Mutant

Update (06.12.2017): Second go at making a PCB layout. This time I didn’t need as many revisions.

Goal was to fit everything on a board and make room for six board-mounted pots (to cut down on the tedious wiring and make things a bit more efficient). Again, since it’s a PCB, I added a u-controller to handle soft-touch stomp switch toggling via relays and LED control, while also including the same reverse polarity power protection I tried on the Workhorse board.

I’m really happy I managed to get everything together with space enough for all the hardware to fit in a 1590BB 🙂

A/B testing with the vero build and I can’t hear any difference, so that’s good too.


This is another attempt at a high-gain distortion effect. The “Lighthaus” I did previously sounds great, but can get a bit noisy, so that was a design goal for this next one.

mutant_1_0.pngThe “Mutant” (I don’t know why it ended up with that name, suggestions for a better one?) is another high-gain, “amp-like” if you will, distortion effect with a very flexible EQ section and a cool sound.

Mutant 1.0I used the Marshall Shredmaster circuit as a starting point, and the initial gain stages remain quite similar. But this is mostly where the similarities end.

  • The Bass and Treble controls were taken pretty much straight from the “Lighthaus”, which is to say it’s an active baxandall setup.
  • The Mid control is something I borrowed from Douglas Self’s excellent book “Small Signal Audio Design”. It’s something called a Wien sweep filter; it’s an active Mid control with plenty of boost/cut, that can be placed at a wide range of frequencies.
  • The Sweep control moves the Mid boost/cut either down towards the bass or up towards the treble side; what we would call “mid voicing” in the guitar world. At noon/centered it lines up with the baxandall control’s center frequency.
  • I really, really like how the old ShredMaster circuit cuts a lot of the top end using large feedback capacitors, but it doesn’t work for every scenario, so I placed this on a “Top” switch, allowing for a more flexible choice. Activate to help get some of those liquid high-gain sounds, or deactivate to retain all of the brightness 🙂
  • The circuit end with an active volume control. I could have kept the original passive one, but there’s a bit of an active theme going on here, and it’s more fun doing things a bit different.

Adobe_PDF_file_icon_32x32Brought this box with me to some friends without telling them what it was. Their first comment was that this sounds a lot like a big Marshall amp, so that was pretty spot on. We also got some fairly cool baritone-like sounds out of it with the gain at minimum (see settings in picture to the left). I thought the “Lighthaus” was fairly cool, but I’m absolutely loving this one! And it’s much more quiet, both on min gain/max volume and max gain/low volume, so design goal accomplished 🙂

Let me know what you think if you give it a try.

2 thoughts on “Mutant

  1. Hi, Jim
    No, something is definitely wrong. It’s not subtle at all, the switch takes out/brings in lots of treble. Also, the mid shouldn’t cut away at any point.

  2. Harold, finished the mutant. It is nice high gain dirt box. The tone stack bass and treble is very responsive, but on my build the mid cuts off at extreme left and right. Also the frequency pot does not sound like it does anything at all. I also get no change in sound with the use of the top switch. Is suppose to be subtle effect, because I can’t hear any change at all.

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