Perfecting the SoScreamer (with schem)

[Dave Z]

Well I'm done and I'm pretty jazzed...I had the goal of replicating either the F*lltone F*lldrive or my Barber pedal in my first build and I figured out how to do BOTH of them....in one pedal. Here's the scoop:

1) The F*lltone has a nice mellow musical sound, so I wanted to have a couple germanium diodes in the feedback loop across from a silicon (asymm clipping). Also, reducing the Drive resistor allows very low drive settings

2) I also liked the symmetric, all-silicon drive of the Barber, so I also wanted 2 silicons across from each other (symmetrical clipping).

So, to rectify 1 & 2, added an on-off-on switch, so I can switch between either the two germaniums or a silicon...one silicon is always in the feedback loop...the "off" position is like a comp cut, but with one diode still in the loop you get some cool harmonics, sounds pretty awesome. Loud, though, great for hammering the front of a tube amp!

3) For full range sound (not that bee in a box sound my SD1 gets) used larger input & fdbk loop capacitors.

4) The F*lltone and my original build had lousy tone ctrls...unless it was full open, sounded like mud (not a big deal on a homebrew but the $200 F*lltone had a useless tone ctrl!)...how to fix? Well, you can remove C4 (in Jack O's SOS schem) but that's too much hash..instead, I put a trimpot between C4 & ground, so you can dial in extra treble. A 560 pF cap bypasses to skim off the real high hash. Result is a useable tone control - you can crank it for a bit of treble boost, or turn it down & get tuneful mellows.

This is way cool...try this: bridge PU, tone cranked DOWN, drive & tone up on the Screamer, lots of treble in the amp...sounds like that lo-Fi stuff like some folks do with a transistor radio as an amp.

That's about it, I have a schematic if you're interested in my Yahoo briefcase under "StompProjects" folder..got a couple pics there (but before I added the switch for the diodes).

http://briefcase.yahoo.com/fenderelectric

Frankly I think this is about as good as the screamer design gets...captures the F*lldrive vibe and the cranking nasty Barber Direct Drive sound as well. I've been going crazy playing with all the sounds I can get out of this since I finished it yesterday.

[petemoore]

I suppose I'm up for another TS try!
 I tried a couple, but never got the tone knob to work right, and always opted instead for use of the SD-1 clone.
 I'm not sure I ever really got a TS done completely 'right' enough to state an 'entirely conclusive' opinion, if there is such a thing.
 Did you leave the buffer sections out of your build?

[Dave Z]

Hi Pete, correct, no buffer sections, just the Son of Screamer with some mods. The SD1 definately has a more useful tone ctrl than the stock Son of Screamer (and I may mod the SD1 I have to see if I can get rid of that "guitar in a vacuum hose" sound!) but the additions I made resulted in a much more useful control.

[Lonestarjohnny]

Nice Build, I'm a fan of the T/S,  there were some good tone's to be had with the T/S & F/D but you also found the thing's you listed in your dislike colume, sound's like you found the cure for them, I;d like to try this out if you don't mind,
JD

[Dave Z]

Hi JD, the whole point of my doing up the schem as a PDF was to share a bit with the community. I learned a lot, wanted to add something. Good luck with your build.

[stm]

Congratulations. Nice & simple.

My only mods would be to increase the gain pot to 1Meg LOG, cut R2 in half and double C3 (so as to keep frequency response identical), in order to have more available gain, just in case.

Gotta try it!

[petemoore]

(and I may mod the SD1 I have to see if I can get rid of that "guitar in a vacuum hose" sound!)
 ...excellent analogy...now I know it's not just me/my SD-1.
  Tho it is nice [SD-1] for those gigs where the "Fuzz Haters Club' hangs out...just about "enough gain to make lead playing fun, not so Fuzzy as to upset sensative ears"
 Thanks to Dave Z. for sharing, and I will have a build report hopefully very soon! ! !

[petemoore]

Starting it off...
 Nice big piece of perf with room on both ends for [?], or to be cut off later.
 R9:   10k ..for the V divider
 4700k = 4m7 Large there, a departure from the TS Schem. I should be able to find one of those.

[Dave Z]

Mea culpa, screwed the pooch there, had mislabeled R3 and misnumberd others as I had had one more resistor in there....Schem fixed in my Briefcase.

BTW on the gain pot - one reason I went with 500K not 1M is that I wanted more control at the low-gain settings...kinda liked the f*lldive for that.

[petemoore]

Here's something I think I can use1
 This thing sounds great!!!
 I Have an N5532 in it [from the '1rst' TS build], and it is sweet sounding.
 I had to use a 10kB for the tone knob, even still it's working much better than #1's, somehow, now I'm having no troubles with setting the voiceing, which is very nice, and N/P getting the high end!!!
 I used the 386 method to set 1/2v.
 I used a 10K pot to set OA 2's gain, but thinking of tagging something say between 4k7 and 10k on it so OA 2's gain can go higher...it sounds like it probably could w/no troubles.
 I used a 250k for the Volume Pot.
 All the controls working good, the Harmonics knob does a fine job retaining the high end content.
 I [dohh] hooked the input to Pin 5, [dohh] then swapped the usual wiring of two OA's, actually it seemed easier and maybe a little neater having swapped my ordinary OA positions. On perf of Course...
 Box :roll:  :twisted: ?

[Dave Z]

Hi Pete - glad it's working for you.

So what's the effect of altering the second stage gain? can you describe?

I've wondered whether you could get a clean boost by doing that -- switch out the diodes, adjust "drive" and 2nd stage gain for a clean boost?

[aron]

Dave,

Thanks for your contribution on this topic.

VERY COOL!

[Dave Z]

Wow, a "VERY COOL" from Aron, that makes my day

Off to more mundane tasks....

[petemoore]

That resistor going across just under the second OA....I turned that into a 10k pot + 12k, right now the knob is set for less than full.
 I was just playing with it through a couple L.GEMkII's  [less than 2w ea.]stereo echoverb, it went
 Comp. [on or off], Alexa, 12ax7 RV3 [which splits signal] to each MkII...
 Strat and Les Paul sound just wonderful, mongo boost if needed, Low Noise [5532 I think did better than TL's I tried], I have great confidence that the big amp will like it.
 This one has N/P at all getting the highs up, between the 5k and the Tone Knob, I'm getting more than enough control, very usable settings...from very bright to thick mudness .
 So Thank's for sharing, Cave Z, I'm sure you're liking it as much as I am.