Distron Thrust

[WGTP]

http://aronnelson.com/gallery/WGTP/DistronThrust

Hey, I figured out the Gallery.  Cool.

This is the culmination of my op amp distortion research for the past several years.  Since I couldn't decide which combo I liked best, I found a way to do all of them.

The best part is the clipping diode switching taken from John Hollis' OmniDrive.  You can either have diodes in the feedback loop or to ground or out of the circuit and there are 2 sets.

Other feature is a notch filter between the 2 clipping stages simulating a tone stack between the pre amp and power amp.  Let me know if you see anything stupid.  

[Marcos - Munky]

Really interesting idea. Do you have soundclips? And what about two more switches, to add another pair od diodes/leds and select between them? Like this: a switch to select between a pair of leds or a pair of diodes in the first stage, and one to do the same thing in the second stage.

[petemoore]

Slick... :shock: Looks like it sounds like a couple/few circuits,  at least. :wink:

[MartyMart]

WGTP, I like this a LOT  !!
I made a version without the "switching" just both sets of diodes
connected via 4.5v - not a huge fan of "to ground" clippers and I have a
bunch of feedback loop diode crunchers ......
I went for 3x1N4148 and then 2x 1N4001 rather than LED's
I can get everything from "clean" through "mild OD" to "mind blowing
distortion"   :twisted:
Reminds me of a certain "Marshall" box........ but has much more
variation and a nice "bite" to the tone ( 22k-22n-22k with 47n to 4.5v )
Perhaps a version of the BMPI tonestack would be nice ....?
Not important, but I used a JRC4558DD op-amp.

Nice work mate and thanks for sharing the schemo  
which works perfectly BTW

Marty.

[MartyMart]

WGTP, I presume that both the caps near the output are 4.7uf ? ...
A few "tweaks" this morning, as it was way too early to be making noise
this morning !  ( I'm on a coupe of late night duties )

I had some "high end" crap going on, which was a bit too much at higher
gains ( I know, with "gain" comes "noise" !! ) so I used 330pf caps across
the feedback loops and tagged a 1n cap to ground before the 4.7uf
output cap.
Sounds very nice now, and I still have enough "sparkle" at low/mid gain
settings.
It was very high "fizz" and had nothing to do with a normal gtr sound....
I'll get a couple of samples done tomorrow and post them up.

This thing is F***** great !!  I can get an almost "mongoose" fuzz at very
high gain, right down to beautiful clean sparkle at zero gain and a touch
off the gtr vol knob

Cool ...
Marty.

[WGTP]

I have wondered about too much high freq. because my amp is dark and I have the presence turned down.  The 1N cap probably needs to be on the schematic.  Might need an additional 1K to 10K resistor between stages to tame it some.

I think the diodes going to 4.5v work essentially the same as going to ground.

As I was posting it I thought about additional switches for various diode combinations.  Cool idea if you can deal with the extra wires.

You could also add switchs for different caps in the notch filter.  Let's see that's at least 6 now.

I probably prefer a .22uf cap to the .47uf cap in the first stage for tighter bass, but again, it depends on whether I'm using a new or vintage battery.

Glad you like it.  I thought the switching idea was a cool idea from John Hollis that hasn't gotten much attention.  

[MartyMart]

Yeah, i may go with a 220n also, just to tame the bass end a bit, though
it's not a problem through my "small" combo's   :wink:
Time to get the 4x12 out ..........  :roll:

Thanks again, great little circuit

Marty.

[WGTP]

I revised the schematic to include the .001uf cap at output for reduced highs and changed the 220pF cap in the second stage to 470pF.  Thanks for the input.  

I'm wondering if the 500K pots should be reduced to 100K for a more useful range.   :?:

[MartyMart]

I revised the schematic to include the .001uf cap at output for reduced highs and changed the 220pF cap in the second stage to 470pF.  Thanks for the input.  

I'm wondering if the 500K pots should be reduced to 100K for a more useful range.   :?:

No problem, glad that I could help a "little" bit !!
I think the pot values are good to go, my problem is that I'm out of
audio taper, so have all linear.... the drive/gains are VERY sensitive on
mine, so I need 500k Logs asap !!
I have "Full metal jacket" at 1/3 rotation .... :oops:
OR I could try tapering them a bit to make them more "Log-like"

BTW I went with a 330n off the first gain stage, sounds great now
and that pair of 1N4001's is very fine !

Marty.

[cbriere]

The second stage has no serie resistor to the neg pin?
or it's meant like this?
what's in your proto?
cbriere

[MartyMart]

The second stage has no serie resistor to the neg pin?
or it's meant like this?
what's in your proto?
cbriere

Sorry if there's confusion :
Pin 1 & 2 first stage feedback loop (1 also couples to to Pin 6 after diode)
Pin 3 is input
Pin 4 is grounded
Pin 5 is connected to +4.5v (Vb)
Pin 6 & 7 second stage feedback loop ( 7 is also output -  1k - 4.7uf )
Pin 8 is connected to +9v

Hope that helps ?

Marty.

[WGTP]

I forgot to acknowledge that this is sort of a reorganized version of Mark Hammer's Chaos and RoseyRay based on the Marhal Blues Breaker by way of the op amp Muff Fuzz, the difference being that the second op amp is inverting rather than non-inverting like most of the others.  That is why the second op amp looks different.  This "may" have an advantage in that the output is out of phase with the input "perhaps" reducing potential for oscillation.  

I was messing with it last night and I really like the .47uf cap reduced to .22uf for a smoother bass.  As noted above, rolling the highs off smooths things out a lot, but that will all vary depending on your amp setup and your guitar.   I also prefer the battery at around 7v. but that could vary according to the op amp used.  

[cbriere]

I protoed this circuit and i found that i could get
better overdrive sound by changing the second opamp
to non-inverting type. Second stage is builted veri similar to the
first one.
By adjusting the gain to be just on the edge of lighting
the LEDs (second tage) and first stage just to overdrive,
I could get a nice variation just by lowering the guitar volume.
Range from a clean tone (guit vol @ 2-3, LED are off)  to nice overdrive
crunchy at full volume (LEDs are lighting).

Now i am thinking of putting an transistor inverting stage bettween the
2 opamps. Cause i was getting oscillations.

I will use the one from Mongoose, 2n3904 ,

we'll see...
cbriere
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