The interesting thing about the Guv'nor... (build report inside)

[Hardtailed]

The interesting thing about the Guv'nor is that most of the clipping seems to come from the opamp!
Or at least it does in the one I've just built.
For fun I included a small switch that remove the LED clipping from the circuit (simply put it between the LEDs and ground).
I thought it wasn't working, then I looked at the LEDs, they did stop glowing when the switch was "on".
Then I opened my ears and realized the sound did change, it seemed to get more body and a bit less compression.
So conclusion: most of the clipping comes from the opamp! Which is normal since the LEDs are post op-amp, the poor little bugger is forced to amplify the signal way more than the power supply will allow.
Which explains another fact: different opamps do sound much different. I tried a JRC4558D, TL072 and OPA2604. So far the 2604 is my favorite, it's got this little extra bite (which is what I use the Guv'nor for!). The TL072 was ok, but a bit dull sounding, the JRC4558D was somehow similar, but it oscillated at full gain.
Removing the LEDs from the circuit is definitely a plus when using the Guv' as a dirty boost in front of an amp.

Anyway, for a first build, it went pretty smoothly. Took me a while to get it finished, but I got it done tonight! A 5 pot + 1 switch project is quite a task for a beginner! I had to go to the store to pickup a bigger enclosure, ended up with a Hammond 1590J, which looks stupidly big. But this works for me, I use this pedal a lot live and I need to be able to easily find it with my feet. I guess that using smaller pots would've made it possible to use a smaller enclosure. Other problem I've had is that I can't use the metal standoff I ordered from Small Bear, the washer is too big and will short other part of the circuit (I used the PCB from GGG). So right now I just taped the back to prevent shorts and the amazing mess of wires is keeping it from moving too much. I also got the same problem as someone else reported: the bass pot is wired backward. So I guess the drawing on GGG needs to be revised.

I'll try to post some soundclips later, with clips of the original pedal for reference (yes, I own it, I cloned it so it could stay home, although my clone has all film caps and 25k tone pots, so it's not exactly a clone).

[MartyMart]

Many circuits use a degree of opamp clipping, either with/without diodes.
The "Hotcake" doesn't use any clipping diodes at all
In these cases, you're right, the opamp will have a significant effect on the sound/grind

MM.

[Bernardduur]

The Rat does the same; I added the stock diodes, LED's and none and between the LED's and the none position I can only hear a difference on higher gain settings........

[Hardtailed]

The thing that suprised me the most is that the opamp overdrive actually sounds good! It's quite warm actually. I guess those small capacitors in the feedback path are the secret.

[mojotron]

Diodes are for Sissies! 

A few mods - from one who has spent way too much time on tweaking this circuit... for those who like a beefier sound... Referring to GGG's schematic:

http://www.generalguitargadgets.com/diagrams/guvnor_sc.gif

• Use the red 3mm LEDs - they sound great. I also like a Ge diode in series with one of the LEDs. Route the LEDs up to the top of the enclosure - these light up great!
• The 2nd sound I really like - as mentioned above - just go with no clippers... In addition to that, I really don't like the sound of a clipping diode with a forward voltage less than like .6v - the higher the better
• If you like more extreme Marshall sounds - I've really liked the sound of connecting VR1's whipper to the C3 side of VR1 Then you pretty much have a variable resistor for a great metal sound
• A switch on VR1 allows you to switch in/out that mod.... Also, along with the switch, you can add a 2nd pot (50-20kB) on VR1's whipper - going from the VR1 wiper to the C3 side of VR1 to create a "FD2-like" "boost" control.
• A 5kB pot on R1 allows you to move the corner freq of the mid-range attack - up and down. This is a lot more versatile in an opamp distortion circuit like this too

[Mark Hammer]

Assuming Michael Burgundy's schem is accurate, we see a max gain in the first stage of 46.5.  We then see a fixed gain of 68 in the subsequent stage.  How much overall gain is that?  Let's see.....times 8, carry the 4....scribble scribble scribble....about x3158.  WHAT?!! You heard me.  A max gain of 3158.  Under those circumstances, the LEDs are serving a volume-limiting function rather than a distortion function.  There is no way on earth ANY op-amp could maintain a clean tone under those circumstances.

[mojotron]

That's odd, sure sounds like the gain is closer to 3200 

Great point Mark, limiting volume is certainly an issue without the clippers - I personally like the lightshow on the floor.

[Hardtailed]

Assuming Michael Burgundy's schem is accurate, we see a max gain in the first stage of 46.5.  We then see a fixed gain of 68 in the subsequent stage.  How much overall gain is that?  Let's see.....times 8, carry the 4....scribble scribble scribble....about x3158.  WHAT?!! You heard me.  A max gain of 3158.  Under those circumstances, the LEDs are serving a volume-limiting function rather than a distortion function.  There is no way on earth ANY op-amp could maintain a clean tone under those circumstances.

Pfff, that's not even 70dB of gain

Volume-limiting hey? Funny thing is, it doesn't change the volume that much (just feels like it restricting the sound). Even with the volume maxed, this is not a very high-output pedal (even with the LEDs off), I guess the tone stack must be sucking a bit of juice.
Now it is very tempting to try and run this puppy at 18v, it's quite easy to do with 2 batteries

[syndromet]

I changed the op amp of my Daddy-O wich is virtualy a Guv'nor for a lm 358. Great improvement.