Phase 90 univibe question

[manson]

Hi all,

I have a MXR Phase 90 that I'd like to do the Univibe cap mods on. I know the values to use (0.015uF, 0.22uF, 470pF, 0.0047uF). But exactly which caps on the board are the ones that I need to replace?

Please have a look at the photo's I took of the board. Can someone point out which cap is which? Thanks!

http://i113.photobucket.com/albums/n236/hoppekee/phase90-1.jpg
http://i113.photobucket.com/albums/n236/hoppekee/phase90-2.jpg

[jonathan perez]

check out indyguitarist.com, Wampler has those mods...come to think of it, i did that mod!

now if only i can find those guts ....

[Seljer]

I believe it'd be C1 -> 0.015uF, C3->0.22uF, C6->470pf and C9->0.0047uF

http://aronnelson.com/gallery/Schematics-etc/MXR_Phase_90?full=1
http://aronnelson.com/gallery/Schematics-etc/phase_90_board

[manson]

Thanks, those links are great! What kind of capacitors would be best suited for this job?

[Seljer]

I'm not good with capacitor types but some kind of polyester film/mylar are the most common ones for anything between 1nF and 1uF. The common "greenies" (like on your one) and the brown ones (in the image of the board with the parts labelled) work fine. There are also the various box shaped ones, whatever they're made out of, but they fall in the same group.

For the 470pF one you might want to use silver mica cap, since the otherwise cheaper common ceramic capacitors are known to not sound good in audio circuits (they add a bit of their own distortion)...but both types should work