Country Fried Overdrive (Ver. 1)

[Earthscum]

Working up from this as a base: SSAS...

I came up with the Country Fried Overdrive. I'm working on a more versatile version, but this was so damn pleasing, I had to share it with you guys. The "more" version will just be the "Country Fried Overdrive II". I think y'all will dig the results!



Basically, I used the input stage I used in my Big Muff, without the feedback cap or 33k resistor in line to the base. Nice, simple boost. I had hit the SSAS with some hard signals to see how it would clip (I was afraid of, you know... that ultra loud ZAP that makes the sound guy turn pale). I really think this is the trick to the "odd stage" in the Gemini II. You can hit it pretty hard, and it seems to soften the signal as well as give it's own form of clipping. Hit it with the clean stage, and it was on!

Really reactive to your playing, great fuzz that decays out to clean. Volume knob reactive, cleans up really good. Seems to me to play nice with lower and higher guitar outputs equally, not too harsh or too weak.

It's a fairly stable to tweak around with, as well. Different transistors can be easily swapped in and out of Q2 with no value changes. Juest remember it's upside down, and if you pop one in and it hardly works or sputters, doesn't sound right, Q2 is probably backwards backwards. If you want to sub a different transistor in Q1, you may need to change the 150k from Base to Ground to adjust the bias back to around half VDD.

[rutabaga bob]

Can't wait to put one together!  Thanks, Dave!

[Strat68okc]

Well, you got my attention at "Country Fried". I gotta go get those transistors now. That MPSA13 is like a 2N3904, correct?

[rutabaga bob]

MPSA13 is a darlington transistor.

[Earthscum]

If you have a regular in Q1 transistor, you should be able to use 510k/100k instead of 470k/180k.

Some notes on Q2 transistors I tried:
2n2222A - 2 of my lot (and an NTE123AP) bias in just under 3V. All the rest bias in about 3.5V
2N3904 - Average bias of about 4.6V
2N5088 - Average bias of about 6V
BC108 - 6V
BC109 - 6V

I didn't really muck with the ones that were biasing higher. There wasn't much of a difference in sound (to my ears) to warrant a total re-bias when the 2N2222 sat just right. 3904's sounded pretty good, but the higher the bias, the more it clips the top of the signal. About 3V seems to be a great spot to get from a pretty heavy fuzz to a nice decay to clean . You can try different values in place of the 100k feedback to try to get your bias lower for different transistors, if you like. Try a 120k and see which way the bias moves, that will give you an indicator of which way you need to go in resistance to get where you want.

Like I said, it sounds great to me, but it's a totally "tinker tolerant" circuit. Always play if you can and make it yours.   

[rutabaga bob]

[Strat68okc]

Awesome... Jeez I just hate waiting on parts.

[Gus]

Why a MPSA13 for Q1?  The input resistance is low with that circuit because of the feedback from collector to base and the 180k base to ground.  Why not a 2N5088 etc?

You could adjust the 100k from Q2 C to B (E to B if it is flipped like in the schematic) for different transistors  Lower value should drop the collector voltage

Why the 10K at the output in || with the 100k volume control?  Why not a 10K volume control?  The 10k fixed resistor uses more of the output drive current making less available for the 100k volume control

Two stage fuzzs can be fun however sim/measure what happens when a guitar and cable "feeds" the circuit and what happens when a buffered effect "feeds" the circuit.