Boss OS-2 Distortion Appreciation

[WGTP]

Take a Ratish/Ds-1 distortion with a big mid-range notch and combine it in the same pedal with a Tube Screamerish/SDS-1 distortion with lots of mids, add a blend/color circuit and TS/SDS-1 type tone control and your ready to rock.  The Color control is what makes it so cool.  You can go all the way from soft fat 80's TS/SDS-1 type tone with asymmetrical distortion to modern metal Rat/DS-1 symmetrical distortion tones with a notched mid-range OR ANYWHERE IN BETWEEN.  The Color control pans between the two different distortions so it not only works as a mid-range control, but also varies the type of distortion.  With a 50/50 mix most of the highs and lows come from the Rat/DS-1 stage and the mids from the TS/SDS-1 stage.  It uses the lowly 1458 IC.  Most of the standard Rat/DS-1 or TS/SDS-1 modifications should work.  It's also a good source of circuit bits, like the midrange notch or blend circuit.  

I wish it was purple instead of yellow.

http://www.freeinfosociety.com/electronics/schemview.php?id=163

[thejoe]

I've got one that I loved until it stopped working. Now I've been hoarding parts out of it.

[ayayay!]

Whoa Nelly!  I had an OS-2 schem, but it's only a small stage of this (DS-1/Rat side.)  I didn't know this was such a cool design with that color knob.

So I have a question.  In the DS-1 stage NFB, there's a 10uF cap there next to the drive control.  (One of the circled areas)  What would that accomplish?  I'm guessing it's going to retain more of the lower distortion signal, especially at low drive settings, correct?  

I'd also think C18 on that should be 4.7uF, not .47uF. 

I also forgot about "twin" gain rolloffs on that stage.  Very interesting.  I've got a design I've been working up at home, and this may be just what it needs.  

Thanks for sharing.  

[asatbluesboy]

I learned to associate it with the nasty Placebo sound, but it does look interesting.

[WGTP]

I haven't verified this schematic, mostly just pointing out the overall concept.  C15 10uf cap, I have seen in some other designs, but I'm not sure the purpose.  C18 .47uf seems about right.  This is the Ratish part with the double RC network to ground from the FBL.  4.7uf would be too large with a 100 ohm resistor.  It's interesting that Boss didn't exactly clone the DS-1 or SDS-1 but made variations to emphasize the difference between the 2 for more range with the Color control.  It would be simple enough to mod them to the original DS-1 or SDS-1 values or some of the other mods around.

I thought the Color control might be helpful for those that are interested in Blending circuits.

My son was sort of using the Color control like a time machine.  Playing classic rock at around 50% of the color knob and new metal at 90%. 

[ghostsauce]

http://ghostsauce.net/random/Boss%20OS-2%20-%20Schematic.jpg
http://ghostsauce.net/random/Boss%20OS-2%20-%20True%20Bypass.gif

Just posting these schematics here for future people searching for it - it was a real pain in the ass to find.

Anyways, yeah I've got an OS-2 that I use as my primary source of OD. I've got it cranked 100% to the OD side, and have the gain up to something like 5/12.. I love it, but I'm soon hoping to swap it out for an OCD.. since I have the OS-2 and a son of screamer built into the same box, and I (like everybody else out there it seems, lol) want a more transparent OD. The OS-2 sucks at that, but it has served me well for 5+ years ^^