There was a time in history when Marshall Amplification was on top of the world. The time was the late ‘80s and early ‘90s, when the JCM line was in full swing, with the 800 straddling past and present and the 900 vaulting into the future. During this time, Marshall’s amps were doing so well that the company decided to get into the pedal game (again, if you count the Sola Sound-built Supa Fuzz and the Supa Wah from the ‘60s).
Unpredictably, all four of these pedals would become collectible and iconic, used by several guitar visionaries over the years. The pedals were the Shredmaster, Drivemaster, Bluesbreaker and Guv’nor. The Shredmaster was based on a higher-gain JCM 800, the Drivemaster was based on a regular JCM 800, the Bluesbreaker was allegedly based on the amp of the same name, and the Guv’nor . . . well, that’s a mystery.
The Guv’nor was supposedly based off “a Marshall stack.” This vague descriptor can mean many things to many people, and regardless of what pops into your head when you think “Marshall stack,” one thing about the Guv’nor is equivocally objective: It kicks ass.
In an era where no amp-in-a-box pedals existed, the Guv’nor is a downright noble effort. It contains knobs for standard volume and gain, but also a generous three-band EQ circuit that seems to come straight from one of the amps sold in parallel with the Guv’nor. Furthermore, most modern amp-in-a-box builders simply take the original preamp schematics, replace the tubes with FETs and then tweak to taste. The Guv’nor did no such thing, instead relying on a carefully-voiced op-amp circuit. The result is a decidedly accurate Marshall emulation, one that you’re going to build.
But first, let me hit you with that disclaimer:
Neither I, nor Tone Report Weekly bears any responsibility for any kind of personal or property damage that may occur as a result of the instructions provided herein. Legal mumbo-jumbo aside, we ask that readers be familiar with a soldering iron and its accompanying safety procedures before trying anything listed here. Furthermore, if you fire the pedal up and it does not work, it will need troubleshooting. Assuming the components are not damaged, the pedal will work. I built this very unit according to these instructions and it fired up, first shot, so I know the instructions are correct.
The original Marshall Guv’nors were built with parts that weren’t of the finest quality. The switches, jacks and caps are universally known as detractors, as a measurement of a real vintage unit turned up wacky part values that differed from the label, as well as piles of Guv’nor jacks and switches that ended up failing. This build uses higher-quality parts with tighter tolerances and substitutions only when necessary. I also took the liberty of removing the funky FX Loop jack, as it simply isn’t a desirably feature to us, the modern player. The result is a tighter, louder version of the Guv in a much smaller enclosure, with a couple extra bells and whistles.
One such extra is the addition of a clipping selector. The original uses red LEDs to generate the clipping, but I included a three-position switch to select silicon clipping. Because the diodes are mounted directly to the switch, you can use whatever you want. Try germanium diodes for a gainy and more compressed tone, or try Shottkey diodes for a more ragged sound. You can even try a different color of LEDs and see if you notice a difference.
With that said, here’s what you need for the circuit board!
1x 100 ohm
2x 680 ohm
1x 120pF ceramic
1x 220pF ceramic
1x 470pF ceramic
1x 3.9nF film (0.0039uF)
2x 10nF film (0.01uF)
1x 68nF film (0.068uF)
3x 100nF film (0.1uF)
3x 220nF film (0.22uF)
1x 10uF (16v+) electrolytic
3x 10kA (logarithmic taper)
2x 100kB (linear taper)
1x TL072 op-amp
2x red LED
3x 1n4148 diodes (you can use whatever you want, this is a suggestion)
1x Veroboard (stripboard) cut and prepared according to the diagram
1x 8-pin DIP socket (for the op-amp)
1x 3-position DPDT on-off-on toggle
1x toggle switch cover (optional)
Place the resistors in the board. Bend the leads outward, solder them in and clip them. Save the leads.
Step 2: Bend the leads to use as the jumper wires. Some jumpers may be too long, so feel free to use a regular piece of wire or clip a lead from something else.
Step 3: Place the film and ceramic caps in, bend the leads out and solder in.
Step 4: Place the op-amp socket and electrolytic capacitor in the board and solder them in. At this time, you can place the op-amp in its socket, but be sure to hold a piece of conductive metal in your hand to discharge electrostatic.
Step 5: Insert the diodes into your toggle switch, bend the leads outward and solder them in place.
Step 6: Measure and cut all the wires (and there are a lot), then place them into the board and solder them in. You might find it easier to do this in groups of four or so at a time.
Step 7: Attach the wires to the pots and switch.
Before we continue . . .
Do you have a multimeter? You should. Not only is it a useful tool for all kinds of things (including pickup impedance), but using it on the continuity setting (looks like a sound wave) can be a headache and time saver.
With that, I strongly urge you to use one on this setting and check for continuity across adjacent rows and across track cuts. Some rows will be linked on the board, such as A and B (right side), B and C (left side), C and D (in the middle) and so on. There should NEVER be continuity across track cuts. If you hear a beep, it’s time to inspect that row or cut. Look for little flakes of solder bridging the rows or flecks of copper that connect the traces across the cuts.
Ok, enough technical stuff, let’s build the enclosure!
You’ll need the following:
1x enclosure, drilled for input and output jacks, LED, DC power, footswitch, five knobs and one toggle
1x 3PDT latching (not momentary) footswitch
2x ¼” mono jacks
1x DC power jack (I use the three-lug version)
1x LED bezel (the same size, obviously)
1x LED resistor (between 1.5k and 10k)
1x 47–100uF electrolytic capacitor (for filtering)
5x knobs of your choosing
Let’s get to work!
Step 1: Mount the DC jack, input and output jacks, footswitch and LED.
Step 2: Thread the LED negative leg through lug 1 on the footswitch. Run the saved lead through lugs 4 and 9 on the footswitch. Solder lug 4 but NOT lug 9. Thread the electrolytic capacitor through the DC jack: Negative to negative and positive to BOTH positive lugs. Do not solder any DC lugs.
Step 3: This is where we ground everything but the board. Run a wire through lugs 2 and 6 on the switch, and attach that to the negative lug of the DC jack. Solder the switch lugs. Run another wire from the negative DC lug to the sleeve lug of one of the jacks. Solder the DC negative lug. Run another wire from the first jack sleeve lug to the other, and solder the first jack’s sleeve lug. Leave the last one unsoldered.
Step 4: Run the resistor from the LED’s positive leg to one of the DC positive lugs. Solder whichever one to which you attach the resistor.
Step 5: Now we mount the board. The pots likely have tiny metal tabs on the side that prevent them from being fully mounted. Snap these off with pliers, then mount the pots and the switch in the enclosure. Note that the direction that the toggle switch points will activate the diodes on the opposite side of the switch. That said, if you want your LEDs to be active when the toggle is in the “up” position, make sure they are facing downward when you mount the switch.
Step 6: Three of the pots have lugs that go to ground. Now that the pots are mounted, link all these lugs with wires, and feed the last one to the unsoldered sleeve lug on the jack. Do not solder this yet.
Step 7: Hook all the stray wires up, such as the ground wire to the unsoldered jack sleeve lug, input and output.
Step 8: Hook the jack tip lugs to their spots on the switch, including the input jack tip to the as-of-yet-unsoldered footswitch lug 9. Finally, solder this.
Step 9: You’re done! Let’s get Guv’d out!
So, how does it sound?
In a word: outstanding. It doesn’t sound like “the first amp-in-a-box” pedal, it sounds amazing as its own thing. This DIY version is much more robust and meaty than the originals we have here, and the addition of the clipping toggle really opens the thing up. The middle position on a toggle can only ever be “no diodes” so that setting was incidental and it sounds as much—very ok. The stock LED clipping sounds great but the silicon position was and is the star of the show. Here’s a clip of Andy playing it!
Until next time, up the irons!