advanced tube screamer

[cbriere]

I want to design this:
Tube screamer based overdrive +
1-more transparent ,
2-add a indepandant boost circuit in same box for more output during solos
3- add a second stage to have LED to ground clipping adjustable range from clean to hard clipping.
4- add bass, treble tone stack.

so the controls would be: OD, DIST, B ,T,OUTPUT, boost output 
footswitchs: BOOST ON/OFF  , OD ON/OFF

any idea to put this into working circuit?
second stage to put before or after TubeScreamer?
...
comments invited. christian

[Jaicen_solo]

So basically, you want to take a TS, and make t into a whole other pedal?
Right....

Why not look at something like the AMZ Overdrive-Pro:
http://www.tonepad.com/project.asp?id=20

or the Hollis Omnidrive:
http://www.hollis.co.uk/john/circuits.html

Either of these designs will do what you're asking. I'd start with the Omnidrive as it's less of a distortion than the AMZ.

[Mark Hammer]

Jaicen is right.  The suggested changes, while not BAD, will transform it from a TS into something else.  In which case, why start with a TS as your base?  Why not start with something else?

[aron]

Tube screamer based overdrive +
1-more transparent ,
2-add a indepandant boost circuit in same box for more output during solos
3- add a second stage to have LED to ground clipping adjustable range from clean to hard clipping.
4- add bass, treble tone stack.

Substitute "feedback loop clipper" for "Tube screamer based overdrive" and you have something.

GOOD IDEA.

Here are some very simple suggestions which can be implemented in many other ways.

1-more transparent ,

OK, put back the bass (see the Shaka series for how to put more bass back in the pedal). It's the capacitor that goes to ground in the feedback loop. Add different clipping diodes (if you want).

2-add a indepandant boost circuit in same box for more output during solos

Good idea. Either increase the resistance in the feedback loop (more drive) or simply adjust series resistance before the output volume pot (for a louder, but not more distorted output).

3- add a second stage to have LED to ground clipping adjustable range from clean to hard clipping.

Actually a good idea. You can use the 2nd part of a dual op amp for the secondary clipping circuit.

4- add bass, treble tone stack.

Yeah, another good idea. See the schematics forum for some tone stacks.

I was just thinking of something like this recently.

BTW: look at this pedal:

http://users.chariot.net.au/~gmarts/pix/a_amp-odis.gif

I say, go for it!

[cbriere]

thanks for the replies and interest,,
here are my comments:
1- my boost function will be an independant section that i can use even without the overdrive.
  as an volume boost for solo.

2- THinking about it, i want to put the led clipping section before the tube screamer section.
    logicaly the tube screamer emulate an tube amp. so the added section must be put before.
    Also, I want the led clipiing section to have a range from clean to full clipping.
    Any idea how to do that???

3- I think it'll still be a advanced tube screamer because the other clipping section will have a range from
     clean to full clipping. The idea is that i want to make something similar to a setup where you would
      put the AMZ overdrive pedal before a tube screamer. All this in one pedal.

cb

[MartyMart]

You could try a dual ganged 100k pot for the "LED" section, like a "Blend" pot
100% clean at one end to 100% LED clip at the other...?
I can't quite remember the pedal, is it a VOODOO that has this feature ?
It's based on a TS-9 also and the schem is here somewhere  !
Increasing that 0.047uf cap in the TS to 0.1 gets you're bass back with
roll off nearer 330hz than 750hz on an original.

MM.

[TheBigMan]

You could try a dual ganged 100k pot for the "LED" section, like a "Blend" pot
100% clean at one end to 100% LED clip at the other...?
I can't quite remember the pedal, is it a VOODOO that has this feature ?
It's based on a TS-9 also and the schem is here somewhere  !
Increasing that 0.047uf cap in the TS to 0.1 gets you're bass back with
roll off nearer 330hz than 750hz on an original.

MM.

Indeed it is Marty, the Voodoo Lab Sparkle Drive has a blend between a TS-a-like drive section and a clean booster based round the NE5532.  I think though you could also have a "softness" pot controlling how much of the signal is slipped at each stage though.  Aron has something in the Site FAQ (not the forum) on this IIRC.

Rather than the clean/dirty blend you'll probably want the boost to be in series with the OD for a solo boost.  There's any number of cool little boosters you could fit in.  One of my personal favourites is to use Don Tillman's FET preamp (do a search, and theres a vero layout in my gallery) with an extra pot and 10uF cap tied to ground via a switch.  That way you can always maintain a high input impedence and you can switch the boost on and off as needed.  I'll be adding this to my layouts gallery very shortly.

[Melanhead]

You may wanna consider building the AMZ Mini Booster and placing it in series after the tubescreamer circuit. I built a TS-808 clone and a mini booster and have 'em set up this way. the solo boost is great! ... lot's more volume ... I've thought about putting the two circuits in one box but never bothered ....

Good luck ....

[12afael]

I ´ve heard that the Francisco Peña tubescreamer is really transparent. I suppose he is using wima caps.

[cbriere]

I have done some experiements with this circuit and found that,
-with LED diode clipping : Since they clip at around 1.5V, the opamp in front of it must have high gain.
and i could not get the sound i wanted. I will try with liquid drve type of circuit
http://fuzzcentral.tripod.com/liquid.html
I will try to place the diodes just after the first opamp and have some control over this clipping.
I will put a pot in serie with the 2 diodes. We'll see.....

Basic idea: I like the overdrive of the Tube Screamer but it find it miss some crunch or grit. THe way to have it
is to setup my tube amp. to give some overdrive. but i would prefer having it in one pedal. Don't you?

christian

[Melanhead]

.... having the amp break up a bit is how I use it, sound's too clean otherwise ... I prefer the amp breaking up a bit with humbuckers as I can roll down the volume and split the coils to clean it up ... When I set my amp to clean I don't get the tone I'm looking for out of any pedal, just seems to be lacking the extra tube break-up and punch.

[cbriere]

here is the result of my work on this project,
schematics


and photo of the pedal


basicly i have added to the basic tube screamer:
1: assymetric clipping with 1 germanium. this had some nice harmonics
2: output germanium to ground option with a switch, to have more distorsion
3: BMT tone stack , taken from marshall shreadmaster
4: input/output buffers are done with opamps.
5: independant boost addition. nice to have to solo in a band situation

really happy with it   
comments invited  , cb