Holy Grail Plus Instructions

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Congratulations on your purchase of the Holy Grail Plus. The Holy Grail Plus starts with the sounds found in the Holy Grail and Holier Grail: Spring, Hall, Room and Flerb. An AMOUNT knob has been added to give the musician further control over the reverbs. 


The Spring Reverb effect is a simulation of the spring reverb found in many classic guitar amps. In SPRING mode, the AMOUNT knob controls the size of the spring reverb. The further you turn the AMOUNT knob clockwise, the bigger the spring reverb will be.  Set the AMOUNT knob to 3 o’clock to obtain the Spring Reverb found in the Holy Grail.

Hall Reverb is a simulation of the reverb heard in a large space In HALL mode, the AMOUNT knob controls the reverb time. The further you turn the AMOUNT knob clockwise, the longer the reverb time and the larger the reverb space. Using the AMOUNT control you can obtain reverb spaces from a room to a large hall. To obtain the Hall Reverb sound found in the Holy Grail, turn the AMOUNT knob to 4 o’clock.

Room Reverb is a simulation of the reverb heard in a small space. In ROOM mode, the AMOUNT knob controls the damping factor of the reverb. As the AMOUNT knob is turned clockwise, the reverb will be less damped. Set the AMOUNT knob to its minimum position (full counter-clockwise) and the reverb will be heavily damped, sounding like a bathtub reverb. Turn the AMOUNT knob to full clockwise and the reverb sounds like an open room with no damping.

The Flerb Reverb effect is made up of a reverb followed in series by a flanger. In FLERB mode, the AMOUNT knob controls the rate of the Flerb’s modulation. As you turn AMOUNT clockwise, the rate of modulation increases. To obtain the Flerb sound found in the Holy Grail, turn the AMOUNT knob to 8 o’clock.


REVERB Switch - Chooses the reverb mode. From left to right, the modes are SPRING, HALL, ROOM and FLERB.

AMOUNT Knob - The function of the AMOUNT knob changes with each REVERB mode:

SpringSpring Time/Reverb Time
HallReverb Time
RoomDamping Amount
FlerbModulation Rate/Flanger Feedback

BLEND Knob -  Controls the wet/dry mix from 100% Dry (counter-clockwise position) to 100% Wet (clockwise position). Set the BLEND to about 1 o’clock for a nice mix of both.

STATUS LED and BYPASS FOOTSWITCH -  When the LED is lit, the Holy Grail Plus effect is active, when the LED is off, the Holy Grail Plus is in True Bypass mode. Use the Bypass Footswitch to toggle between the two modes.

INPUT Jack - This 1/4” jack is the audio input to the Holy Grail Plus. The input impedance presented at this jack is 680k(.

OUTPUT Jack - This 1/4” jack is the audio output from the Holy Grail Plus.  The output impedance at this jack is 360(.

9V Power Jack - Plug the output of the AC Adapter supplied with the Holy Grail Plus into this jack located at the top of the Holy Grail Plus. The Holy Grail Plus requires 9VDC at 200mA with a center negative plug. The Holy Grail Plus accepts Boss style AC Adapters.

WARNING: Use only the 9.6VDC/200mA AC adapter the Holy Grail + comes supplied with.  Do not use any other AC adapters. Using other AC adapters, even those made by Electro-Harmonix, could cause harm to the unit, the adapter or you. The Holy Grail + does not use batteries.


Please register online at https://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 info@ehx.com 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
Email: info@ehx.com

Tel: +44 179 247 3258
Email: electroharmonixuk@virginmedia.com

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 www.ehx.com
Email us at info@ehx.com


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.


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Quick Specs
True bypass
Tough and compact die-cast chassis
96DC-200BI power supply included
Dimensions in inches: 4.0 (w) x 4.75 (l) x 2.25 (h)
Dimensions in mm: 102 (w) x 121 (l) x 89 (h)
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