First one I built to completion was the SS-2 from the Guitar PCB Super Sonic SS-02 PCB and build guide.
They randomly changed the output pot from 10K to 100K without telling you. "No no no." So I went ahead and subbed in a 10KB pot. (Not a 10KA, I guess I like the B taper better in this circuit.) One of Cornish's ad slogans is "Low output impedance, capable of driving long cables," etc. So I decided to stick with the Cornish program.
Diodes are a little "tricky." 11 Gauge has a great post on diodes on the TDPRI forum. I just went quickly with the recommended 1N60P diodes recommended by GuitarPCB and they sound fine.
1N60P is NOT a Germanium diode. (Despite what some Chinese eBay sellers will tell you!) It is a Schottky silicon diode with a similar forward voltage to a lot of the germanium parts, so it is used by a lot of modern pedal makers as a substitution (MXR Distortion+ for example) that meets ROHS requirements. Whereas the germanium parts would not meet ROHS laws and therefore would not be legally allowed to sell in some markets today. (Yikes!!) Maybe that's some of the complaint about the modern MXR yellow pedal.
In my Distortion+ build I find the 1N60P to be a bit brighter sounding than some generic NOS 1N34A in the same spot. Same in this pedal--it's a little bright, but I like it. I just have to run the tone control a little bit lower than noon at highly boosted settings. This is a fun diode trick in the Dist+ and the SS-2. It would be great to have them on a toggle switch.
If I had thought about it I might have stuck some old germanium diodes in there but I'm leaving it for now. This was a fairly straightforward build.
Stick with the LM741 op amps it's part of the sound. They are slow, dirty op amps and that's part of pedals like this one. They contribute some clipping and sonic degredation that is part of the recipe.
It's capable of massive gain and output volume which can get a bit hissy at certain settings so I added extra filtering on the 9V supply (total of 330 uF.) Another thing GuitarPCB randomly changed for no reason. I also shielded some of the I/O wires to help again with noise.
If you crank up your Marshall or other Doomy amp and boost the SS-2, you will get wall-shaking bass out of this circuit...pretty cool. Once again Pete Cornish is telling it on the tin, "Better low end retention than any other pedal circuit." -O_o-
I didn't mess with the buffer on this one because buffers are a pain in the ass.
This one came second, and I'm glad because it was hard. And there are a lot of common problems and misconceptions about this circuit.
I believe what a lot of people have come to agree that the original Dirk H. trace was wrong.
When you build this circuit to those schematics it's a muddy, flabby mess of a sound. Just terrible sounding. Any quick listen to a decent G-2 demo of a Cornish pedal on YouTube will show you how far off it is. The video where Shnobel compares it to the Vick Audio pedal (probably built to this wrong schematic) is a good real world demonstration of how far off these builds can be.
Chasing the diode fairy is not the right way to "fix" this pedal. It's just salt on a burnt duck. And a significant waste of time.
However I did go with NOS germaniums this time after some swapping, the 1N695 are good sounding and in the general correct range. You want somewhere between .20 and .30 V on the diode tester on your multimeter for forward voltage. Mine are on the higher side of that range.
I decided to go for the simplest solutions first. There's a giant filter cap across the transistor on the gain stage right before the sustain pot. It's a 1 nF cap in a lot of these circuit traces including the GuitarPCB PCB I am building on. You need to change that to a 100 pF!!!!!! Picked this tip up deep in the comments on Iviark's blogspot.
Suddenly, a LOT of your highs came back and the tone control is now useful.
The second cap to change is another 1 nF. On the first clipping stage, change this to 560 pF. Got this tip from GuitarPCB themselves in their most recent revision, so props to them for that.
Now you have that glassy chime that this circuit is supposed to have, as well as a truly useful range on the tone control.
Two simple cap swaps to go from mud to sweet chimey sustain.
God knows how close this is to an original in a side-by-side shootout... but it sounds damn good.
Guitar PCB told me to change the transistors. Once again, "No." I went with the intended BC549. They also want you to change the tone pot to 100K on the newest board but I'm sticking with the stock 25K tone pot and 10n cap.
I did a buffered bypass and some shielded wiring and it took me a few extra hours to get this wired up in the box.
It was worth the trouble though, these are some fun pedals. They are not particularly "amp like" or "organic" or anything of that nature but they sound "Cool and good," as Billy Cardigan might say. The thing that's notable is that they are indeed pretty far away from your typical dirt boxes. Cornish has his own thing going on and I like that.