Mod Aggressor User manual

1Copyright © 2016 by modkitsdiy.com
Use these instructions to learn:
How to build an effects pedal for aggressive distortion sounds.
The Aggressor was designed to melt your face off. It's an aggressive distortion pedal with a mid-shift switch
that allows for an instantaneous scoop or bump of the mid frequencies.
THE AGGRESSOR (K-995)
Warning: This circuit was designed for use with a 9 VDC power supply only.
Unplug when not in use
to save battery life.
9 VDC
CENTER (-)
ADAPTER
Signal Input
(From Guitar)
Signal Output
(To Amplifier)

2
TOOL LIST
TABLE OF CONTENTS
TOOL LIST p. 2
PARTS LIST DRAWINGS pp. 3, 4
SOLDERING TIPS p. 6
STEP BY STEP ASSEMBLY INSTRUCTIONS pp. 7 - 11
Section 1 - Mount Large Components p. 7
Section 2 - Wire Large Components p. 7
Section 3 - Mount Components to Terminal Strips p. 9
Section 4 - Finishing Up p. 11
ASSEMBLY DRAWINGS (5 Drawings) pp. 12 - 14
These are the last 3 pages. They should be used as a reference for assembly.
Wire Strippers
Needle Nose Pliers
Cutting Pliers
Desoldering Pump
Solder (60/40 rosin core)
Soldering Station
Phillips Head Screwdrivers
Slotted tip screwdrivers (3 mm tip)
Channellock Pliers (or similar type)
Ruler
Hobby Vise (or other means to secure box while working)
FINAL ASSEMBLY REFERENCE DRAWING p. 5

Enclosure
P-H1590BBCE-DB (1)
Clear Knob with Black Line
P-K380CL (3)
Battery Clip
S-H155 (1)
¼” Mono Jack (Output Jack)
W-SC-11 (1)
¼” Stereo Jack (Input Jack)
W-SC-12B (1)
Stranded Wire (22 AWG) - White
K-PUL1569-WHITE (5 FT)
PARTS LIST 1
3
RING LUG
SLEEVE LUG
TIP LUG
GROUND LUG
TIP LUG
Potentiometers:
R-VAM10KL-SS ("B10K") (1)
R-VAM100KL-SS ("B100K") (1)
#4 Screw (3/8" long)
S-HS440-38 (6)
#4 Nut
S-HHN440 (6)
#4 Lock Washer
S-HLW4 (6)
Terminal Strip with 8 Terminals
P-0802H (3)
DC Power Jack
S-H750 (1)
3PDT Foot Switch
P-H501 (1)
R-VAM100KA-SS ("A100K") (1)
Bezel with red LED
P-L400 (1)
+
-
Red LED
P-L302 (2)
+
-

PARTS LIST 2
4
MPS
A13
EBC
P-QMPSA13 (1)
NPN Darlington (MPSA13)
P-Q2N5088 (1)
NPN BJT (2N5088)
2N
5088
E B C
DPDT Mini Toggle Switch
P-H541 (1)
brown
black
orange
gold
10K
10kΩ Resistor ½ W
R-A10K (1)
2MΩ Resistor ½ W
R-A2M (2)
red
black
green
gold
2M
180 Ω Resistor ½ W
R-A180 (1)
brown
grey
brown
gold
180
8.2kΩ Resistor ½ W
R-A8D2K (2)
grey
red
red
gold
8.2K
1MΩ Resistor ½ W
R-A1M (3)
brown
black
green
gold
1M
red
red
orange
gold
22K
22kΩ Resistor ½ W
R-A22K (1)
orange
white
orange
gold
39K
39kΩ Resistor ½ W
R-A39K (1)
220pFCapacitor 500V
C-D220-500 (1)
221K
470pFCapacitor 2kV
C-D470-2000 (1)
471K
0.1µF Capacitor 100V
C-PEID1-100 (2)
104J
224J
0.22µF Capacitor 100V
C-PEID22-100 (1)
K-PC4D7-35 (1)
4.7µF Polarized Capacitor 35V
4.7µF35V
0.047µF Capacitor
C-PEID047-100 (1)
473J
0.01µF Capacitor
C-PEID01-100 (2)
103J
.0039µF Capacitor 100V
C-PEID0039-100 (2)
392K

FINAL ASSEMBLY REFERENCE DRAWING
This is a large version of the final assembly drawing. Refer to this drawing as you make your way through each step of the instructions. Before you make a new
connection at a particular terminal or solder lug, notice how many other connections will be made at that terminal. That way you can decide whether it’s best for
you to solder the connection and leave space open for future connections or hold off on soldering until after every connection at that location has been made.
5
2M
Distortion Tone Volume
-
+
1 2 3 1231 2 3
1234 678
16 15 14 13 12 11 10 9
17
18
19 20 21 22 23 24
1
2
3
4
5
6
1
2
3
4
5
6
7
8
9
TIP TIP
SLEEVE
RING
A100KB100KB10K
22K
39K
.0039µ
.22µF
.01µ
.0039µ
2M
10K
4.7µF35V
470p .1µF
.047µ
8.2K
1M
1M
1M
8.2K
220p
.1µF
MPSA13
E B C
Q2
2N5088
E B C
Q1
SLEEVE
180
RED
BLK
103J

SOLDERING TIPS
1. Bend the component lead
and wrap it around the
connection point.
2. Wrap the component lead
so that it can hold itself to the
connection point.
3. Heat up both component
lead and connection point with
the soldering iron.
4. Apply solder to both
component lead and
connection point.
2. Apply fresh solder to mix in
with old solder joint
1. Heat up old solder joint
with the soldering iron.
3. Use a de-soldering tool to
remove the old solder joint
while it is heated.
De-Soldering Tip
6
It is important to make a good solder joint at each connection point. A cold solder joint is a connection that
may look connected but is actually disconnected or intermittently connected. (A cold solder joint can keep
your project from working.)
Follow these tips to make a good solder joint. Take your time with each connection and make sure that all
components are connected and will remain connected if your project is bumped or shaken.
Bend the component lead or wire ending and wrap it around the connection point.
Make sure it is not too close to a neighboring component which could cause an
unintended connection.
2. Wrap the component lead so that it can hold itself to the connection point.
Touch the soldering iron to both the component lead and the connection point allowing both to
warm up just before applying the solder to them.
Be sure to adequately cover both component lead and connection point with melted solder.
Remove the soldering iron from your work and allow the solder joint to cool. (The
solder joint should be shiny and smooth after solidifying.)
Cut off any excess wire or component leads with cutting pliers.
Clean the soldering iron's tip by wiping it across the wet sponge again after making the
solder joint.

SECTION 1 – Mount Large Components
Stripping wire, tinning wire and soldering. Throughout these instructions you will be told to strip
and tin a length of wire numerous times. Unless noted otherwise, cut the wire to the length stated in
the instructions. Then strip ¼” of insulation off each end. Twist each end of the stranded wire, and
apply a small amount of solder to each end (i.e. tin the wire ends). This will prevent the stranded
wire from fraying and will make the final soldering much easier.
Please refer to DRAWING 1 and DRAWING 2.
Orient the enclosure with the three 9/32" holes on top.
Mount the DC power jack in the 15/32" hole on the left side of the enclosure. Orient its solder
lugs so that the center-pin lug is facing the bottom side of the enclosure.
Mount the input jack in the 3/8" hole on the left side of the enclosure with the hardware provided.
The washer goes under the nut on the outside of the enclosure. Make sure the center solder lug
of the input jack is facing up. Correct positioning of the jack makes soldering the connections
easier.
Mount the output jack in the 3/8" hole on the right side of the enclosure. Make sure the two
solder lugs are in their most upright position before tightening the nut.
Mount the footswitch in the 15/32" hole in the center of the enclosure. The nylon washer goes
under the mounting nut on the outside of the enclosure. Then the lock washer mounts on the
inside between the enclosure surface and the other nut. Make sure that the footswitch is
oriented to match DRAWING 2.
SECTION 2 – Wire Large Components
Please refer to DRAWING 3.
7
Mount the LED and bezel holder in the ¼” hole below the middle
9/32" hole. Align the LED leads so that the anode (positive lead) is
closer to the left side of the enclosure as shown in Drawing 2.
The Anode (+) side of the LED is
indicated by a slightly longer lead
and/or a positive sign.
LED Physical
Representation
+
-
+-
LED Schematic
Symbol
anode cathode
Mount the toggle switch in the ¼" hole between the middle and
right side of the enclosure. Make sure its solder lugs are oriented
as shown in Drawing 2.
Correct Orientation Incorrect Orientation
Bend back and remove the alignment tab on the top of each potentiometer using a pair of
pliers before mounting the pots so that they can mount flush against the enclosure surface.
Alignment
Tab
Mount the three pots in their respective 9/32" holes as shown in
Drawing 2.
Using the 6 screws, nuts and lock washers, fasten the 3 terminal strips to match Drawing 2.
You might find it difficult to fit the nut for the DC power jack on to the power
jack due to the proximity of the two terminal strip screws. If so, one way to
make it easier would be to loosen those screws temporarily so that there is
more space for the power jack's nut to fit through. CENTER-PIN LUG
POSITIVE-SWITCH
LUG
POSITIVE LUG
Temporarily loosen screw
to fasten Power Jack nut

lower holes
Tip: Some terminals will have three or more wire/component connections which can
make it difficult to find room for everything that needs to be connect to that terminal. In
this case, we will provide a warning and suggest connecting wires to the lower terminal
holes.
When connecting wires to lower terminal holes, just be sure that the exposed wire end is resting against the metal of the
terminal while adding solder. Hold the wire in place for a few seconds while the connection cools. After cooling, tug on
the wire slightly to ensure it is secured to the lower terminal hole.
8
Strip and tin a 2" piece of wire and connect footswitch lug 8 to the output jack's tip lug.
Strip and tin a 1 ½" piece of wire and connect footswitch lugs 3 and 9.
Strip and tin a 2" piece of wire and connect footswitch lug 2 to the input jack's tip lug.
Strip and tin a 5" piece of wire and connect footswitch lug 7 to volume pot lug2.
Strip and tin a 1 ¾" piece of wire and connect footswitch lug 1 to terminal #2.
Strip and tin a 2 ½" piece of wire and connect footswitch lug 4 to the anode (+) lead of the
indicator LED. After connections are made, push this wire down so it runs along the surface of
the enclosure (between the two terminal strips). This will leave more room for components that
will be mounted to the terminal strips later in these instructions.
Tip: Form a hook in both the LED's lead and the wire-end. Hook them to each other and press the hooks closed
together. Apply solder after the LED lead and wire-end are tightly hooked to each other.
Strip and tin a 2" piece of wire and connect terminal #9 to the cathode (-) lead of the indicator
LED.
Strip and tin a 2" piece of wire and connect to terminals #1 and #4. After connections are made
push this wire down so it runs along the surface of the enclosure.
Strip and tin a 2" piece of wire and connect to terminals #5 and #12. After connections are made
push this wire down so it runs along the surface of the enclosure.
Strip and tin a 1 ½" piece of wire and connect to terminals #5 and #7. This piece of wire should
be connected on the side of the terminal strip that faces the footswitch.
Strip and tin a 1 ½" piece of wire and connect terminal #3 to the DC power jack's positive lug.
Strip and tin a 2" piece of wire and connect terminals #6 and #11.
Strip and tin a ¾" piece of insulation from one end of the wire provided. Twist and tin this end.
Clip off this tinned length of wire and use it to connect terminal #1 to the DC power jack's center-
pin lug.
Strip and tin a ¾" piece of insulation from one end of the wire provided. Twist and tin this end.
Clip off this tinned length of wire and use it to connect terminal #17 to distortion pot lug 2. (Do
not solder the pot lug 2 connection, yet).
Strip and tin a 1 ½" piece of wire and connect terminal #18 to distortion pot lug 1.
Strip and tin a 3" piece of wire and connect terminal #19 to toggle switch lug 1.
Tip: The toggle switch lugs are small and close together. Consider clipping the tinned wire-ends to 1/8" before inserting
them through the toggle switch lugs.

Strip and tin a 2 ½" piece of wire and connect tone pot lug 1 to toggle switch lug 2. (Do not
solder the connection on lug 1 of the tone pot, yet).
Strip and tin a 1 ½" piece of wire and connect tone pot lug 2 to volume pot lug 1.
Strip and tin a 1 ½" piece of wire and connect toggle switch lug 3 to terminal #20.
Strip and tin a 2" piece of wire and connect toggle switch lug 4 to terminal #23.
Strip and tin a 1 ¾" piece of wire and connect toggle switch lug 5 to tone pot lug 3. (Do not
solder the tone pot lug 3 connection, yet).
Strip 1" of insulation off of the wire provided. Twist and tin the 1" bare wire-end. When cool, clip
the tinned wire off and use it to connect terminal #22 to toggle switch lug 6.
Strip 1" of insulation off of the wire provided. Twist and tin the 1" bare wire-end. When cool, clip
the tinned wire off and use it to connect volume pot lug 3 to terminal #24.
SECTION 3 – Mount Components to Terminal Strips
Please refer to DRAWING 4.
9
Unless noted otherwise, “connect” means to trim the component’s leads to a reasonable length, wrap them tightly
around their connection points and then add solder. (See “Soldering Tips” on page 5).
Connect and solder all the following components to their respective terminals as listed. (Make sure
that none of the component leads are so close together that it could cause an unintended short).
Connect the 22K resistor from distortion pot lugs 2 & 3 to tone pot lug 1. (Solder the connections
at all three potentiometer lugs, now).
To do this, thread one lead of the resistor through distortion pot lug 3 and bend it back to go through lug 2 as well.
Connect the 39K resistor from terminal #21 to tone pot lug 3. (Solder the connections at tone pot
lug 3, now).
Warning: Make sure the resistor lead connected to the tone pot does not touch the pot's body. This would short out the
signal path of the effects circuit and could result in no sound output when the effect is engaged.
Connect one of the .0039µF capacitors from terminal #22 to #24. This cap should be mounted
upside down to allow room for other components.
Connect one of the .01µF caps from terminal #23 to #24.
Connect the .22µF cap from terminal #11 to #21. Mount this cap upside down.
Connect the remaining .01µF cap from terminal #20 to #21. Mount this cap upside down.
Connect the remaining .0039µF cap from terminal #19 to #21. Mount this cap upside down.
Connect one of the 2M resistors from terminal #16 to #14.
Tip: 5 components will be connected to terminal #14. Consider connecting to the lower terminal holes and do not
solder the connection at #14's lower hole, yet.
Connect the remaining 2M resistors from terminal #14 to #13.
Tip: Consider connecting to the lower terminal holes and now solder the connection at #14's lower hole.

Connect the 10K resistor from terminal #16 to #15.
Connect the positive (+) lead of the 4.7µF capacitor to terminal #15 and connect its negative (-)
lead to terminal #18.
Connect the 470pF cap from terminal #13 to #14. Mount this cap upside down and position it so
there will be room to mount components above it later.
Connect one of the 8.2K resistors from terminals #3 to #6.
Tip: More than 3 components will be connected to terminals #3 and #6. Consider connecting to the lower terminal
holes and do not solder the connection at terminal #6's lower hole, yet.
Connect one of the 1M resistors from terminal #5 to #8.
Connect one of the 1M resistors from terminal #5 to #6.
Tip: Consider connecting to the lower terminal holes. Solder the connection at terminal #6's lower hole, but leave
terminal #5's lower hold unsoldered.
Tip: Consider connecting to the lower terminal holes. Now solder the connection at terminal #5's lower hole.
Connect one the remaining 1M resistor from terminal #1 to #2.
Connect the remaining 8.2K resistor from terminal #3 to #13.
Connect the 220pF cap from terminal #5 to #11. Mount this cap upside down and make sure the
leads do not touch the leads of other components.
Connect the two red LED's from terminals #7 to #10. The LED's are polarized
and will be mounted in opposing directions. The LED cathode (-) side is flat.
Mount the LED's so that the flat side of one LED faces terminal #7 and the flat
side of the other LED faces terminal #10.
+
-
A flat side and
slightly shorter lead
identify the cathode
(-) of the LED.
Connect the remaining .1µF cap from terminal #12 to #13. Mount this capacitor upside down.
Please refer to DRAWING 5.
Connect the MPSA13 transistor ("Q2") to terminals #4, #5 and #6 as listed:
Terminal #4: Emitter
Terminal #5: Base
Terminal #6: Collector
Connect the 2N5088 transistor ("Q1") to terminals #15, #14 and #13 as listed:
Terminal #15: Emitter
Terminal #14: Base
Terminal #13: Collector
MPS
A13
EBC
2N
5088
E B C
10
Connect a .1µF cap from terminal #10 to #11.
Connect the .047µF cap from terminal #2 to #14. Mount this capacitor upside down.
Tip: You will also be connecting the "base" lead of the MPSA13 to terminal #5, so be sure to leave some room for it.

11
Locate the battery snap connector. Connect its red wire to the DC power jack's "positive-switch"
lug and connect its black wire to the input jack's ring lug.
SECTION 4 – Finishing Up
Fasten the knobs to the potentiometer shafts by tightening their set screws. Install a 9 volt
battery if needed. Fasten the cover using the four screws provided. Plug your guitar into the
input jack on the right side of the pedal. This turns power on when you are not using an AC
adapter for power. Plug another cable from the output jack (left side) to your amp's input.
When using a battery for power, remember to unplug from the input jack of the pedal to turn it off
and save battery life.
It’s always a good idea to thoroughly double-check your connections before applying power. This
will minimize the risk of damaging components.
Connect the 180Ω resistor from terminal #3 to footswitch lug 5.
Tip: To prevent the resistor from shorting to the other lugs, insulate that lead of the
resistor. Strip a ½" piece of insulation from the wire provided. Next, cut one lead of
the resistor to a length of ¾". Slide the ½" piece of insulation over this lead. Connect
the insulated lead to lug 5 with the resistor going to the left side of the switch.
Connect the other lead to terminal #3 and cut off any excess.
180
¾"
½"

15/32"
1/8"1/8"
1/8" 1/8"
1/4"
3/8"
3/8"
15/32"
9/32"9/32" 9/32" 1/4"
1/8"1/8"
LEFT SIDE
RIGHT SIDE
DRAWING 1
DRAWING 2
12
INSIDE VIEW OF THE
ENCLOSURE
B10K B100K A100K
Distortion Tone Volume
-
+
1 2 3 1231 2 3
1 2 3 4 5678
16 15 14 13 12 11 10 9
17 18 19 20 21 22 23 24
1
2
3
4
5
6
1
2
3
4
5
6
7
8
9
INPUT OUTPUT

2M
DRAWING 3
DRAWING 4
13
Distortion Tone Volume
-
+
1 2 3 1231 2 3
1 2 3 4
5
678
16 15 14 13 12 11 10 9
17
18
19 20 21 22 23 24
1
2
3
4
5
6
1
2
3
4
5
6
7
8
9
TIP TIP
SLEEVE
SLEEVE
RING
A100KB100KB10K
22K
39K
.0039µ
.22µF
.01µ
.0039µ
2M
10K
4.7µF35V
470p .1µF
.047µ
8.2K
1M
1M
1M
8.2K
220p
.1µF
Distortion Tone Volume
-
+
1 2 3 1231 2 3
1 2 3 4 5678
16 15 14 13 12 11 10 9
17 18 19 20 21 22 23 24
1
2
3
4
5
6
1
2
3
4
5
6
7
8
9
TIP TIP
SLEEVE
SLEEVE
RING
A100KB100KB10K
INPUT OUTPUT
103J

2M
DRAWING 5
Distortion Tone Volume
-
+
1 2 3 1231 2 3
1 2 3 4 6 78
16 15 14 13 12 11 10 9
17
18
19 20 21 22 23 24
1
2
3
4
5
6
1
2
3
4
5
6
7
8
9
TIP TIP
SLEEVE
RING
A100KB100KB10K
22K
39K
.0039µ
.22µF
.01µ
.0039µ
2M
10K
4.7µF35V
470p .1µF
.047µ
8.2K
1M
1M
1M
8.2K
220p
.1µF
MPS
A13
E B C
Q2
2N
5088
E B C
Q1
SLEEVE
180
14
RED
BLK
103J

2M
Distortion Tone Volume
-
+
1 2 3 1231 2 3
1 2 3 4 6 78
16 15 14 13 12 11 10 9
17
18
19 20 21 22 23 24
1
2
3
4
5
6
1
2
3
4
5
6
7
8
9
TIP TIP
SLEEVE
RING
A100KB100KB10K
22K
39K
.0039µ
.22µF
.01µ
.0039µ
2M
10K
4.7µF35V
470p .1µF
.047µ
8.2K
1M
1M
1M
8.2K
220p
.1µF
MPS
A13
E B C
Q2
MPS
A18
E B C
Q1
SLEEVE
180
RED
BLK
103J
A
B
EDC
HGF
Using a volt meter, connect the ground side lead of the meter to any
ground point on the pedal. One ground point would be the input or
output jack’s sleeve lug. The other volt meter lead will be used to
measure DC voltage at the test points listed here.
If you are using only a battery for power, be sure to
plug a guitar cable into the input jack when taking
measurements. Any major differences from the
voltages listed should indicate a problem area.
A(Power Supply)
B(Indicator LED Anode)
C(Q1 Collector)
D (Q1 Base)
E(Q1 Emitter)
F(Q2 Collector)
G(Q2 Base)
H (Q2 Emitter)
DC Test Points
9.1 VDC
2.6 VDC
2.6 VDC
3.0 VDC
7.0 VDC
2.2 VDC
1.1 VDC
0.0 VDC
Measurement
The Aggressor Troubleshooting Supplement
After thoroughly double-checking your connections, the next step is
to take DC voltage measurements to help locate problem areas.
Measuring AC Voltages from the Guitar Signal
Once your DC voltages are in order, if your kit is still not working properly, you can
measure AC voltages along the signal path to troubleshoot further.
You will need a volt meter that can measure the small signal AC voltages that electric
guitars put out. The output signal from your guitar will likely be less than 1 V.
First, measure the output signal directly from your guitar. You can do this by plugging your
guitar cable into the guitar and leaving the other end of the cable disconnected. Connect your
meter across the disconnected ¼" plug's "tip" and "sleeve" sections. Make sure your guitar's
volume and tone controls are turned up and strum a chord. When you strum, you should see
the AC voltage reading on the meter quickly rise to some maximum value and then fall back to
0 VAC when you stop strumming and the strings are at rest.
Sleeve Tip
Sleeve
Terminal
(Ground)
Tip
Terminal
(Output)
Tip
Spring
¼” (Mono) Plug
¼” Jack
Once you are able to measure the output signal from your guitar directly, plug the guitar into the input jack of your kit and use the AC test points to measure the guitar
signal along the signal path. Start with test point one and move along in order. You should be looking to identify the last test point where the signal seems normal and the
first test point where the signal seems unusual or where it is no longer even present.
12
34
5
6
Lettered test points are for DC
Numbered test points are for AC

Copyright © 2014 by modkitsdiy.com
“The Aggressor” (K-995)
Schematic
2M
.047µ Output
Input
Foot
Switch
(A) Foot
Switch
(C)
2
1
3
7
8
9
+
-
9 VDC
Battery
DC Power
Jack
center (-)
100KA
www.modkitsdiy.com
1M
+-
180 Ω
5
6
4
Foot
Switch
(B)
VOLUME
MPSA13
C
E
B
2
3
1
10K
Base
Emitter
Collector
MPSA18
NPN BJT
BCE
Q1
MPSA18
C
B
E
4.7µ
+
MPSA13
NPN Darlington Transistor
B C
E
MPSA13
C
E
B
10KL
DISTORTION
.1µ
8.2K
2M
470p
8.2K
1M
1M
+-
+- .1µ
220p
Q2
.22µ
5
6 4
MID-SHIFT
(B)
MID-SHIFT
(A)
39K
22K
100KL
TONE
.01µ
.0039µ
.0039µ
.01µ
1
2
3
AB C
3PDT
Footswitch
4
5
6
7
8
9
P-H501
ScoopBump
Scoop
Bump
DPDT "Mid-Shift"
Toggle Switch
P-H541
1
2
3
4
5
6
AB
9.1 VDC
2.6
VDC
7.0
VDC
2.6 VDC
3.0
VDC 1.1
VDC
0.0 VDC
2.2
VDC
0.1 VAC
0.1 VAC
1.4 VAC
1.7 VAC
2.0 VAC
0.1 VAC
0.4 VAC
0.4 VAC
0.5 VAC
All voltages measured with respect to ground using a strat in neck
position strumming an open E chord for the signal.
Where two AC voltage measurements are listed, the measurement
on top is for the distortion pot set to max and the measurement on
the bottom is for the distortion pot set to min. (The volume control
was set to max and the tone control was set to half-way).
0.4 VAC
0.5 VAC
E
D
C
H
G
F
A
B
1
2
3
4
5
6