Question for people who have added a depth pot to the phase 90...

joelap · February 12, 2006, 12:02:38 AM

...where the hell did you put it?!

There's almost no space inside this thing! I think I could barely fit a mini DPDT switch on the right side of the PC board to the right of the pot... anyone add a depth pot successfully?

Another idea I had, is it possible to remove two of the stages via a switch to switch it to sound like a phase 45?

joelap · February 12, 2006, 04:31:11 PM

...anyone?

Mark Hammer · February 12, 2006, 07:27:35 PM

You can pretty much select between different tap points on virtually any phaser. All you need to do is route the 150k mixing resistor that normally takes the output of the 4th phase shift stage to the output of the 2nd stage. The whole thing can be done with a SPDT toggle that ties the 150k resistor to the one output or the other. No need to bypass anything. .The thing you'll need to keep in mind, though, is that the feedback is still coming from the last stage. So, you'll get a single notch but a different sort of regeneration sound than you'd get with a 2-stage unit.

joelap · February 12, 2006, 08:09:31 PM

I sort of see what you're saying... forgive the newbie in me. If I was looking at the schematic below, which R are you referring to... R29? I understand what you are saying but not entirely certain as to how I'd go about implementing it. Have one output of the SPDT send the signal through R29 and back into the path, but the other output... would it be a straight wire with no resistor into the path or would I be essentially removing R29 and leaving it as an open circuit? I'm still new to this so I hope I'm making sense and not babbling...

EDIT: I added the switch into the schematic using MS Paint as to what I think you are saying... is my diagram below what you are saying I should do? Thanks a lot!

joelap · February 13, 2006, 07:46:00 AM

Bump for Mark Hammer

Mark Hammer · February 13, 2006, 09:43:46 AM

The "free" end of R29 is indeed where the switch will be situated. That free end will go to the common (centre lug) of a SPDT toggle. One side lug of that toggle will have a wire that goes to pin 7 of U2b, and the other side lug will have a wire that goes to pin 14 of U2d. Naturally, you will have to cut the trace that normally connects R29 to pin 7 or else the switch won't really have any effect. You won't have to make any other cuts to have the connection to pin 14 be useful.

R28 is the feedback resistor coming from the 4th stage. If you wanted, you could use a DPDT toggle, and use one half to select where you tap the phase signal, and the other half to enable/disable the feedback.. This would give a "truer" P45 sound. To do *this*, you would need to cut the trace joining R28 to pin 13 of U2d. Next, you would have a wire lead from pin 13 and another from that newly freed end of R28. One of those leads would go to the centre lug on the other set of contacts on your toggle, The other lead would go to the side lug where the pin 7 connection is. That way, when you flick the switch in one direction, the feedbasck loop is cut and the stage-4 tap is cancelled and replaced with the stage-2 tap. Flick the switch the other way and the phased signal comes form stage 4, with the feedback path reinstated.

Alternatively (and this may be an issue given your comments about lack of space), R28 gets replaced with a 10k fixed resistor in series with a 250k pot wired as variable resistor. This will give you a broad range of regeneration sounds from LOTS to barely audible. If you can turn the regen practically off with such a control, then the toggle arrangement is unnecessary. Some folks, however, might consider it a downside to not be able to nail the stock sound.

joelap · February 13, 2006, 11:10:33 AM

Ok, Now I think I understand... does this new image do what you are trying to tell me to do? I apologize for the badly drawn wire to pin14, I am on a buddy's laptop and I'm touchpad-challenged.

nero1985 · February 13, 2006, 11:17:25 AM

ooooooooopss i made a mistake there!, yes thats how you bypass it for 2 stages

i did all this mods to my phase 90 but in the end it just DIED

i did so much to it that i just couldn't take it any more but in the process i did get to discover all the mods for the phase 90 and the actual schematic of the new phase 90!

i added a Depth pot to mine and i put it where the battery goes, to the side along with a script switch

theres also a STEP mod, by switching a resistor on the LFO i just cant remember which one, i gotta check it out again

joelap · February 13, 2006, 01:49:34 PM

Quote from: nero1985 on February 13, 2006, 11:17:25 AMi added a Depth pot to mine and i put it where the battery goes, to the side along with a script switch

theres also a STEP mod, by switching a resistor on the LFO i just cant remember which one, i gotta check it out again

Yeah, I'm planning on buying another box the same size as the phase 90, finiding a similar color paint, and drilling a hole in the side of the phase 90 congruent to the new box, and routing wires through there to go to a depth pot, resonance pot, switch for 45/90, and univibe switch... and I really hope you can find the step mod because I would absolutely LOVE to have that as an option to add on there too!

So my second diagram is legit?

News:

Question for people who have added a depth pot to the phase 90...