MXR Phase 90 (a tonepad project) build report

[mugan]

Yeah! It worked almost at first try, i did just a little short connecting the input to +9v  :roll:  but after that it worked fine! I've used first 4 non-matched 5952's and then 4 matched. The difference in sound is noticeable in terms of quality and "swooosh". I used three ne5532 instead of tl072's and 2 elecs in parallel to obtain a 15uF cap. I also modded the pcb from www.tonepad.com (great project as usual) to install a level pot (100k lin) and a intensity pot (500k lin) (it's all written on the build reports, anyway).

I like very much this pedal, it's so much fun!

The only "negative" thing is that the rate pot (500k rev log) acts only in a small part of the coarse, let's say a 25%, and in this part a very little movement determines a big change in the output. I'd like to fix this but i have no idea on how to do...

[petemoore]

You can 'adjust the pot to act differently with fixed resistors,
 I'm having troubles seeing Tonepad stuff.
 What size pot is used on the build, and how many lugs are connected?
 You can push resistors 'on' [steady hand there] the pot lugs, 1 to 2 , 2 to 3 or 1 to 3 etc. to simulate the effect of a smaller pot and taper
 or...break the connections from lugs 1 and 3 and insert resistors there for higher resistances.
 Resistors + pot...you can basically get any resistance you want, but a 500k will only make 500k of it variable...this might be fine for a PHaze 90...I don't know what I used for speed on mine [I just pulled it from some long wires, and plan reboxing it 'soon's the paint dries], but my speed control is a little bunches up at one end of the pot travel...perhaps I should be doing some tapering also...actually I kind of like it this way, I think theres enough speed difference with this limited travel that I could directly couple a Wah foot treadle to it and have an 'accelerator' PH90.

[petemoore]

I used a couple 5532's and a TL072 on mine, I love the sound...the sweet swoosh is cool but even just the sound of the 90 [in slow mode]...smoothie sounding...hard to put into words, but I sure like hearing and playing it.

[Fret Wire]

The only "negative" thing is that the rate pot (500k rev log) acts only in a small part of the coarse, let's say a 25%, and in this part a very little movement determines a big change in the output. I'd like to fix this but i have no idea on how to do...

That's odd, because the 500k rev. log is what has always been used in the P-90. That taper is what  gives it a nice range of adjustment. Maybe the intensity pot is affecting it's adjustment.

[vdm]

this might sound silly, but try reversing lugs 1 and 3, and see if this helps. it will obviously reverse the direction you turn the pot, but if this does help to smooth the transition out it might mean your pot is actually be a mis-labelled log taper pot, instead of the reverse log.

just a thought....

trent

[mugan]

:roll:  :roll:  :roll:  i have wired it counterwise..... EHEHEHEHEH

Now it's fine! thank you!