Deluxe Bass Big Muff Pi Instructions

Back to Product Page / Instructions (PDF)

Congratulations! You have just purchased the finest harmonic distortion-sustain device
developed to date for the electric bass guitar player: the Deluxe Bass Big Muff Pi! We took our
beloved Bass Big Muff Pi and carefully added select new features to create an even bigger
sounding, more versatile bass distortion. Please review this manual to learn the unique
potential of this pedal.

Features Include:

• Big Muff Knob Layout — Sustain, Tone and Volume
• Crossover Filtering — further sculpt your distorted and dry tones
• Gate — remove unwanted hum
• Input Pad — accommodate active pickups
• Blend — control the mix between effect and dry signals
• DI Output — connect directly to mixing consoles and recording equipment
• Volume — obtain just the right balance between bypass and effect
• Buffered Bypass — high quality buffer with extended low frequency response
• Direct Output — outputs your buffered dry signal for secondary signal chain

The Deluxe Bass Big Muff draws its roots from the legendary Sovtek battle-tank green Big Muff
Pi from the late ‘90s as well as from the original Electro-Harmonix Big Muff Pi from the early
‘70s. The Deluxe Bass Big Muff takes the best elements from both of these classics, employs
sonic elements that were specifically designed for your bass and gives you even more toneshaping
options than ever before.


VOLUME — Works as a master volume for the entire pedal and is capable of boosting the input
signal by 14dB above unity gain.

BLEND — This mixes between the dry and distorted signals. Turn this knob fully
counterclockwise for 100% dry signal and fully clockwise for 100% wet signal. Setting the
BLEND knob to noon yields a 50/50 mix of dry/distorted signal.

TONE — Provides a range of sounds from high treble to deep bass on the distorted effect only.
The overall tone filter frequencies were carefully chosen to enhance your bass guitar. As you
turn the TONE knob clockwise the treble response of the Big Muff distortion increases.

SUSTAIN — As in the original Big Muff Pi, adjusts the amount of sustain and distortion.

GATE — Controls the input amplitude needed to open the noise gate. As you turn the GATE
knob clockwise, the amount of gating increases, requiring a louder signal to open the gate and
allow your instrument to pass through. Turning the GATE knob down all the way disables the
noise gate function.

HPF — When CROSSOVER is engaged, the signal just prior to entering the distortion circuit is
sent through a second-order high pass filter. The HPF knob adjusts the cutoff frequency range
of the high pass filter from 125Hz to 1.75kHz, with the frequency increasing as the knob is
turned clockwise.

LPF — When CROSSOVER is engaged the dry signal is sent through a second-order low pass
filter. The LPF knob adjusts the cutoff frequency range of the low pass filter from 60Hz to
10kHz, with the frequency increasing as the knob is turned clockwise.

INPUT — This toggle switch engages 10dB of attenuation on the input to make the Deluxe Bass
Big Muff friendlier to basses with active pickups.

BYPASS FOOTSWITCH — Toggles between effect mode and a high quality buffered bypass.
When the red status LED is lit, the effect is active. When the LED is off, the Deluxe Bass Big
Muff Pi is in bypass mode.

CROSSOVER FOOTSWITCH — Turns the crossover circuit on and off. When the green status
LED is lit, the crossover circuit is active and the HPF and LPF knobs can be used to produce a
multitude of different tones.


INPUT — Musical instrument input. Plug your instrument into here. The input impedance
presented at this jack is approximately 2MΩ.

OUTPUT — This is the main output of the Deluxe Bass Big Muff Pi. Connect it to the input of
your amp or another effects pedal.

DIRECT OUT — This is a buffered output of the original bass signal. You can connect this jack
to an amplifier or different effects chain.

DI OUTPUT — Low impedance output capable of driving 600 so that you can plug directly into
a mixing console and recording equipment. This output’s signal is the same as that of the
OUTPUT jack.

9V POWER — The Deluxe Bass Big Muff Pi can run off of a 9V battery or you can use a 9VDC
battery eliminator capable of delivering at least 100mA to the 9V power jack. The optional 9V
power supply from Electro-Harmonix is 9.6DC-200BI (same as used by Boss© & Ibanez©) 9.6
Volts DC 200mA. The battery eliminator must have a barrel connector with center negative.
The battery may be left in or taken out when using an eliminator.


To change the 9-volt battery, you must remove the 4 screws on the bottom of the Deluxe Bass
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.
To achieve its long sustain, the Deluxe Bass Big Muff Pi has 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.


Please register online at 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 the appropriate office listed below. Customers outside the regions listed below, please contact EHX Customer Service for information on warranty repairs at or +1-718-937-8300. USA and Canadian customers: please obtain a Return Authorization Number (RA#) from EHX Customer Service before returning your product. Include with your returned unit:  a written description of the problem as well as your name, address, telephone number, e-mail address, and RA#; and a copy of your receipt clearly showing the purchase date.

United States & Canada
55-01 2ND STREET
Tel: 718-937-8300

Tel: +44 179 247 3258

This warranty gives a purchaser specific legal rights.  A purchaser may have even greater rights depending upon the laws of the jurisdiction within which the product was purchased.

To hear demos on all EHX pedals visit us on the web at
Email us at


Note: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:

• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.

Modifications not expressly approved by the manufacturer could void the user’s authority to operate the equipment under FCC rules.

mouse over image to zoom
Quick Specs
Pad on the input that's switchable between 0dB and -10dB ensures the pedal is optimized for use with both passive and active pickups
Blend allows a player to mix to taste the direct and distorted signals
Three outputs: a 1/4″ effect out, 1/4″ direct (buffered dry) out and XLR DI out give complete control of your output signal and sound
Foot-switchable crossover section with a variable low pass filter on the dry signal and a variable high pass filter on the distorted signal give bassists the ability to sculpt their sound
Crossover circuit, in conjunction with the Blend control, lets you keep the low-end clear and focused and the high-end bright and cutting
Built-in noise gate with an adjust threshold eliminates unwanted noise at any level
Tough and compact die-cast chassis
9-Volt battery included
Optional 9.6DC-2000BI power supply available
Dimensions in inches: 4.75 (w) x 5.75 (l) x 2.5 (h)
Dimensions in mm: 146 (w) x 121 (l) x 64 (h)
Mailing List
Sign up to receive all the latest EHX news!
To withdraw from this service, e-mail us and action will be taken within 2 weeks.
The EHX Community
Here are a few easy ways to stay informed on the latest news from Electro-Harmonix...
Forums (Discussion & Support)
Have a question, comment, suggestion? Come join the EHX Forums! You'll meet EHX staff and knowledgeable users from around the world.

Show your colors with genuine EHX tee shirts and authentic Electro-Harmonix accessories!
Get this limited-edition Day-Glo poster of the original 1968 art that inspired the Electro-Harmonix logo!

Mike Matthews stated: “The image on our Flashback Poster is of the original artwork that inspired the famous Electro-Harmonix logo. I think players who dig our pedals will also enjoy the chance to own a piece of EHX memorabilia.”
Did you know that Electro-Harmonix makes many of the world's greatest vacuum tubes? The next time you need to re-tube your guitar, bass, or hi-fi amp, be sure to insist on getting authentic Electro-Harmonix tubes.
Our new EHX Strings Electro-Harmonix electric guitar strings are custom-designed to our specifications and made in the USA by a premiere string manufacturer. Each wound string is precision wrapped with round nickel-plated steel onto a high carbon, hexagon-shaped steel core. The plain strings are made from the same high carbon steel as the hex cores. The high quality steel and computer controlled winding process results in strings that intonate accurately, are better at staying in tune and vibrate evenly for maximum sustain.
Dig it, now you can rock EHX in our new heavy-duty black hoodie! It’s emblazoned with the iconic Electro-Harmonix Flashback logo in white on the left chest and back.