Ross Phase Distortion

[foxfire]

i just got this off ebay. i figured i'd post some pictures of it along with some comments. there isn't a whole lot out there on this pedal. well it's pretty cool. i spent some time reading up on both the phaser and distortion while i was waiting for it to arrive. so i know most of you out there already know these circuits pretty well. for those that don't, the phaser is pretty deep and lush. you can get some weird neat sounds from it. i haven't traced my pedal but i'm thinking that someone has played with a few values to adjust the rate pots range. with it maxed i can get some cool machine gun sounds. i was expecting the distortion circuit to be to the Taiwan version but, it's the U.S.A. version with the 2 ge diodes. so it only just gets above unity and sounds a lot like tearing paper. my pedal came with all 4 knobs. one of them had a broken socket which i was able to fix with a few coats of super glue. the pot that the broken knob went on was also broken. i'm guessing that when the knob removed shaft of the pot was pulled with it. i'll have to replace that someday if i can find one or rig a new pot to work.

i'm not sure if i should leave it stock and sell it someday or mod it for use now? as i said i like the phaser but the distortion kind of sucks. i breadboarded the circuit to make sure that the pedal is functioning as it should. and it is. so i changed some values on the breadboard and it's a good bit louder and has more bottom end. it's a common circuit so no real magic was used. i'm leaning towards modding it. rylan

                                     

[George Giblet]

> i haven't traced my pedal but i'm thinking that someone has played with a few values to adjust the rate pots range.

The distortion part looks like an MXR distortion plus.  There's plenty of mod recommendations in the archives.  See also the DOD overdrive and associated mods.

The phaser part looks like the later black Ross Phaser.

You should be able to get the schematics for each are available on the web. Here's the phaser,

http://www.home-wrecker.com/ross_phaser_black.png

The rate pot uses a C taper pot to make the adjustment smoother over a wider range.  To make the range more narrow increase R31 (at the bottom).  To adjust the frequency change the 3.3uF cap C11.

[foxfire]

what i ended up doing is going with the liquid drive mods. http://fuzzcentral.ssguitar.com/liquid.php well of course i had to change a few of the values but, it's a whole new pedal. i hate taking out the ge diodes but they sound like crap. thanks for the hints George, i had seen that schematic and the one at Tonepad. by trace i meant, i hadn't checked my pedal to see what all had been changed. i read about a few mods i may try someday but for now i really like it. i'm toiling over whether or not to add indicator leds? i saved all the parts i removed and made a list of the changes should i want to return it to stock. but drilling holes is a whole other game. i may put them in the walls of the of the cups underneath the knobs to hide the holes. rylan 

[petemoore]

  It looks like there may be room to wiggle a Jfet board [something with a touch of distortion, by the switch where the transformer isn't.
  That and a little extra attention to the Hf's...maybe a little less intrusive and can be tried outside the existing box first to see..
  Dist+'s can be fine alone too, depends to a great degree on everything else [amp/guitar].
  When I see a 'double' like that, and a nice old board, well you know what can happen when they're 'dug into'...so @@Rate...nice score !
  Especially of interest with those circuits is the actual value/sound of the HF rolloff cap across the diodes..and the diode [or diodes]...try assymetric clipping, pull a Ge and get an Si in where it was...I've managed this above board...break the Ge, clean up the leads a bit [gently] with a vaccuum, wrap an 1n4148's legs around the clean copper part of the Ge's leads, solder...you can pretty much leave the leads in place, when soldering, a teensy bit of 'side pressure' keeps the lead from just falling out the bottom of the board.

[foxfire]

i tried a bunch of different diode combinations. i ended up with 3) 1N914's. with the mods it's twice the pedal it was. i thought about playing with the second half of the 4558 and or putting a little boost in there but decided to work with what i've got for now. it big enough that i couldn't justify putting it on my board if i'm not gonna use both halves. either way like you said Pete, it was still a good score. rylan
 

[petemoore]

  That should do it ! two Ge diodes...for low volume crunch can be cool, but really limits output and doesn't 'crank' right IME.
  Even 1 Si in there opens the sound markedly.
  Nice pedal it is too...as said, those D+'s [don't have much as far as knobs for fine adjustment] but matched to the right stuff...works great.
 

[foxfire]

i had the circuit on the breadboard so i quickly wired up a booster on the second half of the 4558. so far it isn't adding enough to the over all sound to justify the work but, we'll see. rylan