Red Llama

[WGTP]

http://www.aronnelson.com/gallery/main.php/v/WGTP/CMOSerizer.gif.html?g2_imageViewsIndex=1

I have refused to add other chips to one that has 6 cool little amps (it complicates the breadoard).  I have tried to design around some of the problems that presents, including lots of EQ.  This is a little noisey and may not work well at high volumes, but sounds good in the bedroom. 

[fuzzo]

The use of 2 stages has two rationales.  One is that the industry tries to have the output be in phase with the output whenever possible.  So inverting, then inverting again, gets you there.  The other is that multiple gain stages lend themselves to a certain "smoothness", and the hex inverter has 6 potential stages just sitting around and available for duty.

Personally, I've found that I like the way inverters sound when the gain is not concentrated in those stages, but is more broadly distributed.  Whether an op-amp or inverter stage provide the better platform for doing that, I can't say.  I know how to anticipate and shape the content and gain of an op-amp stage more than I know about discrete or inverter-based stages, though, and have opted for that in my own builds.

Nothing wrong with trying alternatives, though.  Just don't expect miracles to increase linearly with number of stages.

Incidentally, take a look at Charles Fischer's interesting 4049-based overdrive here: http://www.generalguitargadgets.com/tech-pages/46-articles/36-em-fuzz  You may be surprised to find it uses only a single inverter stage, albeit with current control over the inverter (which we never seem to get around to discussing or experimenting with here, including me) and plenty of op-amp support around it.

I tried a CD4049UB with 3 gain stages, works good I can say , some tone shaping job must be done but the basic is here. I put tree CMOS stages with 470K in the feedback loop. I think I'll make more work on that , adding a tone control first.

But , how calculate the gain of the stage ? like the inverting AOP , Rloop/Rin ?   

[Nasse]

Do you have your pen and paper ready and your calculator batteries o.k. Something like this?

http://www.diystompboxes.com/smfforum/index.php?topic=75833.0

[WGTP]

May be of interest. 

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