Negative Feedback: Cap to Ground between Resistors?

[thehallofshields]

I've been trying this out with a 2-stage 4069 Distortion.
In Stage 2, I'm using 2 100k Resistors and a .1u Cap. Sounds great.

Observations:
-There isn't much sound difference between this INF Gain Cap configuration and a High Gain of 1M/1K.
-There isn't much sound difference between this INF Gain Cap configuration and an OPEN Feedback loop.

-The Cap configuration seems slightly less noise prone than a 1M Resistor.
-The Cap configuration is less prone to oscillation than an Open Loop.

[anotherjim]

That all chimes with expectations
There isn't much gain anyway and high ratio Rin/Rf won't make it so.
High value resistors are noisy. Metal film resistors are some help tho'.
You will typically see >100k to 10M values in CMOS inverter circuits. That's usually because they aim for low parts count and want Rin > 100k so as not to tone suck the guitar input (when the intentions are linear).

But if you only want the soft clip character of the inverter, put a conventional Hi-Z pre-amp in front, use Rin=10k & Rf=100k on the inverter. Consider running the inverter at 5v - it has slightly more gain at lower supply voltage and the signal will spend more time in the soft clip zone. The lower resistor values are less noisy, and there's no reason they couldn't be lower, but you have to consider the effect on the preceding stage when Rin gets small.

[thehallofshields]

But if you only want the soft clip character of the inverter, put a conventional Hi-Z pre-amp in front, use Rin=10k & Rf=100k on the inverter. Consider running the inverter at 5v - it has slightly more gain at lower supply voltage and the signal will spend more time in the soft clip zone.

Ive read a lot of arguing about CMOS noise on forums so I was thinking of creating a thread dedicated to CMOS noise minimization.

I'm currently running my circuit close to 5V using a Blue LED. I've also experimented with a constant a current diode JFET config quite a bit but its a little too extreme (hi gain and thrashy) for my tastes.

[thehallofshields]

I picked up a Yamaha COD-100 for myself over Christmas and its amazingly silent for 3 stages and the amount of gain. Ofc this is mainly due to the Commander but the pre-amplification and 330k Feedback Resistors certainly help.