Octal Six

“Put aside any notions of what a guitar amp can sound like and plug into an Octal Six!” – Dr. Z

Specifications

General Information

One of the greatest challenges of having 36 years of amplifiers, music, and business under your belt is maintaining the spark of inspiration. Sometimes that spark jumps from the embers of Dr. Z’s oldest collaborators, so when the phone rings and Joe Walsh, legendary solo artist and guitarist/songwriter for the Eagles, is on the other line, one can be assured there is a wellspring of ideas, interests, and inspiration to be tapped.

The Octal Six is result of the 4th collaboration between Dr. Z and Joe Walsh, birthed from the need to go somewhere different, untread upon and new, then road-mapped through Dr. Z’s 36 years of experience designing and building guitar amps. Joe is no stranger to electronics, being a hobbyist HAM radio operator and having played countless amps through his storied career. He always brings a unique, informed perspective to the drawing board while sending Z down uncharted territory; the Octal 6 is no different in this regard. Yet, under the hood, this amp is uncanny in almost every other regard in the history of Dr. Z Amplifiers.

Starting with a pair of octal preamps, the 6SL7 and 6SN7, the guitar signal is amplified by these large bottle tubes that are more commonly used as power tubes than preamp, marked by a their distinctive 8-pin octal base as opposed to the 9-pin 12ax7 types seen in 95% of all other amplifiers. These are supplied with their own independent DC heater supply, resulting in extremely low noise operation in ratio to gain. The distortion signature and compression character is simultaneously smooth, yet harmonically dense with a churning overdrive texture reminiscent of the 50s Tweed amplifiers, without the mush or lack or articulation common in those more archaic designs. The Octal Six has a recognizably vintage sound with expressive, blooming compression but with a string articulation and dynamic bandwidth only these octal tubes can supply. Play-feel and volume knob clean up, even at the high-overdrive settings rival the lauded Dr. Z Z Wreck, with a delicate balance between gain and fidelity.

After Joe first suggested the 6V6 as power tube, Dr. Z found these octal tubes to be exceptionally lively in the audio spectrum and needed a power tube to match their vigorous output. Striving for efficiency in both the top and bottom of the signal, he settled on the less common 7591 power tube, the last major power tube designed before the end of the vacuum tube era and the transition into solid state transistors. These are noted for their high sensitivity input resulting in unparalleled playing dynamics, with a clean and robust output with no loss in detail, seen by hi-fi and tube aficionados as the “perfected” form of the classic 6L6 tube.

A paper-wound, vintage spec’ed output transformer manufactured by Heyboer Transformers drives the speaker, while our Mk. II style Post-Phase Inverter Master Volume offers smooth volume operation at any level. Two guitars inputs are included to optimize for the amount of clean headroom desired. Joe requested a transparent FX loop for his bevy of guitar pedals, so the ever-reliable Metro “Zero-Loss” FX loop was included in the Octal Six.

Finally, debuting in the combo version of the Octal 6 is a Warehouse Guitar Speaker G12C/S orange basket speaker, a versatile American-voiced speaker with a very punchy, forward response and a smooth, silky top end. This is a speaker that was carefully selected through numerous candidates, and matched the distinguished quality of the Octal Six while also making in its exclusive debut in this design.

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