Apocalypse Audio 4 Horsemen

One last one, for tonight.

From RnFR:

well, i came up with another dirt pedal the other day.  lately, i've been experimenting with mixing different types of transistors together to achieve new tones, and this one kind of  takes that idea to the extreme.  it's designed under the premise that the stages increase in breakup as it goes along in the circuit, but instead of using stages that increase in gain, different types of transistors are used that exceedingly distort as the the circuit progresses.  for instance, the first gain stage is a silicon BJT.  this is used to get a decent push going and a very slight amount of drive.  next, is a MOSFET transistor, which like to distort a little easier, and in a bit more pleasing and richer way than the previous Si transistor.  finally, there is a germanium stage, which of course loves to distort in a very full and heavy overdrive, especially when driven by the previous gain stages.  the result is a very clear, yet complex crunch, that has a very nice character to it.  to round things out, in the beginning of the circuit is a JFET buffer, which helps to increase the current, and gives a nice high input impedance for the guitar pickup to see.  so in the end there is a total of 4 different types of transistors, each of which i tried to use to their optimum potential.  hence the name, the Four Horsemen Overdrive.

the tone control is a variation on the SWTC, but it has an added pole for a steeper rolloff.  the frequency point where the curve begins is rather high, so it is really more like a presence control- just taming the highest of frequencies, keeping the basic tone intact.

Apocalypse Audio Dirty Boots Version 5

Continuing with the layouts I made that day. Here's the fifth version of the dirty boots. It's a germanium overdrive based on the first version, there's an additional pre-gain pot that controls ho much signal is entering the effect.

Apocalypse Audio Thunder Tone

From RnFR:

here's something i churned out the other day. i have been thinking about modeling the Supro Thunderbolt with FETs, but then thought- i just got in these cool new Tesla GE's, why not use those? so that's what it is, the preamp section of the legendary amp used by Page and supposedly Hendrix, done up NPN germanium style. i had to eliminate a few resistors towards the end to bring up the volume and lowered the value of an emitter resistor to up the gain a bit. also, i made the resistor on the input variable so you can adjust the input impedance for guitars with different pickups.

the real gem of this circuit is the tone pot- totally counter-clockwise you get a nice full range tone with plenty of mids. as you go clockwise it goes to a very muffled tone, and as you go even further, it goes to a very thin, cutting tone. there are some very cool sweet spots, and a lot of versatility. i like it better than a regular muff style control, but it does cut plenty of signal- hence the two gain stages after it.

it's a cool sounding circuit. nicely voiced and does a good overdrive type sound. if you don't have the trannys, you could change out the 33K Rc's to trimmers and adjust to taste. the tesla trannies are extremely consistent, so no trimmers needed. the layout below uses some large axial caps and is yet unverified, but hopefully i'll get it done sometime soon.

Apocalypse Audio Dirty Boots Version 6

So the other day I was looking over some of the info RnFR has posted on Apocalypse Audio and came across some pedal designs that caught my eye. I ended up sitting and doing a couple layouts for a few of them.

Here's the sixth version of the dirty boots. It's a germanium overdrive based on the first version, but i with a couple extra controls.  There's a pre-bass and post-treble tone control combo that's based on similar methods used in many distortion pedals.