User Manual
MIDS LEVEL Knob – When MIDS is engaged (LED near MIDS Footswitch is lit) the MIDS LEVEL
knob either boosts or cuts up to +/- 10dB, at the frequency set by the FREQ knob located below it. Turn
MIDS LEVEL clockwise from its center 12 o’clock position to boost the center frequency. To cut, turn
MIDS LEVEL counter-clockwise from the 12 o’clock position. This knob has a notch near the 12 o’clock
position to help identify the center of the knob’s travel. In the center position, MIDS EQ is flat; it does not
boost or cut. The MIDS LEVEL knob has no function when MIDS is bypassed (LED near MIDS
Footswitch is off).
MIDS FREQ Knob – Sets the center frequency of the MIDS EQ circuit ranging from 310Hz to 5.0kHz.
To hear the range of the MIDS FREQ knob, turn the MIDS LEVEL knob up past 3 o’clock, make sure
MIDS is enabled (LED near MIDS Footswitch is lit), then play your instrument while turning the MIDS
FREQ knob. This knob has no function if either the MIDS section is bypassed (LED near MIDS
Footswitch is off) or the MIDS LEVEL knob is set to its center position.
The MIDS FREQ knob can be controlled by an external expression pedal or control voltage (CV).
Connect the external device to the EXP jack on the input side of the Deluxe Big Muff. The position of the
MIDS FREQ knob sets the toe position of the expression pedal or maximum frequency for CV. The heel
position of the expression pedal equals the MIDS FREQ knob’s fully counter-clockwise position. Please
see EXP Input below for more on the expression pedal.
MIDS Q Switch (HIGH/LOW) – The Q switch sets the resonance or bandwidth of the MIDS EQ. What
this means is in LOW mode the EQ sounds broader or rounder and affects a larger range of frequencies; in
HIGH mode the EQ sounds sharper or peakier and affects a narrow range of frequencies.
MIDS FOOTSWITCH / LED – Engages or bypasses the MIDS EQ section. When the white status LED
is lit, the MIDS EQ circuit is active and the MIDS LEVEL and FREQ knobs can be used to produce a
multitude of different tones.
BYPASS FOOTSWITCH / LED – Toggles between effect mode and true bypass. When the red status
LED is lit, the effect is active. When the LED is off, the Deluxe Big Muff Pi is in True Bypass mode.
-I/O AND POWER CONNECTIONS -
INPUT – Plug your instrument into here. The input impedance presented at this jack is approximately
130kΩ.
OUTPUT – This is the output of the Deluxe Big Muff Pi. Connect it to the input of your amp or another
effects pedal. The output impedance at the OUTPUT jack is 300 ohms.
EXP Input– Connect an expression pedal with a TRS plug to this jack to sweep the MIDS center
frequency with your foot or other extremity. Additionally, the EXP IN jack can be connected to a Control
Voltage (CV) source using a TS plug; the acceptable range for the control voltage is 0V to 5V. Some
suggested Expression Pedals: EHX Expression Pedal, M-Audio
®
EX-P, Moog
®
EP-2, Roland
®
EV-5 or
Boss
®
FV-500L. The polarity of the expression pedal’s plug must connect the Sleeve to the heel position,
Ring connected to the toe position and the Tip connected to the wiper. The nominal expression pedal
impedance is 10k but it can accept impedances ranging from 6k to 100k. Please note: if the MIDS EQ
section is bypassed, the expression pedal is disabled.
9V POWER – The Deluxe Big Muff can run off of a 9V battery or you can use a 9VDC AC Adapter
capable of delivering at least 50mA. The optional 9V power supply from Electro-Harmonix is the 9.6DC-
200BI (same as used by Boss™ & Ibanez™) and delivers up to 200mA at 9.6 Volts DC. The actual
current draw of the Deluxe Big Muff is 22mA at 9VDC. The AC Adapter must have a barrel connector
with center negative plug. The Deluxe Big Muff accepts most BOSS® style AC Adapters. Please do not
exceed 12VDC at the power jack. The battery may be left in or taken out when using an AC Adapter.
-OPERATION AND WARNINGS -
CHANGING THE BATTERY
To change the 9-Volt battery, you must remove the 4 screws on the bottom of the Deluxe Big Muff Pi.
Once the screws are removed, you can take off the bottom plate and change the battery. Please do not
touch the circuit board while the bottom plate is off or you risk damaging a component.
SHIELDING
To achieve its long sustain, the Deluxe Big Muff Pi has a very high maximum gain. This requires that
pickups and cables be well shielded and properly grounded to avoid excessive hum when high sustain
knob settings are used.
INTERNAL TRIM POTS
The Deluxe Big Muff Pi’s MIDS EQ section has three trim pots for adjusting the following: 1) High Q
bandwidth, 2) High Q Output Volume and 3) overall MIDS EQ Output Volume. We set these trim pots at
the factory so that 1) HIGH Q mode is very resonant but does not self-oscillate, 2) HIGH Q mode is just a
bit louder than LOW Q mode and 3) when engaged, MIDS EQ creates a slight volume boost over MIDS
EQ bypassed for most settings of MIDS knobs.
We realize our settings may not be perfect for everyone. If you would like to make adjustments to the trim
pots, remove the 4 screws on the bottom of the unit and remove the bottom plate. Place the pedal knob-
side-down with the power jack facing away from you. In the upper left area of the printed circuit board
you will see three small trim pots.
Before you start: we recommend you photograph or sketch the position of each trim pot as it came to you
from the factory in case you want to go back to those settings. The factory trim pot settings vary
considerably from unit to unit.
When adjusting the trim pots use a small flat head or slotted screwdriver with a width of 2mm. Please do
not touch any other parts of the circuit board while the bottom plate is off or you risk damaging a
component.
The signal path through the trim pots goes in this order:
HI Q AMT (TRIM1) HI Q VOL (TRIM2) MID EQ OUT VOL (TRIM3)
Change HI Q’s bandwidth by adjusting HI Q AMT. The volume level of HI Q mode also changes:
increasing HI Q AMT increases HIGH Q’s volume; decreasing HI Q AMT decreases HIGH Q’s volume.
Therefore if you adjust HI Q AMT you may also need to adjust the HI Q VOL trim pot.
If you want to change the volume of LOW Q mode: 1) adjust the MID EQ OUT VOL trim appropriately
until you are happy with LOW Q’s volume, 2) compare HIGH Q’s volume to LOW Q’s volume and
adjust the HI Q VOL trim if necessary.