Thrax Audio Products 

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The  “Why Thrax Uses Triodes”  Story


Audiophiles have been led to believe through published measurements at maximum output power and uneducated reviewers that single-ended triode amplifiers produce vast amounts of harmonic distortion.
As a matter of fact triode vacuum tubes are by far the most linear amplifying devices in existence today. They produce the least amount of distortion, and that distortion is the predominately second harmonic, which is the least obtrusive type for the sound. By contrast, pentodes produce greater distortion, and the third harmonic tends to dominate. A transistor looks at best like a very bad pentode.  Click here

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Thrax Audio Libra 300B Tube Pre-AmplifierThrax Libra

Thrax Libra balanced differential 300B tube pre-amplifier launched.

Thrax Audio is based in Sofia, Bulgaria. The team lead by founder and chief designer, Rumen Artarski, produces fine audio components, apparently inspired by Japanese tube gurus such as Shishido San, Sakuma San and Kondo San.

What Thrax Audio does is to use modern techniques and materials to create a listening experience that comes closest to the original, according to the company.

Thrax Audio’s Libra uses a pair of 300B tubes per channel in true dual-mono differential pure class A triode operation to form its gain stage. The Libra pre-amp has been designed to be paired with the Thrax Spartacus 300 mono power amplifiers.

The Libra features auto-bias to compensate for tube ageing and correct operation of any 300B valves. Furthermore, there is a post-amplification volume control.

For optimal operation, Libra’s DHT tubes require a lot of auxiliary electronics. This lead Thrax to split the unit into two parts – a power supply and the active unit. This keeps all mains AC and rectifier noise in a separate box while final regulation and filtering remains accomplished next to each element in the amplification circuit. Moreover, the external dual-mono power supply sports a choke input rectifier for lowest possible switching noise.

Everything is microprocessor controlled with a large colour LCD showing you the status of the unit.

Libra features two independent outputs that can be offset to each other to allow for bi-amplification with different amplifiers for mid/hi and bass. For instance, a single-ended triode amplifier for mid/hi and a powerful push-pull amplifier for the low frequencies. The offset enables you to adjust for different amplifier gain, keeping the volume in sync on both.

For open-reel tape lovers, the Libra also offers a fully balanced Tape loop for the use of professional tape recorders allowing you to take full advantage of the quality of your master tapes, says Thrax.

Additionally, a home cinema bypass is available should you want to integrate the Libra into your media room. Also, remote power amplifier on/off is provided for installations where the power amplifiers are not easily accessible.

All-in-all, the Thrax Libra boasts four sets of balanced XLR and two sets of RCA inputs.

The Thrax Audio Libra pre-amplifier is available now in black or silver anodised aluminium.

    Gallery by StereoNet

    GAY GARRET StereoNET UK’s Editor