Hifi News

Thrax Audio’s TERES: A TRANSFORMER COUPLED HYBRID POWER AMPLIFIER

Screen Shot 2017-03-30 at 11.36.46

This 120W design is based upon single-ended valve input, stage-loaded with a phase splitting transformer controlling two separate single ended, out of phase, amplifiers

The Siemens C3g valve (with a battery bias for low noise), according to the company, handles all the voltage gain needed and uses, “…a new generation or our choke-rectified, shunt-regulated power supply providing a stable noise-free operating point.” The CR2032 3V lithium battery bias lasts for around five years before a battery replacement is required, incidentally.

Screen Shot 2017-03-30 at 11.36.22

The output stages power JFET cascodes. The two output stages actually enclose the load in their control loops and try to correct each-other’s errors, reducing the distortion. Leaving only the “character” of the input stage.

Screen Shot 2017-03-30 at 11.37.32

To reduce the amount of heat generated, the amplifier is biased so only the first few watts are in true Class A. Peaks can reach over 100W during playback, but only for few milliseconds. For those peaks the amplifier switches to Class B using only one leg of the output stage.

Screen Shot 2017-03-30 at 11.37.10

“The driver stage is isolated by the interstage transformer and is not influenced in any way by the output stage,” said the company. “Having the output stages floating around the load prompted 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.”

Screen Shot 2017-03-30 at 11.51.17

Spanning 340 x 400 x 230 mm, it weighs in at 25kg. To learn more about the company, click HERE .

Subscribe to my email updates

Join my mailing list to receive the latest posts into your email inbox

You have Successfully Subscribed!

You Might Also Like

No Comments

Leave a Reply

Subscribe to my email updates

Join my mailing list to receive the latest posts into your email inbox

You have Successfully Subscribed!

Pin It on Pinterest

Share This