Electra Experimenting Help

[pryde]

So I am messing around with breadboarding some simple circuits and learning/tweaking components, tone stacks, etc. I am pretty green with the breadboard and schematics so the Electra distortion circuit has been good to start with.

I actually am liking the sound of this little circuit with a MPSA18 transistor, and BAT 46 diodes. Besides that, I  just added a 100k volume at the end of the circuit and put a 50k pot after the diodes with a .022uf cap (to bleed in some treble?) for a simple tone control.

Now I know I could add a gain control by putting a VR on the MPSA18 Emitter to ground but right now I am using a fixed 390 ohm as it sounds good.

Just out of curiousity, how would one add MORE gain to this circuit, i.e. more saturation and breakup, not volume? Right now it is a pleasant-sounding overdrive, how could it be more into distortion territory?

What other things would you guru's do just for kicks/experimenting with such a circuit? Thanks for the insight and sharing!

[midwayfair]

So I am messing around with breadboarding some simple circuits and learning/tweaking components, tone stacks, etc. I am pretty green with the breadboard and schematics so the Electra distortion circuit has been good to start with.

I actually am liking the sound of this little circuit with a MPSA18 transistor, and BAT 46 diodes. Besides that, I  just added a 100k volume at the end of the circuit and put a 50k pot after the diodes with a .022uf cap (to bleed in some treble?) for a simple tone control.

Now I know I could add a gain control by putting a VR on the MPSA18 Emitter to ground but right now I am using a fixed 390 ohm as it sounds good.

Just out of curiousity, how would one add MORE gain to this circuit, i.e. more saturation and breakup, not volume? Right now it is a pleasant-sounding overdrive, how could it be more into distortion territory?

What other things would you guru's do just for kicks/experimenting with such a circuit? Thanks for the insight and sharing!

Yikes. More gain even after using a Darlington? Well, you can go up to an MPSA13 (hfe 5,000) or even MPSA14 (hfe 10,000). I'm not saying it'll sound good, but you can do it.

More distortion is easy ... use more diodes with a lower clipping threshold.

Reducing that 390Ohm resistor will also increase your gain. I wouldn't necessarily jumper it, but you could use an exceptionally small value like 47 Ohms.

Finally, this circuit will distort more if you feed it more volume. Therefore, a boost in front will certainly give you more gain. Might I suggest a ThunderPuss? That's 30dB of gain right into the cow's face.

[pryde]

Thanks midway. I don't think the MPSA18 is a very high gain transistor, it doesn't sound to much different than a 2n3904 in this circuit.

So what diodes would be good then? would they just be added on after the 2 existing BAT46's (i.e. asymmetrical orientation to ground?)

[stecykmi]

i believe increasing R1 will also increase gain, but you don't have as many choices of resistor values in that range. 4.7M or so might work.

in general, germanium diodes have the lowest Vf (voltage before it conducts), however, schottky diodes (like the BAT46) also have very low Vf. They should still sound different, though so they might be worth trying. Examples might include 1n34a or the 1n60.

using diodes with a high Vf (such as LED's, usually 2.3V or upwards) might actually increase the output since the wave should be much larger. obviously there is less clipping though.

also worth noting, if you remove the diodes and R1, and and replace it with a 1n4148, you basically have the BazzFuss, which has a synth-like texture to it's fuzz. http://home-wrecker.com/bazz.html

[bigmufffuzzwizz]

Have you poked around on FSB or DIYSB for mod ideas...there's usually a thread with guys throwing ideas out there especially with a circuit like this.

[pryde]

Thanks for the responses. Yes I did get some good ideas from FSB and played with a bucnh of different options just mainly to learn. I made notes of what I liked best and filed it away.

I now have a "Vulcan Overdrive" on the breadboard and am playing playing around with it. Crazy amounts of dirt with four gain stages using 2n5089's  Sounds really cool and more tame using 2n3904's.