’66 brit-74x 18w 74x-f4.pdf · stewmac.com 1 ©2018 stewmac ’66 brit-74x 18w combo amp kit...
TRANSCRIPT
A S S E M B LY I N S T R U C T I O N SWith loads of helpful tips!
’66 BRIT-74X 18W C O M B O A M P K I T ORIGINAL BRITISH CIRCUIT
Leave your half-stack at home!
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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
Prepping the cabinet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Prepping the turret boards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Tips for great soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Installing the chassis-mounted components . . . . . . . . . . . . . . . . . . . 11
Wrapping parts onto the turret board . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Installing the board in the chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Installing the fuse and knobs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Testing and troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Final assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Tips for using the ’66 Brit-74X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Learning more: secrets revealed in the schematic . . . . . . . . . . . . . . 40
Circuit schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
More iconic amp kits from StewMac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Complete wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Tube replacement chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
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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’66 BRIT-74X 18W COMBO AMP KIT ORIGINAL BRITISH CIRCUIT
Iconic British tone is now in your hands
Be excited!Your new StewMac ’66 Brit-74X will be a blast to play through and even more fun to build .
Born in London, this little blues blaster earns its living every night, gigging in clubs across the USA .
This amp is an ICONLaunched 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!
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 ’66 Brit-74X . 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!
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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 cabinet ready, starting at Step 1 on page 8.You’ll prep the metal chassis and the eyelet board 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 40.
Sort your components by type, using the parts list.Quick look:
#10732 © 2018 StewMac
GroundJackTransformer Preamp tube
plategrid
cathode
Power tube
grid
plate
cathode
screen
Capacitor Electrolytic Cap. DiodeResistor Potentiometers Rectifier tube
plate cathode
filamentplate
Shieldedcable
’66 BRIT-74X 18WO R I G I N A L B R I T I S H C I R C U I T
Gain Gain
Output
Processing Output
Power
Power
100K
100K
470K
470K
2.2K
6V
6V5V
2.2K
820
Ω
2.2
M5K
L
1M
1M
1MA
2.2K
470K
470K
56K
820
Ω
820
Ω
100K
100K
100K
100K
100K
470
K47
0K
10K 2W
1MA
1MA
1MA
1M
1M1M
68K
220K
68K
130K 3W
5.1K
16μF
50μF
50V
50μF
50V
32μF
32μF
.022μF
.0047μF.0047μF
.01μF CD
.01μF CD.01μF CD.01μF CD
250μF 25V
2.7K 2W
.01μF
5.1K
Mains
SPEA
KER
S
16
8
4
.01μF
.01μF
.01μ
F
TON
E
VO
LUM
E
TREM
OLO
NO
RM
AL
VO
LUM
E
SPEE
D
FOO
T SW
ITC
H
FOO
T SW
ITC
H
INTE
NSI
TY
1MA
TON
E
HEATERS
.004
7μF
.004
7μF
.047
μF
500p
F
STANDBY
FUSESlow-blow120V: 1A240V: 1/2A
LIGHT120V
TRANSFORMERMojo 18W power
TRANSFORMERMojo 18W ouput
V112AX7
V212AX7
V312AX7
V4EL84
V5EL84
V6EZ81
B
B
A
A
OutputGain Processing
See page 9
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Capacitors
r (1) 500pF 500V silver mica
r (4) .01μF 500V ceramic disk
r (4) .0047μF 630V Mojo Dijon
r (4) .01μF 630V Mojo Dijon
r (1) .022μF 630V Mojo Dijon
r (1) .047μF 630V Mojo Dijon
r (1) 50μF 50V aluminum electrolytic
r (1) 16μF 475V aluminum electrolytic
r (1) 50μF 50V Sprague Atom
r (1) 250μF 25V bipolar electrolytic
r (1) 32μF+32μF 500V filter
500pf
.01μF
500V
.022μF
.0047μF
.01μF
.047μF
16μF
50μF
50μF
250μF
Resistors
r (3) 820Ω .5W carbon composite
r (3) 2.2K .5W carbon composite
r (2) 5.1K .5W carbon composite
r (1) 56K .5W carbon composite
r (2) 68K .5W carbon composite
r (5) 100K .5W carbon composite
r (1) 220K .5W carbon composite
r (6) 470K .5W carbon composite
r (5) 1M .5W carbon composite
r (1) 2.2M .5W carbon composite
r (2) 100Ω 1W carbon composite
r (2) 2.7K 2W metal oxide
r (2) 10K 2W metal oxide
r (1) 130Ω 3W ceramic
Gray Red Brown Gold
Red Red Red Gold
Green Brown Red Gold
Green Blue Orange Gold
Blue Gray Orange Gold
Brown Black Yellow Gold
Red Red Yellow Gold
Yellow Violet Yellow Gold
Brown Black Green Gold
Red Red Green Gold
Brown Black Brown Gold
Red Violet Red Gold
Brown Black Orange Gold
Brown Orange Brown Gold
A magnifier helps!
Hardware
r (4) 10-32 machine screw, 1-1/2"r (4) 10-32 locknut
r (2) 8-32 machine screw, 1/4"r (6) 8-32 locknut
r (2) 6-32 machine screw, 1/2"r (2) 6-32 locknut
r (20) 4-40 machine screw, 1/4"r (12) 4-40 locknut
r (4) 4-40 threaded standoff, 1/2"
r (2) Switch mounting nut
r (2) Rubber grommet
r (1) Filter cap mounting clamp
r (1) Cabinet
r (1) Chassis
r (1) Turret board
r (1) Faceplate/backplate set
r (1) 12” speaker
r (1) Footswitch
Parts list
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Parts listTerminals, knobs, and cords
r (1) 5K control pot (L–linear taper)
r (5) 1M control pot (A–audio taper)
r (1) Selector switch
r (7) Knob
r (1) Power cord
r (2) Three-lug terminal strip
r (2) Two-lug switch
Transformers
r (1) Power transformer
r (1) Output transformer
Wire
r (1) Yellow push-back wire
r (1) Green push-back wire
r (1) Shielded wire
r (1) Heater wires (pre-tinned)
r (1) Speaker wires (multi-strand)
Heat-shrink tubing
r (8) 1/8" diameter
r (2) 1/16" diameter
12AX
7EL84
6CA
4
6
4 3 21
987
51M
A
5KL
Tubes, lamps, fuses, and sockets
r (1) Two-lug jack
r (5) Four-lug jack
r (1) Six-lug jack
r (1) Speaker plug (with shield and cover)
r (6) 9-pin tube socket
r (3) Shield for 9-pin tube socket
r (3) Tube retainer
r (3) 12AX7 preamp tube (also called ECC83S)
r (2) EL84 power tube
r (1) 6CA4 rectifier tube (also called EZ81)
r (1) Fuse socket
r (1) Fuse (5x20mm, 1 amp, slow blow)
r (1) Indicator light
r (1) Power inlet
Vintage-style push-back wire lets you push the fabric insulation back instead of cutting it away.BUT: Trimming the insulation still works better.
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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
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
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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 8μF and 16μF electrolytic capacitors .
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
NegativePositive
+ 25μF
8μf
How to read resistor values Capacitor values
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STEP 2
Solder the speaker leadsBefore soldering the speaker leads, place a business card or other pro-tection under the speaker terminals to prevent solder dripping onto the speaker cone .
Strip the insulation back 3/8" . Solder the white lead to the positive terminal and the black to the negative .
STEP 3
Glue the tube placement chartCut out the chart on page 45 . With a thin coat of glue or contact cement, glue it to the inside wall of the cabinet .
Remove the cabinet’s two back panels to prepare for installing the speaker .
STEP 1
Solder the speaker plugTwist your black and white speaker wires together to keep them neat .
Slide the cover of the 1/4" plug over the twisted wires, and then the plastic shielding . Strip both black and white wires back 3/8" . Insert the white lead onto the short tab corresponding with the tip of the plug and solder it in place . Tin the black lead and solder it to the long lug corresponding to the shield . See “Tips for great soldering!" on the next page for an explanation of tinning .
The long lug has a two metal prongs . Crimp these together firmly around the speaker wires . This provides strain relief so that a tug on the wires doesn’t pull on the solder joints .
Slide the plastic shield back over the solder joints and screw on the cover .
Use your multimeter to test for conti-nuity between the tip and the sleeve of the 1/4" speaker plug . If you have continuity, that means that one of your leads is shorted . If that’s the case, remove the cover and resolder the plug .
Start by prepping the cabinet
STEP 4
Install the speakerRemove the four speaker-mounting screws . Lay the cabinet flat on its face and lay the speaker on the back of the baffle, lining up the mounting holes in the speaker with the mounting holes in the baffle .
Install the screws so they’re lightly touching the speaker frame . Don’t tighten the screws in a circular pattern around the speaker, because this can warp the speaker frame .
Tighten one screw with a quarter turn so it’s just snug, then do the same to the opposite side . Then snug the third screw and the fourth . Repeat this criss-cross pattern of quarter-turns until all four screws have had one full turn . This gives proper tension to compress the speaker gasket . Over-tightening can damage the speaker and cause unwanted distortion .
Criss-cross tightening prevents warping.
’66 BRIT-74X 18WO 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
Use only 1-amp slow-blow fuse, size 5mm x 20mm.
DANGER: Unplug the amp before changing tubes.Tube locations from left to right:
12AX7(ECC83)
12AX7(ECC83)
V2 V1
EL84 12AX7(ECC83)
V4 V3
6CA4(EZ81)
EL84
V6 V5
#10732
Check off eachcompleted step
Tip
Sleeve
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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 5
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 (#23–29) 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 .
21
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
22
31 51
23
3024 25 26 27 28 29
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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thre
e lu
gs . T
his
will
be
used
as
a g
roun
ding
str
ip .
Leav
e th
e th
ree
lugs
of t
he o
ther
term
inal
st
rip u
ncon
nect
ed .
S
TE
P 7
Inst
all t
wo
ru
bb
er g
rom
met
sTh
ese
pro
vid
e st
rain
rel
ief f
or t
he t
rans
-fo
rmer
wire
s p
assi
ng t
hrou
gh t
he m
etal
ch
assi
s . S
qu
eeze
th
em i
nto
th
eir
two
hole
s as
sho
wn .
S
TE
P 8
Mo
un
t th
e p
ow
er t
ran
sfo
rmer
The
pow
er tr
ansf
orm
er h
as tw
elve
lead
s .
Sepa
rate
thes
e in
to c
olor
-cod
ed p
airs
and
tw
ist t
hese
pai
rs to
geth
er:
Tw
o re
d le
ads
Two
gree
n le
ads
Yello
w +
whi
te
Strip
es: g
reen
/yel
low
+ re
d/y
ello
w
This
tra
nsfo
rmer
is d
esig
ned
for
eit
her
120V
or
240V
op
erat
ion,
dep
endi
ng o
n yo
ur c
ount
ry’s
vol
tage
(120
V is
sta
ndar
d in
th
e U
nit
ed S
tate
s) .
The
dif
fere
nce
am
ount
s to
choo
sing
bet
wee
n tw
o w
ires :
n 1
20V
uses
the
bla
ck/w
hite
str
iped
wire
n 2
40V
uses
the
bla
ck/r
ed s
trip
ed w
ire
The
wire
you
’re n
ot g
oing
to
use
will
be
safe
ly te
rmin
ated
alo
ng w
ith th
e ye
llow
/w
hite
strip
ed w
ire, w
hich
is a
lso
not u
sed
in th
e 74
X .
Twis
t th
e w
ire
you’
re n
ot
goi
ng t
o us
e to
get
her
wit
h th
e ye
llow
/whi
te s
trip
ed
wire
. The
dia
gram
s in
thi
s m
anua
l sho
w
120V
wiri
ng, s
o th
e b
lack
/red
strip
ed w
ire
is t
wis
ted
with
the
yel
low
/whi
te s
trip
ed
wire
. Fee
d al
l the
tra
nsfo
rmer
lead
s in
to
the
chas
sis
thro
ugh
the
squa
re h
ole .
Inst
all
the
tran
sfo
rmer
on
th
e o
uts
ide
of t
he c
hass
is, u
sing
fou
r 8-
32 lo
cknu
ts
insi
de .
Ad
d t
he
term
inal
str
ips
at t
wo
corn
ers
as s
how
n . T
he g
roun
din
g st
rip
yo
u cr
eate
d g
oes
to t
he f
ront
nea
r th
e p
ower
sw
itch
and
the
othe
r str
ip is
at t
he
bac
k ne
ar th
e fu
se s
ocke
t .
S
TE
P 9
Mo
un
t th
e o
utp
ut
tran
sfo
rmer
Twis
t th
e re
d +
blu
e +
bro
wn
wir
es
tog
ethe
r . Pa
ss t
hese
thr
ee t
hrou
gh t
he
gro
mm
eted
ho
le n
eare
st t
he
po
wer
tr
ansf
orm
er .
Twis
t the
ora
nge
+ g
reen
+ y
ello
w w
ires
toge
ther
. Pas
s th
ese
thro
ugh
the
othe
r g
rom
met
ed h
ole
alon
g w
ith
th
e b
lack
w
ire (f
our w
ires
thro
ugh
this
gro
mm
et) .
Use
two
8-32
x 1
/4" m
achi
ne s
crew
s w
ith
lock
nuts
to m
ount
the
tran
sfor
mer
on
the
outs
ide
of th
e ch
assi
s .
S
TE
P 1
0
Mo
un
t th
e fi
lter
cap
The
filte
r ca
pac
itor
is h
eld
to t
he c
hass
is
wit
h i
ts m
ou
nti
ng
cla
mp
. Th
is c
lam
p
atta
ches
to
the
cap
acito
r ne
ar t
he lu
gs,
and
is th
en m
ount
ed to
the
chas
sis u
sing
6-
32 x
1/2
" scr
ews
and
nuts
. Pos
ition
the
clam
p s
o th
at y
ou c
an m
ount
the
cap
ac-
itor’s
neg
ativ
e (–
) lug
tow
ard
the
pow
er
tran
sfor
mer
.
S
TE
P 1
1
Mo
un
t si
x tu
be
sock
ets
Use
4-4
0 x
1/4"
scr
ews
and
lock
nuts
to
inst
all
the
sock
ets .
Ori
ent
each
so
cket
w
ith
pin
1 t
urn
ed a
way
fro
m t
he
bac
k p
anel
of t
he c
hass
is .
Incl
ude
a tu
be
reta
iner
on
sock
ets
V4, V
5 an
d V6
to p
rovi
de su
pp
ort f
or th
ese
thre
e tu
bes
whe
n th
ey’re
inst
alle
d la
ter .
S
TE
P 1
2
Mo
un
t th
e fa
cep
late
an
d b
ack
pla
tePe
el t
he p
rote
ctiv
e fil
m o
ff t
he c
hass
is .
Secu
re th
e fa
cep
late
by
pla
cing
the
con
-tr
ol p
ots
in t
hei
r h
oles
an
d s
lidin
g t
he
face
pla
te o
ver t
hem
. Ins
tall
was
hers
and
nu
ts o
n th
e p
ots t
o ho
ld th
e pl
ate
in p
lace
.
Five
of t
he s
ix c
ontr
ols
are
1MA
pot
s . T
he
inte
nsit
y co
ntro
l is a
5KL
pot
. Ins
tall
them
w
ith th
eir l
ugs
faci
ng u
p fo
r sol
der
ing,
as
show
n in
the
diag
ram
.
Whe
n th
e in
stru
ctio
ns re
fer t
o th
e le
ft o
r rig
ht lu
g of
a p
ot, i
t m
eans
left
or
right
fr
om th
e p
oint
of v
iew
of t
he d
iagr
am .
Att
ach
th
e b
ackp
late
by
inst
allin
g t
he
4-lu
g sp
eake
r ou
tput
jack
and
the
2-lu
g ex
tens
ion
spea
ker j
ack
to h
old
it in
pla
ce .
Mou
nt th
ese
jack
s us
ing
only
one
of t
he
two
was
hers
pro
vid
ed .
stew
mac
.co
m
12
©20
18 S
tew
Mac
FUSE
IMPE
DA
NC
ESP
EAK
EREX
TEN
SIO
NPO
WER
INPU
TFO
OT
SWIT
CH
IND
ICAT
OR
LIG
HT
STA
ND
BYPO
WER
SPEE
DIN
TEN
SITY
TON
EV
OLU
ME
TON
EV
OLU
ME
NO
RM. I
NPU
TTR
EM. I
NPU
T
V6
EZ81
V5
EL84
FILT
ER C
AP
V4
EL84
V3
12A
X7
V2
12A
X7
V1
12A
X7
2 1
2 1
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
12
43
12
43
AA BB
12
43
12
43
12
43
12
43
ST
EP
18
ST
EP
19
12
43
12
43
Enla
rged
tosh
ow d
etai
lM
ount
jack
s ou
tsid
eon
the
fron
t pan
el
AA BB
AA BB
AA BB
ST
EP
17
stew
mac
.co
m
13
©20
18 S
tew
Mac
S
TE
P 1
3
Inst
all t
he
fuse
so
cket
Inst
all t
he fu
se s
ocke
t in
the
bac
k p
anel
.
S
TE
P 14
Inst
all t
he
po
wer
inp
ut
Inse
rt t
he
pow
er i
nput
wit
h it
s ce
ntra
l gr
ound
lug
faci
ng u
p to
war
d yo
u .
S
TE
P 1
5
Inst
all t
he
ind
icat
or
lig
ht
Inst
all t
he in
dica
tor l
ight
in th
e fr
ont p
anel
an
d tw
ist t
he t
wo
wire
s to
geth
er .
Coil
thes
e w
ires t
emp
orar
ily to
kee
p th
em
out o
f you
r way
, sin
ce th
ey w
on’t
be
con
-ne
cted
unt
il la
ter .
S
TE
P 1
6
Ad
d t
he
stan
db
y +
po
wer
sw
itch
esM
ount
the
tw
o-lu
g st
andb
y an
d p
ower
sw
itch
es,
usi
ng
th
e sw
itch
mo
un
tin
g nu
ts . A
fter
inse
rtin
g a
switc
h th
roug
h th
e ho
le, p
lace
its
was
her
on t
he t
hrea
ded
sh
aft b
efor
e ad
ding
the
nut .
S
TE
P 1
7
Wir
e th
e n
orm
al c
han
nel
inp
ut
jack
sU
se tw
o 4-
lug
jack
s fo
r the
inp
uts
on th
e n
orm
al c
han
nel
. Fo
r th
ese
step
s, w
e’ll
refe
r to
thes
e in
put
jack
s as
A a
nd B
.
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 with
thei
r lug
s poi
ntin
g to
war
d th
e in
dic
ator
lig
ht . A
fter
ins
erti
ng
th
e ja
ck
thro
ugh
the
hole
, pla
ce a
was
her o
n th
e th
read
ed s
haft
bef
ore
addi
ng th
e nu
t .
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 .
In b
uild
ing
th
is a
mp
, yo
u’ll
cu
t p
iece
s o
f w
ire
to m
ake
con
nec
tio
ns .
Th
ese
con
nec
tin
g w
ires
are
cal
led
ju
mp
ers,
an
d yo
u’ll
use
a lo
t of
the
m in
bui
ldin
g th
is a
mp .
Cut a
2" l
engt
h of
yel
low
wire
. Rem
ove
the
insu
latio
n to
cre
ate
a b
are
wire
jum
per
.
Bend
a sm
all h
ook
on o
ne e
nd a
nd w
rap
it th
roug
h lu
g 1
of ja
ck A
. Run
the
wire
ove
r an
d d
own
thro
ugh
lugs
2 a
nd 3
.
Sold
er t
his
jum
per
to
lug
1 a
nd
lu
g 2
, le
avin
g it
unso
lder
ed a
t lug
3 .
S
TE
P 1
8
No
rmal
ch
ann
el ja
cks,
co
nti
nu
ed…
Usi
ng a
1M
resi
stor
, run
one
lead
thro
ugh
lug
3 of
jack
A . R
un th
is sa
me
lead
stra
ight
d
own
thro
ugh
lug
2 of
jack
B .
Run
th
is r
esis
tor’s
oth
er l
ead
th
rou
gh
lug
4 of
jack
A a
nd d
own
thro
ugh
lug
1 of
jack
B .
Sold
er th
e re
sist
or le
ad a
nd ju
mp
er le
ad
to lu
g 3
of ja
ck A
and
trim
aw
ay a
ny e
xces
s ju
mp
er (d
on’t
cut t
he re
sist
or le
ad) .
Sold
er th
e re
sist
or le
ad to
lug
1 of
jack
B
and
trim
aw
ay a
ny e
xces
s .
Cut a
1" p
iece
of y
ello
w w
ire a
nd re
mov
e th
e in
sula
tio
n .
Ru
n t
his
bar
e ju
mp
er
thro
ugh
lug
2 an
d lu
g 3
of ja
ck B
. Sol
der
th
is ju
mp
er w
ith th
e re
sist
or le
ad to
lug
2 .
S
TE
P 19
No
rmal
ch
ann
el ja
cks,
co
nti
nu
ed…
With
ano
ther
1M
res
isto
r, ru
n th
e le
ads
dow
n th
roug
h lu
g 3
and
lug
4 of
jack
B .
Cut a
4" g
reen
jum
per
and
sold
er o
ne e
nd
to lu
g 3
of ja
ck B
, with
the
jum
per
fro
m
lug
2 an
d th
e re
sist
or le
ad .
Cut t
wo
7" y
ello
w ju
mp
ers .
Sol
der
one
to
lug
4 of
jack
A a
long
with
the
resi
stor
lead
.
Sold
er th
e ot
her y
ello
w ju
mp
er to
lug
4 of
ja
ck B
alo
ng w
ith th
e re
sist
or le
ad .
Twis
t th
ese
yello
w j
um
per
s to
get
her
, st
artin
g ab
out 1
" fro
m th
ese
sold
er jo
ints
. Le
ave
abou
t 2" u
ntw
iste
d at
the
othe
r end
of
the
jum
per
s .
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 a
way
from
the
indi
cato
r lig
ht .)
Run
the
gree
n ju
mp
er u
nder
jack
B, w
hich
is
now
nor
mal
inp
ut ja
ck 1
.
Run
the
yello
w ju
mp
ers
to s
ocke
t V1
but
d
o no
t sol
der
them
yet
.
For ne
at loo
king w
iring,
use wi
re str
ippers
to
trim 1/
4" of t
he ins
ulation
fro
m the
ends o
f the
push-b
ack wi
re.
stew
mac
.co
m
14
©20
18 S
tew
Mac
FUSE
IMPE
DA
NC
ESP
EAK
EREX
TEN
SIO
NPO
WER
INPU
TFO
OT
SWIT
CH
IND
ICAT
OR
LIG
HT
STA
ND
BYPO
WER
SPEE
DIN
TEN
SITY
TON
EV
OLU
ME
TON
EV
OLU
ME
NO
RM. I
NPU
TTR
EM. I
NPU
T
V6
EZ81
V5
EL84
FILT
ER C
AP
V4
EL84
V3
12A
X7
V2
12A
X7
V1
12A
X7
2 1
2 1
1MA
1MA
1MA
1MA
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
12
43
12
43
AA BB
12
43
12
43
AA BB
ST
EP
22
12
43
12
43
AA BB
ST
EP
21
12
43
12
43
AA BB
ST
EP
20
Enla
rged
tosh
ow d
etai
lM
ount
jack
s ou
tsid
eon
the
fron
t pan
el
stew
mac
.co
m
15
©20
18 S
tew
Mac
S
TE
P 2
0
Wir
e th
e tr
emo
lo c
han
nel
jack
sA
gai
n, u
se t
wo
4-lu
g j
acks
whi
ch w
e’ll
refe
r to
as A
and
B .
As y
ou d
id w
ith th
e no
rmal
cha
nnel
jack
s,
asse
mb
le t
hes
e o
n t
he
outs
ide
of
the
chas
sis
wit
h th
eir
lugs
poi
ntin
g to
war
d th
e in
dica
tor l
ight
.
Cut a
2" l
engt
h of
yel
low
wire
. Rem
ove
the
insu
latio
n to
cre
ate
a b
are
wire
jum
per
.
Bend
a sm
all h
ook
on o
ne e
nd a
nd w
rap
it th
roug
h lu
g 1
of ja
ck A
. Run
the
wire
ove
r an
d d
own
thro
ugh
lugs
2 a
nd 3
.
Sold
er t
his
jum
per
to
lug
1 a
nd
lu
g 2
, le
avin
g it
unso
lder
ed a
t lug
3 .
S
TE
P 2
1
Trem
olo
ch
ann
el ja
cks,
co
nti
nu
ed…
Usi
ng a
1M
resi
stor
, run
one
lead
thro
ugh
lug
3 of
jack
A . R
un th
is sa
me
lead
stra
ight
d
own
thro
ugh
lug
2 of
jack
B .
Run
the
othe
r lea
d th
roug
h lu
g 4
of ja
ck A
an
d d
own
thro
ugh
lug
1 of
jack
B .
Sold
er th
e re
sist
or le
ad a
nd ju
mp
er le
ad
to lu
g 3
of ja
ck A
and
trim
aw
ay a
ny e
xces
s ju
mp
er (d
on’t
cut t
he re
sist
or le
ad) .
Sold
er th
e re
sist
or le
ad to
lug
1 of
jack
B
and
trim
aw
ay a
ny e
xces
s .
Cut a
1" p
iece
of y
ello
w w
ire a
nd re
mov
e th
e in
sula
tio
n .
Ru
n t
his
bar
e ju
mp
er
thro
ugh
lug
2 an
d lu
g 3
of ja
ck B
. Sol
der
th
is ju
mp
er w
ith th
e re
sist
or le
ad to
lug
2 .
S
TE
P 2
2
Trem
olo
ch
ann
el ja
cks,
co
nti
nu
ed…
Cut
a 4
" g
reen
jum
per
an
d s
old
er o
ne
end
to lu
g 3
of ja
ck B
, with
the
jum
per
fr
om lu
g 2 .
On
each
of
two
68K
resi
stor
s, t
rim
one
le
ad to
3/4
" lon
g .
Sold
er o
ne o
f the
se tr
imm
ed 6
8K re
sist
or
lead
s to
lug
4 of
jack
A, a
long
with
the
re
sist
or le
ad .
Sold
er t
he t
rimm
ed le
ad fr
om t
he o
ther
68
K re
sist
or to
lug
4 of
jack
B .
If yo
ur w
iring
of t
hese
resi
stor
lead
s mig
ht
cont
act
othe
r w
ires
or lu
gs, i
nsul
ate
the
lead
s w
ith
hea
t-sh
rin
k tu
bin
g b
efo
re
sold
erin
g th
em . S
lide
the
tub
ing
onto
the
lead
and
shrin
k it
to fi
t . Se
e th
e ill
ustr
atio
n on
pag
e 17
.
Cut
a 5"
yel
low
jum
per
and
tri
m a
bou
t 1/
2" o
f the
insu
latio
n fr
om o
ne e
nd . T
wis
t th
is t
og
eth
er w
ith
th
e re
mai
nin
g 6
8K
resi
stor
lead
s and
sold
er th
is c
onne
ctio
n .
Aft
er s
old
erin
g th
is j
oint
, ins
ulat
e it
by
slid
ing
a p
iece
of 1
/8" h
eat-
shrin
k tu
bin
g on
to th
e w
ire a
nd o
ver t
he jo
int .
Add
hea
t to
shr
ink
the
tub
ing .
Mou
nt th
ese
wire
d-u
p in
put
jack
s in
sid
e of
th
e ch
assi
s . A
s yo
u d
o th
is, r
un t
he
gree
n ju
mp
er u
nder
jack
B, w
hich
is n
ow
trem
olo
inp
ut ja
ck 1
.
Run
the
yello
w ju
mp
er to
war
d so
cket
V3 .
S
TE
P 2
3
Gro
un
d t
he
con
tro
l po
tsTu
rn a
ll th
e p
ots s
haft
s cou
nter
cloc
kwis
e to
thei
r zer
o p
ositi
on b
efor
e st
artin
g th
is
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 .
Cut
a 2"
jum
per
of
gree
n w
ire a
nd p
ull
off th
e in
sula
tion .
Sol
der
one
end
to th
e m
iddl
e lu
g of
the
nor
mal
cha
nnel
ton
e p
ot . B
end
this
wire
to c
onta
ct th
e b
ack
of
that
pot
and
jum
p o
ver t
o th
e b
ack
of th
e no
rmal
cha
nnel
vol
ume
pot
. Sol
der
thi
s ju
mp
er to
the
bac
ks o
f the
se t
wo
pot
s .
Cut
and
strip
ano
ther
2"
gree
n ju
mp
er .
Sold
er o
ne
end
to
th
e le
ft l
ug
of
the
trem
olo
chan
nel v
olum
e p
ot . S
old
er th
is
jum
per
to th
e b
acks
of t
he tr
emol
o ch
an-
nel v
olum
e an
d to
ne p
ots
to g
ive
them
a
shar
ed g
roun
d . T
his
shar
ed g
roun
d is
ca
lled
a gr
ound
bus
.
S
TE
P 2
4
Gro
un
d t
he
inp
ut
jack
sW
rap
the
gree
n ju
mp
er fr
om th
e no
rmal
ch
anne
l inp
ut ja
cks
onto
the
grou
nd b
us
bet
wee
n th
e no
rmal
vol
ume
and
ton
e p
ots .
Sol
der
this
con
nect
ion .
Wra
p th
e gr
een
jum
per
from
the
trem
olo
chan
nel i
nput
jack
s on
to th
e gr
ound
bus
b
etw
een
the
trem
olo
volu
me
and
tone
p
ots .
Sol
der
this
con
nect
ion .
S
TE
P 2
5
Inst
all a
gro
un
din
g ju
mp
erCu
t a 3
/4" g
reen
jum
per
and
rem
ove
the
insu
latio
n . S
old
er o
ne e
nd to
the
left
lug
of t
he n
orm
al c
hann
el v
olum
e p
ot a
nd
sold
er t
he o
ther
end
to
the
bac
k of
the
sa
me
pot
.
stew
mac
.co
m
16
©20
18 S
tew
Mac
FUSE
IMPE
DA
NC
ESP
EAK
EREX
TEN
SIO
NPO
WER
INPU
TFO
OT
SWIT
CH
IND
ICAT
OR
LIG
HT
STA
ND
BYPO
WER
SPEE
DIN
TEN
SITY
TON
EV
OLU
ME
TON
EV
OLU
ME
NO
RM. I
NPU
TTR
EM. I
NPU
T
V6
EZ81
V5
EL84
FILT
ER C
AP
V4
EL84
V3
12A
X7
V2
12A
X7
V1
12A
X7
2 1
2 1
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
.0047μF
stew
mac
.co
m
17
©20
18 S
tew
Mac
S
TE
P 2
6
Ad
d a
.00
47μ
F ca
pac
ito
rSo
lder
a .0
047μ
F D
ijon
cap
bet
wee
n th
e le
ft lu
g of
the
trem
olo
chan
nel t
one
pot
an
d th
e b
ack
of th
e sa
me
pot
. Trim
aw
ay
any
exce
ss le
ad .
S
TE
P 2
7
Ad
d a
n in
sula
ted
2.2
K r
esis
tor
Plac
e tw
o 3/
4" le
ngth
s of 1
/16"
hea
t-sh
rink
tub
ing
onto
the
lead
s of t
he 2
.2K
resi
stor
. A
dd
hea
t to
cre
ate
elec
tric
al in
sula
tion
ov
er th
e b
are
wire
of t
hese
lead
s .
Wra
p t
his
resi
stor
bet
wee
n th
e m
idd
le
lugs
of
the
trem
olo
chan
nel’s
ton
e an
d vo
lum
e p
ots .
Sol
der
the
con
nect
ion
to
the
ton
e p
ot,
bu
t d
on
’t s
old
er t
o t
he
volu
me
pot
yet
.
S
TE
P 2
8
Ad
d a
n in
sula
ted
1M
res
isto
rA
dd
two
3/4"
leng
ths o
f 1/1
6" h
eat-
shrin
k tu
bin
g on
to th
e le
ads
of a
1M
resi
stor
.
Pass
one
lead
thro
ugh
the
mid
dle
lug
of
the
spee
d p
ot a
nd s
old
er it
to th
e le
ft lu
g of
tha
t p
ot . L
eave
the
mid
dle
lug
unso
l-d
ered
for n
ow .
Pass
the
resi
stor
’s o
ther
lead
thro
ugh
the
mid
dle
lug
of th
e in
tens
ity
pot
and
sold
er
it to
the
right
lug
of th
at p
ot . T
he m
iddl
e lu
g ge
ts s
old
ered
in th
e ne
xt s
tep .
S
TE
P 2
9
Ad
d a
sh
ort
bar
e ju
mp
erCu
t a
1" g
reen
jum
per
and
rem
ove
the
insu
latio
n . S
old
er th
is b
etw
een
the
mid
-dl
e lu
g of
the
inte
nsit
y p
ot a
nd th
e b
ack
of th
e sa
me
pot
.
S
TE
P 3
0
Co
nn
ect
the
po
wer
tra
nsf
orm
er’s
re
d le
ads
Run
the
two
red
wire
s fr
om t
he p
ower
tr
ansf
orm
er to
the
V6 re
ctifi
er tu
be
sock
et
(eit
her
wir
e ca
n g
o to
eit
her
lug
) . Tr
im
thes
e w
ires
to le
ngth
and
sol
der
one
to
pin
7 a
nd th
e ot
her t
o p
in 1
.
S
TE
P 3
1
Co
nn
ect
the
po
wer
tra
nsf
orm
er’s
w
hit
e an
d y
ello
w le
ads
Trim
th
e p
ow
er t
ran
sfo
rmer
’s t
wis
ted
wh
ite
and
yel
low
lea
ds
to l
eng
th f
or
conn
ectin
g to
sock
et V
6 . S
olde
r the
whi
te
lead
to p
in 5
and
the
yello
w le
ad to
pin
4 .
S
TE
P 3
2
Ad
d a
yel
low
jum
per
Cut
a 10
-1/2
" ye
llow
jum
per
. Sol
der
one
en
d i
n t
o t
he
left
lu
g o
f th
e st
and
by
swit
ch,
and
th
e o
ther
en
d t
o p
in 3
of
sock
et V
6 .
S
TE
P 3
3
Co
nn
ect
the
po
wer
tra
nsf
orm
er
bla
ck le
adRu
n th
e b
lack
pow
er tr
ansf
orm
er le
ad to
th
e rig
ht lu
g of
the
pow
er s
witc
h an
d cu
t it
to le
ngth
. Don
’t so
lder
it y
et .
S
TE
P 3
4
Co
nn
ect
on
e in
dic
ato
r li
gh
t le
adRu
n ei
ther
of t
he o
ne o
f the
indi
cato
r lig
ht
lead
s to
the
right
lug
of th
e p
ower
switc
h .
Cut i
t to
leng
th a
nd s
old
er it
ther
e al
ong
with
the
pow
er tr
ansf
orm
er’s
bla
ck le
ad .
S
TE
P 3
5
Ro
ute
th
e o
ther
ind
icat
or
lead
Run
the
othe
r ind
icat
or li
ght
lead
to th
e le
ft lu
g of
the
fus
e so
cket
and
trim
it t
o le
ngth
. Don
’t so
lder
it y
et .
S
TE
P 3
6
Co
nn
ect
the
po
wer
tra
nsf
orm
er
bla
ck/w
hit
e o
r b
lack
/red
lead
For 1
20V
use,
run
the
bla
ck/w
hite
strip
ed
pow
er t
rans
form
er l
ead
to
the
left
lug
of
the
fuse
soc
ket .
Trim
it t
o le
ngth
and
so
lder
it to
the
left
lug
alon
g w
ith th
e le
ad
from
the
indi
cato
r lig
ht .
If yo
u’re
wiri
ng fo
r 240
V us
age,
follo
w th
e ab
ove
step
usi
ng t
he b
lack
/red
str
iped
le
ad in
stea
d o
f th
e b
lack
/whi
te s
trip
ed
lead
.
S
TE
P 3
7
Ad
d t
wo
yel
low
jum
per
sCu
t a 8
-1/2
" yel
low
jum
per
and
sold
er o
ne
end
to t
he r
ight
lug
of t
he p
ower
inp
ut .
Sold
er th
e ot
her e
nd to
the
left
lug
of th
e p
ower
sw
itch .
Cut a
3-1
/2" y
ello
w ju
mp
er a
nd so
lder
one
en
d t
o th
e le
ft lu
g of
the
pow
er in
put
. So
lder
the
oth
er e
nd t
o th
e rig
ht lu
g of
th
e fu
se s
ocke
t .
Use a
match
or lig
hter
to ins
ulate
wires
with
heat-s
hrink
tubing
stew
mac
.co
m
18
©20
18 S
tew
Mac
FUSE
IMPE
DA
NC
ESP
EAK
EREX
TEN
SIO
NPO
WER
INPU
TFO
OT
SWIT
CH
IND
ICAT
OR
LIG
HT
STA
ND
BYPO
WER
SPEE
DIN
TEN
SITY
TON
EV
OLU
ME
TON
EV
OLU
ME
NO
RM. I
NPU
TTR
EM. I
NPU
T
V6
EZ81
V5
EL84
FILT
ER C
AP
V4
EL84
V3
12A
X7
V2
12A
X7
V1
12A
X7
2 1
2 1
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
stew
mac
.co
m
19
©20
18 S
tew
Mac
S
TE
P 3
8
Co
nn
ect
the
po
wer
tra
nsf
orm
er’s
g
reen
/yel
low
an
d r
ed/y
ello
w le
ads
Run
the
gree
n/y
ello
w s
trip
ed a
nd r
ed/
yello
w s
trip
ed t
wis
ted
pai
r to
the
3-lu
g gr
ound
ing
strip
nea
r th
e p
ower
sw
itch .
Tr
im th
em a
nd so
lder
them
to th
e m
iddl
e lu
g of
the
strip
.
S
TE
P 3
9
Term
inat
e th
e p
ow
er t
ran
sfo
rmer
’s
two
un
use
d le
ads
Run
th
e b
lack
/red
str
iped
an
d y
ello
w/
whi
te s
trip
ed t
wis
ted
pai
r to
the
3-l
ug
strip
nea
r the
fuse
soc
ket .
(For
240
V w
ir-in
g, t
his
will
be
the
bla
ck/w
hite
inst
ead
of b
lack
/red
wire
.)
Trim
the
two
wire
s to
leng
th, a
nd s
old
er
them
indi
vidu
ally
to
the
two
oute
r lu
gs .
Thes
e un
used
wire
s ar
e no
w e
lect
rical
ly
isol
ated
an
d s
old
ered
to
sep
arat
e, u
n-
gro
un
ded
lu
gs
wit
h n
o o
ther
co
nn
ec-
tions
. Thi
s is a
safe
way
to te
rmin
ate
them
so
they
don
’t in
terf
ere
with
oth
er w
ires .
S
TE
P 4
0
Ad
d a
gro
un
d ju
mp
erCu
t one
4" g
reen
jum
per
and
sol
der
one
en
d in
to
the
mid
dle
lug
of
the
pow
er
inp
ut . S
olde
r the
oth
er e
nd to
the
mid
dle
lug
of th
e 3-
lug
strip
nea
r the
fuse
sock
et .
Unl
ike
the
two
othe
r lu
gs o
n th
is s
trip
, th
is m
iddl
e lu
g is
gro
und
ed th
roug
h th
e m
ount
ing
bol
t to
the
chas
sis .
S
TE
P 4
1
Ad
d a
2.7
K r
esis
tor
Run
one
leg
of
a 2 .
7K r
esis
tor
thro
ugh
each
of
the
two
po
siti
ve l
ug
s o
n t
he
filte
r cap
acito
r . Po
sitio
n th
e re
sist
or s
o it
stan
ds u
p o
ff o
f the
lugs
by
at le
ast
1/2"
an
d w
rap
the
lead
s so
it s
tays
in p
lace
. D
on’t
sold
er it
yet
.
S
TE
P 4
2
Ad
d a
yel
low
jum
per
Cut o
ne 9
-1/4
" yel
low
jum
per
and
sol
der
on
e en
d to
the
rig
ht lu
g of
the
sta
ndby
sw
itch .
Run
the
othe
r end
to th
e le
ft p
os-
itive
lug
of th
e fil
ter c
apac
itor .
S
TE
P 4
3
Co
nn
ect
the
ou
tpu
t tr
ansf
orm
er’s
re
d, b
lue,
an
d b
row
n le
ads
Unt
wis
t th
e re
d, b
lue,
and
bro
wn
wire
s fr
om th
e ou
tput
tran
sfor
mer
just
eno
ugh
to c
onne
ct to
the
filte
r cap
and
sock
ets V
5 an
d V4
. The
tw
iste
d p
ortio
n of
the
wire
s sh
ould
rem
ain
long
eno
ugh
to re
ach
the
rear
wal
l of t
he c
hass
is .
Run
the
red
wire
to
the
left
pos
itive
lug
of th
e fil
ter c
apac
itor a
nd s
old
er in
pla
ce
with
the
res
isto
r an
d th
e ye
llow
jum
per
fr
om th
e p
revi
ous
step
.
Run
th
e b
row
n a
nd
blu
e w
ires
in
th
e op
pos
ite d
irect
ion,
kee
pin
g th
em c
lose
to
the
rea
r w
all o
f th
e ch
assi
s . T
rim t
he
bro
wn
wire
to le
ngth
and
sol
der
it to
pin
7
of s
ocke
t V5 .
Trim
and
sol
der
the
blu
e w
ire in
to p
in 7
of
soc
ket V
4 .
STOP
S
TE
P 4
4
Co
nn
ect
the
ou
tpu
t tr
ansf
orm
er’s
b
lack
lead
Ru
n t
he
bla
ck w
ire
fro
m t
he
ou
tpu
t tr
ansf
orm
er to
the
3-lu
g gr
ound
ing
strip
ne
ar t
he p
ower
sw
itch .
Trim
it t
o le
ngth
an
d so
lder
it to
the
right
lug
of th
e st
rip .
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 . Be
suspic
ious
There's
a mis
take, a
nd you
’re gon
na find
it!
stew
mac
.co
m
20
©
2018
Ste
wM
ac
21
34
56
78
910
1112
1314
1516
1718
1920
21
3233
3435
3637
3839
4041
4243
4445
4647
4849
50
22
3151
30
2425
2627
2829
23
50μF
.022μF
500p
F
.01μF
.01μF
.0047μF
.0047μF
.0047μF
.047μF
.01μF
.01μF
stew
mac
.co
m
21
©
2018
Ste
wM
ac
Wra
pp
ing
par
ts o
nto
th
e tu
rret
bo
ard
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 4
5
Wra
p a
n 8
20Ω
res
isto
rW
rap
an
820Ω
res
isto
r b
etw
een
turr
ets
22 a
nd 5
1 .
S
TE
P 4
6
Ad
d a
50
μF
cap
+ t
wo
jum
per
sN
ote
that
this
50μ
F el
ectr
olyt
ic c
apac
itor
is p
olar
ized
, so
it m
ust b
e in
stal
led
in th
e co
rrec
t pos
itive
/neg
ativ
e or
ient
atio
n . T
he
pos
itive
end
of t
he c
ap h
as a
n in
den
ted
ring,
and
the
arr
ow d
esig
ns p
oint
to t
he
nega
tive
end
.
Wra
p th
e ca
p’s p
ositi
ve le
ad a
roun
d tu
rret
50
and
the
nega
tive
lead
aro
und
turr
et 2
1 .
Cut
two
1" ju
mp
ers
of y
ello
w w
ire a
nd
rem
ove
the
insu
latio
n . W
rap
one
of t
hese
sh
ort b
are
wire
s b
etw
een
turr
ets
50 a
nd
51 . W
rap
the
othe
r wire
bet
wee
n tu
rret
s 21
and
22 .
S
TE
P 4
7
Ad
d g
reen
+ y
ello
w ju
mp
ers
Cut
a 3"
gre
en ju
mp
er a
nd w
rap
it o
nto
turr
et 2
1 .
Cut
a 2-
1/4"
yel
low
jum
per
and
wra
p it
on
to tu
rret
50 .
S
TE
P 4
8
Ad
d t
wo
cap
acit
ors
+ o
ne
resi
sto
rA
dd
a .0
1μF
cap
acit
or b
etw
een
turr
ets
20 a
nd 4
9 . T
his
and
the
follo
win
g ye
llow
ca
pac
ito
rs a
re n
ot
po
lari
zed
, so
yo
u ca
n in
stal
l the
m in
eith
er d
irect
ion .
We
reco
mm
end
faci
ng th
em a
ll in
the
sam
e d
irec
tio
n,
mak
ing
th
eir
pri
nte
d s
pec
s ea
sy to
read
.
Ad
d a
.004
7μF
cap
acito
r bet
wee
n tu
rret
s 29
and
49 .
Ad
d a
100K
res
isto
r b
etw
een
turr
ets
19
and
29 .
S
TE
P 4
9
Ad
d fo
ur
jum
per
sA
dd
a 5-
1/2"
yel
low
jum
per
to tu
rret
20 .
Ad
d a
5" y
ello
w ju
mp
er t
o tu
rret
29
and
run
it to
the
top
of t
he b
oard
.
Ad
d a
3-3/
4" y
ello
w ju
mp
er to
turr
et 1
9 .
Ad
d a
2-1/
4" y
ello
w ju
mp
er to
turr
et 4
9 .
S
TE
P 5
0
Ad
d o
ne
cap
acit
or
+ o
ne
jum
per
Add
a .0
22μF
cap
acito
r bet
wee
n tu
rret
s 18
and
48 .
Ad
d a
4" y
ello
w ju
mp
er to
turr
et 1
8 .
S
TE
P 5
1
Ad
d fo
ur
resi
sto
rsA
dd
a 56
K re
sist
or b
etw
een
turr
ets
17
and
28 .
Ad
d an
820
Ω r
esis
tor
bet
wee
n tu
rret
s 28
and
47 .
Ad
d a
470
K re
sist
or
bet
wee
n t
urre
ts
28 a
nd 4
8 .
Ad
d a
no
ther
470
K r
esis
tor
bet
wee
n tu
rret
s 28
and
46 .
S
TE
P 5
2
Ad
d o
ne
cap
acit
or
+ fi
ve ju
mp
ers
Ad
d a
.01μ
F ca
pac
itor b
etw
een
turr
ets
16 a
nd 4
6 .
Ad
d a
1-3/
4" g
reen
jum
per
to tu
rret
17 .
Ad
d a
5-1/
4" y
ello
w ju
mp
er to
turr
et 1
6 .
Ad
d a
3" y
ello
w ju
mp
er to
turr
et 4
8 .
Ad
d a
2-1/
2" y
ello
w ju
mp
er to
turr
et 4
7 .
Add
a 3
-1/2
" yel
low
jum
per
to tu
rret
46 .
S
TE
P 5
3
Ad
d t
wo
cap
acit
ors
+ t
wo
jum
per
sA
dd
a .0
047μ
F ca
pac
itor b
etw
een
turr
ets
15 a
nd 2
7 .
Ad
d an
othe
r .00
47μF
cap
acito
r bet
wee
n tu
rret
s 27
and
43 .
Ad
d a
2-1/
2" y
ello
w ju
mp
er to
turr
et 4
5 .
Ad
d a
4" y
ello
w ju
mp
er to
turr
et 4
4 .
S
TE
P 5
4
Ad
d o
ne
cap
acit
or
+ t
wo
jum
per
sA
dd
a 5
00p
F si
lver
mic
a ca
pac
itor
be-
twee
n tu
rret
s 14
and
15 .
Ad
d a
4-1/
2" y
ello
w ju
mp
er to
turr
et 1
5 .
Ad
d a
6-1/
4" y
ello
w ju
mp
er to
turr
et 1
4 .
S
TE
P 5
5
Ad
d a
res
isto
r +
cap
acit
or
+ ju
mp
erA
dd
a 47
0K r
esis
tor
bet
wee
n tu
rret
s 13
an
d 27
.
Ad
d a
.047
μF c
apac
itor
bet
wee
n tu
rret
s 13
and
26 .
Ad
d a
1-3
/4"
yello
w j
um
per
bet
wee
n tu
rret
s 11
and
13 .
S
TE
P 5
6
Ad
d o
ne
resi
sto
r +
tw
o c
apac
ito
rsA
dd
a 22
0K r
esis
tor
bet
wee
n tu
rret
s 26
an
d 43
.
Ad
d t
wo
.01μ
F ce
ram
ic d
isk
cap
acit
ors
bet
wee
n tu
rret
s 26
and
42 .
stew
mac
.co
m
22
©
2018
Ste
wM
ac
21
34
56
78
910
1112
1314
1516
1718
1920
2122
23 3024
2526
2728
29
3233
3435
3637
3839
4041
4243
4445
4647
4849
5031
51.01μF
16μF
250μF
.01μF
.01μF
50μF
.01μF
stew
mac
.co
m
23
©
2018
Ste
wM
ac
S
TE
P 5
7
Ad
d o
ne
resi
sto
r +
th
ree
jum
per
sCu
t one
1" y
ello
w ju
mp
er a
nd re
mov
e th
e in
sula
tion .
Wra
p a
nd s
old
er t
his
jum
per
ar
ound
one
lead
of a
470
K re
sist
or to
ex-
tend
the
lead
of
the
resi
stor
. Doi
ng t
his
will
allo
w t
he ju
mp
er t
o re
ach
bet
wee
n tu
rret
s 12
and
42 .
Ad
d th
is 4
70K
resi
stor
with
the
exte
nsio
n b
etw
een
turr
ets
12 a
nd 4
2 .
Ad
d a
5" y
ello
w ju
mp
er to
turr
et 2
6 . R
un
this
jum
per
tow
ard
th
e b
otto
m o
f th
e b
oard
and
und
er th
e le
ad o
f the
.004
7μF
cap
acito
r att
ache
d to
turr
et 4
3 .
Ad
d a
2-1/
4" y
ello
w ju
mp
er to
turr
et 4
3 .
Ad
d a
7-3/
4" y
ello
w ju
mp
er to
turr
et 1
2 .
S
TE
P 5
8
Ad
d t
wo
cap
acit
ors
+ o
ne
resi
sto
r A
dd
on
e .0
1μF
cera
mic
dis
k ca
pac
ito
r b
etw
een
turr
ets
25 a
nd 4
2 .
Add
ano
ther
.01μ
F ce
ram
ic d
isk
cap
acito
r b
etw
een
turr
ets
25 a
nd 4
1 .
Ad
d a
1M
res
isto
r b
etw
een
tu
rret
s 11
an
d 25
.
S
TE
P 5
9
Inst
all t
hre
e re
sist
ors
Ad
d a
2 .2M
res
isto
r b
etw
een
turr
ets
10
and
24 .
Cut o
ne 1
" yel
low
jum
per
and
rem
ove
the
insu
latio
n . W
rap
and
sol
der
thi
s ju
mp
er
arou
nd o
ne le
ad o
f an
820
Ω r
esis
tor
to
exte
nd th
e le
ad o
f the
resi
stor
.
Add
this
820
Ω re
sist
or w
ith th
e ex
tens
ion
bet
wee
n tu
rret
s 10
and
40 .
Ad
d a
2 .2
K re
sist
or
bet
wee
n t
urr
ets
9 an
d 10
.
S
TE
P 6
0
Ad
d o
ne
cap
acit
or
+ o
ne
jum
per
Ad
d a
50μ
F el
ectr
oly
tic
cap
acit
or
be-
twee
n tu
rret
s 9
and
39 . T
his
cap
is p
olar
-iz
ed, s
o b
e su
re th
e ne
gativ
e le
ad g
oes t
o tu
rret
9 a
nd th
e p
ositi
ve le
ad to
turr
et 3
9 .
Ad
d a
1" y
ello
w ju
mp
er, w
ith t
he in
sula
-tio
n re
mov
ed, b
etw
een
turr
ets 3
9 an
d 40
.
S
TE
P 6
1
Ad
d fi
ve ju
mp
ers
Ad
d a
3" y
ello
w ju
mp
er to
turr
et 4
1 .
Ad
d a
3-1/
4" y
ello
w ju
mp
er to
turr
et 4
0 .
Ad
d a
7-1/
2" y
ello
w ju
mp
er to
turr
et 1
0 .
Ad
d a
1-3
/4"
yello
w j
um
per
bet
wee
n tu
rret
s 9
and
11 .
Ad
d a
7" g
reen
jum
per
to tu
rret
9 .
S
TE
P 6
2
Ad
d fo
ur
resi
sto
rsA
dd
a 1
00K
resi
stor
bet
wee
n t
urre
ts 8
an
d 23
.
Ad
d an
othe
r 10
0K r
esis
tor
bet
wee
n tu
r-re
ts 7
and
23 .
Ad
d a
470K
res
isto
r b
etw
een
turr
ets
30
and
38 .
Ad
d an
othe
r 47
0K r
esis
tor
bet
wee
n tu
r-re
ts 3
0 an
d 37
.
S
TE
P 6
3
Ad
d t
wo
.01μ
F ca
pac
ito
rsA
dd
a .0
1μF
cap
acit
or b
etw
een
turr
ets
8 an
d 38
.
Ad
d a
not
her
.01μ
F ca
pac
ito
r b
etw
een
turr
ets
7 an
d 37
.
S
TE
P 6
4
Ad
d t
wo
res
isto
rsCu
t tw
o 1"
yel
low
jum
per
s an
d re
mov
e th
e in
sula
tion .
Wra
p an
d so
lder
one
jum
p-
er a
roun
d on
e le
ad o
f a 1
00K
resi
stor
to
exte
nd th
e le
ad o
f the
resi
stor
. Wra
p a
nd
sold
er th
e ot
her j
ump
er a
roun
d on
e le
ad
of a
10K
resi
stor
to e
xten
d it
s le
ad .
Ad
d t
he
100K
res
isto
r w
ith
ext
ensi
on
bet
wee
n tu
rret
s 6
and
36 .
Ad
d th
e 10
K re
sist
or w
ith e
xten
sion
be-
twee
n tu
rret
s 5
and
35 .
S
TE
P 6
5
Ad
d o
ne
cap
acit
or
+ o
ne
resi
sto
rA
dd
a 1
6μF
elec
trol
ytic
cap
acit
or w
ith
the
pos
itiv
e le
ad g
oing
to
turr
et 4
and
th
e ne
gativ
e le
ad to
turr
et 3
4 .
Cut o
ne 1
" yel
low
jum
per
and
rem
ove
the
insu
latio
n . W
rap
and
sol
der
it t
o a
100K
re
sist
or
to e
xten
d t
he
lead
. W
rap
th
is
resi
stor
bet
wee
n tu
rret
s 3
and
33 .
S
TE
P 6
6
Ad
d o
ne
resi
sto
r +
on
e ca
pac
ito
rA
dd
a 13
0Ω 3
W re
sist
or b
etw
een
turr
ets
2 an
d 32
.
Ad
d a
250μ
F b
ipol
ar c
apac
itor
bet
wee
n tu
rret
s 1
and
31 . T
his
cap
look
s lik
e a
po
-la
rize
d e
lect
roly
tic
cap
but
it’s
act
ually
b
ipol
ar, m
eani
ng
it
can
be
inst
alle
d i
n ei
ther
dire
ctio
n .
S
TE
P 6
7
Ad
d t
wo
jum
per
sCu
t tw
o 1"
yel
low
jum
per
s an
d re
mov
e th
e in
sula
tion .
Wra
p o
ne a
roun
d tu
rret
s 1
and
2 an
d w
rap
the
othe
r aro
und
turr
ets
31 a
nd 3
2 .
stew
mac
.co
m
24
©20
18 S
tew
Mac
21
34
56
78
910
1112
1314
1516
1718
1920
2122
23 3024
2526
2728
29
3233
3435
3637
3839
4041
4243
4445
4647
4849
5031
51
stew
mac
.co
m
25
©
2018
Ste
wM
ac
S
TE
P 6
8
Ad
d o
ne
jum
per
Cut o
ne 3
" jum
per
and
rem
ove
the
insu
la-
tion .
Sta
rtin
g at
turr
et 3
, wra
p in
a fi
gure
8
pat
tern
aro
und
turr
ets
4 an
d 5,
com
-p
lete
ly a
roun
d tu
rret
6, a
nd t
hen
in a
n op
pos
ite fi
gure
8 p
atte
rn a
roun
d tu
rret
s 5
and
4, a
nd b
ack
to tu
rret
3 . T
his
crea
tes
a b
us c
onne
ctin
g tu
rret
s 3,
4, 5
, and
6 .
S
TE
P 6
9
Ad
d t
hre
e m
ore
jum
per
sA
dd
a 4-
1/4"
gre
en ju
mp
er to
turr
et 3
4 .
Ad
d a
3" y
ello
w ju
mp
er to
turr
et 3
2 .
Ad
d a
4-3/
4" y
ello
w ju
mp
er to
turr
et 3
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
it’s
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 .
S
TE
P 7
0
Sold
er t
he
turr
et
bo
ard
co
nn
ecti
on
sIt
’s t
ime
to s
et a
ll th
e co
nnec
tions
with
sold
er .
Revi
ew t
he
tip
s fo
r g
reat
sol
der
ing
on
pag
e 9,
the
n so
lder
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 t
o m
ake
sure
the
y’re
shi
ny, a
nd t
o se
e th
at y
ou d
idn’
t mis
s on
e .
S
TE
P 7
1
Ad
d e
igh
t b
ack-
of-
bo
ard
jum
per
sCu
t the
se ju
mp
ers t
o le
ngth
and
trim
3/8
" of
insu
latio
n off
eac
h en
d . R
un th
ese
ends
up
int
o th
e b
otto
m o
f th
e tu
rret
s an
d so
lder
them
in to
pla
ce .
Cut
a 3"
yel
low
jum
per
and
sol
der
it t
o th
e b
ack
of t
urre
t 2 .
Pla
ce t
he o
ther
end
in
to t
he b
otto
m o
f tu
rret
34
but
don
’t so
lder
it y
et .
Sold
er a
2" y
ello
w ju
mp
er to
the
bot
tom
of
turr
et 3
0 . S
olde
r the
oth
er e
nd to
turr
et
34, a
lon
g w
ith
th
e ot
her
lea
d y
ou j
ust
pla
ced
ther
e .
Sold
er a
2-1
/2" y
ello
w ju
mp
er to
the
bot
-to
m o
f tur
ret 3
5 . S
olde
r the
the
othe
r end
to
turr
et 2
3, ro
utin
g th
is w
ire a
roun
d, n
ot
over
, the
jum
per
at
turr
et 3
0 . (
It’s
goo
d w
iring
pra
ctic
e to
avo
id lo
catin
g ju
mp
ers
on to
p o
f oth
er le
ads
and
conn
ectio
ns .)
Sold
er a
6"
yello
w ju
mp
er b
etw
een
the
bot
tom
s of
turr
ets
33 a
nd 2
6 .
Sold
er a
5-1
/2"
yello
w ju
mp
er b
etw
een
the
bot
tom
s of
turr
ets
7 an
d 44
.
Sold
er a
5"
yello
w ju
mp
er b
etw
een
the
bot
tom
s of
turr
ets
8 an
d 45
.
Sold
er a
7-1
/4"
yello
w ju
mp
er b
etw
een
the
bot
tom
s of
turr
ets
36 a
nd 4
9 .
Sold
er a
1-1
/2"
yello
w ju
mp
er b
etw
een
the
bot
tom
s of
turr
ets
24 a
nd 4
1 .
S
TE
P 7
2
Test
th
e co
nti
nu
ity
of y
ou
r
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
nn
ect
ed
by
bac
k-o
f-b
oar
d r
un
s .
Use
a m
ultim
eter
for
con
tinui
ty t
estin
g,
as d
escr
ibed
on
pag
e 37
.
You
’re
read
y to
inst
all t
he
tu
rret
bo
ard
in t
he
chas
sis.
It’s
time
to re
mov
e yo
ur ta
pe
with
the
tur-
ret n
umb
ers .
Whe
n th
e b
oard
’s in
stal
led,
yo
u w
on’t
be
able
to
get
at t
he t
ape
to
rem
ove
it . F
rom
thi
s p
oint
on,
you
can
id
entif
y ju
mp
ers
and
turr
ets
by re
ferr
ing
to th
e di
agra
ms .
STOP
Be fus
sy Fin
d the
mistak
e now
, not
later!
stew
mac
.co
m
26
©
2018
Ste
wM
ac
FUSE
IMPE
DA
NC
ESP
EAK
EREX
TEN
SIO
NPO
WER
INPU
TFO
OT
SWIT
CH
IND
ICAT
OR
LIG
HT
STA
ND
BYPO
WER
SPEE
DIN
TEN
SITY
TON
EV
OLU
ME
TON
EV
OLU
ME
NO
RM. I
NPU
TTR
EM. I
NPU
T
V6
EZ81
V5
EL84
FILT
ER C
AP
V4
EL84
V3
12A
X7
V2
12A
X7
V1
12A
X7
2 1
2 1
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
432
1
98
7
5
21
34
56
78
910
1112
1314
1516
1718
1920
21
3233
3435
3637
3839
4041
4243
4445
4647
4849
50
22
3151
23 3024
2526
2728
29
stew
mac
.co
m
27
©20
18 S
tew
Mac
S
TE
P 7
3
Inst
all t
he
turr
et b
oar
dTo
kee
p t
he
turr
et b
oar
d c
on
nec
tio
ns
from
sho
rtin
g ag
ains
t th
e m
etal
cha
ssis
, th
e b
oard
is m
ount
ed o
n fo
ur t
hrea
ded
st
and
off
s th
at h
old
it
away
fro
m t
he
chas
sis .
Usi
ng
4-4
0 sc
rew
s, m
ou
nt
thes
e fo
ur
stan
doff
s to
the
chas
sis .
Lin
e up
the
turr
et
boa
rd o
n th
ese
stan
doff
s .
Rout
e th
e ju
mp
ers
from
tur
rets
14,
15,
an
d 1
6 so
the
y ru
n b
elow
the
tre
mol
o ch
anne
l inp
uts .
Whe
n tw
o ju
mp
ers c
ross
ov
er e
ach
othe
r, b
end
them
so th
ey c
ross
at
90°
ang
les,
rath
er ru
nnin
g si
de-b
y-si
de .
This
det
ail i
nflue
nces
the
am
p’s
sou
nd,
esp
ecia
lly o
n a
high
-gai
n ci
rcui
t lik
e th
is
one .
Be
sure
th
at t
he
flyi
ng
lea
d f
rom
th
e tr
emol
o ch
anne
l inp
ut ja
cks d
oes n
ot g
et
caug
ht o
n an
y of
the
und
erb
oard
lead
s an
d ca
n st
ill re
ach
sock
et V
3 .
S
TE
P 7
4
Sold
er t
he
no
rmal
ch
ann
el
volu
me
+ t
on
e p
ots
Sold
er t
he ju
mp
er f
rom
tur
ret
20 t
o th
e le
ft lu
g of
the
norm
al c
hann
el to
ne p
ot .
Sold
er t
he ju
mp
er f
rom
tur
ret
29 t
o th
e rig
ht lu
g of
the
nor
mal
cha
nnel
vol
ume
pot
.
Sold
er t
he ju
mp
er f
rom
tur
ret
19 t
o th
e rig
ht lu
g of
the
norm
al to
ne p
ot .
Sold
er t
he ju
mp
er f
rom
tur
ret
18 t
o th
e m
iddl
e lu
g of
the
norm
al v
olum
e p
ot .
Sold
er t
he
jum
per
fro
m t
urr
et 2
1 an
d th
e ju
mp
er fr
om tu
rret
17
to th
e gr
ound
b
us
bet
wee
n t
he
no
rmal
vo
lum
e an
d to
ne p
ots .
S
TE
P 7
5
Ad
d a
n in
sula
ted
2.2
K r
esis
tor
Plac
e a
1" p
iece
of 1
/8" h
eat-
shrin
k tu
bin
g ov
er th
e ju
mp
er fr
om tu
rret
16
and
slid
e it
all t
he w
ay d
own
to th
e tu
rret
. Wra
p th
is
jum
per
to
a 2 .
2K r
esis
tor
and
sold
er t
he
conn
ectio
n . A
fter
the
sol
der
coo
ls, s
lide
the
heat
-shr
ink
tub
ing
over
the
join
t and
sh
rink
it to
insu
late
the
sold
er jo
int .
Insu
late
th
e 2 .
2K r
esis
tor’
s o
ther
lea
d w
ith h
eat-
shrin
k tu
bin
g an
d so
lder
it t
o th
e m
idd
le l
ug o
f th
e tr
emol
o vo
lum
e p
ot a
long
with
the
resi
stor
lead
that
you
w
rap
ped
ther
e p
revi
ousl
y .
S
TE
P 7
6
Sold
er t
he
trem
olo
ch
ann
el p
ots
Sold
er t
he ju
mp
er f
rom
tur
ret
15 t
o th
e rig
ht lu
g of
the
trem
olo
chan
nel v
olum
e p
ot .
Sold
er t
he ju
mp
er f
rom
tur
ret
14 t
o th
e rig
ht lu
g of
the
trem
olo
tone
pot
.
Sold
er t
he ju
mp
er f
rom
tur
ret
12 t
o th
e rig
ht lu
g of
the
trem
olo
spee
d p
ot .
Sold
er t
he ju
mp
er f
rom
tur
ret
10 t
o th
e le
ft lu
g of
the
trem
olo
inte
nsit
y p
ot .
S
TE
P 7
7
Sold
er t
he
gro
un
d ju
mp
erSo
lder
the
gre
en j
ump
er f
rom
tur
ret
9 to
th
e 3-
lug
gro
un
din
g s
trip
nea
r th
e p
ower
sw
itch .
S
TE
P 7
8
Ad
d fo
ur
tub
e so
cket
jum
per
sCu
t fou
r 1" y
ello
w ju
mp
ers .
Use
the
first
to c
onne
ct p
in 3
and
pin
8 o
f so
cket
V1 .
Sol
der
it to
pin
8 o
nly .
The
seco
nd c
onne
cts
pin
1 a
nd p
in 6
of
sock
et V
1 . S
old
er it
to p
in 6
onl
y .
The
thir
d c
on
nec
ts p
in 3
an
d p
in 8
of
sock
et V
2 . S
old
er it
to p
in 8
onl
y .
The
four
th c
onne
cts
pin
3 a
nd p
in 8
of
sock
et V
3 . S
old
er it
to p
in 3
onl
y .
S
TE
P 7
9
Sold
er t
he
jum
per
s to
V1
Plug
an
inst
rum
ent
cab
le in
to e
ither
of
the
nor
mal
cha
nnel
inp
ut j
acks
, whi
ch
will
op
en t
he
jack
’s b
uilt
-in
sh
ort
ing
switc
h . T
his i
s nec
essa
ry fo
r the
follo
win
g co
ntin
uity
test
s .
Usi
ng a
mul
timet
er, i
den
tify
the
jum
per
th
at h
as c
ontin
uity
to
the
norm
al c
han
-ne
l’s in
put
jack
2 . S
old
er t
his
jum
per
to
pin
2 o
f soc
ket V
1 .
Iden
tify
the
jum
per
with
con
tinui
ty to
the
norm
al c
hann
el’s
inp
ut ja
ck 1
. Sol
der
this
ju
mp
er to
V1
pin
7 .
Sold
er th
e ju
mp
er fr
om tu
rret
50
to V
1 pi
n 3
alon
g w
ith th
e ju
mp
er a
lread
y in
pla
ce .
Sold
er th
e ju
mp
er fr
om tu
rret
49
to V
1 pi
n 1
alon
g w
ith th
e ju
mp
er a
lread
y in
pla
ce .
S
TE
P 8
0
Sold
er t
he
jum
per
s to
V2
Sold
er th
e le
ad fr
om tu
rret
48
to V
2 p
in 2
.
Sold
er t
he le
ad fr
om t
urre
t 47
to
V2 p
in
3 al
ong
with
the
jum
per
alre
ady
in p
lace
.
Sold
er th
e le
ad fr
om tu
rret
46
to V
2 p
in 7
.
Sold
er th
e le
ad fr
om tu
rret
45
to V
2 p
in 1
.
Sold
er th
e le
ad fr
om tu
rret
44
to V
2 p
in 6
.
Four
sta
nd
offs
Inst
alli
ng
th
e b
oar
d in
th
e ch
assi
s
stew
mac
.co
m
28
©
2018
Ste
wM
ac
FUSE
IMPE
DA
NC
ESP
EAK
EREX
TEN
SIO
NPO
WER
INPU
TFO
OT
SWIT
CH
IND
ICAT
OR
LIG
HT
STA
ND
BYPO
WER
SPEE
DIN
TEN
SITY
TON
EV
OLU
ME
TON
EV
OLU
ME
NO
RM. I
NPU
TTR
EM. I
NPU
T
V6
EZ81
V5
EL84
FILT
ER C
AP
V4
EL84
V3
12A
X7
V2
12A
X7
V1
12A
X7
2 1
2 1
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
21
34
56
78
910
1112
1314
1516
1718
1920
2122
23 3024
2526
2728
29
3233
3435
3637
3839
4041
4243
4445
4647
4849
5031
51
stew
mac
.co
m
29
©20
18 S
tew
Mac
S
TE
P 8
1
Sold
er t
he
jum
per
s to
so
cket
V3
Sold
er t
he ju
mp
er c
omin
g fr
om t
urre
t 26
to V
3 p
in 6
.
Sold
er th
e ju
mp
er fr
om tu
rret
43
to V
3 p
in 1
.
Sold
er t
he ju
mp
er t
hat
runs
und
er t
he
boa
rd fr
om t
he t
rem
olo
chan
nel i
nput
ja
cks
to V
3 p
in 2
.
Wra
p th
e le
ad fr
om tu
rret
41
thro
ugh
V3
pin
7 b
ut d
o no
t sol
der
it y
et .
Sold
er th
e le
ad fr
om tu
rret
40
to V
3 p
in
8 al
ong
with
the
jum
per
alre
ady
in p
lace
.
S
TE
P 8
2
Sold
er t
wo
jum
per
s fr
om
tu
rret
32
Sold
er th
e sh
ort
jum
per
from
tur
ret
32
to V
5 pi
n 3
and
sold
er th
e lo
nger
jum
per
fr
om tu
rret
32
to V
4 p
in 3
.
S
TE
P 8
3
Wra
p t
he
jum
per
fro
m t
urr
et 3
4W
rap
the
jum
per
from
turr
et 3
4 th
roug
h th
e gr
ound
lug
(-) o
f the
filte
r cap
acito
r b
ut d
o no
t sol
der
it y
et .
S
TE
P 8
4
Ad
d o
ne
jum
per
+ t
wo
res
isto
rs
Ad
d 1/
16"
heat
-shr
ink
tub
ing
to a
100
Ω
resi
stor
to
insu
late
the
lead
s . W
rap
thi
s re
sist
or b
etw
een
turr
et 3
5 an
d V4
pin
9 .
Insu
late
ano
ther
100
Ω r
esis
tor w
ith h
eat-
shrin
k tu
bin
g an
d w
rap
it b
etw
een
turr
et
35 a
nd V
5 p
in 9
.
Ad
d a
5" y
ello
w ju
mp
er b
etw
een
turr
et
35 a
nd th
e rig
ht fi
lter c
ap lu
g .
S
TE
P 8
5
Ad
d t
wo
jum
per
s +
tw
o r
esis
tors
Cu
t a
2-1/
2" y
ello
w j
um
per
. Tw
ist
on
e en
d o
f th
is j
ump
er o
nto
a 5 .
1K r
esis
tor
and
sold
er to
geth
er . U
se 1
/8" h
eat-
shrin
k tu
bin
g to
insu
late
thi
s so
lder
joi
nt a
nd
the
bar
e le
ad .
Sold
er th
e fr
ee e
nd o
f the
yel
low
jum
per
to
turr
et 3
8 an
d so
lder
the
free
lead
from
th
e 5 .
1K re
sist
or in
to V
4 p
in 2
.
Cut
a 3
" ye
llow
jum
per
. Tw
ist
one
end
of t
his
jum
per
aro
und
the
lead
of a
5 .1
K re
sist
or a
nd s
old
er t
oget
her .
Inst
all 1
/8"
hea
t-sh
rin
k tu
bin
g a
roun
d t
he
jum
per
an
d so
lder
join
t .
Sold
er th
e fr
ee e
nd o
f the
yel
low
jum
per
to
turr
et 3
7 an
d so
lder
the
free
lead
from
th
e 5 .
1K re
sist
or in
to V
5 p
in 2
.
S
TE
P 8
6
Ad
d a
gro
un
d ju
mp
erCu
t a 4
" gre
en ju
mp
er . S
old
er o
ne e
nd in
to
the
grou
nd lu
g (-)
of t
he fi
lter c
ap a
long
w
ith th
e ju
mp
er fr
om tu
rret
34 .
Sol
der t
he
othe
r en
d of
thi
s gr
ound
jum
per
to
the
near
est
lug
of t
he 3
-lug
grou
ndin
g st
rip
by th
e p
ower
sw
itch .
stew
mac
.co
m
30
©
2018
Ste
wM
ac
FUSE
IMPE
DA
NC
ESP
EAK
EREX
TEN
SIO
NPO
WER
INPU
TFO
OT
SWIT
CH
IND
ICAT
OR
LIG
HT
STA
ND
BYPO
WER
SPEE
DIN
TEN
SITY
TON
EV
OLU
ME
TON
EV
OLU
ME
NO
RM. I
NPU
TTR
EM. I
NPU
T
2 1
2 1
V5:
EL8
4V
4: E
L84
V3:
12A
X7
V6
EZ81
FILT
ER C
AP
V2
12A
X7
V1
12A
X7
9
6
43
21 8
7
5
6
43
21
98
7
5
6
432
1
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
21
34
56
78
910
1112
1314
1516
1718
1920
2122
23 3024
2526
2728
29
3233
3435
3637
3839
4041
4243
4445
4647
4849
5031
51
Keep
the
heat
er w
ires
upan
d aw
ay fr
om th
e so
cket
s
stew
mac
.co
m
31
©
2018
Ste
wM
ac
S
TE
P 8
7
Co
nn
ect
to s
ock
et V
5Ru
n th
e gr
een
pow
er t
rans
form
er w
ires
to so
cket
V5,
kee
ping
them
dow
n as
clo
se
to t
he c
hass
is a
s p
ossi
ble
. The
pre
ferr
ed
pat
h is
to g
o un
der
the
jum
per
s fr
om th
e fil
ter c
ap to
the
turr
et b
oard
and
then
take
a
90° a
ngle
up
and
over
the
blu
e, re
d, a
nd
brow
n w
ires f
rom
the
outp
ut tr
ansf
orm
er .
Cut
two
4-1/
2" h
eate
r w
ires,
one
whi
te
and
on
e b
lack
. Tw
ist
them
to
get
her
ve
ry ti
ghtl
y, le
avin
g ab
out 1
" of t
he e
nds
un
twis
ted
. Jo
in t
he
wh
ite
jum
per
to
eith
er o
f the
gre
en p
ower
supp
ly le
ads b
y tw
istin
g th
e en
ds to
geth
er . J
oin
the
bla
ck
jum
per
to th
e ot
her g
reen
lead
.
Sold
er t
he
pai
r w
ith
th
e w
hite
wir
e to
p
in 4
of
sock
et V
5 . S
old
er t
he p
air
with
th
e b
lack
wire
to p
in 5
of s
ocke
t V5 .
Ben
d th
ese
wire
s up
and
aw
ay fr
om th
e so
cket
. A
t 1"
ab
ove
the
sock
et, b
end
the
bla
ck-
and
-wh
ite
pai
r at
a 9
0° a
ng
le t
ow
ard
sock
et V
4 .
S
TE
P 8
8
Co
nn
ect
to s
ock
et V
4Cu
t t
wo
5" 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 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 4
of
V4 .
Sold
er t
he
bla
ck p
air
onto
pin
5 . B
end
the
wire
s up
aw
ay f
rom
the
soc
ket,
and
on to
war
d so
cket
V3 .
Mak
e su
re t
hat
the
like-
colo
red
jum
per
w
ires
are
goin
g to
the
sam
e-nu
mb
ered
p
ins,
or y
ou w
ill h
ave
a p
hase
issu
e fr
om
the
pul
sing
vol
tage
. For
exa
mp
le, i
f th
e w
hite
wire
is so
lder
ed to
V5
pin
4 a
nd th
e b
lack
wire
is so
lder
ed in
to V
5 p
in 5
, mak
e su
re y
ou c
onne
ct th
e w
hite
wire
to V
4 p
in
4 an
d th
e b
lack
wire
to V
4 p
in 5
.
Sold
er th
ese
jum
per
s to
V4
pin
4 a
nd V
4 p
in 5
. Run
the
bla
ck-a
nd-w
hite
tw
iste
d p
air
up 1
" fr
om t
he t
ube
sock
et, d
irect
ly
over
to V
3, a
nd b
ack
dow
n V3
, but
do
not
sold
er it
in p
lace
yet
.
6
43
21
98
7
5
Twis
t the
end
sto
geth
er
Use t
his he
ater-w
ire tec
hnique
to
minimi
ze the
hum c
aused
by AC
voltag
e
Inst
all t
he
hea
ter
wir
esIt
’s e
asie
r to
inst
all t
he h
eate
r wire
s if y
ou
first
tak
e ou
t th
e sp
eake
r ja
cks,
let
ting
th
e fu
se so
cket
and
pow
er in
put
hol
d th
e b
ackp
late
in p
lace
.
The
twis
ted
gree
n w
ires f
rom
the
pow
er tr
ansf
orm
er c
arry
AC
vol
tage
to
the
heat
ing
filam
ents
in th
e tu
bes
. Thi
s vo
ltag
e w
ill c
ause
you
r am
p to
hu
m if
thes
e w
ires a
re a
llow
ed to
run
too
clos
e to
sign
al-c
arry
ing
wire
s .
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 u
p a
nd
aw
ayTo
kee
p t
wis
ted
heat
er w
ires
away
fro
m s
igna
l-ca
rryi
ng w
ires,
ben
d th
em s
o th
ey’re
up
at l
east
1" f
rom
the
tub
e so
cket
s . G
ive
them
a sh
arp
rig
ht a
ngle
ben
d to
war
d th
e ne
xt so
cket
, and
ano
ther
shar
p b
end
bac
k d
own
to th
at s
ocke
t . Th
is k
eep
s th
em a
t a u
sefu
l dis
tanc
e .
stew
mac
.co
m
32
©
2018
Ste
wM
ac
FUSE
IMPE
DA
NC
ESP
EAK
EREX
TEN
SIO
NPO
WER
INPU
TFO
OT
SWIT
CH
IND
ICAT
OR
LIG
HT
STA
ND
BYPO
WER
SPEE
DIN
TEN
SITY
TON
EV
OLU
ME
TON
EV
OLU
ME
NO
RM. I
NPU
TTR
EM. I
NPU
T
2 1
2 1
V5:
EL8
4V
4: E
L84
V3:
12A
X7
V2:
12A
X7
V1:
12A
X7
V6
EZ81
FILT
ER C
AP
9
6
43
21 8
7
5
6
43
21
98
7
5
6
432
1
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
21
34
56
78
910
1112
1314
1516
1718
1920
2122
23 3024
2526
2728
29
3233
3435
3637
3839
4041
4243
4445
4647
4849
5031
51
1 2 3
6 5 4
stew
mac
.co
m
33
©
2018
Ste
wM
ac
S
TE
P 8
9
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
pin
s 4
and
pin
5 t
owar
d ea
ch o
ther
so
thei
r ey
elet
s lin
e up
. Be
very
car
eful
whi
le d
oing
thi
s as
thes
e p
ins
are
del
icat
e .
Cut
tw
o 5"
hea
ter
wire
s, o
ne w
hite
and
on
e b
lack
. Tw
ist t
hem
tigh
tly
toge
ther
.
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 th
e w
hite
pai
r to
V3 p
in 9
and
sol
-d
er th
e b
lack
pai
r to
com
bin
ed p
ins
4+5
on V
3 . B
end
the
wire
s up
aw
ay fr
om th
e so
cket
, and
on
tow
ard
sock
et V
2 .
S
TE
P 9
0
Co
nn
ect
to s
ock
et V
2Cu
t t
wo
5" h
eate
r w
ires,
one
whi
te a
nd
one
bla
ck . T
wis
t th
em t
ight
ly t
oget
her,
leav
ing
abou
t 1" u
ntw
iste
d at
bot
h en
ds .
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
pai
r of
tw
iste
d w
hit
e w
ires
to
V2
pin
9 a
nd s
old
er t
he t
wis
ted
bla
ck
wire
s to
V2
pin
4+5
.
S
TE
P 9
1
Co
nn
ect
to s
ock
et V
1Ru
n th
e b
lack
-and
-whi
te tw
iste
d p
air u
p
1" fr
om t
he t
ube
sock
et, d
irect
ly o
ver
to
V1, a
nd b
ack
dow
n V1
. Sol
der
the
whi
te
wire
to V
1 p
in 9
and
sold
er th
e b
lack
wire
to
V1
pin
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
away
from
the
tub
e so
cket
s as
far a
s yo
u ca
n .
S
TE
P 9
2
Rei
nst
all t
he
spea
ker
jack
sIf
you
rem
oved
the
jack
s fr
om t
he b
ack
wal
l of
th
e ch
assi
s, r
eins
tall
them
now
w
ith th
eir l
ugs
faci
ng u
p .
S
TE
P 9
3
Inst
all t
he
imp
edan
ce s
wit
chM
ount
the
imp
edan
ce se
lect
or a
s sho
wn
in th
e di
agra
m, w
ith th
e rig
ht lu
g up
and
ot
her l
ugs
faci
ng th
e sp
eake
r jac
ks .
S
TE
P 9
4
Inst
all t
he
foo
t sw
itch
jack
Mou
nt t
he 6
-lug
foot
sw
itch
jac
k in
its
hole
to
the
right
of t
he p
ower
inle
t . U
se
on
e w
ash
er u
nd
er t
he
mo
un
tin
g n
ut .
D
isca
rd th
e se
cond
fib
er w
ashe
r .
Cut
a 1"
gre
en ju
mp
er a
nd r
emov
e th
e in
sula
tion .
Thr
ead
this
wire
thr
ough
the
lu
gs 1
, 2, a
nd 3
on
the
right
sid
e of
the
ja
ck, u
nitin
g th
em in
a c
omm
on g
roun
d .
1 2 3
6 5 4
1 2 3
6 5 4
stew
mac
.co
m
34
©
2018
Ste
wM
ac
FUSE
IMPE
DA
NC
ESP
EAK
EREX
TEN
SIO
NPO
WER
INPU
TFO
OT
SWIT
CH
IND
ICAT
OR
LIG
HT
STA
ND
BYPO
WER
SPEE
DIN
TEN
SITY
TON
EV
OLU
ME
TON
EV
OLU
ME
NO
RM. I
NPU
TTR
EM. I
NPU
T
V6
EZ81
V5
EL84
FILT
ER C
AP
V4
EL84
V3
12A
X7
V2
12A
X7
V1
12A
X7
2 1
2 1
6
43
21
98
7
5
1 2 3
6 5 4
1 2
4 3
1 2
1
4
2 3
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
6
43
21
98
7
5
2
3233
3435
3637
3839
4041
4243
4445
4647
4849
5031
51
13
45
67
89
1011
1213
1415
1617
1819
2021
22
23 3024
2526
2728
29
stew
mac
.co
m
35
©
2018
Ste
wM
ac
S
TE
P 9
5
Co
nn
ect
the
imp
edan
ce s
wit
chCu
t the
out
put
tran
sfor
mer
’s t
wis
ted
or-
ange
, gre
en, a
nd y
ello
w w
ires
to le
ngth
fo
r con
nect
ing
to th
e im
ped
ance
sele
ctor
sw
itch .
Sold
er th
e or
ange
wire
to th
e b
otto
m
lug
(lug
1 in
the
diag
ram
) . So
lder
the
gree
n w
ire to
lug
2, a
nd th
e ye
llow
wire
to
lug
3 . T
he to
p lu
g (4
) is
emp
ty a
t thi
s p
oint
.Th
e im
ped
ance
sel
ecto
r sw
itch
allo
ws
you
to se
t the
am
plifi
er’s
outp
ut to
mat
ch
the
exte
nsio
n sp
eake
rs y
ou m
ight
cho
ose
to a
dd
. Set
this
sw
itch
to 8
Ω w
hen
usin
g th
e in
tern
al s
pea
ker b
y it
self .
S
TE
P 9
6
Co
nn
ect
the
foo
t sw
itch
jack
Cut a
10-
1/2"
leng
th o
f 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 .
Cut
a 2
" ye
llow
jum
per
. Wra
p o
ne e
nd
tight
ly a
roun
d th
e sh
ield
ed w
ire, j
oini
ng
the
two
wir
es s
o th
e ye
llow
ins
ulat
ion
is s
nug
ged
up
to
the
bra
id . S
old
er t
his
conn
ectio
n .
Sold
er a
1" y
ello
w ju
mp
er to
the
othe
r end
of
the
shie
lded
wire
.
Sold
er c
ente
r le
ad o
f th
e sh
ield
ed w
ire
—th
e en
d w
ith th
e sh
ort j
ump
er—
to lu
g 6
of th
e fo
ot s
witc
h ja
ck . W
rap
the
shor
t ju
mp
er o
nto
lug
4, b
ut d
on’t
sold
er it
.
Run
the
shie
lded
wire
alo
ng th
e b
otto
m
corn
er o
f the
cha
ssis
and
sol
der
the
end
to p
in 7
of s
ocke
t V3 .
Wra
p t
he o
ther
yel
low
jum
per
to
lug
2 of
the
2-lu
g ex
tens
ion
spea
ker
jack
, but
d
on’t
sold
er it
yet
.
STOP
S
TE
P 9
7
Co
nn
ect
the
spea
ker
jack
sCu
t a
2" y
ello
w ju
mp
er a
nd s
old
er it
to
lug
1 of
the
2-lu
g ex
tens
ion
spea
ker j
ack
alon
g w
ith th
e ju
mp
er fr
om th
e sh
ield
ed
cab
le .
Wra
p th
e ot
her e
nd o
f thi
s ju
mp
er to
lug
4 of
the
4-lu
g sp
eake
r ja
ck . D
on’t
sold
er
this
con
nect
ion
yet .
Cut
a 2-
1/2"
yel
low
jum
per
and
sol
der
it
to lu
g 4
of t
he 4
-lug
spea
ker
jack
alo
ng
with
the
jum
per
from
the
exte
nsio
n ja
ck .
Sold
er th
e ot
her e
nd o
f thi
s jum
per
to th
e to
p lu
g of
the
imp
edan
ce se
lect
or sw
itch .
Wra
p a
1"
gree
n ju
mp
er b
etw
een
lug
2 of
th
e ex
tens
ion
jac
k an
d l
ug
1 o
f th
e sp
eake
r jac
k . D
on’t
sold
er it
yet
.
Wra
p an
othe
r 1" g
reen
jum
per
dia
gona
lly
bet
wee
n lu
gs 1
and
3 o
n th
e sp
eake
r jac
k .
Don
’t so
lder
it y
et .
Cut a
5-1
/4" g
reen
jum
per
and
sold
er o
ne
end
in to
lug
3 of
the
spea
ker j
ack
alon
g w
ith t
he s
hort
jum
per
just
pla
ced
ther
e .
Sold
er th
e tw
o sh
ort j
ump
ers
at lu
g 1
of
the
spea
ker
jack
, an
d s
old
er t
he
oth
er
end
of t
he s
hort
jum
per
to
lug
2 of
the
ex
tens
ion
spea
ker j
ack .
Run
the
5-1/
4" ju
mp
er fr
om t
he s
pea
ker
jack
alo
ng t
he c
hass
is w
all,
over
the
im-
ped
ance
sw
itch,
and
wra
p it
to
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stewmac.com 36 © 2018 StewMac
STEP 99
Install the fuseInsert the 1-amp fuse into the fuse socket from the back of the chassis . Make sure the socket cap is secure . Never use a fuse rated above 1 amp in this amplifier .
Installing the fuse and knobs
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 101
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 100
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 37 © 2018 StewMac
STEP 104
Test the 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 .
With the amp still unplugged, install the 6CA4 rectifier tube in socket V6 and flip the standby switch on .
Plug the power cord back in . The pi-lot lamp should light, along with the filament inside the 6CA4 tube .
Again, spend a few minutes watching for smoke or smells .
At this point, dangerous voltage is forming in the filter caps . Always dis-charge 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 com-ponent . 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 500V DC and connect the black (negative) probe to ground . Once that probe is secured to ground, measure the DC voltage at the right lug of the filter cap (lug closest to power input) . This B+ volt-age should be roughly 440V DC .
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 mak-ing 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 102
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 in-dication would be that the pilot light will not turn on, since the AC current is going directly to ground .
Plug the power cord in . The pilot lamp should light .
For a few minutes, watch for smoke or unusual smells . If anything seems unusual, disconnect the power imme-diately and carefully review all your connections .
STEP 103
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, unplug the amp and check your connections . If the amp seems normal, unplug the power cord while still leaving the power switch ON .
Testing and troubleshooting
6
4321
98 7 5
V1
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!
stewmac.com 38 © 2018 StewMac
STEP 105
Test the preamp tubesUnplug the amp. Use the snuffer stick (see page 6) to discharge the capac-itors before working on the circuit . Even after discharging the caps, the best habit is to use a wooden chop-stick instead of your fingers when you need to nudge a component .
With the amp unplugged, install the 12AX7 preamp tubes in sockets V1, V2 and V3 . After they’re installed, plug the amp back in . The pilot lamp should light up . Let the amp warm up for a few minutes . Again, if you get smoke or smells, unplug immediately .
Connect your multimeter’s negative lead to ground .
Set the multimeter to 5V DC and check turret 50, which should read around 1 .5V .
Set the multimeter to 200V DC and check turret 43, which should read around 110V .
Set the multimeter to 200V DC and check turret 26, which should read around 175V .
Set the multimeter to 200V DC and check turret 49, which should read around 150V .
Set the multimeter to 500V DC and check turrets 44 and 45, both of which should read around 230V .
If the readings at turrets 44 or 45 show 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 jumpers from turret 7 to turret 44 and turret 8 to turret 45 .
If all of these voltages come within approximately 10% of their expected values, unplug the amp .
STEP 106
Test the EL84 power tubesWith the amp unplugged, install the EL84 power tubes in sockets V4 and V5 .
Plug the speaker into the left speaker jack . The other jack is for an extension cabinet; if you plug the internal speak-er into it, you’ll get no sound .
Plug the foot pedal in as well .
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 . After a few moments you should hear a low hum . If the hum becomes very loud, unplug it imme-diately and review your connections .
After the amp’s warmed up for a few minutes attach your multimeter’s negative lead to ground .
Set your multimeter to read 500V DC, and test for voltage at the left lug of the filter cap (the lug nearest to the impedance selector switch) . This volt-age should read around 315V .
Set your multimeter to 20V DC and check the voltage at turret 32 . This should be around 10V .
Set the normal channel tone knob to 10 . Begin to turn the normal channel volume knob and listen for a slight hiss . As you increase the volume past here the hiss should become much more noticeable . Any sound beyond this hiss and a slight hum is a sign of poor wiring .
Turn the volume knob back to zero and repeat this process with the tremolo channel .
If your voltage readings are correct, plug a guitar in and begin playing at low volume . If the amp is behaving as it should, keep increasing the volume . It should start to break up nicely as you increase the volume . Test the tremolo effect and the foot switch functions at this time as well . The left button on the footswitch will be the “on/off" switch and the right switch will be a “high/low" switch .
If there are any strange oscillations, squeals, or the amp seems at all unsta-ble, 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 like resoldering a loose joint to correct this sort of distortion .
After testing all inputs, if everything seems to be operating normally, turn the amp off . You’re ready to assemble it and play it!
stewmac.com 39 © 2018 StewMac
STEP 107
Install the chassisSecure the chassis to the back panel of the cabinet with the four 10-32 mounting screws and nuts .
Lay the cabinet face down . With the chassis attached, secure the back panel to the cabinet . Also attach the lower back panel .
Final assembly Tips for using the 74X
You might notice this amp is quite a bit “dirtier" than other amps of the 60’s era . One factor contributing to that is the gain stages are all biased extremely hot, with 820Ω resistors . This small value for the bias resis-tor (cathode resistor) both reduces headroom and increases preamp distortion .
You should find that the normal channel has a bit more gain and bass to it than the tremolo channel . You’ll be amazed at how many colors live in this very simple amp . The clean tones won’t be mistaken for Fender or Vox amps, but they still have a certain “airy shimmer" that gives them life . Still, this amp was made for cranking the volume, and that’s where it shines .
One of my favorite ways to play the 74X is through the normal channel with the volume and tone both set to 8 . This puts the amp right on the edge of saturation, and you can push it over that edge by really digging in on your guitar .
If you play with pedals, the tremolo channel will most likely be your favor-ite . The tremolo channel is coupled with smaller caps, which makes the bass less overwhelming than the normal channel . With less bass com-ing from the amp, your boost pedals are free to drive the signal without swamping out .
Both channels of this amp have their own low-loss master tone control . One advantage of this master tone control over a treble-mid-bass setup is that the signal is less processed, which leads to more gain . And this amp is all about gain .
With the tone knob at 5, treble and bass will both be at maximum . As you turn the tone knob down, you start to bleed treble from the tone . With the tone knob at 1 you’ll have nothing
but bass . In the range from 5 to 11, the tone knob is removing bass from the mix . With the tone at 11 you’ll have nothing but treble .
The channels of this amp are out of phase with each other when you jumper them together by placing a cable between the inputs . You might like to jumper the channels together, but I think it makes the sound thin and brittle .
Matt Clouston, StewMac
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 .
For questions and support, StewMac is here to help!For 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!
It's finally time to let it rip!
GO!GO!
stewmac.com 40 © 2018 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 .
This amp’s dirt comes from gain stages that are biased extremely hot: the small-value 820Ω resistors reduce headroom and increase distortion .
The tremolo inputs’ 68K resistors cre-ate less gain and bass than the normal channel, making the tremolo channel a good platform for pedals .
A negative feedback loop is a stage that flattens and extends the amp’s frequency response to reduce the distortion generated in the output stage . This makes an amp’s sound cleaner and more hi-fi .
The 74X, however, has no negative feedback loop . This results in early breakup and plenty of grit .
The processing stage shapes the tone . Each channel on this amp has its own low-loss master tone control . One advantage of this master tone control over a treble/mid/bass setup is that the signal is less processed, which leads to more gain—and this amp is all about gain .
With the tone set to 5 both treble and bass will be at maximum . As you turn the tone down, it begins to bleed treble from the tone . Turning the tone knob all the way down gives you nothing but bass . As you turn the tone knob up past midway towards full, you start to cut bass out of the mix . With the tone knob all the way up, you’ll have nothing but treble .
The power supply stage provides power to the other circuit stages, as well as the tube heaters and pilot light .
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, which converts it to a pulsing DC current .
This then passes through a series of three large electrolytic capacitors which 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 .
In this amp the signal is split, and half of it is inverted through the second half of the 12AX7 tube .
The split signal is then passed to the pair of EL84 tubes for final amplifi-cation and then sent to the output transformer to step down the voltage and step up the current .
The output transformer adjusts the impedance to 4, 8, or 16 ohms to drive the amp’s 8Ω speaker .
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 41 © 2018 StewMac
#10
732
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stewmac.com 42 © 2018 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 Ryan Adams .
#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 / 12" 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 43 © 2018 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 4x12 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 44 © 2018 StewMac
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’66
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#10
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©
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stewmac.com 45 © 2018 StewMac
’66 BRIT-74X 18WO 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
Use only 1-amp slow-blow fuse, size 5mm x 20mm.
DANGER: Unplug the amp before changing tubes.Tube locations from left to right:
12AX7(ECC83)
12AX7(ECC83)
V2 V1
EL84 12AX7(ECC83)
V4 V3
6CA4(EZ81)
EL84
V6 V5
#10732
’66 BRIT-74X 18WO 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
Use only 1-amp slow-blow fuse, size 5mm x 20mm.
DANGER: Unplug the amp before changing tubes.Tube locations from left to right:
12AX7(ECC83)
12AX7(ECC83)
V2 V1
EL84 12AX7(ECC83)
V4 V3
6CA4(EZ81)
EL84
V6 V5
#10732
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 .
stewmac.com 46 © 2018 StewMac
stewmac.com 47 © 2018 StewMac
tools + ideas for guitarmakingStewMac
21 N . Shafer St ., Athens, OH 45701800-848-2273 stewmac .com
©2018 StewMac . All rights reserved .#i10732 Updated March, 2019