I recently purchased a used Holy Grail.

The spring reverb setting works wonderfully, but the hall reverb setting distorts when my volume pedal is 100% opened up. The distortion sounds like the input signal is being overdriven (close to fuzz pedal territory), however the reverb tail still sounds clean.

My signal chain is GFI Ultra pedal steel guitar —> Sarno freeloader —> Goodrich LDR2 volume pedal —> Marshall 2555. The Holy Grail is running through the fx send and return of the Marshall. Although I’m using a Marshall head I run it clean with no overdrive via the amp the majority of the time. I recently was using a Digitech RV7 reverb pedal in the same fx loop and didn’t encounter any trouble of this nature. I’m happy with the spring setting on the holy grail for now so I’m not completely SOL. I would like to experiment with the hall setting though.

I also tried the holy grail pedal out in front of another amp (6 string guitar –> Holy Grail —> Roland Cube 30X amp) and had the same problem.

I’m handy with a soldering iron so if anyone has heard of this problem and knows what to do about it I’d be much obliged for a response.