Electro-Harmonix Deluxe Big Muff Pi Instruction Manual
WARRANTY INFORMATION
Please register online at http://www.ehx.com/product-registration or complete and return the
enclosed warranty card within 10 days of purchase. Electro-Harmonix will repair or replace, at
its discretion, a product that fails to operate due to defects in materials or workmanship for a
period of one year from date of purchase. This applies only to original purchasers who have
bought their product from an authorized Electro-Harmonix retailer. Repaired or replaced units
will then be warranted for the unexpired portion of the original warranty term. If you should
need to return your unit for service within the warranty period, please contact EHX Customer
Service at 718-937-8300 or info@ehx.com for a Return Authorization Number. Along with your
pedal, please include a brief description of the problem as well as your name, address,
telephone number, copy of your receipt, and a check or money order.
United States - $12
Canada - $15
Europe and outside countries - $25
Ship to:
Electro-Harmonix
C/O New Sensor Corporation
55-01 2nd Street
Long Island City, NY, 11101
Attn: Service Department
Please make checks/money orders payable to New Sensor Corporation.
To hear demos on all EHX pedals visit us on the web at www.ehx.com.
Email us at info@ehx.com.
Deluxe Big Muff Pi
Congratulations! You have just purchased the ultimate harmonic distortion-sustain device
developed to date for the electric guitar player: the Deluxe Big Muff Pi! We started with our
beloved NYC Big Muff Pi and carefully added select new features to create a versatile distortion
that is extremely musical sounding. Please review this manual to learn the unique potential of
the Deluxe Big Muff Pi.
Features Include:
Big Muff Knob Layout – familiar Sustain, Tone and Volume controls
MIDS EQ – fully parametric MIDS EQ includes variable frequency sweep, boost or cut
level control and switchable Q or bandwidth amount
Footswitch for MIDS EQ –turn on the MIDS EQ circuit with the stomp of your foot
Gate – remove unwanted hum
Attack –preserves pick attack with an enhanced version of your dry signal
Bass Boost – switchable bass boost
Expression Pedal Input – sweep the frequency of the MIDS EQ with your foot
True Bypass
The Deluxe Big Muff Pi feature set is a culmination of ideas Mike Matthews has always wanted
to see in a Big Muff plus suggestions from many friends of Electro-Harmonix. The MIDS EQ
allows tonal shaping of the Big Muff distortion like never seen before, the GATE function lends
itself to playing the Big Muff in new ways providing blasts of fuzz when you play and silence
when you don’t, the ATTACK control adds definition to chords and riffs without getting in the
way of the Big Muff’s original tone, and BASS BOOST brings back some low end when TONE is
turned up to its treble settings.
-CONTROLS -
VOLUME Knob – Works as a master volume control for the entire pedal.
TONE Knob – Provides a range of sounds from high treble to deep bass. As you turn the TONE
knob clockwise, treble increases and bass decreases.
SUSTAIN Knob – As in the original Big Muff Pi, adjusts the amount of sustain and distortion.
BASS BOOST/NORMAL Switch – When set to NORMAL, the Big Muff circuit is identical to our
NYC Big Muff that we currently manufacture. Flip the switch up to BASS BOOST and the volume
level of bass frequencies through the Big Muff circuit increases. Although the BASS BOOST
function can be subtle it is most useful when TONE is set above the center, 12 o’clock position.
ATTACK Knob – Is a volume control for the Attack effect. As you turn the ATTACK knob
clockwise the Attack volume increases. Turn ATTACK all the way down (fully counter-clockwise)
to turn Attack off.
The Attack signal path runs in parallel to the Big Muff’s circuit. The function of the Attack circuit
is to enhance the sound of your picking by applying 2 carefully chosen bandpass filters to the
input signal followed by a volume expander that ensures your pick attack is louder than the
sustained portion of the note. The Attack signal is not clean; it is usually very gritty but not
nearly as distorted as the Big Muff circuit.
GATE Knob – Turning GATE clockwise raises the Gate threshold requiring greater input
amplitude to open the noise gate, allowing your notes to be heard and your instrument to pass
through. Turn the GATE knob down all the way, to fully counter-clockwise, to disable the noise
gate.
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 130k.
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, MAudio® 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 ElectroHarmonix 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 selfoscillate, 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.
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