Mithra A4 - Booster + Distortion (Mechanical Beasts series)

damianvila

Well-known member
Ok! time to document the building of this pedal. First of all, let me tell you a bit about myself and why I decide to create this.

I'm a Graphic/Web Designer, and I love Industrial Design. I started building pedals as a hobby, mainly using PCBs from Fuzz Dog in the UK. Then started learning how pedals work, reading sites like Electrosmash, Runoffgroove, etc. When Brexit happened, it became harder to keep buying PCBs from the UK, and I thought it may be a good opportunity to make my own PCBs, so that's how it all started. From that idea, Vila Effectors was born.

After a couple experiments, I started to think about something I would like to have in a pedal. Since I normally use pedal pairs I love (like a FET booster with an Electra Distortion, for example) I thought it would be a good idea to create double pedals with combinations that I find interesting. I wanted it to have a late 70s/early 80s vibe, and I took inspiration from Mazinger Z (or rather, its enemies), and that's how the "Mechanical Beasts" series started.

My goals for this series is not to design any novel circuit (I think I have not enough knowledge to create anything particularly original, so it's useless for me to go that way), but to make combinations I like from existing classic circuits, with minimal to no modification. I also want the most professional finish a hobbyist can make (so UV enclosure printing), and a very important one to me is to get rid of as many cables as possible inside the pedal. I use PCB + SMD for the construction.

Mithra A4 (the names are styled to resemble the Mechanical Beasts from Mazinger) is the first in this series, and it's a FET booster (in this case I'm using the AMZ booster) and an Electra Distortion in a 1590BB enclosure, with independent switches and LEDs and an order toggle switch.

Although I've been using EAGLE for most of my past PCBs, I switched to EasyEDA for these pedals, since Autodesk is getting rid of EAGLE in a few years.
So, first things first. Here you have the schematics:
mithra-a4-schematic.png
Nothing too fancy here, I just added a pot to the Electra and changed the clipping section to Schottky diodes, instead of Germaniums.

Here's the switches schematic:
switches-schematic.png

The switches are wired in this way:
connections.png
 
After the basic idea and schematics, I ordered the PCBs:
IMG_1820.jpeg
IMG_1821.jpeg
And then tried to fit the components to see if everything was alright:
IMG_1822.jpeg
It was at this moment that I noticed a couple mistakes: The switches were .5mm too close (so, I needed to correct that board) and I had used a wrong power jack (2.5mm center barrel, instead of 2.1mm), so I needed to correct that too...
Version 1.1 was created and I ordered new PCBs (this time in green, to make them faster).
IMG_1829.png
These new PCBs are arriving today, so I will have progress very soon!
 
Now, the design...

I've never ordered UV printing from Tayda (in fact, I had stopped buying from them the moment EU VAT's scheme was implemented and they refused to adhere to that), so I needed info if I wanted to use that service (no other shop that I know provides a similar service, so I had no choice here). That's when I found the wonderful threads in this forum, that had been so helpful (thanks! all of you).

I created the design:
mithra-a4.png

And then ordered the enclosures from Tayda. After a bit of suffering, I finally got the enclosures:
enclosure.jpg

I drilled one, and tried putting the components there, to see how they looked (you probably saw this before):
mithra-test.jpg

Everything fits fine, so far. As said, the foot switches were a bit too close, but that was corrected. I realized I needed leds with longer legs. And the effects PCB with the potentiometers was just perfect (I'm very proud of how well it fits). The final knobs (Davies 1611 style) are arriving soon (I hope this same week), so a final dress will be tried as soon as those are here. I still need to drill the sides holes for the jacks (audio and power), but I'll wait to have a fully assembled PCB first, as it will make it easier to know where to drill.
So, I hope to keep reporting soon! Cheers.
 
Dude, that looks fantastic. Good job on the PCB and the enclosure design.

I've been using Eagle for a little over a year now I think and it was a bummer when they announced it was going to be discontinued. I tried to figure out Kicad and EasyEDA before I found a good Eagle tutorial. When they announced the end of Eagle I tried to fiddle with Diptrace, but that felt like playing Minesweeper on Windows 3.1 or something (sorry Diptrace lovers).
 
Thanks for all the comments! 😊 I try to make the pcbs interesting. There’s still a few things I want to try, so this one will probably change in the future, when I validate the prototype.

Then I need to see if I can change to silkscreening the design (that’s the reason why I’m using only two colors), but that after I find a reliable and reasonably priced source for the enclosures.

And after that, all the manuals, and boxes (I want to see if I can afford a custom run, using only 1 color), and the website (working on it right now, but still lots to do), and the back cover stickers, and…

It’s really a lot of things, and I understand pedal manufacturers, and how difficult it is to release a product, but I would lie if I say I’m not enjoying the journey… and the best thing is, since I’m doing this only for myself, I have no deadlines, and not in a hurry at all. I just want to learn how to do this. 😁

I’ll keep you updated!
 
Dude, that looks fantastic. Good job on the PCB and the enclosure design.

I've been using Eagle for a little over a year now I think and it was a bummer when they announced it was going to be discontinued. I tried to figure out Kicad and EasyEDA before I found a good Eagle tutorial. When they announced the end of Eagle I tried to fiddle with Diptrace, but that felt like playing Minesweeper on Windows 3.1 or something (sorry Diptrace lovers).
If you have experience with EAGLE, I found EasyEDA rather easy to use. I decided to use it because I normally order my PCBs from JLCPCB, and I plan to order assembly too in the future, so EasyEDA may make things rather smooth. I’m using the desktop version, btw, not the online one. And the Standard, not the Pro.
It’s that, or switching to Fusion 360 (which sounds interesting, but I don’t need that right now).
 
These look great, and I like the concept of designing around useful pairings.

Thanks for sharing so much detail. I'm enjoying following along.

Some of my favorite content on this forum comes from the few folks who are working all the angles of developing a new product for production. I don't know if I'll ever do it, but it's fun to think about.
 
If you have experience with EAGLE, I found EasyEDA rather easy to use. I decided to use it because I normally order my PCBs from JLCPCB, and I plan to order assembly too in the future, so EasyEDA may make things rather smooth. I’m using the desktop version, btw, not the online one. And the Standard, not the Pro.
It’s that, or switching to Fusion 360 (which sounds interesting, but I don’t need that right now).

I've actually messed around with EasyEDA (the online standard version) and drew some schematics. I just have a hard time finding potentiometer footprints that actually matched the 16mm pots so I could mount them directly to the pcb. When I was frustrated I ended up finding the Effects Layouts Eagle tutorial on youtube and that was the end of that. I might mess with it again this weekend.
 
I've actually messed around with EasyEDA (the online standard version) and drew some schematics. I just have a hard time finding potentiometer footprints that actually matched the 16mm pots so I could mount them directly to the pcb. When I was frustrated I ended up finding the Effects Layouts Eagle tutorial on youtube and that was the end of that. I might mess with it again this weekend.
For the components, you need to use the community generated ones. I had the same problem at the beginning, until I found the community generated components, and then I started finding everything I needed.
 
Back
Top