EVH Phase 90 issues?

Picked up a secondhand EVH Phase 90 from a local store. I’m new to phasers.

Sometimes it feels like there is a drop in volume, more akin to a tremolo as part of the sound. I was expecting maybe some sort of a EQ thinning/filtering through the sweep rather than an amplitude drop - am I right to expect this? Or just an idiot that doesn’t know what he is doing. I’m not sure that the effect is a bold as it should be…

I’ll try and post a clip when possible, but wanted to see if anyone had any thoughts…

The EVH Phase 90 should have an internal trimpot. If you’re comfortable with a screwdriver, you can try adjusting it.

The trimpot is not really a very tweakable parameter, it’s there to correct for variance between jfets, which are notoriously inconsistent. There’s usually a very small range where it maximizes the phase effect, and some small flavor differences inside this range. If you go outside the optimal range, the phase effect disappears or turns into a subtle tremolo.

Try adjusting it while you or a friend plays through it. Find the sweet spot and leave it there.


Thanks for the reply and the info! I’ll get on the case!

Friend? What are they? :rofl::thinking::pleading_face::cry::sob:

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I didn’t know what a phaser actually did, so I found this interesting!


I also placed it in the fx loop, which makes it a little more phasey (by phasing the distortion, rather than distorting the phasing).

I hate it when they put trim pots on the inside, why not make them accessible on the outside!

The idea is that it should be set correctly in the factory and never touched again. Both of those assumptions are easily violated. But it is usually good design practice not to give users easy access to parameters that make the pedal stop working entirely. Trimpots cost more than fixed resistors, but I imagine that’s outweighed by the cost difference of paying a human to hand-select the correct fixed resistor for each unit vs. paying them to dial in a trimpot. Otherwise, they’d just use a resistor and it would be non-adjustable.

That’s something I read about on Wikipedia. I was led to believe they were commonplace, but I have no direct evidence so maybe I should be more skeptical. The general public is allowed to edit those pages.


This is expensive because the manufacturer has to make holes in the case and carefully align them with the underlying circuit board. Holes are bad because of water and dirt ingress. If they have potentiometers in the design it is likely tweaked in their assembly process.

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“Friend” is a synonym for “looped recording of your playing” I think.


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Yes, I have a cheapo Mooer looper that just might save the day! He can be my repetitive friend for the task!