R2R Electric MK1.5 Pro Fuzz
R2R Electric returns with a rare one — the MK1.5 Pro, the forgotten link in the Tone Bender lineage. Welcome back to Edge of Breakup.
In this episode the R2R Electric MK1.5 Pro Fuzz takes center stage — featuring the Kauer Guitars Super Chief with Lollar Firebird Neck and Lollar Mini-Humbucker Bridge, into the Benson Amps Monarch 2x12" with Celestion G12H speakers via the Boss Waza Tube Amp Expander. The Echo Fix EF-X3 Tape Echo runs in the loop, and the Effectrode Tube Vibe joins from 06:13.
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The MK1.5 occupies a specific and rarely discussed moment in British fuzz history. The Tone Bender lineage runs MKI (three transistors, 1965) to MKII (three transistors, different topology, 1966) — but the MK1.5 is the transitional variant that fell between them, using only two transistors in a topology closely related to the Fuzz Face rather than the three-transistor Tone Bender structure. Where the MKI and MKII use 500k pots, the MK1.5 uses 100k pots — which narrows the sweep range and emphasizes the brighter, raspier character that distinguishes it from its siblings. OC75 transistors are the transistor of choice here, as in the original.
As with every R2R Electric build, the MK1.5 Pro is built entirely with vintage and NOS components — OC75 germanium transistors hand-matched and selected, 100k vintage potentiometers, period-correct capacitors and resistors, hardwired point-to-point on period-accurate Vero board construction, as close to all-original as the circuit can get.
The "Pro" designation adds three controls to the standard two-knob MK1.5 format: Level (output), Attack (gain), and Bias. The Bias control is the key variable that makes this circuit so interactive — cranked high it produces fat, compressed, sustaining fuzz with strong amp-pushing capability. Cut to minimum, combined with Level near or slightly above unity, and the character shifts completely: buzzing, raspy, ripping fuzz with a ragged edge at the top end. The Bias and Level controls are deeply interactive, explored in detail across the full demo.
Note: plays best first in signal chain before any buffered bypass pedals.
The Kauer Super Chief is Kauer's largest model — a 15.5" wide semi-hollow with I-beam internal construction, Spanish Mahogany core and neck, built in Elk Grove, California. Doug Kauer's personal favorite in the lineup.
🎛️ R2R Electric: https://www.r2relectric.com
🎸 Kauer Guitars: https://www.kauerguitars.com
🎸 Lollar Pickups: https://www.lollarguitars.com/lollar-pickups
🔊 Benson Amps: https://www.bensonamps.com/guitar-amplifiers
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🎸 Kauer Guitars Super Chief | Lollar Firebird (Neck) + Lollar Mini-Humbucker (Bridge) | 15.5" Semi-Hollow
🎛️ R2R Electric MK1.5 Pro | NOS OC75 | 2-Transistor Fuzz Face Topology | Level / Attack / Bias
🎛️ Also: Effectrode Tube Vibe | Echo Fix EF-X3 (loop)
🔊 Benson Amps Monarch 2x12" | Celestion G12H | Boss Waza TAE
Recording: Universal Audio Apollo x4 | Lauten Audio LS-208 | Royer R10 & R121 | Sennheiser E906 | Ableton Live 11
