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"UNIVERSAL DUAL OCTAL" and "ULTRA DUAL OCTAL" are two-unit headphone amplifiers using our third-generation output transformers and are based on previous two-unit series as well as the "Jubilee Series".
Each set comprises two separate chassis with inter-connecting cable between the amplifier and power supply. A toroidal power transformer feeds the system with a tube type rectifier, DC filament supply, and bayonet type connectors on the cable between the units. This arrangement of the "Dual" series totally eliminates any electro‑magnetic influence from the power transformer on the amplifer.
While maintaning our Laboratory's traditional split system designs, the new "Octal" series is constructed with larger external dimensions and wooden decorative panels having a more complex profile. Both units use the highest quality components, octal based tubes and world-class output transformers such as SOWTER and LUNDAHL.
The UNIVERSAL DUAL OCTAL amplifiers use the 6L6 (5881) as output tubes and 6SL7 as the driver while the ULTRA DUAL OCTAL uses the 6V6 and 6SN7 types. Both amplifier power supplies use 6X5 rectifiers.
This new range of amplifiers, while retaining the basic characteristics of previous series, have a more expressive middle frequency range giving a very realistic sound image of the instruments being played as well as their spatial disposition. Bass is solidly fundamental, while the treble is accurate without excessive brightness.

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For personal audio use Arkhipov Laboratores have introduced a new version of the “UNIVERSAL DUAL OCTAL STX” range, specifically designed to drive electrostatic headphones made by the STAX company. This series uses a combination of 6L6 and 6SL7 tubes with LUNDAHL output transformers.
The power transformer uses an M4 steel core, coupling capacitors are JENSEN COPPER paper/oil while signal wiring is single-core silver of various cross-sections also by JENSEN.
These amplifiers exhibit a warm, velvet-like reproduction over the full frequency range. Electrostatic headphones driven by these amplifiers give fully dimensioned and accurate response.

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A defining feature of our Universal series is their balanced performance and compatibility with all music genres, using triode-connected pentode output tubes. The flagship of the Universal series is the “Universal Keno”. It uses two double-function tubes, triode-pentodes ECL805 (ECL85, 6GV8). The power supply uses a 6X5 (EZ35) rectifier.
This range of amplifiers apart from suiting all musical styles, is sonically incredibly light and clear sounding making listening to your favourite music a real pleasure.
Ultra series units on the other hand, employ output pentodes connected in ultra-linear configuration which gives their own special quality to the reproduced sound. The “Ultra EL” probably does this best, using two pentodes EL84 (6BQ5) and double triode 6SN7.
The sound is light and transparent with no confusion between instrumental & vocal content regardless of the scale of the piece. Middle range frequencies reproduce clearly & accurately with a sonic image that is charged with emotion. Particularly suitable for playing classical and or jazz music.

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This design is a two-stage combination employing a tube voltage amplifier input stage and transistors as current amplifiers for the output providing matching for the low impedance (20 to 600 Ohms) loads presented by headphones.
At present these amplifiers are built using selected vintage 6SN7 tubes and point to point wiring in the elite LUX version (Lx) while the simpler STANDARD version (St) is built on printed circuit boards.
Earlier we had made MELO amplifiers based on other double triodes such as 6FQ7, 6CG7 or 12AU7, ECC82, 5963, 6189.
MELO amplifiers display the warm, richly endowed sound characteristic of tubes. At the same time they possess fast attack and magnificently detailed sound with well formed bass and bright trebles.

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Our ALTERNATIVE series is designed and built for enthusiasts who appreciate high quality solid state technology providing another option to units like “Creek” or “Pro-Ject” et al. The design approach is the same as that for high end tube units, namely:

• Single-ended Class A operation
• Minimum number of stages
• Shortest possible signal paths within each unit
• Minimal unwanted local and overall feedback paths
• Selected audiophile-quality components
• Construction, wiring, assembly and set-up exclusively by hand