Pettyjohn GOLD MKII

The Pettyjohn GOLD MKII is an analog overdrive and preamp pedal designed to capture the classic tones of the Marshall Plexi 1959SLP in the simple format of a guitar pedal¹. Made by Pettyjohn Electronics, it is an update to the company's best selling golden amp overdrive, the Gold Version 1, and sits in the Foundry Series as a high gain Plexi overdrive²³. Delicious Audio described the original as "a low noise, edge-of-breakup to distortion with amp-like dynamics and feel" that "ended up as so much more then just an amp-in-a-box"⁴.

The design brief, as Stephen Pettyjohn told it in a 2018 interview, was not a straight Marshall copy: "my goal wasn't to just create a Marshall emulation but to create a desert island golden overdrive that could go from low" gain, pushed amp, edge of breakup all the way to medium-gain distortion⁵. The MKII keeps that character and pushes further, with a gain control that tops out at almost twice the original amount².

What it does to your sound

The Gold MKII is a Plexi-style overdrive in the amp-in-a-box tradition, but its designer framed the gain range conservatively: "It's more JCM800 and lower. But more of the Plexi range, the JTMs and the Blues Breakers," not the high-gain JCM-2000 territory⁵. On the MKII's Gain knob, low gain exists from 7 to 10 o'clock, adding punch to rhythm tones or fattening a bridge or hook¹.

The MKII gain control extends the range at the bottom for preamp or clean boost settings and tops out with almost 2x the original gain amount². Because the drive circuit has no EQ built in, all tone shaping happens in the knobs themselves, which keeps the overdrive character consistent as you dial the EQ⁵.

The controls: gain, lows, mids and highs

The original Gold carried a 3 band EQ with an adjustable mid bell curve plus Gain and Output⁶. The MKII refines that layout into Gain, Output, and a console-style EQ:

The mid circuit is unusual for a pedal. Rather than copying an amp tone stack, it is based on a recording console circuit: "let's create a sweepable bell that covers the entire range that any Marshall has ever had….plus a little bit"⁵. On the original Gold, the low-cut knob swept from 20Hz to 700Hz and was the only low-cut in the entire circuit, with the first third of the range covering 20Hz to 100Hz sub content and tightening around noon in the 200Hz to 300Hz range, which made it usable on bass and other instruments⁵.

Internal toggles: headroom, preamp mode and high-cut capacitor

Inside the pedal are mini toggles that change its character more than the face knobs suggest⁶⁴².

• Headroom toggle: selects High Headroom or Low Headroom for the gain amp. The Gold shipped set in the High Headroom position for the most dynamic, touch sensitive drive experience⁴. The Low Headroom setting adds harmonics and an increased sense of breakup and gain with a slight tightening of the lows, pushing upper gain ranges into classic distortion territory⁴.
• Preamp mode: moving the internal clipping headroom toggle to the middle position bypasses the clipping section entirely, turning the pedal into a full range preamp². With 20Hz to 20kHz of frequency range, the Gold line was described by its maker as a perfect always-on rock/blues preamp in this role⁷.
• High-cut capacitor toggle: switches the high cut cap between a clear, punchy Wima cap and a classic 716 Orange Drop cap for a smoother, vintage flavor². On the original Gold this choice was between an Auri-Cap audiophile capacitor, described as super transparent and the stock setting, and a more vintage sounding Orange Drop⁶. Delicious Audio characterized the Auricap XO option as "smooth and a little bit compressed with tighter low-mids and more clarity and focus on the top end"².

Power: 9V in, 36V of internal headroom

The MKII runs on a standard 9V DC center negative supply drawing 200mA¹. From that input the internal circuit generates 36V of headroom¹. Delicious Audio reported the same arrangement at launch, a 36V dual rail power supply fed from a 9V, 200mA standard adaptor²¹. High headroom and high voltage imparts an openness and 3D quality, according to the same coverage².

The bypass system is also part of the power story: the MKII uses a relay based true bypass circuit with a soft touch switch, and it auto-bypasses when power is disconnected². RockBoard's product page calls it "a totally quiet bypass switching system, that won't obliterate your delay's and reverb's when the unit is engaged"¹.

History and versions: from the Gold to the Gold MKII

The Gold Overdrive was designed by Stephen Pettyjohn, who described the circuit's origins this way: "I was exploring a combo of my take on a Plexi amp with a little bit of Klon influence on the circuitry. I ended up going" in more of a Marshall direction than the Klon idea⁵. Delicious Audio called the result "a simple box inspired by classic 'Golden amps from Britain'" and part of what the company felt was the new golden standard of its Foundry line⁴.

Even the finish has a story: the gold powder coating came from a color swatch from the powder coating company Pettyjohn uses for its enclosures⁵.

The MKII, announced in September 2019 and initially on preorder, brought several changes over the Gold Version 1²:

• Gain range extended at the bottom, topping out with almost 2x the original gain²
• Relay based true bypass with soft touch switch and auto-bypass on power loss²
• Foundry Series MKII custom enclosure with in-set screws²
• NOS germanium diode upgrade, offering a classic sound, tighter low end, richer mids and smoother highs; the diodes are rumored to be found in the original golden centaur pedal²
• Burr Brown OPA input and output buffer²

Is it a Klon clone?

The question comes up because of the germanium diodes, but the answer is no. RockBoard's product page states plainly that "the low headroom section is not a 'klone' circuit," though it likens the pedal to a Klon¹. The designer's own account puts the circuit firmly in Marshall territory with only "a little bit of Klon influence on the circuitry"⁵. The Klon association rests mainly on the NOS germanium diodes, which Delicious Audio notes are "rumored to be found in the original golden centaur pedal"².

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