Phase 90 Mix Mod

[Sweetalk]

Hi everyone!... I just bought a Phase 90 Reissue and I want to make a mod to mix the phased signal with the clean one... How can I make it??... I search in the schematic for a resistor that mix those signals but no succes... Anyone know how to make this??...

Thanks everyone... I working on some other mods so I post them when I finish!

[Mark Hammer]

The clean and phase-shifted signal are passively mixed together via a pair of 150k resistors.  Unfortunately, where they meet is also tied to a third 150k resistor so you need to tell which 2 of the 3 are the critical ones.  Not having a board or board picture, I can't provide any visual direction.  However, the resistors in question will be tied to the output of an op-amp, which will be either pin 1 or pin 7 of a dual op-amp chip.

How to mix?  Tastes vary here.  My own preference is to include a variable level for the phase-shifted signal to produce variations in subtleness, and a switch to cancel the dry/clean signal for vibrato.  Some may find it useful but I've never personally found a reason to want to have, say, a mix of 70% wet/30% dry.

So, for one of the resistors (the dry side), a SPST toggle that lifts one side of the 150k resistor will get you vibrato.  For the other, use a 120k fixed resistor and a 250k pot (lin or log).  Since the fixed resistors are 5% tolerance, use of a slightly smaller value fixed resistor plus large pot will let you nail a perfect 50/50 mix for maximum effect, plus increase resistance (via the pot) to trim back the phaser intensity.

[Sweetalk]

Thanks Mark!!... I tried taking out the 150K resistor and putting a pot, in one of the 150K notice a change of volume, in another one a change in depth or something like that... Here are some gut shots, if you can guide me i'll be really pleased (sorry about my bad english)

http://i126.photobucket.com/albums/p105/Sweetalk_06/Phase_90_2.jpg

http://i126.photobucket.com/albums/p105/Sweetalk_06/Phase_90_1.jpg

Thanks!!!

[RedHouse]

Wow, I see they'e using those cheapie X-wing switches.

[Sweetalk]

Wow, I see they'e using those cheapie X-wing switches.

Yeah... they are very crappy... too soft for my taste. The pot isn't Alpha... I've been looking the PCB and the FET's are marked... but three with purple-white-purple and one with blue-green-blue, looks strange to me... Isn't the four that have to be matched??, btw it sound awesome like this...

[Sweetalk]

Well... I tried what Mark said... I found the 3 150K resistors, one connected to the output of an op-amp.... I lifted it and got vibrato... PERFECT...

Now let's look for the another two... Found the another one to the output of another op-amp... I changed it for a 120K resistor and a 100K pot in series (I tried several values...), when i plug everthing it doesn't worked at all... I have no phaser, no vibrato, just clean and low output guitar... Moving the pot doesn't affect the sound at all...

I Connected like this:


Op-amp output ---> --|120K|--- |  |--| ---> to PCB
                                               1  2 3
                                                POT

1, 2 and 3 are de pot lugs... 2 it's center, 1 and 3 the sides... Solder togheter 2 and 3 and connected to PCB... I'm doing it wrong??... Here's a picture of the Component side of the PCB with the traces, I hope'll someone have an idea of what could be...

http://i126.photobucket.com/albums/p105/Sweetalk_06/Phase_90_3.jpg



Thanks!!!

[Sweetalk]

Hi folks!.... I been thinking about this and came out with this Idea... For mixing the signal use a pot like a volume for clean and phased signal individually... If the phased signal it's on volume 0 I will have the vibrato (I hope)...

Here is a little schem for this, only shows a pot for the clean signal, I thought to put a double pot to vary both signals at once.

http://i126.photobucket.com/albums/p105/Sweetalk_06/Phase_90_mix.jpg

Is this correct?

Thanks!!

[dv8]

Not to answer your question, but..

You can replace the 1M resistor going into the trim with a 1Meg pot.  I think its a "depth" mod.  I did this on my build and it is quite useful.  Sometimes a little phase is enough. 

-brian

[Sweetalk]

Hi!... I tried what mark said but when I turn the pot it gets a distorted phaser... nothing really usefull... I'm trying to figure out another way to do this... any ideas!?!?

[blanik]

So, for one of the resistors (the dry side), a SPST toggle that lifts one side of the 150k resistor will get you vibrato.

do you mean this mod will actually produce a real vibrato effect? (as opposed to tremolo??) i've been using my old Phase 90 for a pseudo tremolo effect when playing on a borrowed amp from time to time but i never really like it... but i shure would like a vibrato effect!! (anyone has soundclips of this Phase 90 "vibrato"?)

could this mod be done on my older mxr (mid-70s, non script, 6 ICs in it...)

R.