Nordic sent us a revision of the gaussmarkov.net Big Muff Pi Triangle layout. He added his own artistic touches and created something that differs from most of our layouts in several ways.

First of all, you may notice all the round corners. These are produced with the same Eagle MITER command as the diagonal corners that you usually see on this site. But you have to switch the shape of the miter. Nordic also added this flourish to T intersections using the Eagle SPLIT command. These are a bit of extra work but they look great.

Second, Nordic lined everything up in straighter rows. When he did this, Nordic also adjusted the box capacitors (with a 100mil lead spacing) so that the boxes are centered along with the resistors. Most gaussmarkov.net layouts tend to keep the pads lined up in rows so that the capacitors’ boxes are off-center.

Third, Nordic rearranged some components to remove a jumper. Whether you consider jumpers inelegant or not is largely a matter of taste. The need for them generally depends on how compact your layout must be. Used appropriately, jumpers do not introduce electronic issues. They are, after all, just resistors with 0K resistance and resistors are all over the place.

When I looked at Nordic’s changes, I noticed a couple of other improvements myself and Nordic let me add them. For example, the transistors are lined up more neatly. I also decided to hook up C11, which is part of the tone stack, to +9V instead of ground. As you can see, it’s awkward to get a ground connection to C11 given the overall layout. Because capacitors block DC, hooking up a capacitor to any constant voltage amounts to the same thing for the effects on the signal.

Now some of these changes require a larger board. Does that matter? Not in this case, as you can see below, Nordic’s revision fits in a 1590B. You can see an example by stobiepole of an actual build like that using the original layout in this post.

If you would like to use the Eagle files for this layout, there in this zip file.

A basic goal of gaussmarkov.net is to provide support for designing your own build. Not only can you get PCB images, but you can also get Eagle CAD files for those images that you can rework. Because the PCB design is already verified, you can be confident that your version is going to work also.

This post is the first of a series that will offer projects by others that are based in part on gaussmarkov.net projects. George Collier took the Thor circuit from runoffgroove.com, the Eagle files from gaussmarkov.net, and put in his own 3 band active tone control. Here’s a gut shot of his build. If you view the image in another browser window, you can see it full size.

George is using his Thor as a preamp in an amp he built and calls the Tone Reaper. “I also attached a shot of the cabinet the preamp is housed in. It’s been rebuilt a few times now to implement some changes since it was first built in 2007. It’s a totally different animal now! I’m using the the Thor with the tone control as a preamp, feeding an LM3875 amp. The cabinet is open back and has a single Eminence 12″ Texas Heat speaker. The LM3875 can drive this thing loud…very very loud ”

Here is a link for the Eagle files George zipped together: gcollier-thor-project.zip. “The layout I sent you is a tad different than the one I am using. The differences are very small, only some slight changes to the ground plane and also I put the diodes for the bridge rectifier on board rather than having to use a separate rectifier. I included pads to power it by a battery or a wall wart (in case you want to use it in a pedal enclosure), if you do this there is no need for the regulator and all the associated parts. Definitely DO NOT plug in a battery if you are using the on board supply. You could actually use the battery connection as a take off to power a pedal if you wanted. I’m sure this layout could be made even smaller (rotating all the tone control components 90 degrees would likely do it).”

For reference, here is an Eagle3D rendering of the layout George sent:

“Thanks for providing such a great layout to modify…so many sites just provide PDF files, the Eagle files are very useful!”