Lithium Grim Epic Polar Boost Instruction Manual

Epic Polar Boost
Building instructions
v1.0

Epic Polar Boost v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
2
Table of contents
PCB layout ............................................................................................................................................... 3
Components ............................................................................................................................................ 4
Original configuration.......................................................................................................................... 4
Optimized configuration...................................................................................................................... 5
Build sequence ........................................................................................................................................ 6
Drill template........................................................................................................................................... 7
Switch .................................................................................................................................................. 7
Off board wiring ...................................................................................................................................... 8
Modifications........................................................................................................................................... 9
Charge pump....................................................................................................................................... 9
Tone section ........................................................................................................................................ 9
Transistors......................................................................................................................................... 10
Calibration ............................................................................................................................................. 11
Troubleshooting .................................................................................................................................... 12
Schematics............................................................................................................................................. 13
Read this entire manual thoroughly before you start building the effect! There are a lot of available
mods and you should choose which one you want to incorporate before starting your build.
Last update: 30-03-2019

Epic Polar Boost v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
3
PCB layout
Dimensions: 49 mm x 49 mm
1.93 inch x 1.93 inch

Epic Polar Boost v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
4
Components
Original configuration
ID
Value
Comment
ID
Value
Comment
C1
47n
SMF/MKT/Wima
R1
1M
1% metalfilm
C2
10u
Electrolytic 25V+
R2
33k
1% metalfilm
C3
10u
Electrolytic 25V+
R3
1M
1% metalfilm
C4
100u
Electrolytic 25V+
R4
4k7
1% metalfilm
C5
3n3
SMF/MKT/Wima
R5
1k
1% metalfilm
C6
10u
Electrolytic 25V+
R6
15k
1% metalfilm
C7
4u7
Electrolytic 25V+
R7
1M
1% metalfilm
C8
100u
Electrolytic 25V+
R8
10k
1% metalfilm
C9
100n
SMF/MKT/Wima
R9
47k
1% metalfilm
C10
10u
Electrolytic 25V+
R10
100R
1% metalfilm
C11
47u
Electrolytic 25V+
R11
33k
1% metalfilm
C12
47u
Electrolytic 25V+
R12
Jump
D1
1N5817
R13
10k
1% metalfilm
D2
1N5817
R14
10k
1% metalfilm
D3
1N5817
R15
Jump
IC1
ICL7660S
SW1
DIP2
Gain/Bright
P1
C10k
Boost
SW2
SPDT
Voltage
P2
NC
VR1
8k2
1% metalfilm
P3
NC
J1
Jump
Q1
2N5457
J2
Jump
Q2
2SC1815
* Optional parts (see modifications section)
All parts need to be 25V+ rated
Jump means place a jumper in this spot instead of a component
NC means Not Connected, so leave it empty
The main effect is configured as the original. The only deviation is the added switchable 18V
charge pump. If you do not want that then read the modifications section on how to leave it
out.
A=Log, B=Lin, C=Rev. Log

Epic Polar Boost v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
5
Optimized configuration
ID
Value
Comment
ID
Value
Comment
C1
47n
SMF/MKT/Wima
R1
1M
1% metalfilm
C2
10u
Electrolytic 25V+
R2
33k
1% metalfilm
C3
10u
Electrolytic 25V+
R3
1M
1% metalfilm
C4
100u
Electrolytic 25V+
R4
4k7
1% metalfilm
C5
3n3
SMF/MKT/Wima
R5
470R
1% metalfilm
C6
10u
Electrolytic 25V+
R6
22k
1% metalfilm
C7
10u
Electrolytic 25V+
R7
1M
1% metalfilm
C8
100u
Electrolytic 25V+
R8
3k3
1% metalfilm
C9
100n
SMF/MKT/Wima
R9
NC
C10
10u
Electrolytic 25V+
R10
Jump
C11
47u
Electrolytic 25V+
R11
4k7
1% metalfilm
C12
100u
Electrolytic 25V+
R12
390R
1% metalfilm
D1
1N5817
R13
10k
1% metalfilm
D2
1N5817
R14
10k
1% metalfilm
D3
1N5817
R15
100R
IC1
ICL7660S
SW1
DIP2
Gain/Bright
P1
C10k
Boost
SW2
SPDT
Voltage
P2
B50k
Tone
VR1
50k
trimpot
P3
B100k
Volume
J1
NC
Q1
2N5457
or J201
J2
NC
Q2
2N5457
or J201
* Optional parts (see modifications section)
All parts need to be 25V+ rated
Jump means place a jumper in this spot instead of a component
NC means Not Connected, so leave it empty
Added Tone (high cut) control, Volume control and transistor bias (Q1) as well as some minor part
optimizations. Read the modifications section for further tone control options.
A=Log, B=Lin, C=Rev. Log

Epic Polar Boost v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
6
Build sequence
Soldering this board can be very complicated for some people since the solder pads are very close
together. Use a magnifying glass to make the job easier.
The trick to soldering a PCB is to work from small to big components. My building sequence
suggestions in this section are based on the parts I used myself. Sometimes some components are
smaller (or bigger) so always use your own common sense and change the order accordingly. Usually
capacitors can differ a lot in size depending on their rating and value.
Note: Do not blow on your solder in an attempt to cool it down. That can result in a bad join that
might corrode! Also take extra care not to short components.
Start by soldering the jumpers (if needed) and resistors. You can create a jumper using a spare piece
of lead from a resistor or diode. The original version puts a 8k2 resistor in VR1. For this there are 2
special pads Xand Ymarked on the PCB which will fit this resistor. Next comes the diodes.
If you want to experiment with another transistors for Q1 and Q2 then you could socket them
instead of soldering them to the board. You’ll need a 20 SIL sockets, break off the sockets and solder
them to the board. Now is the time to solder the sockets for IC1. Place the transistors and IC not
before you are finished with all soldering and off board wiring!
Now continue by soldering the SMF and MKT capacitors then solder the optional internal trimpot
(VR1) and Dip2 for SW1. Finish with soldering the transistor (if not socketed) and the Electrolytics.
Note that the orientation of the transistor may not match your transistors! For that the pads are
marked with the correct pinout. Q2 has an extra base (marked B) pad for transistors that are not ECB
but EBC.
I suggest you now drill the holes in your enclosure so you can use it during the off board wiring and
to correctly fit the pots to the backside of the PCB.
Note: Really take some time to determine where to place the pots, switches, jacks and PCB in the
enclosure before you start drilling. Measure twice, drill once.
You are almost ready to rock, well… not really. The difficult part starts now.

Epic Polar Boost v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
7
Besides the components mentioned in the components table, you will need:
•1 mono input jack socket, 1 stereo output jack socket.
•3PDT footswitch (9 pins)
•2,1mm DC socket (isolated).
•22 gage stranded hook-up wire.
•LED holder. This enables you to mount the LEDs in the enclosure.
•LED (3mm or 5mm depending on your taste). This will be the status LEDs
•Hammond 1590B case (or similar) in your favorite color. This case will fit tightly and leaves
no room for error! If you need more room you could consider using a Hammond 1590N1
(=125B).
Drill template
17,8mm
Volume Tone
Boost
17,8mm 17,8mm
After drilling the holes, insert the potentiometers in the enclosure and then insert them in the back
of the PCB.
You can break off the pin I marked with the yellow circle with a small
pair of pliers. The rectangle pad on the PCB marks the pad for pin 1.
If all fits well you can solder the potentiometers to the PCB.
Switch
You can switch SW2 via a standard internal or external SPDT switch. You should connect it like this:
Pots drill holes 7 mm
Switch drill holes 6 mm
Footswitch drill hole 13 mm
Jacks drill holes 10 mm
DC jack drill holes 12 mm

Epic Polar Boost v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
8
Off board wiring
Ring
Sleeve
Tip
Cathode (short leg)
Input
Anode (long leg)
Tip
Sleeve
Output
R11 is a 4k7 resistors. You can change the value depending on the type of LED you use but 4k7 is safe
enough for almost all LEDs @9V.
Note that the diagram is using star wiring for the ground connection. The sleeve of the output socket
is not connected on purpose. It does however require a good contact between the output socket and
enclosure to work. If this is not possible then connect the sleeve of the output socket to the sleeve of
the input socket.
You should use Switchcraft/Neutrik type metal chassis sockets. When using plastic, you will need to
connect the input socket sleeve to the output socket sleeve!

Epic Polar Boost v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
9
Modifications
Charge pump
If you want to leave out the charge pump then do not solder C8, C9, C10, D2, D3 and IC1. You must
solder a jumper between pad 1 and 2 on SW1 like this:
You could also change D1 back to a 1N4148 like the original. D1 has no tonal function so it would be
for optics/purism only.
Tone section
This is the interesting part and yes we are going to get a bit techy. Let’s start by a simple explanation
of the original tone part in the boost.
First of some EQ definitions:
Bass 60 Hz - 250 Hz
Low Mids 250 Hz –500 Hz
Mids 500 Hz –2kHz
High Mids 2 kHz –4 kHz
Treble 4 kHz –6 kHz
R5 (1k), R6 (15k) and C5 (3n3) form a fixed high cut/low pass RC filter with a cut off frequency of:


        
Note: R5 and R6 are in series so R = R5+R6 = 1k + 15k= 16k
So the original effect cuts off the top high mids and treble part of the signal.

Epic Polar Boost v1.0
Manufacturers and product names are mentioned solely for circuit identification, and where applicable their trademarks are the
property of their respective owners who are in no way associated or affiliated with the author. No cooperation or endorsement
is implied.
10
When you switch the bright switch on (SW1B) the resistance is cut to 1k since the switch bypasses
R6. So the cutoff frequency changes to:


       
So now the signal cuts off in the very high treble section which is almost not audible, but something
else also changed.
By lowering the resistance the gain of Q2 also changed! The effect is now brighter and also a bit
louder (approx. 3db).
By adding a tone control to the effect you can change the bandwidth of the cut off frequency.
Mark Hammer introduced the “Stupidly Wonderful Tone Control” (SWTC) in 2005 which combines a
simple adjustable RC filter with the ability to keep the gain constant. This is done in the optimized
version of the boost by introducing P2 (B50k). If you want to remain close to the original boost but
still want to be able to change the cut off frequency, I changed R6 to 22k.
This way the 50 pot and 22k resistor in parallel give 

 
which is about the same
as R6 in the original. Now the tone control gives you a sweep between 3kHz and 48kHz while not
changing the level of boost while turning the knob! The bright switch (SW1B) will act a bit different
than the original as is will take out R6,P2 and C5 all at once, just leaving R5 in the circuit. This way
there is no RC filter left, just a small extra boost. Changes are that high frequency interference is
more audible when you switch SW1B on.
If you use a jumper in J1 the filter will act more like the original and will cut some volume when you
turn it up (=cut highs). However the bright switch will function exactly as in the original. To end this
lecture, some suggestions to make the tone control even more usable:
Author
R5
R6
P2
C5
fc min
fc max
LG
1k
22k
B50k
3n3
2,9kHz
48kHz
LG
1k
NC
B25k
3n3
1,85kHz
48kHz
LG
1k
NC
B50k
3n3
945 Hz
48 kHz
LG
1k
NC
B100k
3n3
477 Hz
48kHz
F Briggs
470R
NC
B10k
10n
1,5kHz
33,8kHz
NC= not connected
NB. When using J1 “jumped”, the higher P2 the bigger the volume drop when turned down.
Transistors
The original uses a 2N5457 as Q1 and 2SC1815 as Q2. A lot of people prefer a J201 as Q1 since it has
a bit more gain and a 2N5088 as Q2. Check the pinout of your transistors before you solder them!
The correct pinout is printed on the PCB and insert the transistors accordingly. You can always
experiment with other types of transistors and if you find better combinations, please let me know!