WT350 Basic Mono Amplifiers

Aria Whole Tone amplifiers are the culmination of over ten years of research. Utilizing an unique method of interfacing triodes with a solid-state output stage, this technology was first released in the Counterpoint NPS amplifiers in the early 1990's. Though at that time there was only a hint of how exciting the possibilities were, the concept was continually refined over the subsequent ten years, and released to great response in the NP upgrades for the Counterpoint SA amplifiers in the late 1990's. Now the technology has been perfected and is presented in the WT amplifiers.

The rugged full-bridge output stage is completely transparent: it contributes no coloration of its own to the sound, yet it passes the sound of the tube directly to the speaker.

Unconditionally stable into any load down to 2 ohms, this design is consummately musical-sounding and has been field-tested for several years. It has shown itself to be thoroughly reliable. It offers the perfect way to interface a triode amplifier to a speaker.

The bottom line is that you get the naturally lush musicality of triodes; what you don't get are the hassles of big output tubes or the fragility of MOSFETs.

This single octal tube easily drives the WT350 to over 350 watts of power. (WT350XL shown)

Only one tube is used in each WT amplifier. These are easy-to-get tube types, and the amplifiers are tolerant of equivalant type tubes -- no biasing is required. They are available in dozens of varieties, allowing you to fine-tube the sound of your amplifier to match your sound preferences.

Technically speaking, this is a zero negative feedback design. Negative feedback, commonly used to improve any number of on-paper specifications, takes away the natural dyamics and tonality of tube products. Further points to consider are:

	All WT350 amplifiers have two sets of Cardas speaker binding posts per channel for easy speaker bi-wiring.
	You can drive these amplifiers either single-ended through the traditional RCA inputs, or the XLR balanced inputs, both of which are standard equipment. The input stage is totally symmetrical.
	This design is non-polarity (phase) inverting and its high 470k ohm input impedance provides an easy match for all tube and solid-state preamplifiers.
	The rugged output stage is rated to drive 2 ohms.
	All tube voltage supplies, including the filaments, are regulated.
	Tube life can easily exceed five years. The tubes are operated very conservatively. While in standby mode, all current through the tubes is removed, dramatically prolonging tube life, while all the other circuitry is kept in a warmed-up state, eliminating any need to wait for the amplifier to sound its best. No biasing is required for the tubes.
	Construction is robust, using double-sided circuit boards. The highest-quality components are used on all Aria amplifiers, including gold-ceramic tube sockets, precision metal-film resistors custom-built by PRP to Aria specifications (the most transparent metal-film resistor ever made) and carbon-composition resistors, Audience Auricaps, and custom-made Plitron toroidal transformers. Cardas RCA inputs and speaker terminals are standard on the basic WT amps, and output stage energy reserve is provided by four Nichicon Gold Tune main capacitors.

Sensitivity Options
To Match Your System

WT350 amplifiers are available in two levels of sensitivity to best match your system needs. A brief explanation follows, but we recommend that you discuss your amplifier needs with us so we can help you decide which sensitivity level is best match for your system.

Low-sensitivity for tube preamps

Each LS (low sensitivity) version uses a single 6SN7 octal-based triode tube. It is ultra-linear and ultra-quiet. Because of its quietness, this version is ideal for high-sensitivity speakers. The high signal drive required by this amplifier makes it an ideal match with tube preamps, which normally can provide far greater output levels than solid-state preamps. If your preamp is not capable of putting out at least 4 volts rms (12 volts peak-to-peak, check with the manufacturer) you should use the HS version.

High-sensitivity for solid-state or passive preamps

The HS (high-sensitivity) version is suited for systems with solid-state preamps or with passive preamps. It only requires 1.2 volts (rms) of input drive to reach full output power. Suited for all speakers, the HS version uses a single octal-based 6SL7 triode tubes to provide normal sensitivity.

Note: It is not possible to change the sensitivity of the amplifier simply by changing the tube type. The high and low sensitivity versions are built with different values of anode and cathode resistors, required to match the tube type.