er fr
om tu
rret
44
to V
1 pi
n 1
alon
g w
ith t
he c
apac
itor
lead
alre
ady
in p
lace
.
Sold
er t
he ju
mp
er f
rom
tur
ret
43 t
o V1
p
in 6
.
Sold
er t
he ju
mp
er f
rom
tur
ret
28 t
o V1
p
in 2
.
Sold
er t
he ju
mp
er f
rom
tur
ret
45 t
o V1
p
in 8
.
Sold
er th
e ju
mp
er fr
om tu
rret
46
to V
1 pi
n 3
alon
g w
ith t
he c
apac
itor
lead
alre
ady
in p
lace
.
Trim
aw
ay a
ny e
xces
s le
ads .
S
TE
P 8
9
Sold
er t
he
jum
per
s to
V2
Sold
er t
he ju
mp
er f
rom
tur
ret
39 t
o V2
p
in 6
alo
ng w
ith th
e re
sist
or le
ad a
lread
y in
pla
ce .
Sold
er t
he ju
mp
er f
rom
tur
ret
41 t
o V2
p
in 8
.
Sold
er t
he ju
mp
er f
rom
tur
ret
42 t
o V2
p
in 3
.
Sold
er t
he ju
mp
er f
rom
tur
ret
23 t
o V2
p
in 2
.
S
TE
P 9
0
Sold
er t
he
jum
per
s to
V3
Sold
er th
e ju
mp
er fr
om tu
rret
35
to V
3 p
in 1
.
Sold
er th
e ju
mp
er fr
om tu
rret
34
to V
3 p
in 6
.
Sold
er th
e ju
mp
er fr
om tu
rret
36
to V
3 p
in 7
.
Sold
er th
e ju
mp
er fr
om tu
rret
38
to V
3 p
in 2
.
Sold
er th
e ju
mp
er fr
om tu
rret
37
to V
3 p
in 8
alo
ng w
ith th
e ju
mp
er a
lread
y in
p
lace
.
S
TE
P 9
1
Sold
er t
he
jum
per
s to
V4
Sold
er th
e ju
mp
er fr
om tu
rret
8 (r
unni
ng
unde
rnea
th th
e b
oard
with
a 5
.1k
resi
stor
at
tach
ed to
the
end)
to V
4 p
in 5
.
You
wan
t to
so
lder
th
is r
esis
tor
very
cl
ose
to t
he t
ube
sock
et, a
s p
ictu
red
in
the
diag
ram
.
To d
eter
min
e w
hich
jum
per
is c
onne
cted
to
turr
et 8
, tak
e a
resi
stan
ce re
adin
g fr
om
turr
et 8
to
the
two
resi
stor
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stew
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Ste
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St
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S
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Inst
all t
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STOP
stewmac.com 40 © 2019 StewMac
STEP 97
Glue the tube placement chartCut out the chart on page 51 . With a thin coat of glue or contact cement, glue it to the inside wall of the cabinet .
STEP 98
Install the fusesInstall the 3-amp fuse in the mains fuse socket and the 500mA fuse in the H .T . fuse socket .
Installing parts and preparing for testing
STOP!
DON’T INSTALL THE TUBES YET! DON’T PLUG THE AMP IN YET!
The next page is going to keep you out of trouble!
STEP 100
Set the chassis on chassis stand or on blocks for testingSet your chassis up for final testing . Chassis stands are extremely useful for this . If you do not have a chassis stand a couple of blocks of wood can work just fine .
STEP 99
Install the six control knobsTurn the shaft of each pot all the way counterclockwise to the “off” point and install the knob so the indicator line points to zero .
stewmac.com 41 © 2019 StewMac
At this point, dangerous voltage is forming in the filter caps. Always discharge them before working on the circuit, even if the amp is unplugged. See how to use a snuffer stick on page 6 .
For safety, use only one hand to probe the amp during DC tests.
Keep your other hand behind your back when you need to probe a component . This way, you can’t be a path between B+ voltage and ground—a mistake that would send a dangerous charge through your heart .
Set your multimeter to 600V DC and connect the negative lead to ground . Once the negative lead is secured to ground, flip the standby switch to ON . Measure the DC voltage at lug A of filter cap 1 . It should be roughly 500V DC .
Set the multimeter to 5V DC and check turret 46, which should read around 2 .5V .
Set the multimeter to 500V DC and check turret 43 . It should read around 300V .
Set the multimeter to 100V DC and test pin 5 of the V7 and V8 sockets . These readings should be nearly identical .
Any multimeter will work fine for the two types of tests we’re about to do: checking continuity and reading voltages . The instructions that came with your meter will be helpful .
Continuity testing is simply making sure current flows between two points successfully . Touch the meter's red lead to one end of the section being tested, and the black lead to the other end . If the continuity is good, your meter will beep or register this on the display .
Voltage testing is where you need to be careful . Some steps require the amp to be plugged in and turned on . This becomes dangerous if you’re not cautious . Respect the voltages and follow the directions, and these tests are safe and easy .
STEP 101
Perform a safe power-upAt this point, there should be no tubes installed, and the speaker should be disconnected .
Before plugging the amp in, turn the power switch to ON . Switching the amp on before the first power-up protects you from shock if a mistake in your wiring has created a short to the chassis . If this short exists, an indication would be that the pilot light will not turn on, since the AC current is going directly to ground .
Also set the voltage selector switch to match the wall voltage for your home . In the United States, you will want to set the voltage switch to 110V .
Plug the power cord in . The power switch should light .
For a few minutes, watch for smoke or unusual smells . If anything seems unusual, disconnect the power immediately and carefully review all your connections .
STEP 102
Test the standard AC voltageSet your multimeter to 20V AC . Check the heater voltage across pin 9 and pins 4+5 on the V1 12AX7 socket . This should read between 5-7V AC . If this reading is drastically different, disconnect power and check your connections .
If the amp seems normal, unplug the power cord while still leaving the power switch ON .
Testing and troubleshooting
V1D-
-
ALWAYS discharge the filter cap
before working on the circuit. See how
to use a snuffer stick on page 6.
And seriously, keep one hand behind
your back!
STEP 103
Test the preamp tubes + dangerous DC voltageThe dangerously high DC voltage that passes through the rectifier tube and the filter caps is referred to as “B+” . The next step is to test this B+ voltage .
While the amp is unplugged, install the three preamp tubes .
After these tubes are installed, plug the amp back in and flip the power switch ON . The power switch should light up . Let the amp warm up for a few minutes and then flip the standby switch to ON . Again, if you get smoke or smells, unplug immediately .
stewmac.com 42 © 2019 StewMac
Use a small flathead screwdriver to turn the center of the bias pot all the way counterclockwise . This will set the bias for the lowest negative DC voltage . Doing this provides a safe voltage for the power tubes while you set the initial bias .
If all of these voltages come within approximately 10% of their expected values, turn the power switch OFF .
Always turn the power switch off before turning the standby switch off . This will drain the filter capacitors as the amp cools down . After a moment, flip the standby switch OFF as well, and unplug the amp .
If the reading at turret 43 shows no voltage or low voltage, follow this test: unplug the amp, drain the filter caps with the snuffer stick, set your meter to read continuity, and make sure you have properly installed the back-of-board jumper from turret 43 to turret 11 .
Turn the power and standby switches to OFF and unplug the amp .
STEP 104
Test the EL34 power tubesWith the amp unplugged, install the EL34 power tubes, turning them so their indexing keys f it correctly in the socket . Turn all of the front panel controls completely counterclockwise, so the indicator line is pointing to "0" .
Connect the amp to a speaker cabinet, adjust the impedance selector switch for the appropriate impedance, and perform these next tests with the speaker turned away from you . If the amp starts to oscillate and squeal, this will help protect your ears .
Plug the amp in and flip the power switch ON . Give the tubes 30 seconds to warm up and then flip the standby switch to ON as well .
After a few moments you should hear a low hum . If the hum becomes very loud, disconnect the power immediately and review your connections .
Set your multimeter to read 500V DC and test for voltage from pin 3 of both socket V5 and socket V4 . This voltage should read around 420V . Write this number in Box 2 of the calculation in Step 106 . It’ll be needed if you use a bias meter to set your bias .
Set your multimeter to read 50V DC and test for voltage at turret 20 . Adjust the bias pot until this voltage reads around -38V .
If all of these voltages come within approximately 10% of their expected values, turn the power switch OFF . After a few moments turn the standby switch OFF as well, and unplug the amp .
Tube bias affects your sound“Bias” refers to the current of electrons flowing from the cathode to the plate inside your power tubes when the tubes are idle . The bias setting determines this flow and is increased or decreased by the screwdriver-adjustable bias pot .
Adjusting the bias affects your sound: a higher setting gives you punchier cleans and grittier distortion, but your tubes will wear out faster . With a low setting, your tubes last longer but the sound is more sterile . A good bias setting falls between these extremes .
STEP 105
Old method of setting the bias: doing it by earIf you have a bias meter, skip this step and go on to Step 106 .
The old-school way of adjusting the bias is by ear: after setting the bias voltage to a recommended starting point, you make tiny adjustments to the bias pot while listening for the sound you want . This inexact method can shorten the life of your power tubes .
You roughed-in the bias setting in the previous step by setting the bias voltage at -38V .
Danger: set your guitar aside before you adjust the bias pot.
Do not touch any amp circuitry while holding your guitar . Doing so would create an electrocution hazard!
Use a screwdriver to make a tiny adjustment to the bias pot . Turn clockwise to increase the current and counterclockwise to decrease it . Then set the screwdriver aside and play to hear to the result .
Watch out for red-platingYou especially want to avoid too much current turning the gray plates to glowing red . If your tubes start red plating, shut the amp down and let it cool before setting the bias to a lower level .
Testing and troubleshooting
stewmac.com 43 © 2019 StewMac
Plug the amp back in and flip the power switch ON . Give the tubes 30-60 seconds to warm up, then flip the standby switch ON .
Watch the bias meter as the power tubes heat up . Both needles should rise at an equal rate and settle at the same time .
Adjust your bias pot until the bias meter displays the reading you calculated (36mA in our example) . Let the amp idle for a few minutes to make sure that the bias doesn’t drift .
When you see a constant readout of your bias setting, turn the power switch OFF .
After a few moments flip the standby switch OFF and unplug the amp from the wall .
Once the tubes are cool, remove them and the bias probes from the amp and plug the tubes back into the amp's tube sockets without the probes attached .
After removing the bias probes and taking it for a test drive, if the amp is stable and your tests match the voltages specified, feel free to let it rip!
After playing for a few minutes and testing all inputs, if everything seems to be operating normally, go ahead and turn the amp off .
If there are any strange oscillations, squeals, or the amp seems at all unstable, use a wooden chopstick to begin probing for loose connections:
n from the input jacks to the turret boardn from the tube sockets to the turret boardn from the tube sockets to the front panel controls .
It usually takes just a minor wiring adjustment, perhaps resoldering a loose joint, to correct this sort of distortion .
After removing the bias probes and taking it for a test drive, if the amp is stable and your tests match the voltages specified, feel free to let it rip!
STEP 106
Improved method of setting the bias: using a bias meterThe more accurate way to set the bias is by using a bias meter, such as the VHT Bias Tester (StewMac #1580) .
This method starts with a simple calculation to find your bias setting, then you adjust the bias pot until your bias meter displays that reading .
The calculation uses two numbers, the tube’s maximum plate dissipation and its plate voltage .
Plate dissipation . Every power tube has a specified plate dissipation—the maximum wattage the tube can handle . For the EL34 power tubes in this amp, that maximum is 25 watts . Exceeding the 25-watt limit will damage the tube, and operating at the full 25 watts will shorten its life . Our goal is to operate the tube at 60% of the 25-watt limit, or 15 watts . We've entered this number for you in Box 1 of the calculation .
Plate voltage . You already have the plate voltage for these tubes: it’s the number you found in Step 104 and wrote in Box 2 below .
Divide Box 1 by Box 2 . The result is your recommended bias setting for use in the next step . Our example calculation gives a bias recommendation of .0357 Amps . Since bias is typically measured in milliamps, this measurement is written as 36mA .
With the amp unplugged allow the power tubes to cool . Once the power tubes have cooled, remove them from their sockets .
Plug the tubes into the bias probe sockets, which are like tube sockets . Plug the probe sockets with tubes into the power tube sockets .
Testing and troubleshooting
Example:
Your plate voltage from Step 16560% of max. plate dissapation
÷Your bias current setting
=15
BOX 2BOX 1
15 ÷ =
stewmac.com 44 © 2019 StewMac
STEP 107
Install the chassisDischarge the capacitors so you can safely handle the chassis . Remove all the cables from their jacks .
Install the cage nuts in to their holes in each corner of the top lip of the chassis
Slide the chassis in from the back until its front edge meets the front wall of the cabinet . Insert the mounting screws through the f loor of the chassis . Tighten the screws down to hold the chassis tight to the cabinet .
Install the preamp tube shields and install the back panel .
Final assembly
Tube lifeThe life span of the power tubes is affected by how hard you drive the amp . If you are overdriving the amp for hours every day, expect the power tubes to have a shorter life span .
We encourage you to experiment with different tube brands and find the brand that is most favorable to your ears and your wallet .
StewMac is here to helpFor more than fifty years, StewMac has supplied instrument builders and repair shops . Our customer service team really knows how to help if you run into questions .
Call 800-848-2273 from 9AM–6PM
Eastern time, Monday–Friday .
Email: service@stewmac .com
Thanks for choosing this StewMac kit, and welcome to the world of amp building!
Tips for using this ampWhen you think of '80s metal guitar, this is the amp you are hearing . This amp is based on the JCM800 2204 but with a twist . Marshall never released hand-wired versions of the 800s so this is not exactly a replica, but more of a "boutique-style" build . Our version has slightly more gain and sounds a little bit sweeter than its PCB predecessor but make no mistake - the sound is 100% JCM800 .
World renowned for that sizzling in-your-face crunch, this amp is actually a much more flexible circuit than you might think . By working between the two volume controls you can get anywhere from rich clean tones, to sweetened plexi tones, to over the top '80s hair metal tones .
The tone controls are very responsive and need to be adjusted as the master volume is adjusted . At lower volumes, you will want to turn the controls up a bit, especially the treble control, to get an articulate tone . As you turn the master volume up you will want to turn the tone controls down because the overall sound gets brighter as the volume increases .
A good starting point is all knobs except the Master Volume set at 5 . With the master at 0 start turning up the amp until you hit the desired volume level . Use the Pre-Amp control to dial in the amount of overdrive you want, then adjust the tone controls according to your ears .
Here are our favorite settings for medium gain and high volume:
Presence: 2 Bass: 4 Mid: 3 Treble: 2 Master: 6 Preamp: 6
Matt Clouston, StewMac
It's finally time to let it rip!
GO!GO!
stewmac.com 45 © 2019 StewMac
Top
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f wir
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stewmac.com 46 © 2019 StewMac
OutputGain
Negative feedback
Processing
Power
Mic level
Speaker levelLine level Line level
You don’t need to read a schematic to build this kit . But it’s fun to see how the circuit works, and to see the different subcircuits that interact to shape your sound .
Working with the tiny signal from the guitar, the amp creates the power needed to drive the speaker . The signal is affected by the gain, processing, output and power stages as it passes through the circuit .
The gain circuit increases the signal to line level (about 1 volt), by passing it through a 12AX7 preamp tube where electrons flow from a heated cathode to be received by the anode plate . The grid between these receives the tiny voltage from the guitar, whose varying musical signal controls the flow of electrons to the plate .
The gorgeous harmonic distortion provided by this amp is produced by the “cold clipping” preamp design . Cold clipping is a type of harmonic distortion created by setting the bias for a gain stage very cold, and then immediately follow that with another gain stage that is biased very hot . This can be seen with V1b and V2a, where V1b is biased with a 10K resistor and V2a is biased by a 820Ω resistor .
The negative feedback loop flattens and extends the amp’s frequency response, reducing distor tion generated in the output stage . This makes the amp’s sound cleaner and more hi-fi . Some players disable this loop completely or add a potentiometer in place of the resistor to create a “grit control .” We don’t recommend this, because it places stress on the output transformer .
The processing stage shapes the tone . This amp has a universal Treble, Middle, Bass tone control . This allows you to shape each section of the three-band equalizer, and being universal means that the tone controls effect both inputs .
The Presence control of this amp uses the negative feedback circuit to introduce more high frequency to the signal, this can be heard as more "bite" to the naked ear . But don't be surprised if the sound engineer at your next gig asks you to turn down the presence, it can be extremely abrasive when mic'd up .
The signal is then sent to the phase inverter which uses all of V3 . The phase inverter then sends the signal to the output section .
The power supply stage provides power to the other circuit stages, as well as the tube heaters .
This circuit receives the AC power from your wall and passes it through the power transformer to create higher voltage . The electricity then goes to the rectifier, the two 1N5408 diodes, which converts it to a pulsing DC current .
This then passes through the filter choke and the filter capacitors . The filter capacitors filter out the pulsing to create a smooth current . As each cap smoothes a bit more, the current is also passing through resistors that lower the voltage .
As the signal from the guitar becomes more amplified, the ripple of DC current becomes less evident and the fully filtered current is sent to the most sensitive part of the amplifier, the first pre-amp tube in the Gain stage .
The output stage increases the line level signal to speaker level, which is typically 8 volts or greater .
Two EL34 tubes drive the output transformer . They receive the split signal, 180 degrees out of phase, amplify those signals, and send them to the output transformer to be recombined into one signal .
T h is t r a ns f o r m e r a djus t s th e impedance to 4, 8, or 16 ohms to drive an external speaker . This amp has an adjustable fixed bias, which means you need to check the bias and possibly make adjustments when you change power tubes .
cathode
plate
grid
We’ve color-coded these stages on our schematic, to show how the parts work together . Symbols for components are in the key at the bottom of the frame .
On the wiring diagram we build step-by-step in these pages, the parts are easier to recognize . But studying these color-coded stages will help you understand where each component fits into the creation of your sound .
Learning more: secrets revealed in the schematic
stewmac.com 47 © 2019 StewMac
#10
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stewmac.com 48 © 2019 StewMac
It’s your amp. Your tone. You built it!
’57 MINI TWEED 5W AMP KITOne-knob titan of tone.A timeless studio darling whose tiny size hides tremendous punch and versatility .
The 5F1 circuit was meant to be a student amp but wasn’t kid stuff for long; rock’s finest guitarists hijacked it for some of the greatest songs ever recorded . Listen to Eric Clapton (“Layla") or Joe Walsh (“Rocky Mountain Way") while you build this amp!
Our simplest kit; the quickest way to get into amp building .
#10730 5 WATTS / 8" SPEAKER / ORIGINAL 5F1 CIRCUIT
’65 P-REVERB 15W AMP KITSparkling bright, perfect for the surf.Plug your single-coils straight in for that signature clean American tone, or go surfing with onboard effects .
The smallest member of the black-panel family to offer reverb and tremolo, this amp made its name as a jangly pop dream machine . Aficionados treasure its early low-end breakup powered by a pair of 6V6 tubes .
Listen to “Surfin’ USA" and the great sounds of the Heartbreakers .
#10734 15 WATTS / 10" SPEAKER / ORIGINAL AA1164 CIRCUIT
’66 D-REVERB 22W AMP KITFamously clean, with enough guts to gig.Perfect for recording as well as performing, the D-Reverb produces stinging clarity that absolutely refuses to get lost in the mix .
One of the most popular designs ever, this amp lives in the happy middle between bright clarity and rich distortion . It excels in the studio and on the stage . While capable of crystal clear tones at good volume, you can push this one into beautifully saturated, play-sensitive distortion .
It’s all here: clarity, distortion, and rectifier tube sag .
#10737 22 WATTS / 12" SPEAKER / ORIGINAL AB763 CIRCUIT
H OU RS : 6
D I F F I C U LTY
H OU RS : 1 2
D I F F I C U LTY
H OU RS : 8
D I F F I C U LTY
H OU RS : 16
D I F F I C U LTY
’59 TWEED 15W AMP KITDirty little devil that shaped guitar history.With mysteriously fat saturated tone, this little monster makes it easy to achieve seismic distortion .
This amp’s 5E3 circuit is an enigma: Why do the controls on the channel you’re NOT using make your tone so great? The answer: Who cares? This is one of the greatest tone monsters ever created! Listen to Neil Young’s Rust Never Sleeps while building this kit .
Our most popular amp kit and a great learning experience .
#10731 15 WATTS / 10" SPEAKER / ORIGINAL 5E3 CIRCUIT
StewMac ICON KITS teach you the world of amp building, then turn you loose with amazing hand-built tone machines!
stewmac.com 49 © 2019 StewMac
’62 BRIT-PLEX 45W AMP KITThe original British showstopper.This amp started a revolution . It’s been rocking the world for over 50 years, and we still can’t get enough .
Favored by blues and rock players for exceptional sustain and rich creamy tone, the ’62 Brit-Plex is chock-full of harmonic gain, yet it still stays articulate and even a little crispy . Put this head on a classic 4x10 cab and watch out!
While building, listen to Gary Moore’s “Still Got The Blues ."
#10736 45 WATTS / ORIGINAL BRITISH CIRCUIT
’66 BRIT-74X 18W AMP KITLeave your half-stack at home.Born in London, this little blues blaster earns its living every night, gigging in clubs across the USA .
Launched in 1966, this amp quickly became a low-wattage holy grail . This is a stripped-down blues machine: two channels, one tone knob, no master volume . Buckle up and go where this gritty beast takes you! It comes with a footswitch to kick in the onboard tremolo .
Get the plexi tone without blowing the roof off the joint!
#10732 18 WATTS / 12" SPEAKER / ORIGINAL BRITISH CIRCUIT
’81 BRIT-800 50W AMP KITThis hairy monster lives to shred.The defining British circuit that dominated the ’80s .
This 50W giant created your favorite heavy rock and metal albums . Used by Slayer and Pixies, and recorded on early Metallica albums, this circuit produces that screaming guitar tone that your mother despises . With solid-state rectification there’s no sag, and the distortion created by this circuit is way more about treble than mids or bass .
Listen while building: Smashing Pumpkins’ Siamese Dream .
#10735 50 WATTS / ORIGINAL BRITISH CIRCUIT
’64 REVERB UNIT KITReverb you can’t get from a pedal.This is the unit that put the waves in surf music! Looks like an amp, sounds like a beach party .
This tube-driven reverb tank relies on good ol’ physics for a perfect effect . Your guitar signal travels along two large suspended springs to produce the reverb that launched the iconic surf sound . This isn't a pocket-sized digital simulation; this is the real deal!
Listen to Dick Dale’s “Misirlou" while doing this easy build .
#10733 ORIGINAL 6G15 CIRCUIT
H OU RS : 1 2
D I F F I C U LTY
H OU RS : 1 2
D I F F I C U LTY
H OU RS : 16
D I F F I C U LTY
H OU RS : 8
D I F F I C U LTY
Beginner-tested. Pro quality.StewMac ICON KITS are fun to build, with friendly instructions to guide you and loads of info to add to your knowledge.
stewmac.com 50 © 2019 StewMac
V5 EL34
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stewmac.com 51 © 2019 StewMac
’81 BRIT-800 50WA M P L I F I E R K I T O R I G I N A L B R I T I S H C I R C U I T
StewMac®
I C O N K I T S
DANGER: Unplug the amp before changing tubes.Tube locations from left to right:
EL34 EL3412AX7(ECC83)
V5 V4 V1
12AX7(ECC83)
12AX7(ECC83)
V3 V2
’81 BRIT-800 50WA M P L I F I E R K I T O R I G I N A L B R I T I S H C I R C U I T
StewMac®
I C O N K I T S
DANGER: Unplug the amp before changing tubes.Tube locations from left to right:
EL34 EL3412AX7(ECC83)
V5 V4 V1
12AX7(ECC83)
12AX7(ECC83)
V3 V2
Cut this label on the dotted line with a razor knife and metal straightedge .Fasten it inside the cabinet using thinned wood glue or contact cement .
The duplicate copy below is included as a backup .
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stewmac.com 53 © 2019 StewMac
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©2019 StewMac . All rights reserved .#10735 Updated June, 2019