Simple op amp distortion circuit.

[Dragonfly]

I saw some "clipper talk", so I thought I'd dig up this thread...good info by Mark, Gus, etc....

The schematic seems to be missing, so I thought I'd re-post it. This can be found in the "schematics" section of the Dragonfly Gallery pages.

http://www.aronnelson.com/gallery/main.php/v/DRAGONFLY-LAYOUTS_0/album87/album172/SIMPLE_CLIPPER.gif.html?g2_imageViewsIndex=1

[Barcode80]

and the layout i made, still unverified...

http://www.aronnelson.com/gallery/main.php/v/BarcodeVeroLayouts/album120/SimpleClipperPCBLayout.gif.html

[Dragonfly]

SOUND SAMPLE

[John Lyons]

That clips sounds nice!
Also folks, you can put in a 1M pot to lower the gain, in place of the 1M in the Opamps feedback loop.

john

[WGTP]

http://www.aronnelson.com/gallery/main.php/v/WGTP/Simple+Ripper.GIF.html?g2_imageViewsIndex=1

[liddokun]

I don't seem to have any 741's on hand. could I use a 4558 and just use one of the amps in it?

[John Lyons]

WGTP
Let's see.
The .047 softens up the clipping a bit.
The 100K drops the gain a little correct ?
Is the .047/10K a high pass filter controlling the bass a bit?

Liddokun
You can use a dual op amp as well.
It's wired a bit differently though. You could use the other op amp side as a buffer as well...or anything else....

john

[jayp5150]

Is the .047/10K a high pass filter controlling the bass a bit?

More on that; what's the benefit of splitting the 1M resistance there? Why not just before or after the 1M?

[John Lyons]

I think the filter is put between the 470K resistance as a mid point, balancing the filter between what would be a pot in a Tube screamer circuit. Not on the high end or the low end of the full gain resistance. I think that's it at least.

john

[WGTP]

I got that from STM's 22/7th's that uses the CMOS inverters in a 4049ubc.  I THINK it will work in the inverting stages of a regular op amp, but wouldn't bet my life.  It appears that the 10k/.047uf have to be isolated from the input and output for it to work, but I'm just guessing.  With the cmos inverters, it definitely boosts the gain and different values can be used to control gain and low frequency cut off.  I sort of thru it out hoping someone else could elaborate.  Gus?

The 100k resistor reduces gain, but also increases the input impedance for more treble from the guitar pickups.  It will also lower the bass cut off of the input cap by a factor of 100 over the 1k resistor.  The 1k may be a little dull.  That is why I added the "treble boost" to the feedback loop.  

From my experiments with Gus' Muff Fuzz Mod's, lowing the input resistor has sort of a band pass effect because the highs are reduced by the lower impedance and the lows are reduced because the low frequency roll off goes up.  This sort of allows you to tailor the midrangeness of the tone. 

Also checkout the Mockman for relavent info on a dual op amp unit.    

http://www.runoffgroove.com/mockman.html

[jayp5150]

Cool, thank you.

I think I'm going to play around with this when I get the chance. I've yet to really dive into modding opamp effects; this is probably a good place to start.

[WGTP]

http://www.diystompboxes.com/smfforum/index.php?topic=48815.msg362915#msg362915  Ubesreamer & 22/7th's.

I'm not sure how similar using standard op amp imverters is to CMOS inverters, but there are some cool ideas from STM/ROG in this thread.  Opps, I guess it's not so simple anymore.