Electro-Harmonix Holy Grail Max Reverb Pedal


Reverb for the sonically adventurous

The perfect, portable reverb pedal.

  • Spring
  • Hall
  • Plate
  • Reverse
Out of Stock - 01524 410202
Free UK shipping on applicable items
  • Found it cheaper elsewhere? Contact us to see if we can beat their price!
  • Call us for experienced and friendly advice
Safe Checkout

Holy Grail Max Reverb

The Holy Grail Max shares the Holy Grail’s remarkable Spring and Hall reverbs.

Then we added a Plate reverb, with its wonderfully lush tone, and Reverse reverb for the sonically adventurous.

The Max’s multi-function control lets you adjust decay or reverse time.

With the Holy Grail Max your quest for the perfect, portable reverb pedal is answered.


– Spring, Hall, Plate and Reverse reverb
– 9.6DC-200 power supply included
– True bypass for maximum signal path integrity
– Compact, rugged die-cast chassis
– 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)


The HG Max delivers four types of studio quality reverb: SPRING, HALL, PLATE and REVERSE all designed for the discerning guitarist but also great with other instruments on stage or in the studio. Included is a newly designed analog wet/dry control which provides a constant volume curve as you turn the BLEND knob from fully dry to fully wet while also keeping your dry signal analog through the pedal.

WARNING: Your Holy Grail Max comes equipped with an Electro-Harmonix 9.6DC-200BI power supply (same as used by Boss® & Ibanez®: 9.6 Volts DC 200mA). The Holy Grail Max requires 80mA at 9VDC with a center negative plug. Using the wrong adapter or a plug with the wrong polarity may damage your Holy Grail Max and void the warranty.


– Spring Reverb is a simulation of the spring reverb found in many classic guitar amps. In SPRING mode, the TIME knob controls both the size of the springs and the overall decay time. As you turn the TIME knob clockwise, the spring reverb gets bigger and longer.

– is a simulation of the reverberations heard in large spaces such as a concert hall or cathedral. In HALL mode, the TIME knob controls the decay time of the reverb. As you turn TIME clockwise, the reverb time increases creating a larger reverberant space. Using the TIME control you can obtain reverb spaces ranging from a room to a large hall.

PLATE – is an emulation of a metal plate reverb commonly found in high end recording studios during the 1960’s and 70’s. The Plate reverb is a very smooth, tonally balanced sounding reverb that sounds great on many different instruments, especially vocals. Turn the TIME knob clockwise to increase the decay time of the PLATE reverb. When TIME is maxed, the PLATE reverb creates a very long reverb decay; holding each note for over 30 seconds.

REVERSE – Reverse Reverb is an emulation of the reverse reverb trick commonly performed in studios, where a note’s reverb fades-in, in reverse of course, before the note is actually struck. The HG Max works in real time and cannot create backwards reverb for a note before it is actually played so the REVERSE reverb in the HG Max will create reverse reverb after the note is sounded. The length of time between playing a note and hearing the reverse reverb completely fade-in is set by the TIME knob. The further you turn TIME clockwise, the longer the note will take to fade-in. For short TIME settings, the REVERSE mode can sound like a slap-back echo.


Switch Knob – Chooses the reverb mode. From left to right, the modes are SPRING, HALL, PLATE and REVERSE.

TIME Knob – Adjusts the decay time, or reverb length/size, for the SPRING, HALL and PLATE reverbs. In REVERSE mode, the TIME knob sets the length of time between striking a note and the reverb fade-in. While in PLATE mode, when TIME is set to its maximum position, the reverb decay is over 30 seconds creating a lush reverb wash with each new note.

BLEND Knob – Controls the wet/dry mix from 100% Dry (counter-clockwise position) to 100% Wet (clockwise position). As the BLEND knob is turned, the overall output volume remains nearly constant. Your Dry signal remains analog from input to output through the HG Max.

FOOTSWITCH and LED – The Footswitch selects whether the HG Max is engaged or in True Bypass mode. When the effect is engaged, the LED is lit.

Jack – This ¼” jack is the audio input for the HG Max. The input impedance is 1MOhm.

AMP Jack – This ¼” jack is the audio output from the HG Max. The output impedance is 550Ohm.

9V Power Jack – Plug the output of the AC Adapter supplied with the Holy Grail Max into this jack located at the top of the enclosure. The HG Max draws 80mA at 9VDC with a center negative plug and accepts Boss® and Ibanez® style AC Adapters. Please do not allow the power supply voltage to exceed 10VDC. The Holy Grail Max does not take batteries.