Ross Phaser mod locations on Tonepad CB...

[mothercruncher]

Hi all,

I'd be grateful for a second look at my plan, if anyone has a minute to spare.
I'm putting together a Ross Phaser using a TP board (absolutely awesome quality board, by the way).

Using this board, and primarily Mark Hammer's advice on modifications, I've put together a housing design;




... and am now just looking at what goes where for the build.


I got the various mod places marked out on the schematic but am scratching my head a little for the actual board.



The read and brown mods aren't terribly clear- I'm planning to switch out the caps for the univibe stuff (red) via switches and then, for the phase filter I run the connection to ground where the brown squares are?


It's (only slightly) educated guesswork- I'd appreciate it if anyone could confirm things before I heat the iron up

[mothercruncher]

OK, no problem, I'll get stuck into it and see what works!

[oskar]

The only thing I can confirm is that your housing is very good looking...   

[gigimarga]

All the mods are located correct (i've just finished one couple a weeks ago).

[MarcoMike]

1st of all: great graphic on the box!

univibe mod: you change the value of 4 capacitors-> you're using 2 dpdt switches, 1 half every cap. so I would wire every couple of caps (phase and vibe caps) together on one side and to the board. the other "sides" go to the external lugs of the switch an the central goes to where the cap lug should.... not clear, uh?


board1____________
              |                   |
          cap ph          cap vib     
              |                   |
            [ *        *        *]   switch
                         |
board2-----------

and this is for each capacitor

then the filter mode has to switch one side of this device (board1 or board2) to ground instead of connecting it to its board connector. so substitute board2 for instance with the central lug of a switch. one side goes to ground, the other to the actual board2 connector. but you can only switch 2 capacitors with a dpdt switch. you chose which ones!


board1____________
              |                   |
          cap ph          cap vib     
              |                   |
            [ *        *        *]   switch ph/vib
                         |
                         |
            [ *        *        *]   switch ph/filt
              |                   |
              |                    \____ground
board2---

I hope this was clear enough... and pay attention on which "side of the cap" you send to ground instead of it's board connector. they're not the same! (only one is correct

[mothercruncher]

Thanks very much for your help everyone

That diagram totally solidified how I was going to put together both a uni and phase filter option MarcoMike.


I spent this weekend on the insides and have an extremely nice sounding Phaser in my hands. Such a gorgeous smooth liquid sound- this is a keeper.

I didn't get on with the 10k width control and ended up going with Mark's other suggestion of a 180k resistor in series with a 500k pot in place of the 270k resistor next to the 'rate' off-board wiring. I'm ditching the straight level control too... level on a phaser, what was I thinking... I'll just set parity internally and re-appropriate that dial as a level-of-wet-and-dry-mix control. Seamless


I've yet to play with all of the option but I'm getting some really interesting sounds, strange volume swells and whatnot, with the tremolo switch on, stage 3 and 4 of the phase shifted and the two combinations of phase/uni cap values. A very satisfying build.

[mothercruncher]

Oh, by the way, I've updated the "locations" graphic above in case it's of use to anyone else.

[oskar]

I did some simulations on the ross phaser LFO for a depth mod with DC shift, with MarcoMike bravely by my side...   
http://www.diystompboxes.com/smfforum/index.php?topic=73243.0
I'll try this out the next time I unpack my electronic stuff, which could be a while unfortunately.

[MarcoMike]

In this period I was quite busy too... all my current projects are unfinished 

I hope we could find finally a way to take this pedal one step further...

[mothercruncher]

Have I got this right?



I'm attempting to add a "phase amount" dial to the 27k tremolo switch. So, switch off the whole thing is bypassed, switch on the pot comes into play and offer 24k- 124k resistance. And it's the 27k purple resistor indicated in the initial post?

I know this is rudimentary, but I've only been building for a few months

[Mark Hammer]

If you're aiming for a "phaser intensity" control (where the amount of wet signal blended is increased and decreased), yes that's it.

[mothercruncher]

Brilliant, thanks Mark.

[Mark Hammer]

You're welcome.  And now that I can finally see the photobucket picture you posted, I too have to compliment you on the lovely graphics of your chassis.

Just a note about the phase-filter mod.  There are two ways you can do it.  One is to leave the cap's connection to pins 5/7 or 10/12 intact and route the other end either to ground (for lowpass) or the the 27k input resistor.  The other way is to leave the 3300pf cap connected to the 27k input resistor and connect pins 5/7 (or 10/12) to either the free end of that cap or to a different cap connected to ground.

Pros and cons....

Some may find that having the 3300pf cap to ground provides too much lowpass filtering for their tastes (i.e., too low a cutoff), in which case a smaller value (I made one with either 2700pf or 3000pf caps instead) for the lowpass function may be more to their liking.  The advantage is that as the filter sections sweep lower, the sound doesn't get quite as muted.  The disadvantage is that it kind of makes the board even more cluttered than it ought to be.  Your choice, though.