Fingolfen
Well-known member
- Build Rating
- 4.00 star(s)
Unless you've been under a rock, you know I really like the BMP circuit. That being said, I'd never come up with a truly "Steggo" enclosure / pedal name for it, so I decided it was high time to rectify that.
For my first build with the new name / enclosure style I'm using a board I got through Ukraine support laid out by LoudCancer - a Polish builder. This particular build is very similar to some of my early builds in that it is a '73 Gilmour (using the AionFX Halo excel sheet as a guide). This particular one uses vintage Allen Bradley carbon resistors. The capacitors are a mix of panasonic film and some ceramics. The transistors are vintage 2N5133. The diodes are also vintage 1N914s. Once getting the board together, I attached the pots and ran a quick test - which is where I found one problem with the board - the potentiometers are set up backwards.
I double checked to make sure I hadn't soldered them to the board incorrectly, but no, they were right. I then checked the circuit diagram, and all three potentiometers are reversed on the diagram. So while the board is a correct translation of the diagram, the problem was at the circuit diagram. I simply reversed all three and now the pedal works perfectly.
The wiring follows my normal process using a daughter board for the 3PDT footswitch. I'm also running a star ground to the input. I did have to flip the Switchcraft jacks to ensure they fit above the board (as the board is a little higher than I'd like because of the reversed pots). I also decided to go ahead and add the battery snap since all of my BMP enclosures are set up to accept one, and this is an old school pedal.
So I promised a dinosaur, and here he is! The Muttaburrasaurus - that's right, it's the Big Mutt Phi pedal!
Given the Greek letter reference, I went hunting for a suitable background for Mutt to inhabit. I found an old painting in the public domain - Religious Ceremony in Ancient Greece by Francis Oliver Finch from 1835. At this point I'm using actual EHX knobs, but I may change them out at some point.
As to the sound - it is a little bit of a mixed bag. Because of the Allen Bradley carbon resistors, the noise floor is fairly high, but the sound is unmistakably BMP. On its own with a noise gate, the noise floor is easily dealt with, but if you add boost pedals or other effects, the noise is a bit higher than I'd like. I'm planning on making up a 100% modern pedal with the same values (though I may still use vintage transistors - or at least modern transistors with similar gain as the vintage ones) to see if I can bring the noise floor down.
Tiny bit more at the blog: https://steggostudios.blogspot.com/2022/11/finally-true-steggo-bmp-clone.html
For my first build with the new name / enclosure style I'm using a board I got through Ukraine support laid out by LoudCancer - a Polish builder. This particular build is very similar to some of my early builds in that it is a '73 Gilmour (using the AionFX Halo excel sheet as a guide). This particular one uses vintage Allen Bradley carbon resistors. The capacitors are a mix of panasonic film and some ceramics. The transistors are vintage 2N5133. The diodes are also vintage 1N914s. Once getting the board together, I attached the pots and ran a quick test - which is where I found one problem with the board - the potentiometers are set up backwards.
I double checked to make sure I hadn't soldered them to the board incorrectly, but no, they were right. I then checked the circuit diagram, and all three potentiometers are reversed on the diagram. So while the board is a correct translation of the diagram, the problem was at the circuit diagram. I simply reversed all three and now the pedal works perfectly.
The wiring follows my normal process using a daughter board for the 3PDT footswitch. I'm also running a star ground to the input. I did have to flip the Switchcraft jacks to ensure they fit above the board (as the board is a little higher than I'd like because of the reversed pots). I also decided to go ahead and add the battery snap since all of my BMP enclosures are set up to accept one, and this is an old school pedal.
So I promised a dinosaur, and here he is! The Muttaburrasaurus - that's right, it's the Big Mutt Phi pedal!
Given the Greek letter reference, I went hunting for a suitable background for Mutt to inhabit. I found an old painting in the public domain - Religious Ceremony in Ancient Greece by Francis Oliver Finch from 1835. At this point I'm using actual EHX knobs, but I may change them out at some point.
As to the sound - it is a little bit of a mixed bag. Because of the Allen Bradley carbon resistors, the noise floor is fairly high, but the sound is unmistakably BMP. On its own with a noise gate, the noise floor is easily dealt with, but if you add boost pedals or other effects, the noise is a bit higher than I'd like. I'm planning on making up a 100% modern pedal with the same values (though I may still use vintage transistors - or at least modern transistors with similar gain as the vintage ones) to see if I can bring the noise floor down.
Tiny bit more at the blog: https://steggostudios.blogspot.com/2022/11/finally-true-steggo-bmp-clone.html