Tellurian Drive (Sarno Earth Drive)

[MattG]

I built a Tellurian earlier this year, and it's really cut back on my must-try-all-overdrives neurosis. It's a very familiar circuit topology - yet another dual-opamp soft-clipper (YADOSC?). But for me, it's the just-right amount of tuning that it works well in a band mix and sounds good at home.

 

[bluedmc777]

Phew - thanks Slowpogo! I wanted to build this but have no Ge diodes left - but I do have a heap of 1N60Ps. Are they Ge?

And it seems that Michael and I have a love of low-gain ODs in common. I agree - I tend to like the simpler ODs too. I built a Schnobel Daily Driver and I like it but it's kinda lacking in character, something I value in an OD. The Daily Driver has everything you could want except fun. And it uses a ridiculous number of parts.

I also recently built a simplified Blues Power and it is very much a Timmy with a few altered values, but it's simple and sounds great. I am collecting quite a posse of modded Timmys! I have a modded TSV-808 which is a modded Timmy which has become an absolute favourite.

So I'm looking forward to building the Tellurian now.

I know this is an old thread but did this pedal ever find its way to the boneyard @Chuck D. Bones? I know he could make it better. I had one a few years back and loved it but only for soloing. I found that it lacked clarity in chord work and also had some bass roll off. Perhaps adding a bass control, adding some clarity, switchable diodes and maybe a boost of sorts would be cool.

 

[MattG]

I found that it lacked clarity in chord work and also had some bass roll off. Perhaps adding a bass control, adding some clarity, switchable diodes and maybe a boost of sorts would be cool.

That would pretty much be a Timmy. The Tellurian/Earth Drive is an "opinionated" Timmy. By opinionated, I mean that it's literally the same circuit topology as the Timmy, with some values tweaked, and the Timmy's bass knob has been replaced with a fixed high pass (i.e. bass cutoff). Specifically, 2 * pi * 220nF * 1.5kR = 482 Hz. That's the bass roll off you're hearing. Compare the Tellurian schematic to the Tommy III.

This would be a good circuit to breadboard, as it's very simple, and the basis for a lot of similar circuits. For a quick "more bass" mod, you could replace C3/220nF with something bigger, 470nF ought to be quite noticeable, 330nF might be a nice compromise. Increasing C1/2n2 might also be worth a try.

You could, quite literally, build the Earth Drive on a Tommy III PCB, just making all the right component value substitutes (with some omitted or jumpered).