Maximum voltage for Mercurial Boost?

[Alan W]

Seems like most modern Catalinbread runs 9 to 18 volts. But the Varioboost is older, and only labeled for 9v.

Does anyone have any experience with running 15 or 18 v? If not, I'm willing to be the guinea pig. It doesn't seem to me that there should be anything in this that will have a problem with the extra voltage spread. I'm always curious what changes there will be; but am just assuming this will act pretty much like a typical op amp drive.

 

[swyse]

I don't have personal experience but looking at the schematic I'm pretty sure you wont have any issues until you exceed the voltage of your capacitors or the op amps since there is no charge pump and it's all just biased using a voltage divider which is ratio based. The changes you'll see is higher headroom mostly I'd think, I'm not sure if the op amps clip in that circuit or not, but you'll see a reduction in that if they do.

 

[MichaelW]

I can try it later today as I have my Mercurial on my boost board right now. I don't see any issues provided your caps are properly rated.
@swyse there is some opamp clipping depending on where the 12db knob is set, I imagine more headroom at 18v.

 

[Alan W]

Thanks guys. I’ll crank it up. At this point I have fewer pedals at 9 volts than anything else.

In a few days, after I have a better feel for the sound, I’m going to try some OPA2134s in it. I‘m expecting that will open it up further. I’ll hold off on my build report until then. Those are my favorite op amps, until you start spending silly money. From my first listens, for clean tones, I doubt I’d be pushing the db knob past 2 o’clock; last night it seemed to live in 10:30 to 1:30, but I could see with either a bass or with trying to make my baritone a thudmeister pumping it more than that. (At which point a bit of overload wouldn’t be out of place.)

 

[Alan W]

18v is absolutely, totally possible! Just about to put up Build report, will give details there.