Electro-Harmonix OP-AMP-BIG-MUFF Instructions

Op-Amp Big Muff Pi

Congratulations on your purchase of the Op-Amp Big Muff, our faithful re-creation of
the late ‘70s circuit. The circuitry of the Op-Amp Big Muff – sometimes also referred
to as the IC or V4 Big Muff – differs from the traditional transistor-based Big Muff
circuit in that it uses operational amplifiers (op-amps) to achieve its signature
sustaining distortion sound. With widely-sweeping tone controls and a character all
its own, the Op-Amp Big Muff will surely be a formidable addition to your sonic
arsenal.

OPERATING INSTRUCTIONS

VOLUME Control – Sets the output level

TONE Control – Provides a range of sounds from high treble to deep bass. As you

turn the knob clockwise the treble increases and bass decreases.

TONE Switch – Removes the TONE control from the circuit. This switch has been
improved over the original Op-Amp Big Muff in that the volume remains the same in
both positions.

FUZZ Control – Adjusts the amount of sustain and distortion

Footswitch & Status LED – When the LED is lit, the Big Muff effect is active. When

the LED is off, the Big Muff is in true bypass mode. The Footswitch toggles between
effect and bypass modes.

INPUT Jack – This ¼” jack is the audio input to the Op-Amp Big Muff. The input
impedance presented at this jack is 55 kΩ.

AMP Jack – This ¼” jack is the audio output from the Op-Amp Big Muff. When the
Big Muff is in bypass mode, the AMP jack is connected directly to the INPUT jack.

9V Power Jack – The Op-Amp Big Muff is powered from a 9V battery or you can
use an optional 9VDC AC Adapter capable of delivering at least 25mA to the 9V power
jack, such as the EHX9.6DC-200. The AC Adapter must have a center negative plug.
The battery may be left in or taken out when using an AC Adapter. The Op-Amp Big
Muff has a current draw of approximately 5mA at 9VDC.

We recommend the Electro-Harmonix US96DC-200BI AC Adapter to power
your Op-Amp Big Muff.

CHANGING THE BATTERY

To change the 9-volt battery, you must remove the 4 screws on the bottom of the
Op-Amp Big Muff. 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.

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 the appropriate office listed below. Customers outside the regions listed
below, please contact EHX Customer Service for information on warranty repairs at
[e-mail] or [phone]. 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, RA# and a copy of
your receipt clearly showing the purchase date.

United States & Canada Europe

EHX CUSTOMER SERVICE JOHN WILLIAMS
ELECTRO-HARMONIX ELECTRO-HARMONIX UK
c/o NEW SENSOR CORP. 13 CWMDONKIN TERRACE
55-01 2ND STREET SWANSEA SA2 0RQ
LONG ISLAND CITY, NY 11101 UNITED KINGDOM

Tel: [phone] Tel: [phone]
Email: [e-mail] Email: [e-mail]