This is the continuing progress of the Big Muff Pi (David Gilmour circuit) effects pedal. In the previous blog, I thought I'd give you a back story and a potted history around the Big Muff how David Gilmour started using it and also the variability of these pedals, but now I want to get into the building of this pedal proper. I now have all the components except the enclosures (I'll buy them later once the boards have been built and tested) so now all is to be done is etching the boards.
To recap the circuit is based on a schematic that was traced from a pedal that was tested by Kit Rae, in which he identified this particular circuit as the closest in his opinion to the one that has been used by David Gilmour of Pink Floyd from around 1976/7 to the present day. I'm interested in what this sounds like and can't wait to hear it. Apparently this is similar to the Pete Cornish P-1 Custom Fuzz which was Pete's variation of the the Big Muff circuit but with enhancements. we don't know what the circuit is like in the P-1 as it's sealed by Pete Cornish to prevent nosy people stealing his circuit layout. But what we do know is it's heavily based on the Big Muff, and was designed at the time to be an alternative to the EHX Big Muff which David was using at the time. Therefore the sound of the P-1 was designed to be as close to Davids Big Muff as possible.
Both boards have been etched, and now starts the laborious task of drilling the holes........ I hate drilling the holes, as I'm doing them by hand. I need to invest in a Dremel and a stand to speed the process up. Following the etching process you can see that there are some tracks on one of the PCB's that has some breaks on it. In this case I'll bridge them with solder and/or some spare leads that I saved from previous builds. On all my builds I save the off cut component leads. These come in really useful for extending terminals (like on the pot terminals for the power boost), also they're invaluable for repairing broken tracks as in this case. Hopefully i'll be able to just bridge with a little solder, but if the gap is too much, I'll solder in some wire to bridge the gap. Either way, It's an easy fix.
EDIT - 11th Nov 2017: It's now quite a few weeks since the above paragraph was written (I've been ill, as well as other family orientated issues), and I've decided to buy pre-fabricated PC boards. I just wasn't happy with those boards I etched, too many breaks and the tracks looked iffy. They just looked unprofessional and i'm presenting one of these to a professional musician so I want to ensure they look right not only on the outside, but on the inside too. Attention to detail with these pedals is key, and although the pedal I'm giving him will be set up to only use a 9vDC power supply, so he'll likely never open the case up as he won't be changing batteries.... I'll know it's not right. I suppose it's the perfectionist in me coming out
So the boards I'm using are supplied by a company called Pigeon FX. They not only make their own vintage pedals like I do, but they also have vintage design boards fabricated exactly the same as the originals, so this is what I intend to use for these builds. Also, the holes are pre-drilled so that saves me that headache. These boards are available on EBay, for a not unreasonable price... As soon as the boards arrive, which hopefully will be in the next day or two i can then start immediately populating the boards. What i'll likely do is populate one board, test it then use that as a template to populate the second board. Work in progress photos to follow