The Teres Stereo is Thrax’s space saving and cost effective entry point into it’s world of high performance separates amplification. The tonality and dimensionality of tubes delivered with might, authority and power. Teres employs a single-ended tube input stage loaded with a phase splitting transformer which then feeds two separate out of phase single-ended amplifiers. As only the first few watts are biased to Class A, Teres does not run ridiculously hot and the compact form factor and Thrax’s exemplary casework and build means an amplifier that suits UK homes very favourably. Extreme power, clear tone, unbridled dynamics and deeply impressive low level resolution.
Long-life input vacuum tube
Custom phase splitting transformer
Silicon carbide rectifiers
Shunt-regulated power supply for the tube stage
Solar cell bias of output stage
Special grade screened power transformer
JFET/MOSFET cascode output devices
Solid machined aluminum chassis
Stereo output stage implementation with dual mono drivers
|Power||max. 500W 115/230V 50/60Hz|
|Max. input level||5.5V Rms|
|Output power||150W@3% /8Ohm 200W/4Ohm|
|Output impedance||.4 Ohm|
|Signal to Noise||114db|
|Frequency responce||20-20,000Hz +/- 1db|
The output stage’s power JFET cascodes form a bridge that when unbalanced by the input signal via the interstage transformer windings restores balance by adjusting their current conduction through the load. The two output stages actually enclose the load in their control loops and try to correct each-others errors reducing the distortion to insignificant amounts, leaving the “character” of the input stage untouched. Those Fet’s provide no signal gain, they merely satisfy the load’s hunger for current.
To reduce the amount of heat generated the amplifier is biased so only the first few watts are in true class A. Music has a crest factor of 10 on average. This means that most of the time we listen at 1/10th of the peak levels. For most users this translates to under 5W. Peaks can reach over 100 watts during playback, but only for a few milliseconds. For those peaks the amplifier switches to class B using only one leg of the output stage capable to deliver up to 150W/8ohm and 250W/4ohm. The result is an amplifier capable of extreme power while delivering exquisite smoothness and low-level resolution.
The driver stage being isolated by the interstage transformer is not influenced in any way by the output stage operation maintaining tone, colour and resolution at all power levels and loads. Having the output stages floating around the load prompted for the use of a unique biasing technique powered by solar cells. This was the quietest galvanic isolated power we could come up with. Using opto-electrical conversion we control the bias by adjusting light intensity in the control circuit. Teres is an example of modern technology solving age-old problems allowing us to go a step beyond what was possible before. The exquisite aluminum finish adds to the presentation of a solid block of metal.