TRANSFORMER COUPLED HYBRID POWER AMPLIFIER
Teres achieves the unmistakable clarity and tone of tubes delivering it with might and power.
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
Available in stereo and mono version
Transformer input on the XLR for true balanced operation
Solid machined aluminum chassis
Single-ended tube input stage loaded with a phase splitting transformer controlling 2 separate out of phase single-ended amplifiers for output. The tube handles all the voltage gain needed. It uses a new generation of our choke-rectified shunt-regulated power supply providing a noise-free operating point, clear tone and unbelievable dynamics.
The output stage’s power JFET cascodes form a bridge that when unbalanced by the input signal via the 2 transformer windings restores balance by adjusting their current conduction through the load. The 2 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 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 250W/8ohm and 350W/4ohm Not sharing a common reference point apart from the load itself makes the second output stage correct for any error produced by the first one.
The result is an amplifier capable of extreme power while delivering exquisite smoothness and low-level resolution.
The driver stage is isolated by the interstage transformer and is not influenced in any way by the output stage 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 physical appearance of Teres has the kind of understated elegance typical for Thrax.
The exquisite aluminum finish adds to the presentation of a solid block of metal.
SILVER ANODIZED ALUMINUM
BLACK ANODIZED ALUMINUM
Teres was first introduced in 2015 in monoblock version. It featured the legendary C3g input tube biased by a lithium battery. Those are recognizable by the metal C3g tube in the back and the plastic lid of the battery compartment.
In 2018 the Stereo version was developed featuring a more sophisticated shunt regulator and improved circuitry using the now established 6N6P dual triode.
2020 saw the launch of the Mk2 version adding all advancements from the Stereo version to the Mono as well as a new super screened power transformer design and the use of the 6N6P tube - now the established standard for all Thrax hybrids and the Dionysos preamp.