Do the NAND/NOR gate Boogey!

[caspercody]

Thanks! I have seen WGTP does a lot it sounds like first?? with CMOS I want to try his DS-1 version using CMOS, curious what it sounds like first?

[WGTP]

The cmos DS-1 was sort of a theoretical excesses and probably sufferers from excess noise at the least.  I'm also not sure about the tone shaping.  

I've learned alot since then and suggest your try the cmos Obsidian first to get started with.  I have no doubts about it sounding good and working well as drawn.

If you look at the Complement, the second stage is sort of a discrete version of an inverter that Gez and Puretube came up with IIRC.  Sounded good. http://www.aronnelson.com/gallery/main.php/v/WGTP/Complement.JPG.html?g2_imageViewsIndex=1

I'm sure there is info around about using inverters for audio, but as indicated, this is probably the best place for distortion specific info.  I sure don't understand all the EE stuff going on.   Just sort of combined different things from other cmos circuits, with many contributors.  For sure check out the ROG stuff and STM.  

Also some folks prefer to drive the cmos stages with an op amp or jfet stage.  I have been trying to avoid that to keep the parts count down and make full use the stages of the 4049.  Mark Hammer has also done several nice things.  Apparently the Blackstone Appliances distortion uses cmos stages driven that way.  

My breadbaord, sitting on top my amp, has a CMOSerizer with some modified parts values on it and and I keep expecting to see smoke   

[edvard]

Glad to see all the interest in these CMOS dealies, I'm sold so far...

@Earthtonesaudio:
You are correct, using a 4001/4011 with inputs wired together does shift the bias point, depending on what chip you have.
The 4001 has a bias point around ~3 volts and change.
The 4011 biases around 6-7 volts.
I'm sure that with bias points like that, it does make some asymmetrical voodoo happen, and putting resistors at the appropriate power leads does help shift the bias a little, but read on...

@WGTP:
From my calculations, the inverter stages have around 150k input impedance and 30k output, so perhaps a JFET input stage may not be such a bad idea.
If you do a source-follower, it's only 3 more parts 
Also, I think I know why you're getting a neater sound from lower voltage:
I was trying to kill some power supply motorboating on my latest experiment (on battery power there's no problem) and found I had to use a resistor of 1k or more and a 470uf decouple cap.
The PS was ~12 volts and that resistor/cap combo brought the voltage down to almost 6.5 volts. 
Remembering what you said, I checked in LTSpice what that would do to the signal and I saw some definite crossover distortion happening.
Some people believe that is what makes an overdriven tube power section sound sweet, so that may be part of what's happening with your sound. 

@caspercody:
earthtonesaudio is right, a CMOS inverter stage works for the most part like an inverting op-amp.
I don't know the open-loop gain, but it's much lower than the typical tens of thousands that an op-amp can do.
Judging by all the CMOS distorters being designed and lauded, there appears to be enough gain to make most folks happy...

[WGTP]

Good stuff to know.  I had wondered about crossover distortion, since it it a complementary pair.  I find that using at least a 100k resistor at input keeps the treble up and using a small capacitor reduces the bass. Both also reduce gain, but with 3 stages that isn't a problem. Using the treble boost gyrator for the first stage boosts the gain in the right place, plus I'm using 2 470k resistors instead of the 270k used by ROG for more gain. Also different caps. Adding to the parts count  

IIRC the limited bandwidth may also have some impact.   

[Lurco]

I think this forum is the best resource out there.  Just search for 4049 or 4069 based distortions.  Members WGTP, and STM come to my mind because they've done quite a bit with them.  Also there are some projects on runoffgroove.com worth looking into.

A CMOS inverter is a P and N MOSFET with drains and gates coupled, and sources going to positive and negative supply pins, respectively.  Negative feedback together with the symmetry of the two FETs causes the output to bias roughly near the midpoint of the supply, and from there you can basically use any circuit that would work with an inverting op-amp, with the exceptions that there is no non-inverting input and the gain is much lower than a real op-amp.  Alternatively, you can think of the CMOS inverter as a single transistor with no need of drain/collector or source/emitter resistors.  This might be a more accurate model because the input and output impedance characteristics are closer to a single transistor stage.

http://www.diystompboxes.com/smfforum/index.php?topic=69660.0

[edvard]

...
http://www.diystompboxes.com/smfforum/index.php?topic=69660.0

Aw, geez.
Once again, this forum repeats itself, but dressed differently.
I'm gonna hafta read the "Discrete Tubeless" thread all the way through now...

In the interest of consistency, I have to re-iterate that my original point was intended to be about;
1) using 4001/4011 chips instead of the 4049/69's usually used, and...
2) clone the gain and tone response of the Dr. Boogey with them.
I like the sound of the Dr. Boogey, and I'm learning that the NAND/NOR gate chips have some nice sonic properties of their own
Besides, using components for purposes not intended by the manufacturer somehow feels tickly...

I wonder if those 4066 switch chips can amplificate? 

[earthtonesaudio]

I wonder if those 4066 switch chips can amplificate? 

http://www.diystompboxes.com/smfforum/index.php?topic=19154.0

[WGTP]

IIRC Tim Escobedo suggested the CD74HCUO4 as a cmos chip (14 pin) that was designed for audio applications.  It works well in these designs.  He has some cool designs of his on in his Circuit Snippets.   

[edvard]

I wonder if those 4066 switch chips can amplificate? 

http://www.diystompboxes.com/smfforum/index.php?topic=19154.0

You sir, are awesome.
Thanks.

@WGTP:
I saw those and looked up the chip.
Apparently, it's got really good audio characteristics, but is limited to 5 volt operation.
Might be a good choice to mix in with op-amps 'cause you could power it from one side of a voltage divider.