Unlock 5 hidden modes on your Electro Harmonix Holy Grail Reverb
May 13, 2020
The EHX Holy Grail, a personal favourite, holds a little secret. The stock version offers you three modes: Spring, Hall and Flerb. However, the chip inside the pedal can give you more ambient goodness, 8 modes in total! Even better, it’s fairly easy to unlock the extra modes.
Let’s check it out: The 8-modes mod!
First of all, this is how it works:
Three of the pins from the chip are responsible for mode selection. Each pin can be high or low. High means you feed it some voltage, something around 5V, low means it’s tied to ground. In the stock pedal, only two of the pins are used for the three modes you get. The third pin is always high.
Now you can easily unlock the extra modes by following these steps:
ORANGE |
YELLOW |
BLUE |
Spring | 1 | 0 | 1 |
Hall | 1 | 1 | 1 |
Flerb | 0 | 1 | 1 |
Short Spring | 1 | 0 | 0 |
Room | 1 | 1 | 0 |
Ghost | 0 | 1 | 0 |
Dark Room | 0 | 0 | 1 |
Bathroom | 0 | 0 | 0 |
I’ll leave it up to you how you implement this in your own stompbox.
If you let me do the mod, I’ll add a 2P4T Rotary switch who works in conjunction with the stock mode selector to give you acces to all eight modes.
There are many ways to do this. You can simply replace the mode selector with three toggle switches if you want to keep it simple. Or if you want to go all the way, you could even add a programmable chip and a little display to scroll through the modes, because why not !?
Have fun modding your pedal!
However, if you’re not confident doing this, there’s always the option to send your pedal in to let Sonic Fields perform the 8-modes mod!
Thanks for reading. If you have any suggestions to improve this blogpost, please let me know.
Erik
Rerum Novarumlaan 140
2170 Merksem, Belgium
Phone: +32 484 27 43 00
Email: info@sonicfields.be
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