65 Amps, Guitar Amplifiers

Technical Specificiations Model: SuperNatural with Tube Reverb (15-18 Watt)

Amplifier Circuit:

Output topology: Class A, Push-Pull, Pentode-mode with zero negative feedback
Driver/Phase-Inverter: Modified Split-Load, quasi-Concertina, twin triode
Rectification: Tube

Pre-amp: Absolute minimalist, triode

Reverb Circuit:

Output topology: Single-ended, triode-connected pentode (6BM8/ECL82), zero NFB
Pre-amp: Cascaded ECC81/12AT7 (triode-triode)
Recovery amplifier: Triode-section (Gain =70) 6BM8
Cathode follower: 1/2 12AX7 (triode)
Power-supply: CLC (Inductor/Reactor) from fast-recovery diode SS 'doubler' source (a full-wave equivalent, compared with the half-wave rectification of the original 6G15.

Complete Bypass of Reverb Circuit is possible from rear-panel switch. Fully bypassed yields a 2dB increase in gain.

Reverb Kill switch also available through footswitch or rear-panel switch. This maintains the gain structure that is associated with the reverb circuit in the signal path.

All controls are RV4NAY series, sealed, military-grade potentiometers.

Signal capacitor array includes paper-in-oil, film-foil polypropylene, silver mica. Resistors are combination carbon composition, flameproof and wire wound.

Fully fused, including internal fuse.

Standby switch.
External speaker jack
IEC type, removable power cord

Speaker: Eminence Governor 12" Ceramic

Controls:
Front panel - Volume, Tone, Reverb Mix, Reverb Dwell, Reverb Tone, Bypass switch, Power switch;
Rear panel - External Speaker jack, Reverb Complete Bypass switch, Reverb On/Off switch (Reverb still remaining in the circuit)

More general information on the nature of the SuperNatural and why it is called such.

The amplifier design of the "Black/Blue" Zachary Amps represent the pinnacle of the Minimalist Movement approach to amplifier design. Within is the achievement of a fundamental design goal of creating the shortest possible signal path while simultaneously producing a maximum increase in gain, with some basic allowance for the fewest permissible features. There is very little between your fingers and the speaker.

With that comes the 'volume' 'tone' layout associated with these goals. Nothing else is needed.

Pentodes are notorious for instability, which results from their high gain nature; any additional tone circuitry, would nearly necessitate additional gain stages and their corresponding passive elements. To much gain is lost through a typical tone stack to avoid a gain recovery stage, etc. The final results are nearly a mandate for implementation of negative feedback circuitry; and this is because the phase relations and complexities associated with that additional circuitry create further destabilisations and departures from linearity. And while negative feedback may reduce total harmonic distortion, as measured at maximum power levels, the fact remains that it simultaneously reduces overall circuit gain. Sonically, this results in a reduction of vibrancy and vital touch sensitivity, all of which runs counter to the design goals. Consequently neither localised nor global negative feedback are employed.

The outcome, from avoiding needless complexities, is both an unmatched clarity (that feeling that you are really hearing the guitar), and a harmonically rich transition from low-level clean signals to distortion heavy maximum signals. There is a heightened sensitivity that is apparent, which is absent from the common lot of feature laden, knob heavy, heavy NFB amplifiers. And this is where the line in the sand is drawn separating players with real technique and the masking effect that more complex amplifiers generate to hide the lack of technique of those on "the other side of the line".

This forces one to "quit playing with that knob", and actually learn how to play.

The Minimalist School is not for everyone, mind you; but here is an excellent example of a success from that particular intellectual/philosophical movement.