Onyx

All stages operate in pure class A1 single ended and contain automatic self-biasing circuitry. We have maintained our Topaz tradition in the use of exceptionally large value Solen polypropylene coupling capacitors. This together with our custom built Hammond output transformer has endowed this amplifier with very extended low frequency response. Each of the four output triodes are individually self-biased, with only the plates tied together in a quasi-parallel configuration, which is nearly equivalent to having one high-powered triode. Our 11 pound output transformer provides 13 Watts RMS per mono-block with solid bass and absolute stability into all low impedance loads. The output windings can be toggled via two high current switches to allow selection of impedance for 2, 4, 8 or 12 Ohms. We employ no feedback of any kind due to the low distortion ultra-linear amplification stages employed in this design.

Power Supplies

• Toroidal power transformer voltage input can be selected for 115V/230V 50-60 Hz operation via an internal toggle switch. Three output windings provide full-wave rectification using spike & noise suppression circuitry.
• Separate DC power supplies provide total isolation between the INPUT and output stages. These consist of a triple p (pi) filter for the 300 Volt output rail and a double p (pi) filter for the 450 Volt input & driver rail. The use of RC filter networks with very large electrolytic capacitors and wire wound ceramic resistors provide an unparalleled ripple reduction that is too low to be seen on our oscilloscope.
• Rectified and filtered DC provides the power for the input tube filament of the 1st and 2nd stage. The other two output tube filaments are provided with AC connected in a balanced configuration to eliminate any possibility of hum induced distortions. This provides a very low noise floor that allows all subtle nuances in the music to be heard.

Mechanical Construction

• Extremely rugged (14 gauge) all welded steel chassis was implemented to further reduce any possibility of vibration induced signal aberrations.
• Highly polished brass handles allow for easy handling and accentuate the chassis styling.
• Very high quality paint with primer coat and baked on finish to further enhance the artistry.
• A deep lavender colour accentuates the satin black finish of the output transformer and toroid cover.
• A cast aluminium box is used to cover the power Toroid transformer to strengthen an already appealing look.

Circuit Board

The components are mounted on a printed circuit board (PCB) which is made from FR4 glass epoxy with double sided copper traces and plated through holes. Both sides have a protective green solder mask. A silkscreen is printed in white showing the component layout and parts value. This PCB was designed manually in house. It has enlarged power and signal line traces to attain the best analog integrity that automatic routing circuit programs cannot attain. Our Printed Circuit Board program allows for an infinite varieties of traces and component layouts that can be developed into our own custom library parts. We have created a library of custom component layouts that are specifically suited to develop our Analog circuits. Wiring to the PCB is attached via screw down crimp terminals to allow for ease of repair should the need ever occur where the board would need to be removed. Again, like in the Topaz we have reduced the signal path length to less than 6" on the PCB board. The final assembly of parts to the PCB is done by hand soldering of all components, which is superior to automated flow-soldering techniques, by allowing more solder on each and every joint.

Auto-Sequencing

A time-delay relay provides extended tube life and proper power sequencing for stabilized circuitry on power up. The filament voltage is turned on for 45 seconds before applying the DC voltage power.

Power Switch

A toggle switch enables power to the automatic sequencing circuit that delays operation until the green ready LED comes on after the initial 45-second delay.

Impedance Matching

Two high current (25 Amp) toggle switches enable setting for 2, 4, 8 & 12 ohms

(matching numbers indicate which impedance is selected)